ORCID Profile
0000-0002-2831-2933
Current Organisation
James Cook University Cairns Campus
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Plant Physiology | Ecological Impacts of Climate Change | Ecological Applications | Terrestrial Ecology | Ecological Applications not elsewhere classified | Environmental Science and Management | Conservation and Biodiversity | Landscape Ecology | Community Ecology
Forest and Woodlands Flora, Fauna and Biodiversity | Climate Change Adaptation Measures | Ecosystem Adaptation to Climate Change | Ecosystem Assessment and Management of Forest and Woodlands Environments | Rehabilitation of Degraded Forest and Woodlands Environments | Expanding Knowledge in the Biological Sciences |
Publisher: Elsevier BV
Date: 12-2009
DOI: 10.1016/J.TREE.2009.06.009
Abstract: Linear infrastructure such as roads, highways, power lines and gas lines are omnipresent features of human activity and are rapidly expanding in the tropics. Tropical species are especially vulnerable to such infrastructure because they include many ecological specialists that avoid even narrow (<30-m wide) clearings and forest edges, as well as other species that are susceptible to road kill, predation or hunting by humans near roads. In addition, roads have a major role in opening up forested tropical regions to destructive colonization and exploitation. Here, we synthesize existing research on the impacts of roads and other linear clearings on tropical rainforests, and assert that such impacts are often qualitatively and quantitatively different in tropical forests than in other ecosystems. We also highlight practical measures to reduce the negative impacts of roads and other linear infrastructure on tropical species.
Publisher: Resilience Alliance, Inc.
Date: 2016
Publisher: Springer Science and Business Media LLC
Date: 04-2021
DOI: 10.1038/S41559-021-01418-Y
Abstract: The forests of Amazonia are among the most bio erse plant communities on Earth. Given the immediate threats posed by climate and land-use change, an improved understanding of how this extraordinary bio ersity is spatially organized is urgently required to develop effective conservation strategies. Most Amazonian tree species are extremely rare but a few are common across the region. Indeed, just 227 'hyperdominant' species account for >50% of all in iduals >10 cm diameter at 1.3 m in height. Yet, the degree to which the phenomenon of hyperdominance is sensitive to tree size, the extent to which the composition of dominant species changes with size class and how evolutionary history constrains tree hyperdominance, all remain unknown. Here, we use a large floristic dataset to show that, while hyperdominance is a universal phenomenon across forest strata, different species dominate the forest understory, midstory and canopy. We further find that, although species belonging to a range of phylogenetically dispersed lineages have become hyperdominant in small size classes, hyperdominants in large size classes are restricted to a few lineages. Our results demonstrate that it is essential to consider all forest strata to understand regional patterns of dominance and composition in Amazonia. More generally, through the lens of 654 hyperdominant species, we outline a tractable pathway for understanding the functioning of half of Amazonian forests across vertical strata and geographical locations.
Publisher: Wiley
Date: 03-03-2014
DOI: 10.1111/ELE.12252
Publisher: American Association for the Advancement of Science (AAAS)
Date: 03-03-2017
Abstract: The extent to which pre-Columbian societies altered Amazonian landscapes is hotly debated. We performed a basin-wide analysis of pre-Columbian impacts on Amazonian forests by overlaying known archaeological sites in Amazonia with the distributions and abundances of 85 woody species domesticated by pre-Columbian peoples. Domesticated species are five times more likely than nondomesticated species to be hyperdominant. Across the basin, the relative abundance and richness of domesticated species increase in forests on and around archaeological sites. In southwestern and eastern Amazonia, distance to archaeological sites strongly influences the relative abundance and richness of domesticated species. Our analyses indicate that modern tree communities in Amazonia are structured to an important extent by a long history of plant domestication by Amazonian peoples.
Publisher: Wiley
Date: 2007
Publisher: Wiley
Date: 06-2006
Publisher: American Association for the Advancement of Science (AAAS)
Date: 16-10-1998
DOI: 10.1126/SCIENCE.282.5388.439
Abstract: The role of the world's forests as a “sink” for atmospheric carbon dioxide is the subject of active debate. Long-term monitoring of plots in mature humid tropical forests concentrated in South America revealed that biomass gain by tree growth exceeded losses from tree death in 38 of 50 Neotropical sites. These forest plots have accumulated 0.71 ton, plus or minus 0.34 ton, of carbon per hectare per year in recent decades. The data suggest that Neotropical forests may be a significant carbon sink, reducing the rate of increase in atmospheric carbon dioxide.
Publisher: Springer Science and Business Media LLC
Date: 17-01-2018
DOI: 10.1038/S41598-017-18927-1
Abstract: Species distribution models (SDMs) are widely used in ecology and conservation. Presence-only SDMs such as MaxEnt frequently use natural history collections (NHCs) as occurrence data, given their huge numbers and accessibility. NHCs are often spatially biased which may generate inaccuracies in SDMs. Here, we test how the distribution of NHCs and MaxEnt predictions relates to a spatial abundance model, based on a large plot dataset for Amazonian tree species, using inverse distance weighting (IDW). We also propose a new pipeline to deal with inconsistencies in NHCs and to limit the area of occupancy of the species. We found a significant but weak positive relationship between the distribution of NHCs and IDW for 66% of the species. The relationship between SDMs and IDW was also significant but weakly positive for 95% of the species, and sensitivity for both analyses was high. Furthermore, the pipeline removed half of the NHCs records. Presence-only SDM applications should consider this limitation, especially for large bio ersity assessments projects, when they are automatically generated without subsequent checking. Our pipeline provides a conservative estimate of a species’ area of occupancy, within an area slightly larger than its extent of occurrence, compatible to e.g. IUCN red list assessments.
Publisher: Pensoft Publishers
Date: 24-02-2016
DOI: 10.3897/BDJ.4.E7599
Publisher: Springer Science and Business Media LLC
Date: 09-11-2020
DOI: 10.1038/S41467-020-18996-3
Abstract: The carbon sink capacity of tropical forests is substantially affected by tree mortality. However, the main drivers of tropical tree death remain largely unknown. Here we present a pan-Amazonian assessment of how and why trees die, analysing over 120,000 trees representing 3800 species from 189 long-term RAINFOR forest plots. While tree mortality rates vary greatly Amazon-wide, on average trees are as likely to die standing as they are broken or uprooted—modes of death with different ecological consequences. Species-level growth rate is the single most important predictor of tree death in Amazonia, with faster-growing species being at higher risk. Within species, however, the slowest-growing trees are at greatest risk while the effect of tree size varies across the basin. In the driest Amazonian region species-level bioclimatic distributional patterns also predict the risk of death, suggesting that these forests are experiencing climatic conditions beyond their adaptative limits. These results provide not only a holistic pan-Amazonian picture of tree death but large-scale evidence for the overarching importance of the growth–survival trade-off in driving tropical tree mortality.
Publisher: Wiley
Date: 13-09-2022
DOI: 10.1111/ECOG.06125
Abstract: Tree ersity and composition in Amazonia are known to be strongly determined by the water supplied by precipitation. Nevertheless, within the same climatic regime, water availability is modulated by local topography and soil characteristics (hereafter referred to as local hydrological conditions), varying from saturated and poorly drained to well‐drained and potentially dry areas. While these conditions may be expected to influence species distribution, the impacts of local hydrological conditions on tree ersity and composition remain poorly understood at the whole Amazon basin scale. Using a dataset of 443 1‐ha non‐flooded forest plots distributed across the basin, we investigate how local hydrological conditions influence 1) tree alpha ersity, 2) the community‐weighted wood density mean (CWM‐wd) – a proxy for hydraulic resistance and 3) tree species composition. We find that the effect of local hydrological conditions on tree ersity depends on climate, being more evident in wetter forests, where ersity increases towards locations with well‐drained soils. CWM‐wd increased towards better drained soils in Southern and Western Amazonia. Tree species composition changed along local soil hydrological gradients in Central‐Eastern, Western and Southern Amazonia, and those changes were correlated with changes in the mean wood density of plots. Our results suggest that local hydrological gradients filter species, influencing the ersity and composition of Amazonian forests. Overall, this study shows that the effect of local hydrological conditions is pervasive, extending over wide Amazonian regions, and reinforces the importance of accounting for local topography and hydrology to better understand the likely response and resilience of forests to increased frequency of extreme climate events and rising temperatures.
Publisher: Elsevier BV
Date: 10-2017
Publisher: Cambridge University Press (CUP)
Date: 03-2004
DOI: 10.1017/S0266467403001032
Abstract: In fragmented tropical landscapes, among the most pervasive causes of ecological change are edge effects – erse ecological alterations associated with the abrupt, artificial boundaries of forest fragments (Laurance & Bierregaard 1997, Lovejoy et al. 1986, Turner 1996). A striking edge effect in fragmented Amazonian forests is chronically elevated tree mortality (Ferreira & Laurance 1997, Laurance et al. 1998 a ). Large ( 60 cm diameter) trees are especially vulnerable to fragmentation, dying three times faster within 300 m of edges than in forest interiors (Laurance et al. 2000). Elevated tree mortality alters canopy-gap dynamics, promotes a proliferation of disturbance-adapted successional species (Laurance et al. 1998 b ), reduces above-ground biomass (Laurance et al. 1997), and accelerates litter production (Didham & Lawton 1999, Sizer et al. 2000) and carbon cycling (Nascimento & Laurance, in press).
Publisher: Oxford University Press (OUP)
Date: 10-2013
Publisher: Oxford University Press (OUP)
Date: 2014
DOI: 10.1603/ME12216
Abstract: Emerging infectious diseases are on the rise with future outbreaks predicted to occur in frontier regions of tropical countries. Disease surveillance in these hotspots is challenging because s ling techniques often rely on vector attractants that are either unavailable in remote localities or difficult to transport. We examined whether a novel method for producing CO2 from yeast and sugar produces similar mosquito species captures compared with a standard attractant such as dry ice. Across three different vegetation communities, we found traps baited with dry ice frequently captured more mosquitoes than yeast-baited traps however, there was little effect on mosquito community composition. Based on our preliminary experiments, we find that this method of producing CO2 is a realistic alternative to dry ice and would be highly suitable for remote field work.
Publisher: Wiley
Date: 05-05-2020
DOI: 10.1002/ECY.3052
Abstract: Competition among trees is an important driver of community structure and dynamics in tropical forests. Neighboring trees may impact an in idual tree’s growth rate and probability of mortality, but large‐scale geographic and environmental variation in these competitive effects has yet to be evaluated across the tropical forest biome. We quantified effects of competition on tree‐level basal area growth and mortality for trees ≥10‐cm diameter across 151 ~1‐ha plots in mature tropical forests in Amazonia and tropical Africa by developing nonlinear models that accounted for wood density, tree size, and neighborhood crowding. Using these models, we assessed how water availability (i.e., climatic water deficit) and soil fertility influenced the predicted plot‐level strength of competition (i.e., the extent to which growth is reduced, or mortality is increased, by competition across all in idual trees). On both continents, tree basal area growth decreased with wood density and increased with tree size. Growth decreased with neighborhood crowding, which suggests that competition is important. Tree mortality decreased with wood density and generally increased with tree size, but was apparently unaffected by neighborhood crowding. Across plots, variation in the plot‐level strength of competition was most strongly related to plot basal area (i.e., the sum of the basal area of all trees in a plot), with greater reductions in growth occurring in forests with high basal area, but in Amazonia, the strength of competition also varied with plot‐level wood density. In Amazonia, the strength of competition increased with water availability because of the greater basal area of wetter forests, but was only weakly related to soil fertility. In Africa, competition was weakly related to soil fertility and invariant across the shorter water availability gradient. Overall, our results suggest that competition influences the structure and dynamics of tropical forests primarily through effects on in idual tree growth rather than mortality and that the strength of competition largely depends on environment‐mediated variation in basal area.
Publisher: Wiley
Date: 09-1998
Publisher: Springer Science and Business Media LLC
Date: 11-2015
DOI: 10.1038/527305A
Publisher: Springer Science and Business Media LLC
Date: 07-07-2016
Publisher: Wiley
Date: 13-06-2015
DOI: 10.1111/AVSC.12173
Publisher: Oxford University Press (OUP)
Date: 11-2019
Abstract: Climate change scenarios predict increasing atmospheric CO2 concentrations ([CO2]), temperatures and droughts in tropical regions. In idually, the effects of these climate factors on plants are well established, whereas experiments on the interactive effects of a combination of factors are rare. Moreover, how these environmental factors will affect tree species along a wet to dry gradient (e.g., along tropical forest–savanna transitions) remains to be investigated. We hypothesized that under the simulated environmental conditions, plant growth, physiological performance and survivorship would vary in a manner consistent with the species’ positions of origin along this gradient. In a glasshouse experiment, we raised seedlings of three Eucalyptus species, each occurring naturally in a wet forest, savanna and forest–savanna ecotone, respectively. We evaluated the effect of drought, elevated temperature (4 °C above ambient glasshouse temperature of 22 °C) and elevated temperature in combination with elevated [CO2] (400 ppm [CO2] above ambient of 400 ppm), on seedling growth, survivorship and physiological responses (photosynthesis, stomatal conductance and water-use efficiency). Elevated temperature under ambient [CO2] had little effect on growth, biomass and plant performance of well-watered seedlings, but hastened mortality in drought-affected seedlings, affecting the forest and ecotone more strongly than the savanna species. In contrast, elevated [CO2] in combination with elevated temperatures delayed the appearance of drought stress symptoms and enhanced survivorship in drought-affected seedlings, with the savanna species surviving the longest, followed by the ecotone and forest species. Elevated [CO2] in combination with elevated temperatures also enhanced growth and biomass and photosynthesis in well-watered seedlings of all species, but modified shoot:root biomass partitioning and stomatal conductance differentially across species. Our study highlights the need for a better understand of the interactive effects of elevated [CO2], temperature and drought on plants and the potential to upscale these insights for understanding biome changes.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 22-05-2020
Abstract: A key uncertainty in climate change models is the thermal sensitivity of tropical forests and how this value might influence carbon fluxes. Sullivan et al. measured carbon stocks and fluxes in permanent forest plots distributed globally. This synthesis of plot networks across climatic and biogeographic gradients shows that forest thermal sensitivity is dominated by high daytime temperatures. This extreme condition depresses growth rates and shortens the time that carbon resides in the ecosystem by killing trees under hot, dry conditions. The effect of temperature is worse above 32°C, and a greater magnitude of climate change thus risks greater loss of tropical forest carbon stocks. Nevertheless, forest carbon stocks are likely to remain higher under moderate climate change if they are protected from direct impacts such as clearance, logging, or fires. Science , this issue p. 869
Publisher: Wiley
Date: 21-04-2004
Publisher: Public Library of Science (PLoS)
Date: 18-06-2015
Publisher: Proceedings of the National Academy of Sciences
Date: 05-02-2018
Abstract: Identifying and explaining regional differences in tropical forest dynamics, structure, ersity, and composition are critical for anticipating region-specific responses to global environmental change. Floristic classifications are of fundamental importance for these efforts. Here we provide a global tropical forest classification that is explicitly based on community evolutionary similarity, resulting in identification of five major tropical forest regions and their relationships: ( i ) Indo-Pacific, ( ii ) Subtropical, ( iii ) African, ( iv ) American, and ( v ) Dry forests. African and American forests are grouped, reflecting their former western Gondwanan connection, while Indo-Pacific forests range from eastern Africa and Madagascar to Australia and the Pacific. The connection between northern-hemisphere Asian and American forests is confirmed, while Dry forests are identified as a single tropical biome.
Publisher: Proceedings of the National Academy of Sciences
Date: 12-12-2006
Abstract: Forest fragmentation is considered a greater threat to vertebrates than to tree communities because in idual trees are typically long-lived and require only small areas for survival. Here we show that forest fragmentation provokes surprisingly rapid and profound alterations in Amazonian tree-community composition. Results were derived from a 22-year study of exceptionally erse tree communities in 40 1-ha plots in fragmented and intact forests, which were s led repeatedly before and after fragment isolation. Within these plots, trajectories of change in abundance were assessed for 267 genera and 1,162 tree species. Abrupt shifts in floristic composition were driven by sharply accelerated tree mortality and recruitment within ≈100 m of fragment margins, causing rapid species turnover and population declines or local extinctions of many large-seeded, slow-growing, and old-growth taxa a striking increase in a smaller set of disturbance-adapted and abiotically dispersed species and significant shifts in tree size distributions. Even among old-growth trees, species composition in fragments is being restructured substantially, with subcanopy species that rely on animal seed-dispersers and have obligate outbreeding being the most strongly disadvantaged. These erse changes in tree communities are likely to have wide-ranging impacts on forest architecture, canopy-gap dynamics, plant–animal interactions, and forest carbon storage.
Publisher: IOP Publishing
Date: 04-2017
Publisher: IOP Publishing
Date: 05-2023
Abstract: Australia is a world leader in habitat loss and species extinction, and for many species, ecological restoration will be necessary for continued persistence. Between 2014 and 2018, the Australian federal government allocated a substantial portion of funding for threatened species recovery to a nation-wide ecological restoration program called ‘20 Million Trees Land-care Program’, which included a competitive grant round. By comparing successful and unsuccessful grant applications, we were able to identify factors associated with restoration funding allocation. We then assessed the Program’s ability to provide benefits to threatened species by analyzing the overlap between restoration projects and threatened species habitat. We found that funding allocation under the 20 Million Trees Program was primarily driven by ‘value for money’ factors, specifically ‘cost per tree’ and number of trees planted. Additionally, projects were more likely to be funded if they mentioned threatened species in the description, but less likely to be funded if they actually overlapped with areas of high threatened species richness. Of the 1960 threatened species assessed, we found that only 9 received funding for restoration projects covering more than 1% of their range. Conversely, we found that utilizing alternative project selection schemes, such as alternative ‘value for money’ metrics or spatial planning methods, could have delivered better outcomes for some of the threatened species most impacted by habitat loss. Our results show that inopportune selection criteria for awarding of funding for ecological restoration can significantly reduce the benefits delivered by programs.
Publisher: Elsevier BV
Date: 04-1998
Publisher: Springer Science and Business Media LLC
Date: 18-05-2022
DOI: 10.1038/S41586-022-04737-7
Abstract: Evidence exists that tree mortality is accelerating in some regions of the tropics
Publisher: Wiley
Date: 10-11-2017
Publisher: Wiley
Date: 06-2005
Publisher: Wiley
Date: 28-11-2021
DOI: 10.1111/GCB.15982
Abstract: A better understanding of how climate affects growth in tree species is essential for improved predictions of forest dynamics under climate change. Long‐term climate averages (mean climate) drive spatial variations in species’ baseline growth rates, whereas deviations from these averages over time (anomalies) can create growth variation around the local baseline. However, the rarity of long‐term tree census data spanning climatic gradients has so far limited our understanding of their respective role, especially in tropical systems. Furthermore, tree growth sensitivity to climate is likely to vary widely among species, and the ecological strategies underlying these differences remain poorly understood. Here, we utilize an exceptional dataset of 49 years of growth data for 509 tree species across 23 tropical rainforest plots along a climatic gradient to examine how multiannual tree growth responds to both climate means and anomalies, and how species’ functional traits mediate these growth responses to climate. We show that anomalous increases in atmospheric evaporative demand and solar radiation consistently reduced tree growth. Drier forests and fast‐growing species were more sensitive to water stress anomalies. In addition, species traits related to water use and photosynthesis partly explained differences in growth sensitivity to both climate means and anomalies. Our study demonstrates that both climate means and anomalies shape tree growth in tropical forests and that species traits can provide insights into understanding these demographic responses to climate change, offering a promising way forward to forecast tropical forest dynamics under different climate trajectories.
Publisher: Wiley
Date: 08-11-2018
DOI: 10.1111/GCB.14413
Publisher: Cambridge University Press (CUP)
Date: 09-02-2015
DOI: 10.1017/S0376892914000411
Abstract: Rapid population growth and economic change on the tropical islands of Mauritius have led to one of the highest rates of urban build-out in the world. Pressure on many of the island's natural features and resources increasingly risks further degradation to the environmental services that they provide to the country. Fourteen types of marine and terrestrial environmentally sensitive areas (ESAs) are critical to the nation's sustainable development. Twelve of these ESA types are currently at risk of degradation, owing to their spatial proximity to built-up areas (BUAs) and current use designation. There was a bimodal distribution in proximity eight of the 12 ESA types analysed had an area-weighted modal peak 500 m from the nearest BUA, and four ESAs had a modal peak 2–3 km from the nearest BUA. Six coastal and marine ESAs had limited protection from urban expansion and over-use. The Mauritian experience reflects trends that are emerging across many tropical developing countries, where the bulk of future global growth in urban area is expected to occur. The approach detailed in this case study is replicable and may be useful in assessing degradation risk as a result of urban expansion in other island countries.
Publisher: Springer Science and Business Media LLC
Date: 04-09-2016
Publisher: Wiley
Date: 21-09-2021
DOI: 10.1111/GCB.15869
Abstract: Increasing severity and frequency of drought is predicted for large portions of the terrestrial biosphere, with major impacts already documented in wet tropical forests. Using a 4‐year rainfall exclusion experiment in the Daintree Rainforest in northeast Australia, we examined canopy tree responses to reduced precipitation and soil water availability by quantifying seasonal changes in plant hydraulic and carbon traits for 11 tree species between control and drought treatments. Even with reduced soil volumetric water content in the upper 1 m of soil in the drought treatment, we found no significant difference between treatments for predawn and midday leaf water potential, photosynthesis, stomatal conductance, foliar stable carbon isotope composition, leaf mass per area, turgor loss point, xylem vessel anatomy, or leaf and stem nonstructural carbohydrates. While empirical measurements of aboveground traits revealed homeostatic maintenance of plant water status and traits in response to reduced soil moisture, modeled belowground dynamics revealed that trees in the drought treatment shifted the depth from which water was acquired to deeper soil layers. These findings reveal that belowground acclimation of tree water uptake depth may buffer tropical rainforests from more severe droughts that may arise in future with climate change.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 18-10-2013
Abstract: Recent decades have seen a major international effort to inventory tree communities in the Amazon Basin and Guiana Shield (Amazonia), but the vast extent and record ersity of these forests have h ered an understanding of basinwide patterns. To overcome this obstacle, we compiled and standardized species-level data on more than half a million trees in 1170 plots s ling all major lowland forest types to explore patterns of commonness, rarity, and richness. The ~6-million-km 2 Amazonian lowlands were ided into 1° cells, and mean tree density was estimated for each cell by using a loess regression model that included no environmental data but had its basis exclusively in the geographic location of tree plots. A similar model, allied with a bootstrapping exercise to quantify s ling error, was used to generate estimated Amazon-wide abundances of the 4962 valid species in the data set. We estimated the total number of tree species in the Amazon by fitting the mean rank-abundance data to Fisher’s log-series distribution. Our analyses suggest that lowland Amazonia harbors 3.9 × 10 11 trees and ~16,000 tree species. We found 227 “hyperdominant” species (1.4% of the total) to be so common that together they account for half of all trees in Amazonia, whereas the rarest 11,000 species account for just 0.12% of trees. Most hyperdominants are habitat specialists that have large geographic ranges but are only dominant in one or two regions of the basin, and a median of 41% of trees in in idual plots belong to hyperdominants. A disproportionate number of hyperdominants are palms, Myristicaceae, and Lecythidaceae. The finding that Amazonia is dominated by just 227 tree species implies that most biogeochemical cycling in the world’s largest tropical forest is performed by a tiny sliver of its ersity. The causes underlying hyperdominance in these species remain unknown. Both competitive superiority and widespread pre-1492 cultivation by humans are compelling hypotheses that deserve testing. Although the data suggest that spatial models can effectively forecast tree community composition and structure of unstudied sites in Amazonia, incorporating environmental data may yield substantial improvements. An appreciation of how thoroughly common species dominate the basin has the potential to simplify research in Amazonian biogeochemistry, ecology, and vegetation mapping. Such advances are urgently needed in light of the ,000 rare, poorly known, and potentially threatened tree species in the Amazon.
Publisher: Wiley
Date: 29-01-2008
DOI: 10.3170/2008-8-18463
Publisher: Springer Science and Business Media LLC
Date: 03-2015
DOI: 10.1038/NATURE14283
Abstract: Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink erges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 07-11-1997
DOI: 10.1126/SCIENCE.278.5340.1117
Abstract: Rain forest fragments in central Amazonia were found to experience a dramatic loss of above-ground tree biomass that is not offset by recruitment of new trees. These losses were largest within 100 meters of fragment edges, where tree mortality is sharply increased by microclimatic changes and elevated wind turbulence. Permanent study plots within 100 meters of edges lost up to 36 percent of their biomass in the first 10 to 17 years after fragmentation. Lianas (climbing woody vines) increased near edges but usually compensated for only a small fraction of the biomass lost as a result of increased tree mortality.
Publisher: JSTOR
Date: 09-1996
DOI: 10.2307/2389195
Publisher: Elsevier BV
Date: 05-2012
Publisher: Oxford University PressOxford
Date: 08-1970
DOI: 10.1093/ACPROF:OSO/9780198567066.003.0009
Abstract: The rainforests of central Amazonia are some of the most species-rich tree communities on earth. In recent decades, forests in the central-Amazonian landscape have experienced highly non-random changes in dynamics and composition. These analyses are made on a network of eighteen permanent plots unaffected by any detectable disturbance. Within these plots, tree mortality, recruitment, and growth have increased over time. Of 115 relatively abundant tree genera, twenty-seven changed significantly in density or basal area — a value nearly fourteen times greater than that expected by chance. An independent, eight-year study in nearby forests corroborated these shifts in composition. Despite increasing tree mortality, pioneer trees did not increase in abundance, but genera of faster-growing trees, including many canopy and emergent species, are increasing in dominance or density, whereas genera of slower-growing trees, including many subcanopy species, are declining. Rising atmospheric CO2 concentrations may explain these changes, although the effects of this and other large-scale environmental alterations have not been fully explored. These compositional changes could have important effects on the carbon storage, dynamics, and biota of Amazonian forests.
Publisher: Springer Netherlands
Date: 2012
Publisher: Wiley
Date: 04-2002
Publisher: IOP Publishing
Date: 11-2016
Publisher: Wiley
Date: 12-2018
DOI: 10.1002/ECE3.4601
Publisher: Cold Spring Harbor Laboratory
Date: 09-06-2021
DOI: 10.1101/2021.06.08.447571
Abstract: A better understanding of how climate affects growth in tree species is essential for improved predictions of forest dynamics under climate change. Long-term climate averages (mean climate) and short-term deviations from these averages (anomalies) both influence tree growth, but the rarity of long-term data integrating climatic gradients with tree censuses has so far limited our understanding of their respective role, especially in tropical systems. Here, we combined 49 years of growth data for 509 tree species across 23 tropical rainforest plots along a climatic gradient to examine how tree growth responds to both climate means and anomalies, and how species functional traits mediate these tree growth responses to climate. We showed that short-term, anomalous increases in atmospheric evaporative demand and solar radiation consistently reduced tree growth. Drier forests and fast-growing species were more sensitive to water stress anomalies. In addition, species traits related to water use and photosynthesis partly explained differences in growth sensitivity to both long-term and short-term climate variations. Our study demonstrates that both climate means and anomalies shape tree growth in tropical forests, and that species traits can be leveraged to understand these demographic responses to climate change, offering a promising way forward to forecast tropical forest dynamics under different climate trajectories.
Publisher: Springer Science and Business Media LLC
Date: 04-2000
DOI: 10.1038/35009032
Publisher: Elsevier BV
Date: 09-2016
Publisher: Wiley
Date: 24-10-2022
DOI: 10.1111/GEB.13596
Abstract: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser‐availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource‐availability hypothesis). Tree‐inventory plots established between 1934 and 2019. Trees with a diameter at breast height (DBH) ≥ 9.55 cm. Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree‐inventory plots across terra‐firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance‐weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra‐firme forests (excluding podzols) compared to flooded forests. The disperser‐availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types.
Publisher: Wiley
Date: 25-01-2016
DOI: 10.1111/JVS.12376
Publisher: Wiley
Date: 10-2008
Publisher: Wiley
Date: 10-2004
DOI: 10.1890/03-5194
Publisher: Elsevier BV
Date: 11-2010
Publisher: Wiley
Date: 30-06-2023
DOI: 10.1111/GCB.16821
Abstract: For more than three decades, major efforts in s ling and analyzing tree ersity in South America have focused almost exclusively on trees with stems of at least 10 and 2.5 cm diameter, showing highest species ersity in the wetter western and northern Amazon forests. By contrast, little attention has been paid to patterns and drivers of ersity in the largest canopy and emergent trees, which is surprising given these have dominant ecological functions. Here, we use a machine learning approach to quantify the importance of environmental factors and apply it to generate spatial predictions of the species ersity of all trees (dbh ≥ 10 cm) and for very large trees (dbh ≥ 70 cm) using data from 243 forest plots (108,450 trees and 2832 species) distributed across different forest types and biogeographic regions of the Brazilian Amazon. The ersity of large trees and of all trees was significantly associated with three environmental factors, but in contrasting ways across regions and forest types. Environmental variables associated with disturbances, for ex le, the lightning flash rate and wind speed, as well as the fraction of photosynthetically active radiation, tend to govern the ersity of large trees. Upland rainforests in the Guiana Shield and Roraima regions had a high ersity of large trees. By contrast, variables associated with resources tend to govern tree ersity in general. Places such as the province of Imeri and the northern portion of the province of Madeira stand out for their high ersity of species in general. Climatic and topographic stability and functional adaptation mechanisms promote ideal conditions for species ersity. Finally, we mapped general patterns of tree species ersity in the Brazilian Amazon, which differ substantially depending on size class.
Publisher: Wiley
Date: 25-03-2009
Publisher: Elsevier BV
Date: 07-2012
Publisher: Elsevier BV
Date: 12-2011
Publisher: Informa UK Limited
Date: 02-10-2012
Publisher: Wiley
Date: 13-04-2019
DOI: 10.1111/AEC.12746
Publisher: The Royal Society
Date: 14-12-2016
Abstract: Lineages tend to retain ecological characteristics of their ancestors through time. However, for some traits, selection during evolutionary history may have also played a role in determining trait values. To address the relative importance of these processes requires large-scale quantification of traits and evolutionary relationships among species. The Amazonian tree flora comprises a high ersity of angiosperm lineages and species with widely differing life-history characteristics, providing an excellent system to investigate the combined influences of evolutionary heritage and selection in determining trait variation. We used trait data related to the major axes of life-history variation among tropical trees (e.g. growth and mortality rates) from 577 inventory plots in closed-canopy forest, mapped onto a phylogenetic hypothesis spanning more than 300 genera including all major angiosperm clades to test for evolutionary constraints on traits. We found significant phylogenetic signal (PS) for all traits, consistent with evolutionarily related genera having more similar characteristics than expected by chance. Although there is also evidence for repeated evolution of pioneer and shade tolerant life-history strategies within independent lineages, the existence of significant PS allows clearer predictions of the links between evolutionary ersity, ecosystem function and the response of tropical forests to global change.
Publisher: Springer Science and Business Media LLC
Date: 25-07-2012
DOI: 10.1038/NATURE11318
Abstract: The rapid disruption of tropical forests probably imperils global bio ersity more than any other contemporary phenomenon. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses. As pressures mount, it is vital to know whether existing reserves can sustain their bio ersity. A critical constraint in addressing this question has been that data describing a broad array of bio ersity groups have been unavailable for a sufficiently large and representative s le of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environmental change, for 60 protected areas stratified across the world’s major tropical regions. Our analysis reveals great variation in reserve ‘health’: about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of bio ersity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious bio ersity declines.
Publisher: Public Library of Science (PLoS)
Date: 19-11-2014
Publisher: Elsevier BV
Date: 2011
Publisher: Wiley
Date: 31-05-2017
DOI: 10.1111/GCB.13741
Abstract: Our ability to model global carbon fluxes depends on understanding how terrestrial carbon stocks respond to varying environmental conditions. Tropical forests contain the bulk of the biosphere's carbon. However, there is a lack of consensus as to how gradients in environmental conditions affect tropical forest carbon. Papua New Guinea (PNG) lies within one of the largest areas of contiguous tropical forest and is characterized by environmental gradients driven by altitude yet, the region has been grossly understudied. Here, we present the first field assessment of aboveground biomass (AGB) across three main forest types of PNG using 193 plots stratified across 3,100-m elevation gradient. Unexpectedly, AGB had no direct relationship to rainfall, temperature, soil, or topography. Instead, natural disturbances explained most variation in AGB. While large trees (diameter at breast height > 50 cm) drove altitudinal patterns of AGB, resulting in a major peak in AGB (2,200-3,100 m) and some of the most carbon-rich forests at these altitudes anywhere. Large trees were correlated to a set of climatic variables following a hump-shaped curve. The set of "optimal" climatic conditions found in montane cloud forests is similar to that of maritime temperate areas that harbor the largest trees in the world: high ratio of precipitation to evapotranspiration (2.8), moderate mean annual temperature (13.7°C), and low intra-annual temperature range (7.5°C). At extreme altitudes (2,800-3,100 m), where tree ersity elsewhere is usually low and large trees are generally rare or absent, specimens from 18 families had girths >70 cm diameter and maximum heights 20-41 m. These findings indicate that simple AGB-climate-edaphic models may not be suitable for estimating carbon storage in forests where optimal climate niches exist. Our study, conducted in a very remote area, suggests that tropical montane forests may contain greater AGB than previously thought and the importance of securing their future under a changing climate is therefore enhanced.
Publisher: Wiley
Date: 06-07-2020
DOI: 10.1002/AQC.3376
Publisher: Wiley
Date: 11-2009
Publisher: Wiley
Date: 30-05-2017
DOI: 10.1111/BRV.12343
Abstract: We synthesize findings from one of the world's largest and longest-running experimental investigations, the Biological Dynamics of Forest Fragments Project (BDFFP). Spanning an area of ∼1000 km
Publisher: Wiley
Date: 29-04-2004
Publisher: Cold Spring Harbor Laboratory
Date: 19-03-2021
DOI: 10.1101/2021.03.18.436089
Abstract: Urbanization is rapidly transforming much of Southeast Asia, altering the structure and function of the landscape, as well as the frequency and intensity of the interactions between people, animals, and the environment. In this study, we began to explore the impact of urbanization on zoonotic disease risk by simultaneously characterizing changes in the abundance and ersity of reservoir hosts (rodents), ectoparasite vectors (ticks), and microbial pathogens across a gradient of urbanization in Malaysian Borneo. We found that although rodent species ersity decreased with increasing urbanization, two species appeared to thrive in anthropogenic environments: the invasive urban exploiter, Rattus rattus and the native urban adapter, Sundamys muelleri . R. rattus was strongly associated with the presence of built infrastructure across the gradient and dominated the urban rodent community where it was associated with high microbial ersity and multi-host zoonoses capable of environmental transmission, including Leptospira spp., and Toxoplasma gondii . In contrast, S. muelleri was restricted to sites with a significant vegetative component where it was found at high densities in the urban location. This species was strongly associated with the presence of ticks, including the medically important genera Ambylomma , Haemaphysalis , and Ixodes . Overall, our results demonstrate that the response to urbanization varies by species at all levels: host, ectoparasite, and microbe. This may lead to increased zoonotic disease risk in a subset of environments across urban and urbanizing landscapes that can be reduced through improved pest management and public health messaging.
Publisher: Springer Science and Business Media LLC
Date: 17-02-2023
DOI: 10.1038/S41598-023-28132-Y
Abstract: In a time of rapid global change, the question of what determines patterns in species abundance distribution remains a priority for understanding the complex dynamics of ecosystems. The constrained maximization of information entropy provides a framework for the understanding of such complex systems dynamics by a quantitative analysis of important constraints via predictions using least biased probability distributions. We apply it to over two thousand hectares of Amazonian tree inventories across seven forest types and thirteen functional traits, representing major global axes of plant strategies. Results show that constraints formed by regional relative abundances of genera explain eight times more of local relative abundances than constraints based on directional selection for specific functional traits, although the latter does show clear signals of environmental dependency. These results provide a quantitative insight by inference from large-scale data using cross-disciplinary methods, furthering our understanding of ecological dynamics.
Publisher: Copernicus GmbH
Date: 25-02-2009
Abstract: Abstract. Understanding the relationships between plant traits and ecosystem properties at large spatial scales is important for predicting how compositional change will affect carbon cycling in tropical forests. In this study, we examine the relationships between species wood density, maximum height and above-ground, coarse wood production of trees ≥10 cm diameter (CWP) for 60 Amazonian forest plots. Average species maximum height and wood density are lower in Western than Eastern Amazonia and are negatively correlated with CWP. To test the hypothesis that variation in these traits causes the variation in CWP, we generate plot-level estimates of CWP by res ling the full distribution of tree biomass growth rates whilst maintaining the appropriate tree-diameter and functional-trait distributions for each plot. These estimates are then compared with the observed values. Overall, the estimates do not predict the observed, regional-scale pattern of CWP, suggesting that the variation in community-level trait values does not determine variation in coarse wood productivity in Amazonian forests. Instead, the regional gradient in CWP is caused by higher biomass growth rates across all tree types in Western Amazonia. Therefore, the regional gradient in CWP is driven primarily by environmental factors, rather than the particular functional composition of each stand. These results contrast with previous findings for forest biomass, where variation in wood density, associated with variation in species composition, is an important driver of regional-scale patterns in above-ground biomass. Therefore, in tropical forests, above-ground wood productivity may be less sensitive than biomass to compositional change that alters community-level averages of these plant traits.
Publisher: Wiley
Date: 29-06-2015
Publisher: Elsevier BV
Date: 03-2004
Publisher: Emerald
Date: 12-03-2018
Abstract: The purpose of this paper is to examine the potential for eXtensible Business Reporting Language (XBRL) to go beyond static reporting. A taxonomy structure of information is developed for providing a knowledge base and insights for an XBRL taxonomy for integrated reporting (IR). Design Science (DS) research, as a pragmatic exploratory research approach, is embraced to create a new “artefact” and thematic content analysis is used to analyse IR in practice. Using XBRL for IR allows a shift from static and periodic reporting to more relevant and dynamic corporate disclosure for stakeholders, who can navigate and retrieve customised disclosure information according to their interest by exploiting the multidimensionality of IR and overcome some of its criticisms. The bi-dimensional taxonomy structure the authors’ present allows users to navigate disclosure from two different perspectives (content elements (CE) and capitals), display specific themes of interest, and drill down to more detailed information. Because of its evidence-based nature and levels of disaggregation, it provides flexibility to preparers and users of information. Additionally, the findings demonstrate the need to codify sector-specific information for the CE, so that to direct the efforts toward the development of sector-specific taxonomy extensions in developing an XBRL taxonomy for IR. The limitations of DS research are, first, the artefact design and, second, its effects in practice. The first limitation stems from the social actors’ perspective taken into account to develop the taxonomy structure, which derives from the analysis of the reporting practices rather than a pluralistic approach and dialogic engagement. The second limitation relates to the XBRL taxonomy development process because, since the study is limited to the “design” phase being codification and structuring the knowledge base for an XBRL taxonomy, there is a need to develop a taxonomy in XBRL and then apply it in practice to empirically demonstrate the potential and benefits of XBRL in the IR context. The taxonomy structure is targeted at entities interested in designing an XBRL taxonomy for IR. This is a call for academics and practitioners to explore the potential of technology to improve corporate disclosure and open up new projections for resurging themes on intellectual capital (IC) reporting with prospects for IC “fourth-stage” research focused on IC disclosure. This is an interdisciplinary research employing the DS approach, which is rooted in information systems research. It is the first academic study providing pragmatic results for using XBRL in the context of IC and IR.
Publisher: Public Library of Science (PLoS)
Date: 04-10-2013
Publisher: Springer Science and Business Media LLC
Date: 07-09-2004
Publisher: Elsevier BV
Date: 10-2022
Publisher: Springer Science and Business Media LLC
Date: 20-07-2017
DOI: 10.1038/S41598-017-06590-5
Abstract: Human-induced forest fragmentation poses one of the largest threats to global ersity yet its impact on rattans (climbing palms) has remained virtually unexplored. Rattan is arguably the world’s most valuable non-timber forest product though current levels of harvesting and land-use change place wild populations at risk. To assess rattan response to fragmentation exclusive of harvesting impacts we examined rattan abundance, demography and ecology within the forests of northeastern, Australia. We assessed the community abundance of rattans, and component adult ( m) and juvenile (≤3 m) abundance in five intact forests and five fragments (23–58 ha) to determine their response to a range of environmental and ecological parameters. Fragmented forests supported higher abundances of rattans than intact forests. Fragment size and edge degradation significantly increased adult rattan abundance, with more in smaller fragments and near edges. Our findings suggest that rattan increase within fragments is due to canopy disturbance of forest edges resulting in preferential, high-light habitat. However, adult and juvenile rattans may respond inconsistently to fragmentation. In managed forest fragments, a rattan abundance increase may provide economic benefits through sustainable harvesting practices. However, rattan increases in protected area forest fragments could negatively impact conservation outcomes.
Publisher: Public Library of Science (PLoS)
Date: 18-12-2014
Publisher: Research Square Platform LLC
Date: 05-05-2023
DOI: 10.21203/RS.3.RS-2855410/V1
Abstract: Trees adjust their architecture to acclimate to various external stressors, which regulates ecological functions that are needed for growth, reproduction, and survival. Human activities, however, are fragmenting natural habitats apace and could affect tree architecture and allometry, but quantitative assessments remain lacking. Here, we leverage ground surveys of terrestrial LiDAR in Central Amazonia to comprehensively assess forest edge effects on tree architecture and allometry, and their associated impacts on the forest biomass 40 years after fragmentation. We found that young trees colonising the forest fragments have thicker branches and architectural traits that maximise light capture, and can produce 50% more wood than their counterparts of similar stem size and height in interior forests. Large trees that have survived disturbances arising from forest fragmentation are able to acclimate and maintain their wood production, but damages that reduce tree height near the edges can lead to a 30% decline of their woody volume. Despite the large wood production of colonising trees, changes in tree architecture lead to a net loss of 6.6 Mg ha -1 of the forest aboveground biomass, which account for 20% of all edge-related aboveground biomass losses of fragmented Amazonian forests (34.3 Mg ha -1 ). Our findings show a strong influence of edge effects on tree architecture and allometry, and reveal an additional unaccounted factor that exacerbates carbon losses in fragmented forests.
Publisher: Wiley
Date: 02-2010
Publisher: Wiley
Date: 26-04-1998
Publisher: Oxford University Press (OUP)
Date: 06-02-2014
Publisher: Oxford University PressOxford
Date: 30-06-2007
DOI: 10.1093/ACPROF:OSO/9780198567066.003.0010
Abstract: Previous work found that tree turnover, biomass, and large liana densities increased in mature tropical forests in the late 20th century, indicating a concerted shift in forest ecological processes. However, the findings have proved controversial. Here, regional-scale patterns of tree turnover are characterized, using improved datasets available for Amazonia that span the last twenty-five years. The main findings include: trees at least 10 cm in diameter recruit and die twice as fast on the richer soils of western Amazonia compared to trees on the poorer soils of eastern Amazonia turnover rates have increased throughout Amazonia over the last two decades mortality and recruitment rates have tended to increase in every region and environmental zone recruitment rates consistently exceed mortality rates and increases in recruitment and mortality rates are greatest in western Amazonia. These patterns and trends are not caused by obvious artefacts in the data or the analyses, and cannot be directly driven by a mortality driver such as increased drought because the biomass in these forests has simultaneously increased. Apparently, therefore, widespread environmental changes are stimulating the growth and productivity of Amazon forests.
Publisher: Wiley
Date: 2010
Publisher: Oxford University PressOxford
Date: 30-06-2007
DOI: 10.1093/ACPROF:OSO/9780198567066.003.0011
Abstract: This chapter discusses a previous study by Phillips et al. (1998) on biomass changes in Amazonian permanent s le plots which has been used to infer the presence of a regional carbon sink, generating vigorous debate about s ling and methodological issues. A new analysis of biomass change in old-growth Amazonian forest plots is presented here using new inventory data. It has been found that across fifty-nine sites, the above-ground dry biomass in trees of more than 10 cm in diameter has increased since plot establishment by about 1.22 Mg per hectare per year, or about 0.98 Mg per hectare per year if in idual plot values are weighted by the number of hectare years of monitoring. This significant increase is not confounded by spatial or temporal variation in wood specific gravity, nor does it depend on the allometric equation used to estimate biomass. Overall, these results suggest a slightly greater rate of net stand-level change than reported in 1998, and indicate the presence of a significant regional-scale carbon sink in old-growth Amazonian forests during the past two decades.
Publisher: Wiley
Date: 10-10-2018
DOI: 10.1111/GEB.12803
Abstract: Large tropical trees form the interface between ground and airborne observations, offering a unique opportunity to capture forest properties remotely and to investigate their variations on broad scales. However, despite rapid development of metrics to characterize the forest canopy from remotely sensed data, a gap remains between aerial and field inventories. To close this gap, we propose a new pan‐tropical model to predict plot‐level forest structure properties and biomass from only the largest trees. Pan‐tropical. Early 21st century. Woody plants. Using a dataset of 867 plots distributed among 118 sites across the tropics, we tested the prediction of the quadratic mean diameter, basal area, Lorey's height, community wood density and aboveground biomass (AGB) from the i th largest trees. Measuring the largest trees in tropical forests enables unbiased predictions of plot‐ and site‐level forest structure. The 20 largest trees per hectare predicted quadratic mean diameter, basal area, Lorey's height, community wood density and AGB with 12, 16, 4, 4 and 17.7% of relative error, respectively. Most of the remaining error in biomass prediction is driven by differences in the proportion of total biomass held in medium‐sized trees (50–70 cm diameter at breast height), which shows some continental dependency, with American tropical forests presenting the highest proportion of total biomass in these intermediate‐diameter classes relative to other continents. Our approach provides new information on tropical forest structure and can be used to generate accurate field estimates of tropical forest carbon stocks to support the calibration and validation of current and forthcoming space missions. It will reduce the cost of field inventories and contribute to scientific understanding of tropical forest ecosystems and response to climate change.
Publisher: Elsevier BV
Date: 07-2012
Publisher: Springer Berlin Heidelberg
Date: 2003
Publisher: Springer Science and Business Media LLC
Date: 08-2014
DOI: 10.1038/512136B
Publisher: Wiley
Date: 13-01-2010
Publisher: Cambridge University Press (CUP)
Date: 28-04-2003
DOI: 10.1017/S0266467403003389
Abstract: Habitat fragmentation affects the ecology of tropical rain forests in many ways, such as reducing species ersity of many taxa (Laurance et al. 2002, Lovejoy et al. 1986) and increasing rates of tree mortality and canopy-gap formation near forest edges (Laurance et al. 1997, 1998, 2001). Such obvious alterations have been documented in many fragmented forests, but more subtle changes, such as those affecting plant phenology (the timing and frequency of flower, fruit and leaf production), have received far less attention. Adler & Kiepinski (2000) showed that different populations of the successional tree Spondias mombin on small man-made islands in Panama had highly synchronous flowering and fruiting. In montane forests in Colombia, Restrepo et al. (1999) demonstrated that under-storey fruit abundance was consistently increased over time near forest edges relative to forest interiors. Beyond these and a few other studies (Ackerly et al. 1990, Nason & Hamrick 1997), however, the effects of fragmentation on plant phenology have been inadequately assessed, especially in the tropics.
Publisher: Wiley
Date: 21-11-2019
DOI: 10.1111/BRV.12571
Abstract: Increased frequency and severity of drought, as a result of climate change, is expected to drive critical changes in plant-insect interactions that may elevate rates of tree mortality. The mechanisms that link water stress in plants to insect performance are not well understood. Here, we build on previous reviews and develop a framework that incorporates the severity and longevity of drought and captures the plant physiological adjustments that follow moderate and severe drought. Using this framework, we investigate in greater depth how insect performance responds to increasing drought severity for: (i) different feeding guilds (ii) flush feeders and senescence feeders (iii) specialist and generalist insect herbivores and (iv) temperate versus tropical forest communities. We outline how intermittent and moderate drought can result in increases of carbon-based and nitrogen-based chemical defences, whereas long and severe drought events can result in decreases in plant secondary defence compounds. We predict that different herbivore feeding guilds will show different but predictable responses to drought events, with most feeding guilds being negatively affected by water stress, with the exception of wood borers and bark beetles during severe drought and sap-sucking insects and leaf miners during moderate and intermittent drought. Time of feeding and host specificity are important considerations. Some insects, regardless of feeding guild, prefer to feed on younger tissues from leaf flush, whereas others are adapted to feed on senescing tissues of severely stressed trees. We argue that moderate water stress could benefit specialist insect herbivores, while generalists might prefer severe drought conditions. Current evidence suggests that insect outbreaks are shorter and more spatially restricted in tropical than in temperate forests. We suggest that future research on the impact of drought on insect communities should include (i) assessing how drought-induced changes in various plant traits, such as secondary compound concentrations and leaf water potential, affect herbivores (ii) food web implications for other insects and those that feed on them and (iii) interactions between the effects on insects of increasing drought and other forms of environmental change including rising temperatures and CO
Publisher: Elsevier BV
Date: 06-2011
Publisher: Wiley
Date: 02-2006
DOI: 10.1890/05-0064
Publisher: Springer Science and Business Media LLC
Date: 03-2004
DOI: 10.1038/NATURE02383
Publisher: Springer Science and Business Media LLC
Date: 10-10-2018
Publisher: American Association for the Advancement of Science (AAAS)
Date: 06-10-2023
Publisher: Springer Science and Business Media LLC
Date: 28-04-2015
DOI: 10.1038/NCOMMS7857
Abstract: While Amazonian forests are extraordinarily erse, the abundance of trees is skewed strongly towards relatively few ‘hyperdominant’ species. In addition to their ersity, Amazonian trees are a key component of the global carbon cycle, assimilating and storing more carbon than any other ecosystem on Earth. Here we ask, using a unique data set of 530 forest plots, if the functions of storing and producing woody carbon are concentrated in a small number of tree species, whether the most abundant species also dominate carbon cycling, and whether dominant species are characterized by specific functional traits. We find that dominance of forest function is even more concentrated in a few species than is dominance of tree abundance, with only ≈1% of Amazon tree species responsible for 50% of carbon storage and productivity. Although those species that contribute most to biomass and productivity are often abundant, species maximum size is also influential, while the identity and ranking of dominant species varies by function and by region.
Publisher: Elsevier BV
Date: 02-2020
Publisher: Wiley
Date: 24-06-2019
DOI: 10.1111/AVSC.12442
Publisher: Wiley
Date: 06-2014
DOI: 10.1890/13-1571.1
Abstract: Lianas (climbing woody vines) are important structural parasites of tropical trees and may be increasing in abundance in response to global‐change drivers. We assessed long‐term (∼14‐year) changes in liana abundance and forest dynamics within 36 1‐ha permanent plots spanning ∼600 km 2 of undisturbed rainforest in central Amazonia. Within each plot, we counted each liana stem (≥2 cm diameter) and measured its diameter at 1.3 m height, and then used these data to estimate liana aboveground biomass. An initial liana survey was completed in 1997–1999 and then repeated in 2012, using identical methods. Liana abundance in the plots increased by an average of 1.00% ± 0.88% per year, leading to a highly significant ( t = 6.58, df = 35, P 0.00001) increase in liana stem numbers. Liana biomass rose more slowly over time (0.32% ± 1.37% per year) and the mean difference between the two s ling intervals was nonsignificant ( t = 1.46, df = 35, P = 0.15 paired t tests). Liana size distributions shifted significantly (χ 2 = 191, df = 8, P 0.0001 Chi‐square test for independence) between censuses, mainly as a result of a nearly 40% increase in the number of smaller (2–3 cm diameter) lianas, suggesting that lianas recruited rapidly during the study. We used long‐term data on rainfall and forest dynamics from our study site to test hypotheses about potential drivers of change in liana communities. Lianas generally increase with rainfall seasonality, but we found no significant trends over time (1997–2012) in five rainfall parameters (total annual rainfall, dry‐season rainfall, wet‐season rainfall, number of very dry months, CV of monthly rainfall). However, rates of tree mortality and recruitment have increased significantly over time in our plots, and general linear mixed‐effect models suggested that lianas were more abundant at sites with higher tree mortality and flatter topography. Rising concentrations of atmospheric CO 2 , which may stimulate liana growth, might also have promoted liana increases. Our findings clearly support the view that lianas are increasing in abundance in old‐growth tropical forests, possibly in response to accelerating forest dynamics and rising CO 2 concentrations. The aboveground biomass of trees was lowest in plots with abundant lianas, suggesting that lianas could reduce forest carbon storage and potentially alter forest dynamics if they continue to proliferate.
Publisher: Public Library of Science (PLoS)
Date: 10-10-2007
Publisher: The Royal Society
Date: 29-03-2004
Abstract: Previous work has shown that tree turnover, tree biomass and large liana densities have increased in mature tropical forest plots in the late twentieth century. These results point to a concerted shift in forest ecological processes that may already be having significant impacts on terrestrial carbon stocks, fluxes and bio ersity. However, the findings have proved controversial, partly because a rather limited number of permanent plots have been monitored for rather short periods. The aim of this paper is to characterize regional–scale patterns of ‘tree turnover’ (the rate with which trees die and recruit into a population) by using improved datasets now available for Amazonia that span the past 25 years. Specifically, we assess whether concerted changes in turnover are occurring, and if so whether they are general throughout the Amazon or restricted to one region or environmental zone. In addition, we ask whether they are driven by changes in recruitment, mortality or both. We find that: (i) trees 10 cm or more in diameter recruit and die twice as fast on the richer soils of southern and western Amazonia than on the poorer soils of eastern and central Amazonia (ii) turnover rates have increased throughout Amazonia over the past two decades (iii) mortality and recruitment rates have both increased significantly in every region and environmental zone, with the exception of mortality in eastern Amazonia (iv) recruitment rates have consistently exceeded mortality rates (v) absolute increases in recruitment and mortality rates are greatest in western Amazonian sites and (vi) mortality appears to be lagging recruitment at regional scales. These spatial patterns and temporal trends are not caused by obvious artefacts in the data or the analyses. The trends cannot be directly driven by a mortality driver (such as increased drought or fragmentation–related death) because the biomass in these forests has simultaneously increased. Our findings therefore indicate that long–acting and widespread environmental changes are stimulating the growth and productivity of Amazon forests.
Publisher: Elsevier BV
Date: 04-2012
Publisher: Springer Science and Business Media LLC
Date: 20-06-2008
Publisher: Elsevier BV
Date: 06-1999
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.
Publisher: Wiley
Date: 08-2004
Publisher: Wiley
Date: 08-11-2018
DOI: 10.1111/AEC.12559
Publisher: Wiley
Date: 06-2002
Publisher: Springer Science and Business Media LLC
Date: 04-01-2021
DOI: 10.1038/S41467-020-20537-X
Abstract: A Correction to this paper has been published: 0.1038/s41467-020-20537-x
Publisher: Wiley
Date: 11-2014
DOI: 10.1890/14-0330.1
Publisher: Wiley
Date: 10-2016
DOI: 10.1111/AEC.12319
Publisher: Society for Vector Ecology
Date: 05-2012
DOI: 10.1111/J.1948-7134.2012.00201.X
Abstract: Emerging infectious diseases are considered to be a growing threat to human and wildlife health. Such diseases might be facilitated by anthropogenic land-use changes that cause novel juxtapositions of different habitats and species and result in new interchanges of vectors, diseases, and hosts. To search for such effects in tropical Australia, we s led mosquito populations across anthropogenic disturbance gradients of grassland, artificial rainforest edge, and rainforest interior. From >15,000 captured mosquitoes, we identified 26 species and eight genera. Surprisingly, there was no significant difference in community composition or species richness between forest edges and grasslands, but both differed significantly from rainforest interiors. Mosquito species richness was elevated in grasslands relative to the rainforest habitats. Seven species were unique to grasslands and edges, with another 13 found across all habitats. Among the three most abundant species, Culex annulirostris occurred in all habitat types, whereas Verrallina lineata and Cx. pullus were more abundant in forest interiors. Our findings suggest that the creation of anthropogenic grasslands adjacent to rainforests may increase the susceptibility of species in both habitats to transmission of novel diseases via observable changes and mixing of the vector community on rainforest edges.
Publisher: Wiley
Date: 11-11-2017
DOI: 10.1111/ECOG.02585
Publisher: American Association for Cancer Research (AACR)
Date: 02-2015
DOI: 10.1158/1535-7163.MCT-14-0647
Abstract: Genome-wide studies have identified a high-risk subgroup of pediatric acute lymphoblastic leukemia (ALL) harboring mutations in the Janus kinases (JAK). The purpose of this study was to assess the preclinical efficacy of the JAK1/2 inhibitor AZD1480, both as a single agent and in combination with the MEK inhibitor selumetinib, against JAK-mutated patient-derived xenografts. Patient-derived xenografts were established in immunodeficient mice from bone marrow or peripheral blood biopsy specimens, and their gene expression profiles compared with the original patient biopsies by microarray analysis. JAK/STAT and MAPK signaling pathways, and the inhibitory effects of targeted drugs, were interrogated by immunoblotting of phosphoproteins. The antileukemic effects of AZD1480 and selumetinib, alone and in combination, were tested against JAK-mutated ALL xenografts both in vitro and in vivo. Xenografts accurately represented the primary disease as determined by gene expression profiling. Cellular phosphoprotein analysis demonstrated that JAK-mutated xenografts exhibited heightened activation status of JAK/STAT and MAPK signaling pathways compared with typical B-cell precursor ALL xenografts, which were inhibited by AZD1480 exposure. However, AZD1480 exhibited modest single-agent in vivo efficacy against JAK-mutated xenografts. Combining AZD1480 with selumetinib resulted in profound synergistic in vitro cell killing, although these results were not translated in vivo despite evidence of target inhibition. Despite validation of target inhibition and the demonstration of profound in vitro synergy between AZD1480 and selumetinib, it is likely that prolonged target inhibition is required to achieve in vivo therapeutic enhancement between JAK and MEK inhibitors in the treatment of JAK-mutated ALL. Mol Cancer Ther 14(2) 364–74. ©2014 AACR.
Publisher: Springer Science and Business Media LLC
Date: 08-2017
Publisher: Springer Berlin Heidelberg
Date: 1999
Publisher: Proceedings of the National Academy of Sciences
Date: 19-09-2022
Abstract: Urbanization is rapidly transforming much of Southeast Asia, altering the structure and function of the landscape, as well as the frequency and intensity of the interactions between people, animals, and the environment. In this study, we explored the impact of urbanization on zoonotic disease risk by simultaneously characterizing changes in the ecology of animal reservoirs (rodents), ectoparasite vectors (ticks), and pathogens across a gradient of urbanization in Kuching, a city in Malaysian Borneo. We s led 863 rodents across rural, developing, and urban locations and found that rodent species ersity decreased with increasing urbanization—from 10 species in the rural location to 4 in the rural location. Notably, two species appeared to thrive in urban areas, as follows: the invasive urban exploiter Rattus rattus ( n = 375) and the native urban adapter Sundamys muelleri ( n = 331). R. rattus was strongly associated with built infrastructure across the gradient and carried a high ersity of pathogens, including multihost zoonoses capable of environmental transmission (e.g., Leptospira spp.). In contrast, S. muelleri was restricted to green patches where it was found at high densities and was strongly associated with the presence of ticks, including the medically important genera Amblyomma , Haemaphysalis , and Ixodes . Our analyses reveal that zoonotic disease risk is elevated and heterogeneously distributed in urban environments and highlight the potential for targeted risk reduction through pest management and public health messaging.
Publisher: The Royal Society
Date: 29-03-2004
Abstract: A previous study by Phillips et al . of changes in the biomass of permanent s le plots in Amazonian forests was used to infer the presence of a regional carbon sink. However, these results generated a vigorous debate about s ling and methodological issues. Therefore we present a new analysis of biomass change in old–growth Amazonian forest plots using updated inventory data. We find that across 59 sites, the above–ground dry biomass in trees that are more than 10 cm in diameter (AGB) has increased since plot establishment by 1.22 ± 0.43 Mg per hectare per year (ha −1 yr −1 ), where 1 ha = 10 4 m 2 ), or 0.98 ± 0.38 Mg ha −1 yr −1 if in idual plot values are weighted by the number of hectare years of monitoring. This significant increase is neither confounded by spatial or temporal variation in wood specific gravity, nor dependent on the allometric equation used to estimate AGB. The conclusion is also robust to uncertainty about diameter measurements for problematic trees: for 34 plots in western Amazon forests a significant increase in AGB is found even with a conservative assumption of zero growth for all trees where diameter measurements were made using optical methods and/or growth rates needed to be estimated following fieldwork. Overall, our results suggest a slightly greater rate of net stand–level change than was reported by Phillips et al . Considering the spatial and temporal scale of s ling and associated studies showing increases in forest growth and stem turnover, the results presented here suggest that the total biomass of these plots has on average increased and that there has been a regional–scale carbon sink in old–growth Amazonian forests during the previous two decades.
Publisher: Informa UK Limited
Date: 14-03-2014
Publisher: Elsevier BV
Date: 12-1999
Publisher: Wiley
Date: 22-05-2006
Publisher: American Society of Tropical Medicine and Hygiene
Date: 03-02-2016
Publisher: Springer Science and Business Media LLC
Date: 11-11-2019
DOI: 10.1038/S41559-019-1007-Y
Abstract: Higher levels of taxonomic and evolutionary ersity are expected to maximize ecosystem function, yet their relative importance in driving variation in ecosystem function at large scales in erse forests is unknown. Using 90 inventory plots across intact, lowland, terra firme, Amazonian forests and a new phylogeny including 526 angiosperm genera, we investigated the association between taxonomic and evolutionary metrics of ersity and two key measures of ecosystem function: aboveground wood productivity and biomass storage. While taxonomic and phylogenetic ersity were not important predictors of variation in biomass, both emerged as independent predictors of wood productivity. Amazon forests that contain greater evolutionary ersity and a higher proportion of rare species have higher productivity. While climatic and edaphic variables are together the strongest predictors of productivity, our results show that the evolutionary ersity of tree species in erse forest stands also influences productivity. As our models accounted for wood density and tree size, they also suggest that additional, unstudied, evolutionarily correlated traits have significant effects on ecosystem function in tropical forests. Overall, our pan-Amazonian analysis shows that greater phylogenetic ersity translates into higher levels of ecosystem function: tropical forest communities with more distantly related taxa have greater wood productivity.
Publisher: Springer Science and Business Media LLC
Date: 06-2018
Publisher: Wiley
Date: 16-07-2019
DOI: 10.1002/EAP.1952
Abstract: Assessing the persistent impacts of fragmentation on aboveground structure of tropical forests is essential to understanding the consequences of land use change for carbon storage and other ecosystem functions. We investigated the influence of edge distance and fragment size on canopy structure, aboveground woody biomass (AGB), and AGB turnover in the Biological Dynamics of Forest Fragments Project (BDFFP) in central Amazon, Brazil, after 22+ yr of fragment isolation, by combining canopy variables collected with portable canopy profiling lidar and airborne laser scanning surveys with long-term forest inventories. Forest height decreased by 30% at edges of large fragments (>10 ha) and interiors of small fragments (<3 ha). In larger fragments, canopy height was reduced up to 40 m from edges. Leaf area density profiles differed near edges: the density of understory vegetation was higher and midstory vegetation lower, consistent with canopy reorganization via increased regeneration of pioneers following post-fragmentation mortality of large trees. However, canopy openness and leaf area index remained similar to control plots throughout fragments, while canopy spatial heterogeneity was generally lower at edges. AGB stocks and fluxes were positively related to canopy height and negatively related to spatial heterogeneity. Other forest structure variables typically used to assess the ecological impacts of fragmentation (basal area, density of in iduals, and density of pioneer trees) were also related to lidar-derived canopy surface variables. Canopy reorganization through the replacement of edge-sensitive species by disturbance-tolerant ones may have mitigated the biomass loss effects due to fragmentation observed in the earlier years of BDFFP. Lidar technology offered novel insights and observational scales for analysis of the ecological impacts of fragmentation on forest structure and function, specifically aboveground biomass storage.
Start Date: 12-2013
End Date: 12-2021
Amount: $680,065.00
Funder: Australian Research Council
View Funded ActivityStart Date: 12-2011
End Date: 12-2015
Amount: $310,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2013
End Date: 12-2017
Amount: $365,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2020
End Date: 05-2024
Amount: $395,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 03-2021
End Date: 02-2024
Amount: $410,237.00
Funder: Australian Research Council
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