ORCID Profile
0000-0001-7092-6149
Current Organisation
University of South Australia
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Publisher: Wiley
Date: 20-05-2009
Publisher: Elsevier BV
Date: 05-2015
Publisher: Wiley
Date: 11-2016
DOI: 10.2981/WLB.00210
Abstract: Tree hollows constitute crucial habitats for fauna and can buffer ambient environmental conditions. The latter property should be especially relevant during extreme weather conditions, which are forecast to increase under anthropogenic climate change. We investigated the buffering capacity of Eucalyptus oleosa F.Muell. ex Miq. subsp. oleosa tree hollows in semi‐arid southern Australia for 28 days under a wide range of ambient temperatures. Tree hollows provided more stable microclimates than ambient conditions, maintaining lower temperatures and higher humidity during the day and higher temperatures and lower humidity during the night. Daytime buffering capacity increased slightly with depth and we recorded a maximum buffering of 15.1°C below ambient temperatures. Maximum day time buffering capacity increased at a rate of approximately 0.6°C per 1°C increase in ambient temperature, meaning that maximum buffering capacity was reached during the hottest periods. The high buffering capacity of tree hollows suggests that old trees with deep hollows are important in facilitating the persistence of fauna during extreme weather events. Therefore, protecting old‐growth forests and vegetation remnants that are rich in tree hollows is an important strategy for mitigating the impact of climate change on fauna.
Publisher: Wiley
Date: 17-07-2020
DOI: 10.1111/JBI.13925
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/BT18088
Abstract: Invasive ornamental plants are a global problem that can have severe impacts on native bio ersity, especially on islands. To determine whether the invasive, ornamental ivory-cane palm Pinanga coronata could be displacing native bio ersity, we investigated its co-distribution with native tree ferns in a Fijian rainforest. We recorded the abundances of P. coronata and tree ferns and related these to environmental variables using linear models and generalised linear mixed-effect models (GLMMs). Distance to an introduction site was the most significant factor predicting the palm’s distribution and abundance, suggesting that its current distribution is limited by insufficient time for wider dispersal. P. coronata cover was strongly and negatively related with the abundance of native tree ferns and the palm may therefore be displacing native tree ferns. This relationship was strongest with tree fern seedlings and weakest with mature tree ferns, implying that the palm is preventing the establishment of native tree ferns. This study thus provides strong circumstantial evidence that P. coronata is progressively displacing native tree ferns by preventing seedling establishment and poses a severe threat to Fiji’s native bio ersity and ecological processes. Therefore, urgent management is required to control and prevent the further spread of P. coronata and its negative impacts on native plant bio ersity. Management should involve an initial feasibility study to determine the effectiveness of various management strategies, followed by targeted control and/or eradication c aigns and long-term monitoring. Ultimately, well implemented legislation to prevent the spread and introduction of P. coronata and other ornamental plants will be crucial to protect native bio ersity in Fiji and elsewhere.
Publisher: Wiley
Date: 19-01-2013
DOI: 10.1111/DDI.12036
Publisher: Wiley
Date: 02-11-2012
DOI: 10.1111/JBI.12038
Publisher: Wiley
Date: 19-05-2015
DOI: 10.1111/GCB.12936
Publisher: CSIRO Publishing
Date: 2002
DOI: 10.1071/SP02006
Abstract: Using four 100 � 10 m transects, the coastal vegetation types and their horizontal stratification at Taunovo Bay, Pacific Harbour, were investigated. The common stratification pattern of herb zone, shrub zone (dominated by the invasive species Chrysobalanus icaco) and tree zone was observed. Littoral forest composed of species commonly associated with sandy beaches and species commonly associated lowland rainforest was observed. This vegetation type is here reported for the first time from Fiji and is probably caused by siliceous deposits from a nearby river. A detailed study of the extend, composition and distribution of this unique vegetation type should be conducted before the development project (planned at the study site) is approved.
Publisher: Wiley
Date: 13-06-2019
DOI: 10.1002/ECE3.5318
Publisher: Wiley
Date: 20-02-2023
DOI: 10.1111/JBI.14571
Abstract: The island species–area relationship (ISAR) assumes that the area of islands is homogeneous, or scales with environmental heterogeneity across an archipelago, which is not always the case. We compare the performance of models that adjust or substitute for island area with measures of habitat ersity, island age and resource availability for two taxonomic groups. Five hotspot archipelagos (Azores, Galapagos, Hawaii, Cape Verde, Canary Islands). Vascular plants, birds. We used the mathematical framework of the power law to compare relevant models, treating the one containing only area as a null model against which others were compared. Data were collated from databases and the literature. Models were compared using linear regression within archipelagos and via mixed effect models with archipelago as a random effect. Weighting of island area by habitat ersity and resource availability systematically improved statistical significance and model fits versus the area only power law. Models including island age did not show the same systematic improvement in model fits. For vascular plants, weighting islands by resource availability (energy and water) performed better than weighting by habitat ersity, although for birds these weightings performed equally well. Given that islands within archipelagos are fairly heterogeneous in climate, topography and geology, it is worth accounting for this in ISARs. Our results suggest that, for islands in volcanic hotspot archipelagos, this is best done by using direct measures of habitat ersity and resource availability rather than using island age as a proxy. We, therefore, recommend using direct measures, rather than proxies, when investigating the drivers of bio ersity patterns on islands.
Publisher: Wiley
Date: 02-05-2023
Abstract: 1. Bio ersity is an important component of natural ecosystems, with higher species richness often correlating with an increase in ecosystem productivity. Yet, this relationship varies substantially across environments, typically becoming less pronounced at high levels of species richness. However, species richness alone cannot reflect all important properties of a community, including community evenness, which may mediate the relationship between bio ersity and productivity. If the evenness of a community correlates negatively with richness across forests globally, then a greater number of species may not always increase overall ersity and productivity of the system. Theoretical work and local empirical studies have shown that the effect of evenness on ecosystem functioning may be especially strong at high richness levels, yet the consistency of this remains untested at a global scale. 2. Here, we used a dataset of forests from across the globe, which includes composition, biomass accumulation and net primary productivity, to explore whether productivity correlates with community evenness and richness in a way that evenness appears to buffer the effect of richness. Specifically, we evaluated whether low levels of evenness in speciose communities correlate with the attenuation of the richness–productivity relationship. 3. We found that tree species richness and evenness are negatively correlated across forests globally, with highly speciose forests typically comprising a few dominant and many rare species. Furthermore, we found that the correlation between ersity and productivity changes with evenness: at low richness, uneven communities are more productive, while at high richness, even communities are more productive. 4. Synthesis . Collectively, these results demonstrate that evenness is an integral component of the relationship between bio ersity and productivity, and that the attenuating effect of richness on forest productivity might be partly explained by low evenness in speciose communities. Productivity generally increases with species richness, until reduced evenness limits the overall increases in community ersity. Our research suggests that evenness is a fundamental component of bio ersity–ecosystem function relationships, and is of critical importance for guiding conservation and sustainable ecosystem management decisions.
Publisher: Elsevier BV
Date: 03-2018
Publisher: Pacific Science
Date: 04-2011
DOI: 10.2984/65.2.127
Publisher: Wiley
Date: 25-04-2008
Publisher: Oxford University Press (OUP)
Date: 15-09-2016
DOI: 10.1093/AOB/MCW182
Publisher: Wiley
Date: 11-12-2010
Publisher: Informa UK Limited
Date: 02-01-2023
Publisher: Wiley
Date: 14-06-2011
Publisher: CSIRO Publishing
Date: 15-06-2021
DOI: 10.1071/PC20068
Abstract: Expert knowledge is widely used for assessing the conservation status of little-known species. Pterocymbium oceanicum is a large, emergent tree endemic to Fiji. Experts classified the species as ‘Critically Endangered’ (IUCN Red List) in 2016 and estimated the population size at mature in iduals with the largest subpopulation consisting of a single stand of 100 in iduals. We surveyed this stand and counted 133 in iduals, which validated the expert estimate. However, we discovered an additional three stands nearby, increasing the total subpopulation size to 433 in iduals. Therefore, the expert estimate reliably and conservatively estimated population size but missed important information. Field surveys suggest that P. oceanicum has a narrow ecological niche as a long-lived early pioneer at mid-elevations (400–800 m) in seasonally dry forests, one of Fiji’s most degraded ecosystems. The introduced African Tulip Tree, Spathodea c anulata, is invading the s led subpopulation and shares the characteristics of being a large, fast-growing and early successional tree. Therefore, the narrow niche of P. oceanicum may now be threatened by S. c anulata. Our study highlights that expert knowledge can provide valuable information about threatened species but also has limitations. IUCN Red List assessments based solely on expert assessments should therefore be cautiously interpreted. The invasion by S. c anulata poses a serious threat to P. oceanicum and needs to be carefully monitored, with the impacts of S. c anulata on the establishment and growth of P. oceanicum requiring urgent investigation.
Publisher: Cambridge University Press (CUP)
Date: 02-08-2011
DOI: 10.1017/S0266467411000241
Abstract: Island biotas often have lower species ersity and less intense competition has been hypothesized as a result. This should result in lower habitat specificity compared with mainland habitats due to larger realized niches. We investigate microhabitat associations of canopy trees with regard to differences in topography on an oceanic island (Viti Levu, Fiji) using twenty 10 × 60-m plots. We find high tree-species ersity (112 species with dbh ≥ 10 cm in a total of 1.08 ha) and high endemism ( c . 60%), compared with other islands in Western Polynesia. Our s le plots aggregate into three distinct groups that are mostly defined by micro-topography: (1) ridges and steep slopes (well-drained sites), (2) moderate slopes and ridge flats (moderate drainage), and (3) flats (poor drainage). Associations with microhabitat are found for more than 50% of the 41 most common species but only one species is apparently restricted to a single habitat. These findings are similar to other rain forests and demonstrate considerable niche differentiation among island rain-forest tree species.
Publisher: CSIRO Publishing
Date: 04-2022
DOI: 10.1071/PC21039
Abstract: Context Habitat loss is a global problem and in Fiji % of the land area once covered by forests has been converted to grasslands and agricultural land. About 99% of Fiji’s endemic bio ersity and 80% of the land bird species have been identified as forest species. Aims In this study, we compare forest and grassland sites and test for consistency in avian ersity, abundance, foraging guild, and distribution status (endemic, native, introduced to Fiji) over a 5-year period (2016–2020). Methods We surveyed bird communities using the point count method with a 100 m radius and 7-min observation period per site. Key results A one-way analysis of similarities (ANOSIM) analysis showed significant differences in species composition and bird abundance between the forested habitats and grassland habitats. A general linear model test showed significant differences in foraging guild composition and distribution status between forested and grassland habitats. There were no significant differences between the three forested sites (primary montane forest, secondary old-growth forest, old-growth mahogany plantations with regenerating native species), while grassland sites had stronger annual change in species composition. Implications Forest cover, irrespective of whether these forests are of primary or secondary nature, therefore plays an important role in maintaining the native and endemic land bird species and other bio ersity in oceanic island ecosystems such as Viti Levu Island, Fiji.
Publisher: Wiley
Date: 20-06-2016
DOI: 10.1111/JBI.12805
Publisher: Springer Science and Business Media LLC
Date: 11-2012
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2015
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/SP12005
Abstract: Mahogany (Swietenia macrophylla King) plantations cover a considerable area on the south-eastern parts of Viti Levu, Fiji. The understorey of these plantations often comprise a erse, but undocumented, assemblage of native plant species. This study investigates the ersity, composition and regeneration potential of native plant species in the Wainiveiota mahogany plantation 40?50 years after establishment. Ten 10 m x 10 m plots were alternately placed at 10 m intervals perpendicular to a 200 m line transect. A total of 491 in idual plants with dbh ≥ 1 cm, comprising 69 species, 51 genera and 34 families, were s led. In addition to the exotic mahogany, there were 68 native (39 endemic, 24 indigenous and 5 identified to genus only) species recorded. Girronniera celtidifolia Gaud., Dillenia biflora (A.Gray) Martelli ex Dur. & Jacks and Barringtonia edulis Seem. had the highest recruitment and Endospermum macrophyllum (Muell.Arg.) Pax & Hoffm. was the dominant native species. Syzygium Gaertn. (Myrtaceae) was the most erse genus and Myrtaceae the most erse family. With 98% of the sapling recruitment consisting of native species, there is potential for re-establishment of a lowland rainforest dominated by native species over time.
Publisher: Oxford University Press (OUP)
Date: 10-08-2017
Abstract: Refugia can facilitate the persistence of bio ersity under changing environmental conditions, such as anthropogenic climate change, and therefore constitute the best chance of survival for many coral species in the wild. Despite an increasing amount of literature, the concept of coral reef refugia remains poorly defined so that climate change refugia have been confused with other phenomena, including temporal refuges, pristine habitats and physiological processes such as adaptation and acclimatization. We propose six criteria that determine the capacity of refugia to facilitate species persistence, including long-term buffering, protection from multiple climatic stressors, accessibility, microclimatic heterogeneity, size, and low exposure to non-climate disturbances. Any effective, high-capacity coral reef refugium should be characterized by long-term buffering of environmental conditions (for several decades) and multi-stressor buffering (provision of suitable environmental conditions with respect to climatic change, particularly ocean warming and acidification). Although not always essential, the remaining criteria are important for quantifying the capacity of potential refugia.
Publisher: Oxford University Press (OUP)
Date: 25-10-2017
DOI: 10.1093/AOB/MCX107
Publisher: Wiley
Date: 06-09-2020
DOI: 10.1111/OIK.07501
Publisher: Elsevier BV
Date: 06-2023
Publisher: Wiley
Date: 21-12-2017
DOI: 10.1111/AEC.12571
Publisher: Elsevier
Date: 2022
Publisher: Wiley
Date: 13-05-2019
DOI: 10.1111/ECOG.04512
Publisher: Springer Science and Business Media LLC
Date: 05-2019
DOI: 10.1038/S41586-019-1128-0
Abstract: The identity of the dominant root-associated microbial symbionts in a forest determines the ability of trees to access limiting nutrients from atmospheric or soil pools
Publisher: California Digital Library (CDL)
Date: 29-07-2019
DOI: 10.21425/F5FBG43187
Publisher: Wiley
Date: 03-2015
DOI: 10.1890/140055
Publisher: Wiley
Date: 30-11-2017
DOI: 10.1002/ECE3.3541
Publisher: Elsevier BV
Date: 02-2020
Publisher: Cambridge University Press (CUP)
Date: 17-02-2014
DOI: 10.1017/S0030605313000264
Abstract: To identify forests of high priority for conservation in tropical dry forests of New Caledonia, Fiji, the Marquesas and Hawaii, we examined patterns of woody plant species richness (total, native and endemic) and threatened species (IUCN categorization and density) at the stand level, using Gentry's transect method. There were associations between total, native and endemic plant species richness in all four Pacific dry forest regions but we found no significant association with the presence or density of species listed on the IUCN Red List. Dry forests in New Caledonia and Hawaii merit the highest conservation priority in the Pacific, based on level of endemism and number of threatened species. The study sites that merit high conservation priority are Metzdorf, Nekoro and Pindai, in New Caledonia, Kokee and Kaupulehu, in Hawaii, and Vatia, in Fiji. New Caledonia and Fiji have a small dry forest extent and protected area extent compared with other dry forests in bio ersity hotspots. Although we identified priority areas for dry forest conservation, more comparative plot data, presence/absence data in fragments and regional geographical data are needed to adequately manage and protect dry forests in the Pacific.
Publisher: Wiley
Date: 10-07-2012
Publisher: Wiley
Date: 30-07-2018
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/SP09004
Abstract: Cycas seemannii (Cycadaceae) is a widespread and highly variable species. This study investigates morphological variability and ethnobotanical uses throughout the entire range (Torres Strait Islands, Vanuatu, New Caledonia, Fiji and Tonga) of the species. The morphological characters studied are highly variable among populations and unrelated to genetic differences. Characters are also more variable than previously assumed and because of this we provide an updated, detailed taxonomic description of Cycas seemannii based on extensive morphometric data, fieldwork and herbarium specimens. The plant is of great cultural importance in Vanuatu, its seeds are utilised as a source of starch and it is a widely cultivated ornamental. Possible consequences of the plant's decreasing cultural importance are discussed.
Publisher: Wiley
Date: 02-09-2019
DOI: 10.1111/GEB.13001
Publisher: Wiley
Date: 03-10-2020
DOI: 10.1111/JBI.13944
Publisher: Pacific Science
Date: 04-2009
DOI: 10.2984/049.063.0205
Publisher: American Thoracic Society
Date: 15-06-2015
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/SP09004
Abstract: Cycas seemannii (Cycadaceae) is a widespread and highly variable species. This study investigates morphological variability and ethnobotanical uses throughout the entire range (Torres Strait Islands, Vanuatu, New Caledonia, Fiji and Tonga) of the species. The morphological characters studied are highly variable among populations and unrelated to genetic differences. Characters are also more variable than previously assumed and because of this we provide an updated, detailed taxonomic description of Cycas seemannii based on extensive morphometric data, fieldwork and herbarium specimens. The plant is of great cultural importance in Vanuatu, its seeds are utilised as a source of starch and it is a widely cultivated ornamental. Possible consequences of the plant's decreasing cultural importance are discussed.
Publisher: Public Library of Science (PLoS)
Date: 08-01-2014
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/PC18071
Abstract: Despite worldwide knowledge of the importance of the Galápagos archipelago, there is little comparative plot data from the forests in the dry regions. We examined patterns of woody plant (≥2.5cm diameter at breast height (DBH)) species richness and structure using Gentry’s transect method (0.1ha) on the three largest islands in the Galápagos. We identified the conservation status of woody plants within the dry forest region, assessed forest cover and change in the region, and compared field results to other tropical dry forests in the Pacific. Of the 22 species encountered (11 native, 11 endemic), there were no non-native species and only one threatened species. Isabela, Santa Cruz and San Cristóbal have similar overall levels of species, genera, family and liana richness per site, but significantly different tree species richness, density and tree height per transect. Geospatial databases identified 51 species (native 40%, endemic 60%) of woody plants (≥2.5cm DBH) within the dry forest region of the Galápagos and 13 species (10 from the genus Scalesia) on the IUCN Red List. There is an estimated 551.97km2 of dry forest in the Galápagos and there has been little change (& .01%) in forest cover from 2000 to 2015. Dry forests of the Galápagos have similar levels of species richness to Hawaii and the Marquesas but contain lower densities, basal areas and tree heights than other dry forests in the Pacific. These dry forests appear to be the best preserved and protected tropical dry forest in the Pacific.
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/BT10181
Abstract: We examined evolutionary relationships, hybridisation and genetic ersity in species of Dacrydium (Podocarpaceae) in Remote Oceania, where it is restricted to New Caledonia and Fiji. We used cpDNA sequence (trnL–trnF) data to construct a phylogeny and estimate taxon ergence by using a relaxed molecular clock approach. The phylogeny was verified using allozymes, which were also used to investigate genetic ersity of all species and the hybridisation dynamics of two endangered species, D. guillauminii and D. nidulum. Our results suggested that Dacrydium species in Remote Oceania form a monophyletic group that arose and ersified within the last 20 million years through long-distance dispersal and a range of speciation mechanisms. Whereas we detected no hybridisation between the Fijian species D. nausoriense and D. nidulum, we confirmed hybridisation between D. guillauminii and D. araucarioides in New Caledonia and determined introgression to be assymetric from the widespread D. araucarioides into the rare, restricted-range species D. guillauminii. In addition, D. guillauminii had lower genetic ersity than did the other species of Dacrydium studied, which had genetic ersity similar to that of other gymnosperms. Our results provided evidence for the recent and complex ersification of Dacrydium in Remote Oceania. In addition, low genetic ersity of and introgression from D. araucarioides, are of grave concern for the conservation of D. guillauminii.
Publisher: Cambridge University Press (CUP)
Date: 09-2018
DOI: 10.1017/S0266467418000299
Abstract: To investigate changes in vegetation and climate with altitude, we established forest plots and recorded climatic data at 100-m intervals between 550–1100 m asl on the western slopes of Mount Batilamu, Mount Koroyanitu range, Viti Levu, Fiji. Trees with a dbh ≥10 cm were identified and measured in 21 10 × 10-m plots, starting at 750 m altitude. Temperature and relative humidity sensors were deployed in two habitats, leaf litter and 50 cm above the ground, and two vegetation types, grasslands and forest, at six altitudes over a 48-h period. Two significantly distinct forest types, lowland and montane, were present. Montane forest was found at higher elevations ( m asl) and had significantly higher stem density. Mean temperature decreased significantly with altitude and was strongly moderated by vegetation type (lower average and less variation in forest). While average relative humidity significantly increased with altitude, it was strongly moderated by both habitat and vegetation type (higher average and less variation in leaf litter and forest). The lapse rate varied with time of day (higher during the day) and vegetation type (higher in grasslands). Therefore, vegetation and microhabitats create unique microclimates, and this should be considered when investigating current or future climatic patterns along altitudinal gradients on forested mountains.
Publisher: Springer Science and Business Media LLC
Date: 23-10-2023
Publisher: University of South Australia & University of Adelaide
Date: 2022
DOI: 10.25954/FR78-QH71
Publisher: Wiley
Date: 31-03-2021
Abstract: Conservation management to protect coastal ecosystems sometimes overlooks site‐specific fine‐scale heterogeneity. For ex le, while habitat loss is a known key driver of population declines in many shorebirds, these birds are also dependent on high‐quality habitats to maximize energy stores. Here we describe the microhabitats provided by beach‐cast wrack (washed up macroalgae and seagrasses), a resource threatened by harvesting and beach cleaning, and how shorebirds utilize these. We measured the temperature and absolute humidity at 10 cm above three substrates (fresh wrack, aged wrack and sand) and then related bird behaviour (roosting vs. foraging) to climatic and environmental data. Freshly beach‐cast wrack mostly provided cooler and less humid habitats, but warmer temperatures than aged wrack or sand in the early mornings. Microtopography created by shelter from prevailing winds and wrack depth modified these general trends. Generally, temperature predicted where shorebirds overall and the two most common species, the double‐banded plover Charadrius bicinctus and red‐necked stint Calidris ruficollis , were observed. During most of the day, foraging and roosting were more likely to occur on the warmer aged wrack. In the early morning, when fresh wrack provided the warmer temperatures, birds tended to roost and forage on fresh wrack. Synthesis and Applications . Beach‐cast wrack creates a complex mosaic of unique microclimates varying in space and time, which allows shorebirds to minimize energy expenditure by selecting the thermally most favourable habitats for roosting and foraging. Removal of beach‐cast wrack for commercial and aesthetic reasons thus reduces habitat quality and increases energy expenditure in shorebirds. Associated declines in energy stores may be contributing to declines in shorebird populations. Management of coastal ecosystems and shorebirds therefore needs to consider and maintain fine‐scale environmental heterogeneity at local scales.
Publisher: Wiley
Date: 09-01-2018
DOI: 10.1111/GEB.12712
Publisher: Elsevier BV
Date: 12-2022
DOI: 10.1016/J.TPLANTS.2022.08.005
Abstract: Global change is altering interactions between ecological disturbances. We review interactions between tropical cyclones and fires that affect woody biomes in many islands and coastal areas. Cyclone-induced damage to trees can increase fuel loads on the ground and dryness in the understory, which increases the likelihood, intensity, and area of subsequent fires. In forest biomes, cyclone-fire interactions may initiate a grass-fire cycle and establish stable open-canopy biomes. In cyclone-prone regions, frequent cyclone-enhanced fires may generate and maintain stable open-canopy biomes (e.g., savannas and woodlands). We discuss how global change is transforming fire and cyclone regimes, extensively altering cyclone-fire interactions. These altered cyclone-fire interactions are shifting biomes away from historical states and causing loss of bio ersity.
Publisher: Springer Science and Business Media LLC
Date: 22-02-2023
DOI: 10.1007/S10666-023-09873-6
Abstract: The species-area relationship (SAR) is widely applied in ecology. Mathematically, it is usually expressed as either a semi-log or power-law relationship, with the former being introduced by Gleason and the latter by Arrhenius. We here resolve the dispute about which form of the SAR to prefer by introducing a novel model that smoothly transforms between the Gleason semi-log (GSL) and Arrhenius power law (APL) forms. The model introduced has the form of ln q ( S ) = a + z ln A , with ln q being a generalized logarithmic function, which is a linear map ( y = x ) for q = 0 and a logarithmic map ( y = ln x ) for q = 1 and q can take any intermediate value between 0 and 1. We applied this model to 100 datasets (mostly islands), linking species richness to island area. The APL was the preferred model in 68% of head-to-head comparisons with the GSL. Both models were supported in 40% of cases. In just under half (44%) of the cases, an intermediate model best explained the data. The results demonstrate the utility of a simple intermediate SAR model. Visualizing the profile of the range of model fits for all q ∈ [0 , 1] (a q chart) allows us to gain extra insight into SARs not yielded by head-to-head comparisons of GSL and APL. The mathematics related to the generalized logarithmic function introduced here should have applications to other areas of ecological modelling.
Publisher: Springer Science and Business Media LLC
Date: 23-08-2023
DOI: 10.1038/S41586-023-06440-7
Abstract: Determining the drivers of non-native plant invasions is critical for managing native ecosystems and limiting the spread of invasive species 1,2 . Tree invasions in particular have been relatively overlooked, even though they have the potential to transform ecosystems and economies 3,4 . Here, leveraging global tree databases 5–7 , we explore how the phylogenetic and functional ersity of native tree communities, human pressure and the environment influence the establishment of non-native tree species and the subsequent invasion severity. We find that anthropogenic factors are key to predicting whether a location is invaded, but that invasion severity is underpinned by native ersity, with higher ersity predicting lower invasion severity. Temperature and precipitation emerge as strong predictors of invasion strategy, with non-native species invading successfully when they are similar to the native community in cold or dry extremes. Yet, despite the influence of these ecological forces in determining invasion strategy, we find evidence that these patterns can be obscured by human activity, with lower ecological signal in areas with higher proximity to shipping ports. Our global perspective of non-native tree invasion highlights that human drivers influence non-native tree presence, and that native phylogenetic and functional ersity have a critical role in the establishment and spread of subsequent invasions.
Publisher: Wiley
Date: 08-05-2012
Publisher: Informa UK Limited
Date: 02-07-2020
Publisher: CSIRO Publishing
Date: 2002
DOI: 10.1071/SP02006
Abstract: Using four 100 � 10 m transects, the coastal vegetation types and their horizontal stratification at Taunovo Bay, Pacific Harbour, were investigated. The common stratification pattern of herb zone, shrub zone (dominated by the invasive species Chrysobalanus icaco) and tree zone was observed. Littoral forest composed of species commonly associated with sandy beaches and species commonly associated lowland rainforest was observed. This vegetation type is here reported for the first time from Fiji and is probably caused by siliceous deposits from a nearby river. A detailed study of the extend, composition and distribution of this unique vegetation type should be conducted before the development project (planned at the study site) is approved.
Publisher: MDPI AG
Date: 25-03-0025
DOI: 10.3390/D14030223
Abstract: Charles Darwin proposed his ‘principle of ergence’ to account for changes in traits that could promote speciation and coexistence of erse forms through occupation of different niches to reduce interspecific competition. We explore interspecific foraging behaviour overlap in Fiji’s forest birds, and address two main questions: (1) Is there vertical stratification of foraging behavior? and (2) Is there evidence of interspecific competition driving the differences in foraging behaviour? We explore these questions across three foraging guilds, nectarivores (three species), insectivores (two species), and omnivores (two species), and find vertical portioning of foraging in each group. To investigate the effect of interspecific competition, we compared foraging heights of the Orange-breasted Myzomela (Myzomela jugularis) honeyeater on Viti Levu Island (where it coexists with two other honeyeater species) and Leleuvia Island (no other honeyeater species). On the main island Viti Levu, we found evidence for vertical niche partitioning within each foraging guild. On Leleuvia, with the ‘one-species only foraging guild’, Orange-breasted Myzomela occupied broader vertical foraging niche than on Viti Levu with two other competitor honeyeater species. This result supports the idea that vertical foraging height can be shaped by interspecific competition. The findings of this study support Darwin’s principle of ergence in Fiji’s forest birds for every foraging guild measured and adds to our understanding of the significance of interspecific competition and niche ergence for patterns of ecological speciation on islands.
Publisher: Public Library of Science (PLoS)
Date: 20-05-2021
DOI: 10.1371/JOURNAL.PONE.0252063
Abstract: There is a debate concerning the definition and extent of tropical dry forest biome and vegetation type at a global spatial scale. We identify the potential extent of the tropical dry forest biome based on bioclimatic definitions and climatic data sets to improve global estimates of distribution, cover, and change. We compared four bioclimatic definitions of the tropical dry forest biome–Murphy and Lugo, Food and Agriculture Organization (FAO), DryFlor, aridity index–using two climatic data sets: WorldClim and Climatologies at High-resolution for the Earth’s Land Surface Areas (CHELSA). We then compared each of the eight unique combinations of bioclimatic definitions and climatic data sets using 540 field plots identified as tropical dry forest from a literature search and evaluated the accuracy of World Wildlife Fund tropical and subtropical dry broadleaf forest ecoregions. We used the definition and climate data that most closely matched field data to calculate forest cover in 2000 and change from 2001 to 2020. Globally, there was low agreement ( 58%) between bioclimatic definitions and WWF ecoregions and only 40% of field plots fell within these ecoregions. FAO using CHELSA had the highest agreement with field plots (81%) and was not correlated with the biome extent. Using the FAO definition with CHELSA climatic data set, we estimate 4,931,414 km 2 of closed canopy (≥ 40% forest cover) tropical dry forest in 2000 and 4,369,695 km 2 in 2020 with a gross loss of 561,719 km 2 (11.4%) from 2001 to 2020. Tropical dry forest biome extent varies significantly based on bioclimatic definition used, with nearly half of all tropical dry forest vegetation missed when using ecoregion boundaries alone, especially in Africa. Using site-specific field validation, we find that the FAO definition using CHELSA provides an accurate, standard, and repeatable way to assess tropical dry forest cover and change at a global scale.
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/BT17096
Abstract: Rainforests in the South Pacific hold a considerable amount of plant ersity, with rates of species endemism % in some countries. This ersity is rapidly disappearing under pressure from logging, clearing for agriculture or mining, introduced pests and diseases and other anthropogenic sources. Ex situ conservation techniques offer a means to limit the loss of plant ersity. Seed banking is considered the most efficient and cost effective of these techniques but is applicable only to seed capable of tolerating desiccation and cold storage. Data on the degree of tolerance of these conditions was lacking for more than half of the 1503 South Pacific rainforest genera examined for this review. Of the 710 genera for which data were available, the storage behaviour of 324 was based on an assessment of only one or two species, although 76% of those genera contained at least 10 species. Many of the unstudied or poorly studied genera are shared across several South Pacific nations, providing an excellent opportunity for collaboration on future ex situ research and conservation. Of the 386 genera for which three or more species have been studied, 343 have a very high proportion of species ( % of those tested) that are suitable for seed banking. Seed banking could therefore provide a suitable means for preserving a large proportion of the rainforest flora before it becomes extinct in the wild. Alternatives for preserving species that are not suitable for seed banking are also discussed.
Publisher: Wiley
Date: 16-12-2016
DOI: 10.1111/JBI.12927
Publisher: CSIRO Publishing
Date: 2001
DOI: 10.1071/SP01007
Abstract: Cycas seemannii occurs in several habitats in Vanuatu, New Caledonia, Fiji and Tonga, but is mostly coastal. Growth rates are about 5-15cm.yr-1 and sex ratios observed were almost neutral. Mechanisms to survive in adverse environments are discussed. Female plants were found to produce, on average, longer leaves with more leaflets than male plants. Larvae of an unidentified moth, which are parasitised by at least two species of wasps, mine the leaflets of C. seemannii. Reproduction occurs mainly by seeds and bulbils. Wind appears to be the major pollination agent. Seed dispersal, other than oceanic, appears to be inefficient.
Publisher: Wiley
Date: 27-01-2021
DOI: 10.1111/ECOG.05410
Abstract: The extraordinary ersity of orchids has captivated scientists for more than a century, yet their complex spatial patterns at large scales remain poorly resolved. On islands, orchid ersity patterns are especially puzzling. While some islands are centres of orchid ersity, orchids are underrepresented on most islands. To disentangle such complex patterns, key functional differences among orchids must be considered – a distinction seldom made in biogeographical analyses. Using a global dataset of 454 islands, we tested prominent hypotheses in island biogeography, while simultaneously making the distinction between epiphytes and two terrestrial life forms (geophytes and non‐geophytes). Orchid ersity was unevenly distributed across islands and life forms. Epiphytic orchid ersity strongly increased with temperature, illustrating the near confinement of epiphytes to the tropics. Geophytes became proportionally more important with increasing seasonality, highlighting their ability to withstand harsh climatic conditions. Epiphytes and non‐geophytes both displayed responses (e.g. negative relationship with seasonality) related to their dependence on consistently favourable conditions, possibly because of the absence of subterranean storage organs. This highlights that the factors explaining orchid ersity differ strongly with, and are related to, life form. We suggest that key functional differences within and across plant families be considered in future studies to better understand drivers of complex ersity patterns.
Publisher: Oxford University Press (OUP)
Date: 26-12-2016
DOI: 10.1093/AOB/MCW233
Publisher: Public Library of Science (PLoS)
Date: 14-08-2017
Publisher: CSIRO Publishing
Date: 2021
DOI: 10.1071/PC19052
Abstract: Ebony wood, the black heartwood of trees in the genus Diospyros, is a high-value commodity of many Pacific Islands. The revenue earned from the sale of ebony carvings is important for many low-income rural communities, resulting in high harvesting pressure and reported declines of ebony-producing species. This study investigates the impact of ebony wood harvesting on species of Diospyros on Vangunu Island, Western Solomon Islands. Diospyros samoensis, locally known as ‘rihe’, was the main source of ebony wood, with D. vera occasionally harvested but producing poorer quality wood. For D. samoensis, we investigated the existing ethnobotanical knowledge and harvesting dynamics using questionnaires and surveyed 11 populations using five 15×15m plots. Although D. samoensis was common throughout the study area, trees with harvestable ebony heartwood were considered rare. The sale of ebony carvings contributed substantially to the livelihood of carvers. Harvesting practices cause considerable damage to the stem and appeared to alter population structure, with fewer seedlings found in stands with higher harvesting intensities (r=−0.704, P=0.008). Therefore, populations of D. samoensis appear to be negatively impacted by current harvesting practices, which should be modified to (1) cause less damage to in idual trees and populations, and (2) protect larger and older trees to help regeneration. Therefore, the increasing rarity of ebony heartwood in the Pacific may not equate to dangerous declines in Diospyros species and implementing low-impact harvesting practices could help improve the health and long-term persistence of Diospyros populations.
Publisher: Elsevier
Date: 2015
Publisher: Elsevier BV
Date: 09-2014
Publisher: Wiley
Date: 03-03-2014
DOI: 10.1111/DDI.12185
Publisher: MDPI AG
Date: 21-06-2023
DOI: 10.3390/LAND12071271
Abstract: A disjunct population of red stringybark (Eucalyptus macrorhyncha) trees in South Australia is experiencing increasing amounts of dieback. Because the population is considered vulnerable to extinction, we investigated spatiotemporal vegetation changes, quantified the extent of dieback, and determined how topography influences dieback using aerial and satellite imagery. Classification of vegetation health status using hyperspectral aerial imagery indicated that 37% (accuracy = 0.87 Kappa) of the population was unhealthy and potentially experiencing dieback. When correlating this classification with a digital terrain model (DTM), the aspect and amount of solar radiation had the strongest relationship with the presence of unhealthy vegetation. PlanetScope satellite-derived, and spectral index-based analysis indicated that 7% of the red stringybark population experienced negative vegetation health changes during a five-year period (2017–2022), with positive vegetation health changes (9.5%) noted on pole-facing slopes. Therefore, our integrated remote sensing approach documented the extent and spatiotemporal dynamics of dieback, suggesting it could be applied in other studies. Topographical aspects exposed to high-solar radiation were particularly vulnerable to dieback, and pole-facing aspects demonstrated some recovery between droughts. The influence of topography and maps of vegetation health can be used to guide future management and restoration of the population.
Publisher: Informa UK Limited
Date: 09-05-2019
Publisher: CSIRO Publishing
Date: 2001
DOI: 10.1071/SP01007
Abstract: Cycas seemannii occurs in several habitats in Vanuatu, New Caledonia, Fiji and Tonga, but is mostly coastal. Growth rates are about 5-15cm.yr-1 and sex ratios observed were almost neutral. Mechanisms to survive in adverse environments are discussed. Female plants were found to produce, on average, longer leaves with more leaflets than male plants. Larvae of an unidentified moth, which are parasitised by at least two species of wasps, mine the leaflets of C. seemannii. Reproduction occurs mainly by seeds and bulbils. Wind appears to be the major pollination agent. Seed dispersal, other than oceanic, appears to be inefficient.
Publisher: Springer Science and Business Media LLC
Date: 09-05-2019
DOI: 10.1038/S41598-019-43603-X
Abstract: Fine-scale topographic complexity creates important microclimates that can facilitate species to grow outside their main distributional range and increase bio ersity locally. Enclosed depressions in karst landscapes (‘dolines’) are topographically complex environments which produce microclimates that are drier and warmer (equator-facing slopes) and cooler and moister (pole-facing slopes and depression bottoms) than the surrounding climate. We show that the distribution patterns of functional groups for organisms in two different phyla, Arthropoda (ants) and Tracheophyta (vascular plants), mirror this variation of microclimate. We found that north-facing slopes and bottoms of solution dolines in northern Hungary provided key habitats for ant and plant species associated with cooler and/or moister conditions. Contrarily, south-facing slopes of dolines provided key habitats for species associated with warmer and/or drier conditions. Species occurring on the surrounding plateau were associated with intermediate conditions. We conclude that karst dolines provide a ersity of microclimatic habitats that may facilitate the persistence of taxa with erse environmental preferences, indicating these dolines to be potential safe havens for multiple phyla under local and global climate oscillations.
Publisher: Wiley
Date: 16-05-2014
DOI: 10.1111/JBI.12343
Publisher: Elsevier BV
Date: 04-2020
DOI: 10.1016/J.TPLANTS.2019.12.022
Abstract: The study of insular systems has a long history in ecology and biogeography. Island plants often differ remarkably from their noninsular counterparts, constituting excellent models for exploring eco-evolutionary processes. Trait-based approaches can help to answer important questions in island biogeography, yet plant trait patterns on islands remain understudied. We discuss three key hypotheses linking functional ecology to island biogeography: (i) plants in insular systems are characterized by distinct functional trait syndromes (compared with noninsular environments) (ii) these syndromes differ between true islands and terrestrial habitat islands and (iii) island characteristics influence trait syndromes in a predictable manner. We are convinced that implementing trait-based comparative approaches would considerably further our understanding of plant ecology and evolution in insular systems.
Publisher: Wiley
Date: 05-05-2014
DOI: 10.1111/AEC.12146
Publisher: Wiley
Date: 04-2022
DOI: 10.1002/ECE3.8817
Abstract: The importance of terrestrial coastal ecosystems for maintaining healthy coral reef ecosystems remains understudied. Sea kraits are hibious snakes that require healthy coral reefs for foraging, but little is known about their requirements of terrestrial habitats, where they slough their skin, digest prey, and breed. Using concurrent microclimate measurements and behavior surveys, we show that a small, topographically flat atoll in Fiji with coastal forest provides many microhabitats that relate to the behaviors of Yellow Lipped Sea Kraits, Laticauda colubrina . Microclimates were significantly related to canopy cover, leaf litter depth, and distance from the high‐water mark (HWM). Sea kraits were almost exclusively observed in coastal forest within 30 m of the HWM. Sloughing of skins only occurred within crevices of mature or dying trees. Resting L. colubrina were significantly more likely to occur at locations with higher mean diurnal temperatures, lower leaf litter depths, and shorter distances from the HWM. On Leleuvia, behavior of L. colubrina therefore relates to environmental heterogeneity created by old‐growth coastal forests, particularly canopy cover and crevices in mature and dead tree trunks. The importance of healthy coastal habitats, both terrestrial and marine, for L. colubrina suggests it could be a good flagship species for advocating integrated land‐sea management. Furthermore, our study highlights the importance of coastal forests and topographically flat atolls for bio ersity conservation. Effective conservation management of hibious species that utilize land‐ and seascapes is therefore likely to require a holistic approach that incorporates connectivity among ecosystems and environmental heterogeneity at all relevant scales.
Publisher: Wiley
Date: 05-2021
DOI: 10.1111/JVS.13021
Abstract: Trees dominate the biomass in many ecosystems and are essential for ecosystem functioning and human well‐being. They are also one of the best‐studied functional groups of plants, with vast amounts of bio ersity data available in scattered sources. We here aim to illustrate that an efficient integration of these data could produce a more holistic understanding of vegetation. To assess the extent of potential data integration, we use key databases of plant bio ersity to: (a) obtain a list of tree species and their distributions (b) identify coverage of and gaps in different aspects of tree bio ersity data and (c) discuss large‐scale patterns of tree bio ersity in relation to vegetation. Our global list of trees included 58,044 species. Taxonomic coverage varies in three key databases, with data on the distribution, functional traits, and molecular sequences for about 84%, 45% and 44% of all tree species, which is % greater than for plants overall. For 28% of all tree species, data are available in all three databases. However, less data are digitally accessible about the demography, ecological interactions, and socio‐economic role of tree species. Integrating and imputing existing tree bio ersity data, mobilization of non‐digitized resources and targeted data collection, especially in tropical countries, could help closing some of the remaining data gaps. Due to their key ecosystem roles and having large amounts of accessible data, trees are a good model group for understanding vegetation patterns. Indeed, tree bio ersity data are already beginning to elucidate the community dynamics, functional ersity, evolutionary history and ecological interactions of vegetation, with great potential for future applications. An interoperable and openly accessible framework linking various databases would greatly benefit future macroecological studies and should be linked to a platform that makes information readily accessible to end users in bio ersity conservation and management.
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/PC14920
Abstract: In many developing countries, threatened species lists are unavailable and IUCN Red Lists are very incomplete. Because limited resources are available for conservation in developing countries, detailed field assessments and scientific study of threatened species are often not feasible. However, considerable knowledge about bio ersity exists among experts and local land users. We used questionnaires as part of field surveys to compile information about the abundance, conservation threats, distribution, and ecology of populations of four threatened and iconic target species in Fiji (Acmopyle sahniana, Dacrydium nausoriense, Podocarpus affinis [all Podocarpaceae], and Cynometra falcata [Leguminosae]). These questionnaires were completed in the field for all known populations by an assessor, compiling field observations and measurements with information from local land users and local and outside experts. For the four species in this study, the questionnaires improved estimates of population size, identified previously unknown populations, provided estimates of regeneration, and identified key conservation threats. Species of highly fragmented remnants in drier climates were less protected than those in more contiguous forests of moist climates. The methods employed provided rapid, cost-effective information that can be used to revise IUCN Red List and conservation status assessments and are applicable to other Pacific Island and developing countries.
Publisher: Wiley
Date: 18-03-2019
DOI: 10.1111/AEC.12745
Publisher: Frontiers Media SA
Date: 27-09-2021
Publisher: Springer Science and Business Media LLC
Date: 08-08-2022
DOI: 10.1038/S41559-022-01831-X
Abstract: The latitudinal ersity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with in idual tree information and local biophysical characteristics from ~1.3 million s le plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of bio ersity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers.
Publisher: Cambridge University Press (CUP)
Date: 2002
DOI: 10.1017/S0030605302000078
Abstract: The conservation status of Cycas seemannii , native to Vanuatu, New Caledonia, Fiji and Tonga, is assessed based on isozyme analysis, abundance estimates and factors affecting the survival of the species. Genetic variation in the species is low and genetic differentiation between populations is high, as compared to plants in general and to other cycads. Lower genetic variation was detected in a fragmented population as compared to less disturbed populations. Low gene flow was also detected, implying little contact between the various populations. A conservative estimate of 17,000 in iduals remaining in the wild was obtained, with more than half of these located on the islands of Vanuatu. Accounts of past abundance suggest declining population sizes, most likely the result of repeated burning. Other factors that may be contributing to the decline are decreasing importance to and protection by humans, habitat alteration for agricultural and developmental purposes, and poor dispersal and recolonisation potential. An assessment based on the present estimated abundance and what is known of recent declines in numbers, indicates that the species should be categorised as Vulnerable on the IUCN Red List. On some of the densely populated islands, such as Viti Levu in Fiji and Nukualofa in Tonga, the species is locally Endangered or Critically Endangered. Possible conservation measures are suggested, and it is emphasised that populations on different islands must be considered separately because of their genetic differentiation.
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/SP12005
Abstract: Mahogany (Swietenia macrophylla King) plantations cover a considerable area on the south-eastern parts of Viti Levu, Fiji. The understorey of these plantations often comprise a erse, but undocumented, assemblage of native plant species. This study investigates the ersity, composition and regeneration potential of native plant species in the Wainiveiota mahogany plantation 40?50 years after establishment. Ten 10 m x 10 m plots were alternately placed at 10 m intervals perpendicular to a 200 m line transect. A total of 491 in idual plants with dbh ≥ 1 cm, comprising 69 species, 51 genera and 34 families, were s led. In addition to the exotic mahogany, there were 68 native (39 endemic, 24 indigenous and 5 identified to genus only) species recorded. Girronniera celtidifolia Gaud., Dillenia biflora (A.Gray) Martelli ex Dur. & Jacks and Barringtonia edulis Seem. had the highest recruitment and Endospermum macrophyllum (Muell.Arg.) Pax & Hoffm. was the dominant native species. Syzygium Gaertn. (Myrtaceae) was the most erse genus and Myrtaceae the most erse family. With 98% of the sapling recruitment consisting of native species, there is potential for re-establishment of a lowland rainforest dominated by native species over time.
Publisher: Springer Science and Business Media LLC
Date: 09-11-2019
DOI: 10.1007/S10531-019-01896-4
Abstract: Dolines are depressions in karst landscapes that are of high value for conservation, providing habitats and supporting species not found in the surrounding landscape. This is due to their high microhabitat ersity and ability to decouple microclimate from regional climate changes, making them potential refugia for bio ersity. Nevertheless, local anthropogenic disturbances have had considerable impact on the species composition and vegetation structure of many dolines. Here we investigate the conservation value of dolines in three European karst areas, where different levels and types of anthropogenic disturbances have been shaping the vegetation for centuries, using the number of plant species that are cool-adapted, moist-adapted and of high conservation importance (i.e. vulnerable species) as indicators. We found that anthropogenic disturbances generally have a negative impact, reducing the number of vulnerable species supported by dolines. However, more cool-adapted and moist-adapted species were found in some dolines planted with non-native Picea abies than in less disturbed dolines, indicating that anthropogenic disturbances can also have positive consequences for bio ersity. We conclude that anthropogenic disturbances alter the capacity of dolines to support vulnerable species, and that this will impact survival of species in landscapes under global warming. In this context, the effects of various disturbances on species composition and ersity need to carefully considered to determine the best conservation and/or management options.
Publisher: Oxford University Press (OUP)
Date: 15-09-2018
DOI: 10.1093/AOB/MCY173
No related grants have been discovered for Gunnar Keppel.