ORCID Profile
0000-0002-5101-6542
Current Organisations
University of Melbourne
,
University of Queensland
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Ecology | Community Ecology | Population Ecology | Invasive Species Ecology | Environmental Science and Management | Conservation And Biodiversity | Ecology | Global change biology | Environment And Resource Economics | Environmental Management And Rehabilitation | Global Change Biology | Terrestrial Ecology | Ecosystem Function | Environmental Management | Conservation and Biodiversity | Carbon Sequestration Science | Terrestrial Ecology | Population ecology | Community ecology (excl. invasive species ecology) |
ANZSRC Socio-Economic Objective (SEO)
Forest and Woodlands Flora, Fauna and Biodiversity | Ecosystem Adaptation to Climate Change | Rehabilitation of Degraded Forest and Woodlands Environments | Expanding Knowledge in the Biological Sciences | Ecosystem Assessment and Management of Forest and Woodlands Environments | Effects of Climate Change and Variability on Australia (excl. Social Impacts) | Climate Change Mitigation Strategies | Living resources (flora and fauna) | Remnant vegetation and protected conservation areas | Integrated (ecosystem) assessment and management | Rehabilitation/reafforestation | Sparseland, Permanent Grassland and Arid Zone Flora, Fauna and Biodiversity | Remnant Vegetation and Protected Conservation Areas in Forest and Woodlands Environments | Control of Plant Pests, Diseases and Exotic Species in Forest and Woodlands Environments | Remnant Vegetation and Protected Conservation Areas in Farmland, Arable Cropland and Permanent Cropland Environments | Control of Pests, Diseases and Exotic Species in Sparseland, Permanent Grassland and Arid Zone Environments | Flora, Fauna and Biodiversity at Regional or Larger Scales
Related Links
Publications
Landscape structure mediates zoochorous-dispersed seed rain under isolated pasture trees across distinct tropical regions
Publisher: Springer Science and Business Media LLC
Date: 06-2019
Non-additive biotic interactions improve predictions of tropical tree growth and impact community size structure
Publisher: Cold Spring Harbor Laboratory
Date: 18-09-2020
DOI: 10.1101/2020.09.16.300616
Abstract: Growth in in idual size or biomass is a key demographic component in population models, with wide-ranging applications from quantifying species performance across abiotic or biotic conditions to assessing landscape-level dynamics under global change. In forest ecology, the responses of tree growth to biotic interactions are widely held to be crucial for understanding forest ersity, function, and structure. To date, most studies on plant–plant interactions only examine the additive competitive or facilitative interactions between species pairs however, there is increasing evidence of non-additive, higher-order interactions (HOIs) impacting species demographic rates. When HOIs are present, the dynamics of a multi-species community cannot be fully understood or accurately predicted solely from pairwise outcomes because of how additional species ‘interfere’ with the direct, pairwise interactions. Such HOIs should be particularly prevalent where species show nonlinear functional responses to resource availability and resource-acquisition traits themselves are density dependent. With this in mind, we used data from a tropical secondary forest—a system that fulfills both of these conditions—to build a ontogenetic diameter-growth model for in iduals across ten woody-plant species. We allowed both direct and indirect interactions within communities to influence the species-specific growth parameters in a generalized Lotka–Volterra model. Specifically, indirect interactions entered the model as higher-order quadratic terms, i.e. non-additive effects of conspecific and heterospecific neighbour size on the focal in idual’s growth. For the whole community and for four out of ten focal species, the model that included HOIs had more statistical support than the model that included only direct interactions, despite the former containing a far greater number of parameters. HOIs had comparable effect sizes to direct interactions, and tended to further reduce the diameter growth rates of most species beyond what direct interactions had already reduced. In a simulation of successional stand dynamics, the inclusion of HOIs lead to rank swaps in species’ diameter hierarchies, even when community-level size distributions remained qualitatively similar. Our study highlights the implications, and discusses possible mechanisms, of non-additive density dependence in highly erse and light-competitive tropical forests.
Deconstructing pollinator community effectiveness
Publisher: Elsevier BV
Date: 06-2017
Land‐use intensification reduces functional redundancy and response diversity in plant communities
Publisher: Wiley
Date: 21-12-2009
DOI: 10.1111/J.1461-0248.2009.01403.X
Abstract: Ecosystem resilience depends on functional redundancy (the number of species contributing similarly to an ecosystem function) and response ersity (how functionally similar species respond differently to disturbance). Here, we explore how land-use change impacts these attributes in plant communities, using data from 18 land-use intensity gradients that represent five biomes and > 2800 species. We identify functional groups using multivariate analysis of plant traits which influence ecosystem processes. Functional redundancy is calculated as the species richness within each group, and response ersity as the multivariate within-group dispersion in response trait space, using traits that influence responses to disturbances. Meta-analysis across all datasets showed that land-use intensification significantly reduced both functional redundancy and response ersity, although specific relationships varied considerably among the different land-use gradients. These results indicate that intensified management of ecosystems for resource extraction can increase their vulnerability to future disturbances.
Wild Pollinators Enhance Fruit Set of Crops Regardless of Honey Bee Abundance
Publisher: American Association for the Advancement of Science (AAAS)
Date: 28-02-2013
The germination strategies of widespread annual plants are unrelated to regional climate
Publisher: Wiley
Date: 25-08-2014
DOI: 10.1111/GEB.12219
Abstract: Environmentally cued germination and seed banking are strategies employed by annual plants to persist in unpredictable climates. Moreover, such strategies may be key to persistence under more extreme and variable future climates. In regions with a mediterranean climate, cold‐cued germination can allow populations to avoid germinating under unfavourable conditions and seed banks can buffer population growth in the face of inter‐annual climate variability. Using widespread native annual plant species in the C alifornia Floristic Province ( CFP ), we ask: (1) How common are cold‐cued germination and persistent seed banks? (2) Does the prevalence of cold‐cued germination and seed bank maintenance shift predictably with climate? (3) Are germination strategies taxonomically linked? C alifornia, USA . We assessed seed bank persistence and temperature‐cued germination in c . 175 populations of 42 species (eight families) from across C alifornia in the 2006 growing season. We then tested for evidence that the prevalence of these adaptations correlated with latitude, increasing climate variability and taxonomy. Only 19% of populations had significantly cold‐cued seed germination and only 52% of populations had detectable seed banks. There were no significant relationships between the prevalence of cold‐cued germination and any climate factor. Seed banking was significantly more common in regions with warm, dry conditions in the preceding year, but was not related to long‐term climate averages. Variance in temperature‐cued germination was best explained at the species level, with no variance explained by family. Our results suggest that germination of annual plants in the CFP is dominated by general risk aversion strategies rather than locally adaptive strategies linked to long‐term climate factors. High germination variability within and among populations, coupled with increased seed banking under less favourable conditions, suggests that germination strategies are unlikely to limit this flora's persistence under an increasingly harsh and unpredictable climate.
Estimating interaction matrices from performance data for diverse systems
Publisher: Cold Spring Harbor Laboratory
Date: 29-03-2022
DOI: 10.1101/2022.03.28.486154
Abstract: Network theory allows us to understand complex systems by evaluating how their constituent elements interact with one another. Such networks are built from matrices which describe the effect of each element on all others. Quantifying the strength of these interactions from empirical data can be difficult, however, because the number of potential interactions increases non-linearly as more elements are included in the system, and not all interactions may be empirically observable when some elements are rare. We present a novel modelling framework which estimates the strength of pairwise interactions in erse horizontal systems, using measures of species performance in the presence of varying densities of their potential interaction partners. Our method allows us to directly estimate pairwise effects when they are statistically identifiable and approximate pairwise effects when they would otherwise be statistically unidentifiable. The resulting interaction matrices can include positive and negative effects, the effect of a species on itself, and are non-symmetrical. The advantages of these features are illustrated with a case study on an annual wildflower community of 22 focal and 52 neighbouring species, and a discussion of potential applications of this framework extending well beyond plant community ecology.
Ecological and evolutionary insights from species invasions
Publisher: Elsevier BV
Date: 09-2007
DOI: 10.1016/J.TREE.2007.06.009
Abstract: Species invasions provide numerous unplanned and frequently, but imperfectly, replicated experiments that can be used to better understand the natural world. Classic studies by Darwin, Grinnell, Elton and others on these species-invasion experiments provided invaluable insights for ecology and evolutionary biology. Recent studies of invasions have resulted in additional insights, six of which we discuss here these insights highlight the utility of using exotic species as 'model organisms'. We also discuss a nascent hypothesis that might provide a more general, predictive understanding of invasions and community assembly. Finally, we emphasize how the study of invasions can help to inform our understanding of applied problems, such as extinction, ecosystem function and the response of species to climate change.
Specific leaf area responses to environmental gradients through space and time
Publisher: Wiley
Date: 02-2014
DOI: 10.1890/13-0412.1
Abstract: Plant communities can respond to environmental changes by altering their species composition and by in iduals (within species) adjusting their physiology. These responses can be captured by measuring key functional traits among and within species along important environmental gradients. Some anthropogenic changes (such as fertilizer runoff) are known to induce distinct community responses, but rarely have responses across natural and anthropogenic gradients been compared in the same system. In this study, we used comprehensive specific leaf area (SLA) data from a erse Australian annual plant system to examine how in idual species and whole communities respond to natural and anthropogenic gradients, and to climatically different growing seasons. We also investigated the influence of different leaf-s ling strategies on community-level results. Many species had similar mean SLA values but differed in SLA responses to spatial and temporal environmental variation. At the community scale, we identified distinct SLA responses to natural and anthropogenic gradients. Along anthropogenic gradients, increased mean SLA, coupled with SLA convergence, revealed evidence of competitive exclusion. This was further supported by the dominance of species turnover (vs. intraspecific variation) along these gradients. We also revealed strong temporal changes in SLA distributions in response to increasing growing-season precipitation. These climate-driven changes highlight differences among co-occurring species in their adaptive capacity to exploit abundant water resources during favorable seasons, differences that are likely to be important for species coexistence in this system. In relation to leaf-s ling strategies, we found that using leaves from a climatically different growing season can lead to misleading conclusions at the community scale.
Stability of pollination services decreases with isolation from natural areas despite honey bee visits
Publisher: Wiley
Date: 02-08-2011
DOI: 10.1111/J.1461-0248.2011.01669.X
Abstract: Sustainable agricultural landscapes by definition provide high magnitude and stability of ecosystem services, bio ersity and crop productivity. However, few studies have considered landscape effects on the stability of ecosystem services. We tested whether isolation from florally erse natural and semi-natural areas reduces the spatial and temporal stability of flower-visitor richness and pollination services in crop fields. We synthesised data from 29 studies with contrasting biomes, crop species and pollinator communities. Stability of flower-visitor richness, visitation rate (all insects except honey bees) and fruit set all decreased with distance from natural areas. At 1 km from adjacent natural areas, spatial stability decreased by 25, 16 and 9% for richness, visitation and fruit set, respectively, while temporal stability decreased by 39% for richness and 13% for visitation. Mean richness, visitation and fruit set also decreased with isolation, by 34, 27 and 16% at 1 km respectively. In contrast, honey bee visitation did not change with isolation and represented > 25% of crop visits in 21 studies. Therefore, wild pollinators are relevant for crop productivity and stability even when honey bees are abundant. Policies to preserve and restore natural areas in agricultural landscapes should enhance levels and reliability of pollination services.
Disentangling key species interactions in diverse and heterogeneous communities: A Bayesian sparse modelling approach
Publisher: Wiley
Date: 02-02-2022
DOI: 10.1111/ELE.13977
Abstract: Modelling species interactions in erse communities traditionally requires a prohibitively large number of species‐interaction coefficients, especially when considering environmental dependence of parameters. We implemented Bayesian variable selection via sparsity‐inducing priors on non‐linear species abundance models to determine which species interactions should be retained and which can be represented as an average heterospecific interaction term, reducing the number of model parameters. We evaluated model performance using simulated communities, computing out‐of‐s le predictive accuracy and parameter recovery across different input s le sizes. We applied our method to a erse empirical community, allowing us to disentangle the direct role of environmental gradients on species’ intrinsic growth rates from indirect effects via competitive interactions. We also identified a few neighbouring species from the erse community that had non‐generic interactions with our focal species. This sparse modelling approach facilitates exploration of species interactions in erse communities while maintaining a manageable number of parameters.
The diversity and conservation of plant reproductive and dispersal functional traits in human‐dominated tropical landscapes
Publisher: Wiley
Date: 10-04-2006
Aridity drives coordinated trait shifts but not decreased trait variance across the geographic range of eight Australian trees
Publisher: Wiley
Date: 13-08-2020
DOI: 10.1111/NPH.16795
Abstract: Large intraspecific functional trait variation strongly impacts many aspects of communities and ecosystems, and is the medium upon which evolution works. Yet intraspecific trait variation is inconsistent and hard to predict across traits, species and locations. We measured within‐species variation in leaf mass per area (LMA), leaf dry matter content (LDMC), branch wood density (WD), and allocation to stem area vs leaf area in branches (branch Huber value (HV)) across the aridity range of seven Australian eucalypts and a co‐occurring Acacia species to explore how traits and their variances change with aridity. Within species, we found consistent increases in LMA, LDMC and WD and HV with increasing aridity, resulting in consistent trait coordination across leaves and branches. However, this coordination only emerged across sites with large climate differences. Unlike trait means, patterns of trait variance with aridity were mixed across populations and species. Only LDMC showed constrained trait variation in more xeric species and drier populations that could indicate limits to plasticity or heritable trait variation. Our results highlight that climate can drive consistent within‐species trait patterns, but that patterns might often be obscured by the complex nature of morphological traits, s ling incomplete species ranges or s ling confounded stress gradients.
Environmental context, parameter sensitivity and structural sensitivity impact predictions of annual-plant coexistence
Publisher: Cold Spring Harbor Laboratory
Date: 14-02-2023
DOI: 10.1101/2023.02.13.528375
Abstract: Predicting the outcome of interactions between species is central to our current understanding of ersity maintenance. However, we have limited information about the robustness of many model-based predictions of species coexistence. This limitation is partly because several sources of uncertainty are often ignored when making predictions. Here, we introduce a framework to simultaneously explore how different mathematical models, different environmental contexts, and parameter uncertainty impact the probability of predicting species coexistence. Using a set of pairwise competition experiments on annual plants, we provide direct evidence that subtle differences between models lead to contrasting predictions of both coexistence and competitive exclusion. We also show that the effects of environmental context-dependency and parameter uncertainty on predictions of species coexistence are not independent of the model used to describe population dynamics. Our work suggests that predictions of species coexistence and extrapolations thereof may be particularly vulnerable to these underappreciated founts of uncertainty.
Phenotypic differentiation among native, expansive and introduced populations influences invasion success
Publisher: Wiley
Date: 21-09-2021
DOI: 10.1111/JBI.14252
Abstract: Humans influence species distributions by modifying the environment and by dispersing species beyond their natural ranges. Populations of species that have established in disjunct regions of the world may exhibit trait differentiation from native populations due to founder effects and adaptations to selection pressures in each distributional region. We compared multiple native, expansive and introduced populations of a single species across the world, considering the influence of environmental stressors and transgenerational effects. United States Gulf and Atlantic coasts, United States interior, European Atlantic and Mediterranean coasts, east coast of Australia. Baccharis halimifolia L. (eastern baccharis). We monitored seed germination, seedling emergence, survival and early growth in a common garden experiment, conducted with over 18,200 seeds from 80 populations. We also evaluated the influence of environmental stress and maternal traits on progeny performance. Introduced European Atlantic populations had faster germination and early growth than native populations. However, this was not the case for the more recently naturalized European Mediterranean populations. Introduced Australian populations grew faster than native populations in non‐saline environments but had lower survival in saline conditions commonly encountered in the native range. Similarly, expansive inland US populations germinated faster than coastal native populations in non‐saline environments but grew and germinated more slowly in saline environments. Maternal inflorescence and plant size were positively related with seed germination and seedling survival, whereas flower abundance was positively correlated with seedling early growth and survival. However, maternal traits explained a much lower fraction of the total variation in early demographic stages of B. halimifolia than did distributional range. Phenotypic differentiation could allow B. halimifolia to adapt to different biotic and abiotic selection pressures found in each distributional range, potentially contributing to its success in introduced and expansive ranges.
Resilience in ecology: Abstraction, distraction, or where the action is?
Publisher: Elsevier BV
Date: 09-2014
The early response of subtropical tussock grasslands to restoration treatments
Publisher: Wiley
Date: 12-01-2017
DOI: 10.1111/REC.12491
Global patterns in seed size
Publisher: Wiley
Date: 15-12-2007
Patterns of frequency and density dependence are highly variable in diverse annual flowering plant communities
Publisher: Wiley
Date: 27-03-2023
DOI: 10.1002/ECY.4021
Abstract: Applications of ecological theory to natural communities often assume that competitive, negative density‐dependent processes are the only type of interaction important for ersity maintenance. Recent advances suggest that positive interactions within trophic levels (e.g., plant–plant) may also affect plant coexistence. Though positive plant–plant interactions theoretically might result in positive or nonmonotonic frequency or density dependence (FD/DD), less is known about how commonly these patterns occur or which ecological processes might result in such patterns in natural plant communities. In this study we tested for signals of variable frequency and density dependence in annual flowering plant communities in Western Australia and searched for evidence that interactions among plants during flowering might induce positive or nonmonotonic FD/DD in flowering plants. Using four common annual wildflower species, we ask if plant fecundity exhibited positive or nonmonotonic FD/DD and if pollinator‐mediated plant–plant interactions during flowering change patterns of FD/DD relative to pollinator‐independent plant interactions. Three species exhibited nonmonotonic (hump‐shaped) density dependence, and only one species experienced strictly negative density dependence. Each species exhibited a different pattern of frequency dependence (positive, negative, weakly nonmonotonic, and no detectable frequency dependence). Pollinator‐mediated plant–plant interactions during flowering induced both nonmonotonic density dependence and negative frequency dependence in one species. Importantly, the extent of variation in FD/DD observed in our study brings into question the dominance of negative density and frequency dependence in theory, suggesting instead that demographic responses of plants to their communities fall along a continuum of possible density‐ and frequency‐dependent patterns.
Linking local species coexistence to ecosystem functioning: a conceptual framework from ecological first principles in grassland ecosystems
Publisher: Elsevier
Date: 2019
Data from: Potential mechanisms of coexistence in closely related forbs
Publisher: No publisher found
Date: 2016
DOI: 10.5061/DRYAD.05R13
Accurate predictions of coexistence in natural systems require the inclusion of facilitative interactions and environmental dependency
Publisher: Wiley
Date: 13-08-2018
Effects of exotic annual grass litter and local environmental gradients on annual plant community structure
Publisher: Springer Science and Business Media LLC
Date: 03-11-2017
Demographic response and life history of traditional forest resource tree species in a tropical mosaic landscape in Papua New Guinea
Publisher: Elsevier BV
Date: 09-2011
Productivity does not correlate with species and functional diversity in Australian reforestation plantings across a wide climate gradient
Publisher: Wiley
Date: 02-07-2019
DOI: 10.1111/GEB.12962
A global quantitative synthesis of local and landscape effects on wild bee pollinators in agroecosystems
Publisher: Wiley
Date: 11-03-2013
DOI: 10.1111/ELE.12082
Abstract: Bees provide essential pollination services that are potentially affected both by local farm management and the surrounding landscape. To better understand these different factors, we modelled the relative effects of landscape composition (nesting and floral resources within foraging distances), landscape configuration (patch shape, interpatch connectivity and habitat aggregation) and farm management (organic vs. conventional and local-scale field ersity), and their interactions, on wild bee abundance and richness for 39 crop systems globally. Bee abundance and richness were higher in ersified and organic fields and in landscapes comprising more high-quality habitats bee richness on conventional fields with low ersity benefited most from high-quality surrounding land cover. Landscape configuration effects were weak. Bee responses varied slightly by biome. Our synthesis reveals that pollinator persistence will depend on both the maintenance of high-quality habitats around farms and on local management practices that may offset impacts of intensive monoculture agriculture.
Erratum for the Report: “Wild Pollinators Enhance Fruit Set of Crops Regardless of Honey Bee Abundance” by L. A. Garibaldi, I. Steffan-Dewenter, R. Winfree, M. A. Aizen, R. Bommarco, S. A. Cunningham,
Publisher: American Association for the Advancement of Science (AAAS)
Date: 02-05-2014
Species wood density and the location of planted seedlings drive early-stage seedling survival during tropical forest restoration
Publisher: Wiley
Date: 10-11-2018
CropPol : A dynamic, open and global database on crop pollination
Publisher: Wiley
Date: 17-02-2022
DOI: 10.1002/ECY.3614
Abstract: Seventy five percent of the world's food crops benefit from insect pollination. Hence, there has been increased interest in how global change drivers impact this critical ecosystem service. Because standardized data on crop pollination are rarely available, we are limited in our capacity to understand the variation in pollination benefits to crop yield, as well as to anticipate changes in this service, develop predictions, and inform management actions. Here, we present CropPol, a dynamic, open, and global database on crop pollination. It contains measurements recorded from 202 crop studies, covering 3,394 field observations, 2,552 yield measurements (i.e., berry mass, number of fruits, and fruit density [kg/ha], among others), and 47,752 insect records from 48 commercial crops distributed around the globe. CropPol comprises 32 of the 87 leading global crops and commodities that are pollinator dependent. Malus domestica is the most represented crop (32 studies), followed by Brassica napus (22 studies), Vaccinium corymbosum (13 studies), and Citrullus lanatus (12 studies). The most abundant pollinator guilds recorded are honey bees (34.22% counts), bumblebees (19.19%), flies other than Syrphidae and Bombyliidae (13.18%), other wild bees (13.13%), beetles (10.97%), Syrphidae (4.87%), and Bombyliidae (0.05%). Locations comprise 34 countries distributed among Europe (76 studies), North America (60), Latin America and the Caribbean (29), Asia (20), Oceania (10), and Africa (7). S ling spans three decades and is concentrated on 2001–2005 (21 studies), 2006–2010 (40), 2011–2015 (88), and 2016–2020 (50). This is the most comprehensive open global data set on measurements of crop flower visitors, crop pollinators and pollination to date, and we encourage researchers to add more datasets to this database in the future. This data set is released for non‐commercial use only. Credits should be given to this paper (i.e., proper citation), and the products generated with this database should be shared under the same license terms (CC BY‐NC‐SA).
Positive effects of exotic species dampened by neighborhood heterogeneity.
Publisher: Wiley
Date: 07-09-2022
DOI: 10.1002/ECY.3779
Abstract: It is well known that species interactions between exotic and native species are important for determining the success of biological invasions and how influential exotic species become in invaded communities. The strength and type of interactions between species can substantially vary, however, from negative and detrimental to minimal or even positive. Increasing evidence from the literature shows that exotic species have positive interactions with native species more often than originally thought. Gaps in our theory for how population growth is limited when interactions are positive, however, restrict our understanding of the mechanisms by which exotic "facilitators" contribute to ersity maintenance in invaded systems. Here, we quantified interactions between seven native and four exotic (established nonnative) common annual plant species in the highly erse, York Gum woodlands of Western Australia. We used a Bayesian demographic modeling approach that allowed for interaction coefficients to be positive or negative, and explored key sources of variation in species responses to native and exotic neighbors at per capita (in idual) and neighborhood levels. We observed positive per capita effects from exotic neighbors on exotic focal species as well as on several native focal species. However, all focal species were, on average, inhibited by their interaction neighborhood, when the variance in identity and abundance of observed neighbors was considered. At the neighborhood scale, exotic species were found to suppress all focal species, particularly those with high intrinsic fecundity. Our study demonstrates that within-neighborhood heterogeneity can regulate per capita positive effects of invaders, limiting runaway population growth of both natives and exotic invaders.
Janzen–Connell effects partially supported in reef‐building corals: adult presence interacts with settler density to limit establishment
Publisher: Wiley
Date: 21-06-2021
DOI: 10.1111/OIK.08110
Abstract: In many plant and sessile marine invertebrate (SMI) taxa, population and community dynamics are heavily influenced by processes occurring during the dispersal and establishment phases. The Janzen–Connell (J–C) hypothesis predicts increased survival of early life stages with decreasing conspecific density and increased distance from conspecific adults. Evidence of J–C effects in maintaining ersity is common in plant communities, but its importance in SMI communities remains unclear. Under controlled aquarium conditions, we examined the effect of density‐dependence and adult conspecific water treatments (absent resent) on propagule settlement success and settler post‐settlement survival, along with associated spatial patterns, for six broadcast‐spawning, reef‐building coral species from three families. We also tested if settlement success was linked to increasing propagule species ersity for three coral species from two families. We found that the probability of settlement was density independent and not influenced by adult present water treatments. Yet, adult present water treatments and settler density did have a synergistic negative effect on the probability of short‐term settler survival for all species examined. Settlers also showed greater spatial aggregation as their numbers increased, but were less aggregated in adult present water treatments compared to those in adult absent water treatments. We further show evidence of significant species interactions among propagules, as settlement in single‐species trials was four‐fold higher compared to mixed‐species trials. Our findings from controlled experimental arenas indicate that the early establishment of corals was predominantly limited by density‐dependent settler–adult interactions among conspecifics and propagule–propagule interactions among heterospecifics. Thus, the proximity to established conspecific adults, settler density and species ersity of propagules are relevant drivers of local coral community ersity and structure. Based on these outcomes, we suggest that the J–C hypothesis, with demonstrated importance for plants, is partially upheld for reef corals.
The effects of land use change on native dung beetle diversity and function in Australia's Wet Tropics
Publisher: Wiley
Date: 18-07-2016
DOI: 10.1111/AEC.12366
Diverse outcomes of species interactions in an invaded annual plant community
Publisher: Oxford University Press (OUP)
Date: 23-09-2016
DOI: 10.1093/JPE/RTW102
The ‘filtering’ metaphor revisited: competition and environment jointly structure invasibility and coexistence
Publisher: The Royal Society
Date: 08-2018
Abstract: ‘Filtering’, or the reduction in species ersity that occurs because not all species can persist in all locations, is thought to unfold hierarchically, controlled by the environment at large scales and competition at small scales. However, the ecological effects of competition and the environment are not independent, and observational approaches preclude investigation into their interplay. We use a demographic approach with 30 plant species to experimentally test: (i) the effect of competition on species persistence in two soil moisture environments, and (ii) the effect of environmental conditions on mechanisms underlying competitive coexistence. We find that competitors cause differential species persistence across environments even when effects are lacking in the absence of competition, and that the traits which determine persistence depend on the competitive environment. If our study had been observational and trait-based, we would have erroneously concluded that the environment filters species with low biomass, shallow roots and small seeds. Changing environmental conditions generated idiosyncratic effects on coexistence outcomes, increasing competitive exclusion of some species while promoting coexistence of others. Our results highlight the importance of considering environmental filtering in the light of, rather than in isolation from, competition, and challenge community assembly models and approaches to projecting future species distributions.
Using multi‐scale spatially explicit frameworks to understand the relationship between functional diversity and species richness
Publisher: Wiley
Date: 03-01-2022
DOI: 10.1111/ECOG.05844
Abstract: Understanding how ecosystem functioning is impacted by global change drivers is a central topic in ecology and conservation science. We need to assess not only how environmental change affects species richness, but also how the distribution of functional traits (i.e. functional ersity) mediate the relationship between species richness and ecosystem functioning. However, most evidence about the capacity of functional ersity to explain ecosystem functioning has been developed from studies conducted at a single spatial scale. Here, we explore theory, expectations and evidence for why and how species richness and functional ersity relationships vary with spatial scale. Despite the importance of accounting for spatial processes at multiple scales, we show that most studies of the species richness–functional ersity relationship focus on single scale analyses that ignore spatial context. Thus, we discuss the need to establish a spatially explicit, multi‐scale framework for understanding the relationship between species richness and functional ersity. As a starting point to developing such a framework, we detail some expected trajectories and mechanisms by which the ersity of species and functional traits may change across increasing spatial scales. We also explore what is known about two important gaps in the literature about this relationship: 1) the influence of spatial autocorrelation on community assembly processes and 2) the variation in the structure of species interactions across spatial extents. We present some key challenges that could be addressed by integrating approaches from community and landscape ecology. This information will help improve our understanding of the relative influence of local and large‐scale processes on community structure, while providing a foundation for improving bio ersity monitoring, policy and ecosystem function based conservation.
Functional decay in tree community within tropical fragmented landscapes: Effects of landscape-scale forest cover
Publisher: Public Library of Science (PLoS)
Date: 12-04-2017
Environmental context, parameter sensitivity, and structural sensitivity impact predictions of annual‐plant coexistence
Publisher: Wiley
Date: 06-10-2023
DOI: 10.1002/ECM.1592
The loss of functional diversity: A detrimental influence of landscape‐scale deforestation on tree reproductive traits
Publisher: Wiley
Date: 10-07-2019
Non-destructive spatial mapping of vegetation plots: a re-introduction of the pantograph
Publisher: Cold Spring Harbor Laboratory
Date: 29-04-2023
DOI: 10.1101/2023.04.28.538692
Abstract: Non-destructive spatial mapping of herbaceous plants is often not possible with many modern imaging techniques, especially in systems with highly structured, dense herbaceous canopies. For this purpose we suggest using a modern version of the classic pantograph, a simple instrument that allows precisely scaled drawings. The pantograph version we describe here was specifically designed for small-scale herbaceous vegetation mapping. Specifically, our pantograph design is useful for rapidly collecting accurate, spatially explicit data at the scale of 0.1-2 m 2 and includes a paired drawing board for easy use in field conditions. We tested the design and technique on 100 annual plant plots that ranged in total density and in plant stature. Based on this mapping trial, we present guidelines for effective manual mapping and map digitization. A pantograph is a useful and inexpensive to make tool for non-destructively spatially mapping in idual herbaceous plants in the field. Here, we present instructions for the design and fabrication of our modern pantograph, board, and pencil attachment designed specifically for researchers wanting to include small-scale spatial context in their research.
The strength and direction of local (mal)adaptation depends on neighbour density and the environment
Publisher: Wiley
Date: 08-02-2022
Abstract: Populations are embedded in communities, but despite their potential to affect in idual fitness, it is unknown whether and how species interactions evolve in communities. Evolutionary outcomes are likely more complex in natural communities because (a) the evolution of interactions may not be evenly distributed among all community members and (b) coevolution is conditional on the environmental conditions within which interactions are playing out. To test the evolution of interaction strengths in natural communities, we performed two common garden experiments in grassland communities in Northern California. In each garden, we transplanted in iduals of four populations (one local, three foreign) of an annual invasive grass Bromus hordeaceus into natural communities, characterized the interaction neighbourhood around each focal in idual, and quantified in idual fitness. This method allowed us to fit multispecies competition models to fitness data, estimating interaction strengths between focal B. hordeaceus populations and each of seven species that were common in the interaction neighbourhoods, in each garden. We found that interaction strengths significantly differed among local and foreign source populations, but the direction and magnitude of evolution differed among common gardens and among neighbour species—in neither garden were interactions experienced more strongly by foreign populations compared to local populations. The fitness of local populations (relative to foreign populations) decreased when neighbours were removed, strongly enough in one garden to cause strong local maladaptation, and the local population did not perform the best in either garden. Synthesis . Together, our results demonstrate how species interactions evolve to determine fitness in ecological communities, providing a richer view of adaptation in natural systems. In our study, this richness included the unique challenges populations face in nature: uneven abundances and a diffuseness of species interactions, nonlinear density effects on fitness, and evidence of (mal)adaptation that is conditional on local conditions. We conclude by hypothesizing the causes and consequences of challenges to adaptation and how they help identify priority areas for the field.
Invasions: the trail behind, the path ahead, and a test of a disturbing idea
Publisher: Wiley
Date: 13-12-2011
Potential mechanisms of coexistence in closely related forbs
Publisher: Wiley
Date: 02-05-2016
DOI: 10.1111/OIK.03180
Predicting species abundances in a grassland biodiversity experiment: Trade‐offs between model complexity and generality
Publisher: Wiley
Date: 19-11-2019
Opposing effects of competitive exclusion on the phylogenetic structure of communities
Publisher: Wiley
Date: 23-06-2010
DOI: 10.1111/J.1461-0248.2010.01509.X
Abstract: Though many processes are involved in determining which species coexist and assemble into communities, competition is among the best studied. One hypothesis about competition's contribution to community assembly is that more closely related species are less likely to coexist. Though empirical evidence for this hypothesis is mixed, it remains a common assumption in certain phylogenetic approaches for inferring the effects of environmental filtering and competitive exclusion. Here, we relate modern coexistence theory to phylogenetic community assembly approaches to refine expectations for how species relatedness influences the outcome of competition. We argue that two types of species differences determine competitive exclusion with opposing effects on relatedness patterns. Importantly, this means that competition can sometimes eliminate more different and less related taxa, even when the traits underlying the relevant species differences are phylogenetically conserved. Our argument leads to a reinterpretation of the assembly processes inferred from community phylogenetic structure.
Landscape effects on crop pollination services: are there general patterns?
Publisher: Wiley
Date: 05-2008
DOI: 10.1111/J.1461-0248.2008.01157.X
Abstract: Pollination by bees and other animals increases the size, quality, or stability of harvests for 70% of leading global crops. Because native species pollinate many of these crops effectively, conserving habitats for wild pollinators within agricultural landscapes can help maintain pollination services. Using hierarchical Bayesian techniques, we synthesize the results of 23 studies - representing 16 crops on five continents - to estimate the general relationship between pollination services and distance from natural or semi-natural habitats. We find strong exponential declines in both pollinator richness and native visitation rate. Visitation rate declines more steeply, dropping to half of its maximum at 0.6 km from natural habitat, compared to 1.5 km for richness. Evidence of general decline in fruit and seed set - variables that directly affect yields - is less clear. Visitation rate drops more steeply in tropical compared with temperate regions, and slightly more steeply for social compared with solitary bees. Tropical crops pollinated primarily by social bees may therefore be most susceptible to pollination failure from habitat loss. Quantifying these general relationships can help predict consequences of land use change on pollinator communities and crop productivity, and can inform landscape conservation efforts that balance the needs of native species and people.
Climate moderates release from nutrient limitation in natural annual plant communities
Publisher: Wiley
Date: 02-02-2015
DOI: 10.1111/GEB.12277
Differences in forest plant functional trait distributions across land-use and productivity gradient
Publisher: Wiley
Date: 07-2013
DOI: 10.3732/AJB.1200461
Abstract: Plant functional traits are commonly used as proxies for plant responses to environmental challenges, yet few studies have explored how functional trait distributions differ across gradients of land-use change. By comparing trait distributions in intact forests with those across land-use change gradients, we can improve our understanding of the ways land-use change alters the ersity and functioning of plant communities. We examined how the variation and distribution of trait values for seven plant functional traits differ between reference natural forest and three types of land-use conversion (pasture, old-field, or "legacy" sites-regrowth following logging), landscape productivity (NPP) and vegetation strata (tree or non-tree "understory"), in a meta-analysis of studies from 15 landscapes across five continents. Although trait variation often differed between land-uses within a landscape, these patterns were rarely consistent across landscapes. The variance and distribution of traits were more likely to differ consistently between natural forest and land-use conversion categories for understory (non-tree) plants than for trees. Landscape productivity did not significantly alter the difference in trait variance between natural forest and land-use conversion categories for any trait except dispersal. Our results suggest that even for traits well linked to plant environmental response strategies, broad classes of land-use change and landscape productivity are not generally useful indicators of the mechanisms driving compositional changes in human-modified forest systems.
Requirements for the spatial storage effect are weakly evident for common species in natural annual plant assemblages
Publisher: Wiley
Date: 07-10-2020
DOI: 10.1002/ECY.3185
Annual rainfall variation and dispersal limitation combine to alter invaded plant community diversity, dominance hierarchies and seeding phenology
Publisher: Elsevier BV
Date: 12-2021
Diptera species and functional diversity across tropical Australian countryside landscapes
Publisher: Elsevier BV
Date: 11-2015
Links between community ecology theory and ecological restoration are on the rise
Publisher: Wiley
Date: 23-08-2017
Accounting for demographic uncertainty increases predictions for species coexistence: A case study with annual plants.
Publisher: Wiley
Date: 28-05-2022
DOI: 10.1111/ELE.14011
Abstract: Natural systems contain more complexity than is accounted for in models of modern coexistence theory. Coexistence modelling often disregards variation arising from stochasticity in biological processes, heterogeneity among in iduals and plasticity in trait values. However, these unaccounted-for sources of uncertainty are likely to be ecologically important and have the potential to impact estimates of coexistence. We applied a Bayesian modelling framework to data from an annual plant community in Western Australia to propagate uncertainty in coexistence outcomes using the invasion criterion and ratio of niche to fitness differences. We found accounting for this uncertainty altered predictions of coexistence versus competitive exclusion for 3 out of 14 species pairs and yielded a probability of priority effects for an additional species pair. The propagation of uncertainty arising from sources of biological complexity improves our ability to predict coexistence more accurately in natural systems.
Unexpected drought resistance strategies in seedlings of four Brachychiton species
Publisher: Oxford University Press (OUP)
Date: 28-11-2017
Abstract: Functional traits associated with drought resistance can be useful for predicting tree responses to a drying climate. Yet drought resistance is likely achieved through a complex combination of constitutive traits (traits expressed even in benign environments) and plastic traits (traits expressed only in response to drought). Because few studies measure multiple traits for multiple species under both well-watered and drought conditions, we often struggle to identify suites of constitutive and plastic traits indicative of drought resistance strategies. Using a greenhouse experiment, we examined nine drought resistance traits (six morphological/allocation traits plus assimilation, stomatal conductance and water-use efficiency) in well-watered and water-stressed seedlings of four Brachychiton (Malvaceae Juss.) species with ranges spanning a strong aridity gradient in east-central Australia. In benign conditions, constitutive biomass allocation was consistent with expectations, with xeric species investing more heavily in roots and stem tissue and less in leaf tissue than mesic species (P = 0.004). Under drought conditions, xeric species decreased relative biomass allocation below-ground while mesic species increased relative below-ground allocation (treatment × species interaction P = 0.0015). Relative water content of the stems was slightly higher in xeric species (P = 0.055), and remained stable during drought while decreasing in mesic species (treatment × species P = 0.001). Specific leaf area (SLA) and leaf dry matter content (LDMC) did not fit with expectations under either benign or water-limited conditions. Moreover, stomatal conductance and carbon assimilation were unexpectedly highest and intrinsic water-use efficiency (WUEi) lowest in the xeric species in benign conditions. Only under drought did the xeric species manifest higher WUEi than the mesic species (treatment × species P < 0.0001). We found that even closely related species exhibited erse combinations of drought resistance traits. Notably, traits commonly used as proxies for drought tolerance (e.g., SLA, LDMC, well-watered WUEi) performed more poorly than constitutive allocation traits. This study highlights the need to consider multiple traits and phenotypic plasticity when assessing species' drought resistance for forest management in the face of climate change.
EDITOR'S CHOICE: REVIEW: Trait matching of flower visitors and crops predicts fruit set better than trait diversity
Publisher: Wiley
Date: 22-09-2015
Seedling growth responses to species-, neighborhood-, and landscape-scale effects during tropical forest restoration
Publisher: Wiley
Date: 08-2018
DOI: 10.1002/ECS2.2386
Loss of functional diversity under land use intensification across multiple taxa
Publisher: Wiley
Date: 09-12-2008
DOI: 10.1111/J.1461-0248.2008.01255.X
Abstract: Land use intensification can greatly reduce species richness and ecosystem functioning. However, species richness determines ecosystem functioning through the ersity and values of traits of species present. Here, we analyze changes in species richness and functional ersity (FD) at varying agricultural land use intensity levels. We test hypotheses of FD responses to land use intensification in plant, bird, and mammal communities using trait data compiled for 1600+ species. To isolate changes in FD from changes in species richness we compare the FD of communities to the null expectations of FD values. In over one-quarter of the bird and mammal communities impacted by agriculture, declines in FD were steeper than predicted by species number. In plant communities, changes in FD were indistinguishable from changes in species richness. Land use intensification can reduce the functional ersity of animal communities beyond changes in species richness alone, potentially imperiling provisioning of ecosystem services.
Different traits predict competitive effect versus response by Bromus madritensis in its native and invaded ranges
Publisher: Springer Science and Business Media LLC
Date: 05-04-2018
Native turncoats and indirect facilitation of species invasions
Publisher: The Royal Society
Date: 24-01-2018
Abstract: At local scales, native species can resist invasion by feeding on and competing with would-be invasive species. However, this relationship tends to break down or reverse at larger scales. Here, we consider the role of native species as indirect facilitators of invasion and their potential role in this ersity-driven ‘invasion paradox’. We coin the term ‘native turncoats’ to describe native facilitators of non-native species and identify eight ways they may indirectly facilitate species invasion. Some are commonly documented, while others, such as indirect interactions within competitive communities, are largely undocumented in an invasion context. Therefore, we use models to evaluate the likelihood that these competitive interactions influence invasions. We find that native turncoat effects increase with the number of resources and native species. Furthermore, our findings suggest the existence, abundance and effectiveness of native turncoats in a community could greatly influence invasion success at large scales.
Beyond direct neighbourhood effects: higher-order interactions improve modelling and predicting tree survival and growth
Publisher: Oxford University Press (OUP)
Date: 23-09-2020
DOI: 10.1093/NSR/NWAA244
Abstract: It is known that biotic interactions are the key to species coexistence and maintenance of species ersity. Traditional studies focus overwhelmingly on pairwise interactions between organisms, ignoring complex higher-order interactions (HOIs). In this study, we present a novel method of calculating in idual-level HOIs for trees, and use this method to test the importance of size- and distance-dependent in idual-level HOIs to tree performance in a 25-ha temperate forest dynamic plot. We found that full HOI-inclusive models improved our ability to model and predict the survival and growth of trees, providing empirical evidence that HOIs strongly influence tree performance in this temperate forest. Specifically, assessed HOIs mitigate the competitive direct effects of neighbours on survival and growth of focal trees. Our study lays a foundation for future investigations of the prevalence and relative importance of HOIs in global forests and their impact on species ersity.
What does species richness tell us about functional trait diversity? Predictions and evidence for responses of species and functional trait diversity to land-use change
Publisher: Wiley
Date: 08-06-2010
Asteraceae invaders have limited impacts on the pollination of common native annual species in SW Western Australia’s open woodland wildflower communities
Publisher: Springer Science and Business Media LLC
Date: 09-07-2015
Optimal restoration for pollination services increases forest cover while doubling agricultural profits
Publisher: Public Library of Science (PLoS)
Date: 23-05-2023
DOI: 10.1371/JOURNAL.PBIO.3002107
Abstract: Pollinators are currently facing dramatic declines in abundance and richness across the globe. This can have profound impacts on agriculture, as 75% of globally common food crops benefit from pollination services. As many native bee species require natural areas for nesting, restoration efforts within croplands may be beneficial to support pollinators and enhance agricultural yields. Yet, restoration can be challenging to implement due to large upfront costs and the removal of land from production. Designing sustainable landscapes will require planning approaches that include the complex spatiotemporal dynamics of pollination services flowing from (restored) vegetation into crops. We present a novel planning framework to determine the best spatial arrangement for restoration in agricultural landscapes while accounting for yield improvements over 40 years following restoration. We explored a range of production and conservation goals using a coffee production landscape in Costa Rica as a case study. Our results show that strategic restoration can increase forest cover by approximately 20% while doubling collective landholder profits over 40 years, even when accounting for land taken out of production. We show that restoration can provide immense economic benefits in the long run, which may be pivotal to motivating local landholders to undertake conservation endeavours in pollinator-dependent croplands.
Backyard buzz: human population density modifies the value of vegetation cover for insect pollinators in a subtropical city
Publisher: Springer Science and Business Media LLC
Date: 12-09-2022
DOI: 10.1007/S11252-022-01277-W
Abstract: Urbanisation drives overall declines in insect pollinators. Although urban green spaces can provide suitable habitat for pollinators much remains to be learned about how urban landscapes either promote or negatively impact pollinators. We investigated how backyard design, local (100 m) and landscape (500 m) scale vegetation cover and human population density were associated with non-eusocial native bee species, eusocial bees ( Apis mellifera and Tetragonula spp .), and hoverflies, in residential green spaces of the subtropical city Brisbane, Australia. We found that associations between bee abundance and vegetation cover were moderated by human density, but the direction of this effect differed for non-eusocial and eusocial species. Non-eusocial bee abundance was positively associated with tree cover at local and landscape scales when human densities were low, but negatively so at high human population densities. We suggest this may be because the quality of vegetation for non-eusocial bees deteriorates as human density increases. In contrast, abundance of eusocial bees was negatively associated with increasing local cover of grass and shrubs at low levels of human density, but positively associated at high densities. This affinity to humans could partly be explained by domesticated “kept” hives. We found no effect of urban gradients on bee species richness. Hoverfly abundance was negatively related to human density and positively related to vegetation cover at local and landscape scales. At the backyard scale, both bee species richness and bee and hoverfly abundances were positively associated to flower abundance. Backyards with more vegetation cover had higher densities of non-eusocial bees. Our results thus support the idea that urban greening in densely populated areas at multiple spatial scales can benefit a range of insect pollinators.
Higher-order interactions capture unexplained complexity in diverse communities.
Publisher: Springer Science and Business Media LLC
Date: 17-02-2017
Abstract: Natural communities are well known to be maintained by many complex processes. Despite this, the practical aspects of studying them often require some simplification, such as the widespread assumption that direct, additive competition captures the important details about how interactions between species impact community ersity. More complex non-additive 'higher-order' interactions are assumed to be negligible or absent. Notably, these assumptions are poorly supported and have major consequences for the accuracy with which patterns of natural ersity are modelled and explained. We present a mathematically simple framework for incorporating biologically meaningful complexity into models of ersity by including non-additive higher-order interactions. We further provide empirical evidence that such higher-order interactions strongly influence species' performance in natural plant communities, with variation in seed production (as a proxy for per capita fitness) explained dramatically better when at least some higher-order interactions are considered. Our study lays the groundwork for a long-overdue shift in how species interactions are used to study the ersity of natural communities.
Non-additive biotic interactions improve predictions of tropical tree growth and impact community size structure.
Publisher: Wiley
Date: 09-12-2022
DOI: 10.1002/ECY.3588
Abstract: Growth in in idual size or biomass is a key demographic component in population models, with wide-ranging applications from quantifying species performance across abiotic or biotic conditions to assessing landscape-level dynamics under global change. In forest ecology, the responses of tree growth to biotic interactions are widely held to be crucial for understanding forest ersity, function, and structure. To date, most studies on plant-plant interactions only examine the additive competitive or facilitative interactions between species pairs however, there is increasing evidence of non-additive, higher-order interactions (HOIs) impacting species demographic rates. When HOIs are present, the dynamics of a multispecies community cannot be fully understood or accurately predicted solely from pairwise outcomes because of how additional species "interfere" with the direct, pairwise interactions. Such HOIs should be particularly prevalent when species show non-linear functional responses to resource availability and resource-acquisition traits themselves are density dependent. With this in mind, we used data from a tropical secondary forest-a system that fulfills both of these conditions-to build an ontogenetic diameter growth model for in iduals across 10 woody-plant species. We allowed both direct and indirect interactions within communities to influence the species-specific growth parameters in a generalized Lotka-Volterra model. Specifically, indirect interactions entered the model as higher-order quadratic terms, i.e., non-additive effects of conspecific and heterospecific neighbor size on the focal in idual's growth. For the whole community and for four out of 10 focal species, the model that included HOIs had more statistical support than the model that included only direct interactions, despite the former containing a far greater number of parameters. HOIs had comparable effect sizes to direct interactions, and tended to further reduce the diameter growth rates of most species beyond what direct interactions had already reduced. In a simulation of successional stand dynamics, the inclusion of HOIs led to rank swaps in species' diameter hierarchies, even when community-level size distributions remained qualitatively similar. Our study highlights the implications, and discusses possible mechanisms, of non-additive density dependence in highly erse and light-competitive tropical forests.
Traits, Habitats, and Clades: Identifying Traits of Potential Importance to Environmental Filtering
Publisher: University of Chicago Press
Date: 07-2009
DOI: 10.1086/599293
Abstract: Environmental filtering is a fundamental process in the ecological assembly of communities. Recently developed phylogenetic tools identify patterns associated with environmental filtering across whole communities. Here we introduce a novel method that allows the detection of traits involved in the environmental filtering of species from specific clades in specific habitat types. Our approach identifies nonindependent trait/habitat/clade (THC) associations and also provides a framework for detecting clearly defined two-way trait/clade, trait/habitat, and clade/habitat associations. The THC method relies on exact binomial tests and differentiates THC associations resulting from a three-way interaction from those that are generated by one or more underlying significant two-way interactions. It can also detect THC associations for which there are no significant two-way associations (trait/habitat, trait/clade, clade/habitat). To illustrate the THC method, we examine plant pollination and dispersal traits from six habitat types in a fragmented Costa Rican landscape. Results suggest that these traits are not widely important for the environmental filtering of most clades in this landscape, but animal dispersal and insect pollination are involved in the filtering of monocots and the Piperaceae in rain forest understory.
Rethinking Community Assembly through the Lens of Coexistence Theory
Publisher: Annual Reviews
Date: 12-2012
DOI: 10.1146/ANNUREV-ECOLSYS-110411-160411
Abstract: Although research on the role of competitive interactions during community assembly began decades ago, a recent revival of interest has led to new discoveries and research opportunities. Using contemporary coexistence theory that emphasizes stabilizing niche differences and relative fitness differences, we evaluate three empirical approaches for studying community assembly. We show that experimental manipulations of the abiotic or biotic environment, assessments of trait-phylogeny-environment relationships, and investigations of frequency-dependent population growth all suggest strong influences of stabilizing niche differences and fitness differences on the outcome of plant community assembly. Nonetheless, due to the limitations of these approaches applied in isolation, we still have a poor understanding of which niche axes and which traits determine the outcome of competition and community structure. Combining current approaches represents our best chance of achieving this goal, which is fundamental to conceptual ecology and to the management of plant communities under global change.
Exploring the 'most effective pollinator principle' with complex flowers: Bumblebees and Ipomopsis aggregata
Publisher: Oxford University Press (OUP)
Date: 10-2001
Drivers of Acacia and Eucalyptus growth rate differ in strength and direction in restoration plantings across Australia
Publisher: Wiley
Date: 02-06-2022
DOI: 10.1002/EAP.2636
Abstract: Functional traits are proxies for a species' ecology and physiology and are often correlated with plant vital rates. As such they have the potential to guide species selection for restoration projects. However, predictive trait‐based models often only explain a small proportion of plant performance, suggesting that commonly measured traits do not capture all important ecological differences between species. Some residual variation in vital rates may be evolutionarily conserved and captured using taxonomic groupings alongside common functional traits. We tested this hypothesis using growth rate data for 17,299 trees and shrubs from 80 species of Eucalyptus and 43 species of Acacia , two hyper‐ erse and co‐occurring genera, collected from 497 neighborhood plots in 137 Australian mixed‐species revegetation plantings. We modeled relative growth rates of in idual plants as a function of environmental conditions, species‐mean functional traits, and neighbor density and ersity, across a moisture availability gradient. We then assessed whether the strength and direction of these relationships differed between the two genera. We found that the inclusion of genus‐specific relationships offered a significant but modest improvement to model fit (1.6%–1.7% greater R 2 than simpler models). More importantly, almost all correlates of growth rate differed between Eucalyptus and Acacia in strength, direction, or how they changed along the moisture gradient. These differences mapped onto physiological differences between the genera that were not captured solely by measured functional traits. Our findings suggest taxonomic groupings can capture or mediate variation in plant performance missed by common functional traits. The inclusion of taxonomy can provide a more nuanced understanding of how functional traits interact with abiotic and biotic conditions to drive plant performance, which may be important for constructing trait‐based frameworks to improve restoration outcomes.
Understory plant species and functional diversity in the degraded wet tropical forests of Kolombangara Island, Solomon Islands
Publisher: Elsevier BV
Date: 2012
Plant communities, populations and individuals have distinct responses to short‐term warming and neighbour biomass removal in two montane grasslands
Publisher: Wiley
Date: 2021
DOI: 10.1111/AVSC.12557
The evolution of niche overlap and competitive differences.
Publisher: Springer Science and Business Media LLC
Date: 25-01-2021
DOI: 10.1038/S41559-020-01383-Y
Abstract: Competition can result in evolutionary changes to coexistence between competitors but there are no theoretical models that predict how the components of coexistence change during this eco-evolutionary process. Here we study the evolution of the coexistence components, niche overlap and competitive differences, in a two-species eco-evolutionary model based on consumer-resource interactions and quantitative genetic inheritance. Species evolve along a one-dimensional trait axis that allows for changes in both niche position and species intrinsic growth rates. There are three main results. First, the breadth of the environment has a strong effect on the dynamics, with broader environments leading to reduced niche overlap and enhanced coexistence. Second, coexistence often involves a reduction in niche overlap while competitive differences stay relatively constant or vice versa in general changes in competitive differences maintain coexistence only when niche overlap remains constant. Large simultaneous changes in niche overlap and competitive difference often result in one of the species being excluded. Third, provided that the species evolve to a state where they coexist, the final niche overlap and competitive difference values are independent of the system's initial state, although they do depend on the model's parameters. The model suggests that evolution is often a destructive force for coexistence due to evolutionary changes in competitive differences, a finding that expands the paradox of ersity maintenance.
Variation in demographic responses to competition and abiotic conditions in an annual plant community
Publisher: Authorea, Inc.
Date: 08-06-2023
DOI: 10.22541/AU.168623693.35616706/V1
Abstract: Understanding how plant fitness varies along natural gradients is critical for predicting responses to environmental change. However, in idual vital rates are often used as fitness proxies without knowing how other vital rates vary. To address this gap, we investigated how water availability, plant-plant interactions and heterogeneity in shade and soil influenced emergence, survival, seed production, and population growth rates of nine annual plant species in semi-arid Western Australia. We sowed plots of seeds across a reserve, removed all neighbouring plants from half of the interaction neighbourhoods and altered precipitation using rainout shelters. We found high consistency among species’ responses to abiotic and biotic factors. Most species exhibited opposing responses of different vital rates along a natural abiotic gradient which translated to neutral trends in population growth rates across the gradient. This research demonstrates the importance of demographic trade-offs and pitfalls of measuring a single vital rate as a fitness proxy.
Restoration of tropical forests requires more than just planting trees, a lot more…
Publisher: Wiley
Date: 10-2016
DOI: 10.1111/AVSC.12275
Comparing the recovery of richness, structure, and biomass in naturally regrowing and planted reforestation
Publisher: Wiley
Date: 28-11-2020
DOI: 10.1111/REC.13077
Aridity drives coordinated trait shifts but not decreased trait variance across the geographic range of eight Australian trees
Publisher: Cold Spring Harbor Laboratory
Date: 04-02-2020
DOI: 10.1101/2020.02.03.932715
Abstract: Large intraspecific functional trait variation strongly impacts many aspects of natural communities and ecosystems, yet is inconsistent across traits and species. We measured within-species variation in leaf mass per area (LMA), leaf dry matter content (LDMC), branch wood density (WD), and allocation to stem area vs. leaf area in branches (branch Huber value, HV) across the aridity range of seven Australian eucalypts and an Acacia species to explore how traits and their variances change with aridity. Within-species, we found consistent increases in LMA, LDMC and WD, and HV with increasing aridity, resulting in consistent trait coordination across tissues. However, this coordination only emerged across sites with large climate differences. Unlike trait means, patterns of trait variance with aridity were mixed across populations and species and showed limited support for constrained trait variation in dryer populations or more xeric species. Our results highlight that climate can drive consistent within-species trait patterns, but that these patterns might often be obscured by the complex nature of morphological traits and s ling incomplete species ranges or s ling confounded stress gradients.
Estimating interaction strengths for diverse horizontal systems using performance data
Publisher: Wiley
Date: 09-02-2023
Abstract: Network theory allows us to understand complex systems by evaluating how their constituent elements interact with one another. Such networks are built from matrices which describe the effect of each element on all others. Quantifying the strength of these interactions from empirical data can be difficult, however, because the number of potential interactions increases nonlinearly as more elements are included in the system, and not all interactions may be empirically observable when some elements are rare. We present a novel modelling framework which uses measures of species performance in the presence of varying densities of their potential interaction partners to estimate the strength of pairwise interactions in erse horizontal systems. Our method allows us to directly estimate pairwise effects when they are statistically identifiable and to approximate pairwise effects when they would otherwise be statistically unidentifiable. The resulting interaction matrices can include positive and negative effects, the effect of a species on itself, and allows for non‐symmetrical interactions. We show how to link the parameters inferred by our framework to a population dynamics model to make inferences about the effect of interactions on community dynamics and ersity. The advantages of these features are illustrated with a case study on an annual wildflower community of 22 focal and 52 neighbouring species, and a discussion of potential applications of this framework extending well beyond plant community ecology.
Distinct invasion strategies operating within a natural annual plant system
Publisher: Wiley
Date: 24-02-2015
DOI: 10.1111/ELE.12414
Abstract: Alien plant species are known to have a wide range of impacts on recipient communities, from resident species' exclusions to coexistence with resident species. It remains unclear however, if this variety of impacts is due to different invader strategies, features of recipient communities or both. To test this, we examined multiple plant invasions of a single ecosystem in southwestern Australia. We used extensive community data to calculate pairwise segregation between target alien species and many co-occurring species. We related segregation to species' positions along community trait hierarchies and identified at least two distinct invasion strategies: 'exploiters' which occupy high positions along key trait hierarchies and reduce local native species ersity (particularly in nutrient-enriched situations), and 'coexisters' who occupy intermediate trait positions and have no discernable impact on native ersity. We conclude that trait hierarchies, linked to measures of competition, can provide valuable insights about the processes driving different invasion outcomes.
Applied ecological research is on the rise but connectivity barriers persist between four major subfields
Publisher: Wiley
Date: 13-03-2019
Cyclic population dynamics and density‐dependent intransitivity as pathways to coexistence between co‐occurring annual plants
Publisher: Wiley
Date: 16-04-2018
The effect of habitat fragmentation on the bee visitor assemblages of three Australian tropical rainforest tree species
Publisher: Wiley
Date: 22-07-2018
DOI: 10.1002/ECE3.4339
Landscape context explains changes in the functional diversity of regenerating forests better than climate or species richness
Publisher: Wiley
Date: 18-09-2017
DOI: 10.1111/GEB.12627
Global effects of non‐native tree species on multiple ecosystem services
Publisher: Wiley
Date: 11-04-2019
DOI: 10.1111/BRV.12511
Disentangling key species interactions in diverse and heterogeneous communities: A Bayesian sparse modeling approach
Publisher: Cold Spring Harbor Laboratory
Date: 26-07-2021
DOI: 10.1101/2021.07.23.453227
Abstract: 1 Modeling species interactions in erse communities traditionally requires a prohibitively large number of species-interaction coefficients, especially when considering environmental dependence of parameters. We implemented Bayesian variable selection via sparsity-inducing priors on non-linear species abundance models to determine which species-interactions should be retained and which can be represented as an average heterospecific interaction term, reducing the number of model parameters. We evaluated model performance using simulated communities, computing out-of-s le predictive accuracy and parameter recovery across different input s le sizes. We applied our method to a erse empirical community, allowing us to disentangle the direct role of environmental gradients on species’ intrinsic growth rates from indirect effects via competitive interactions. We also identified a few neighboring species from the erse community that had non-generic interactions with our focal species. This sparse modeling approach facilitates exploration of species-interactions in erse communities while maintaining a manageable number of parameters.
Variable seed bed microsite conditions and light influence germination in Australian winter annuals
Publisher: Springer Science and Business Media LLC
Date: 09-01-2022
DOI: 10.1007/S00442-021-05091-7
Abstract: Environmentally cued germination may play an important role in promoting coexistence in Mediterranean annual plant systems if it causes niche differentiation across heterogeneous microsite conditions. In this study, we tested how microsite conditions experienced by seeds in the field and light conditions in the laboratory influenced germination in 12 common annual plant species occurring in the understorey of the York gum-jam woodlands in southwest Western Australia. Specifically, we hypothesized that if germination promotes spatial niche differentiation, then we should observe species-specific germination responses to light. In addition, we hypothesized that species’ laboratory germination response may depend on the microsite conditions experienced by seeds while buried. We tested the laboratory germination response of seeds under diurnally fluctuating light and complete darkness, which were collected from microsites spanning local-scale environmental gradients known to influence community structure in this system. We found that seeds of 6 out of the 12 focal species exhibited significant positive germination responses to light, but that the magnitude of these responses varied greatly with the relative light requirement for germination ranging from 0.51 to 0.86 for these species. In addition, germination increased significantly across a gradient of canopy cover for two species, but we found little evidence to suggest that species’ relative light requirement for germination varied depending on seed bank microsite conditions. Our results suggest that variability in light availability may promote coexistence in this system and that the microsite conditions seeds experience in the intra-growing season period can further nuance species germination behaviour.
Distinct responses of niche and fitness differences to water availability underlie variable coexistence outcomes in semi‐arid annual plant communities
Publisher: Wiley
Date: 13-09-2018
Rainforest seed rain into abandoned tropical Australian pasture is dependent on adjacent rainforest structure and extent
Publisher: Wiley
Date: 09-2017
DOI: 10.1111/AEC.12426
Non-bee insects are important contributors to global crop pollination
Publisher: Proceedings of the National Academy of Sciences
Date: 30-11-2016
Abstract: Many of the world’s crops are pollinated by insects, and bees are often assumed to be the most important pollinators. To our knowledge, our study is the first quantitative evaluation of the relative contribution of non-bee pollinators to global pollinator-dependent crops. Across 39 studies we show that insects other than bees are efficient pollinators providing 39% of visits to crop flowers. A shift in perspective from a bee-only focus is needed for assessments of crop pollinator bio ersity and the economic value of pollination. These studies should also consider the services provided by other types of insects, such as flies, wasps, beetles, and butterflies—important pollinators that are currently overlooked.
The ‘filtering’ metaphor revisited: Competition and environment jointly structure invasibility and coexistence
Publisher: Cold Spring Harbor Laboratory
Date: 27-06-2018
DOI: 10.1101/356360
Abstract: ‘Filtering’, or the reduction in species ersity that occurs because not all species can persist in all locations, is thought to unfold hierarchically, at large scales due to the environment and at small scales due to competition. However, the ecological effects of competition and the environment are not independent, and observational approaches preclude investigation into their interplay. We use a demographic approach with 30 plant species to experimentally test (i) the effect of competition on species persistence in two soil moisture environments, and (ii) the effect of environmental conditions on the mechanisms underlying competitive coexistence. We find that competitors cause differential persistence of species across environments even when these effects are lacking in the absence of competition, and that the traits that determine persistence depend on the competitive environment. Changing environmental conditions generated idiosyncratic effects on coexistence outcomes, increasing competitive exclusion of some species while promoting coexistence of others. Our results highlight the importance of considering environmental filtering in light of, rather than in isolation from, competition, and challenge community assembly models and approaches to projecting future species distributions.
Looks can be deceiving: ecologically similar exotics have different impacts on a native competitor
Publisher: Springer Science and Business Media LLC
Date: 12-07-2019
DOI: 10.1007/S00442-019-04468-Z
Abstract: Exotic species are often predicted to successfully invade when their functional traits differ from species in recipient communities. Many studies have related trait differences among natives and invaders to competitive outcomes. Few studies, however, have tested whether functionally similar invaders have similar competitive impacts on natives. We investigated interactions in communities of a native annual forb Waitzia acuminata (Asteraceae) and two invasive annual grasses that are ecologically similar and co-occur in southwestern Australia. Using a combination of field and laboratory experiments and several performance measures, we assessed impacts of these grasses on W. acuminata. We also examined differences among species in their responses to intraspecific versus interspecific competition, including their frequency dependence. The two similar exotic grasses differed in interaction impacts, with one facilitating and the other suppressing the native. In general, intraspecific competition was stronger than interspecific competition for the native, while evidence of competition was weak for the exotics. These patterns may reflect that W. acuminata does well in these communities due to the combined impacts of stabilization and facilitation, whereas the exotics benefit from limited stabilization (mediated by their weak intraspecific competition) or weak interspecific competition with W. acuminata. We found ergent impacts of the exotic species despite their similar functional traits. We demonstrate that a native species may benefit from interactions with an exotic "benefactor" species, highlighting the potential importance of positive interactions in invaded communities. Our findings underscore the necessity of considering neutral and positive interactions in addition to competition in understanding invasion dynamics in real plant communities.
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