ORCID Profile
0000-0002-5458-9960
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Global Change Biology | Plant Physiology | Terrestrial Ecology | Plant Biology | Plant Physiology | Ecological Impacts of Climate Change | Ecological Applications | Other Biological Sciences | Ecological Applications not elsewhere classified | Landscape Ecology | Management And Environment |
Living resources (flora and fauna) | Biological sciences | Global climate change adaptation measures | Climate change | Climate Change Adaptation Measures | Integrated (ecosystem) assessment and management | Forest and Woodlands Flora, Fauna and Biodiversity
Publisher: Springer Science and Business Media LLC
Date: 10-03-2013
DOI: 10.1038/NGEO1741
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: Elsevier BV
Date: 12-2018
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: 10-06-2013
DOI: 10.1002/JQS.2639
Publisher: The Royal Society
Date: 27-11-2011
Abstract: The rate of above-ground woody biomass production, W P , in some western Amazon forests exceeds those in the east by a factor of 2 or more. Underlying causes may include climate, soil nutrient limitations and species composition. In this modelling paper, we explore the implications of allowing key nutrients such as N and P to constrain the photosynthesis of Amazon forests, and also we examine the relationship between modelled rates of photosynthesis and the observed gradients in W P . We use a model with current understanding of the underpinning biochemical processes as affected by nutrient availability to assess: (i) the degree to which observed spatial variations in foliar [N] and [P] across Amazonia affect stand-level photosynthesis and (ii) how these variations in forest photosynthetic carbon acquisition relate to the observed geographical patterns of stem growth across the Amazon Basin. We find nutrient availability to exert a strong effect on photosynthetic carbon gain across the Basin and to be a likely important contributor to the observed gradient in W P . Phosphorus emerges as more important than nitrogen in accounting for the observed variations in productivity. Implications of these findings are discussed in the context of future tropical forests under a changing climate.
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/FP14040
Publisher: American Geophysical Union (AGU)
Date: 09-2002
DOI: 10.1029/2001GB001466
Publisher: Wiley
Date: 08-11-2018
DOI: 10.1111/GCB.14413
Publisher: Copernicus GmbH
Date: 05-05-2011
Publisher: Copernicus GmbH
Date: 24-03-2014
Publisher: Copernicus GmbH
Date: 13-06-2014
Publisher: Informa UK Limited
Date: 03-2013
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: Wiley
Date: 16-11-2007
Publisher: Springer Science and Business Media LLC
Date: 23-06-2020
DOI: 10.1038/S41598-020-66686-3
Abstract: Amazonian forests are extraordinarily erse, but the estimated species richness is very much debated. Here, we apply an ensemble of parametric estimators and a novel technique that includes conspecific spatial aggregation to an extended database of forest plots with up-to-date taxonomy. We show that the species abundance distribution of Amazonia is best approximated by a logseries with aggregated in iduals, where aggregation increases with rarity. By averaging several methods to estimate total richness, we confirm that over 15,000 tree species are expected to occur in Amazonia. We also show that using ten times the number of plots would result in an increase to just ~50% of those 15,000 estimated species. To get a more complete s le of all tree species, rigorous field c aigns may be needed but the number of trees in Amazonia will remain an estimate for years to come.
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: Wiley
Date: 08-07-2016
DOI: 10.1111/NPH.14079
Abstract: We examined whether variations in photosynthetic capacity are linked to variations in the environment and/or associated leaf traits for tropical moist forests ( TMF s) in the Andes/western Amazon regions of Peru. We compared photosynthetic capacity (maximal rate of carboxylation of Rubisco ( V cmax ), and the maximum rate of electron transport ( J max )), leaf mass, nitrogen (N) and phosphorus (P) per unit leaf area ( M a , N a and P a , respectively), and chlorophyll from 210 species at 18 field sites along a 3300‐m elevation gradient. Western blots were used to quantify the abundance of the CO 2 ‐fixing enzyme Rubisco. Area‐ and N‐based rates of photosynthetic capacity at 25°C were higher in upland than lowland TMF s, underpinned by greater investment of N in photosynthesis in high‐elevation trees. Soil [P] and leaf P a were key explanatory factors for models of area‐based V cmax and J max but did not account for variations in photosynthetic N‐use efficiency. At any given N a and P a , the fraction of N allocated to photosynthesis was higher in upland than lowland species. For a small subset of lowland TMF trees examined, a substantial fraction of Rubisco was inactive. These results highlight the importance of soil‐ and leaf‐P in defining the photosynthetic capacity of TMF s, with variations in N allocation and Rubisco activation state further influencing photosynthetic rates and N‐use efficiency of these critically important forests.
Publisher: Wiley
Date: 15-10-2012
DOI: 10.1002/RCM.6397
Abstract: Pyrogenic carbon (C(P)) is an important component of the global carbon budget. Accurate determination of the abundance and stable isotope composition of C(P) in soils and sediments is crucial for understanding the dynamics of the C(P) cycle and interpreting records of biomass burning, climate and vegetation change in the past. Here we test hydrogen pyrolysis (hypy) as a new technique potentially capable of eliminating labile organic carbon (C(L)) from total organic carbon (C(T)) in a range of matrices in order to enable reliable quantification of both the C(P) component of C(T) and the stable carbon isotope composition of C(P) (δ(13)C(P)). We mixed C(P) at a range of concentrations with common C(P)-free matrices (C(L) = cellulose, chitin, keratin, decomposed wood, leaf litter, grass and algae) and determined the amount of residual carbon not removed by hydrogen pyrolysis (C(R)) as a ratio of C(T) (C(R)/C(T)). Mixing C(P) with a unique δ(13)C value provided a natural abundance isotope label from which to precisely determine the ratio of C(P) to residual C(L) remaining after hypy. All C(P)-free matrices contained trace carbon after hypy, indicating that hypy does not remove all the C(L). However, there was a strong correlation between C(R)/C(T) and C(P)/C(T), viz. C(R)/C(T)= 1.02(C(P)/C(T)) + 4.0 × 10(-3), r(2) = 0.99, p 4% being required for the determination of the δ(13)C(P) values within an interpretable error under our experimental conditions.
Publisher: Wiley
Date: 29-04-2004
Publisher: Springer Science and Business Media LLC
Date: 07-04-2013
Publisher: Copernicus GmbH
Date: 29-05-2015
Publisher: Informa UK Limited
Date: 17-09-2013
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: 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: Copernicus GmbH
Date: 26-08-2015
Abstract: Abstract. Variations in the carbon isotopic composition of soil organic matter (SOM) in bulk and fractionated s les were used to assess the influence of C3 and C4 vegetation on SOM dynamics in semi-natural tropical ecosystems s led along a precipitation gradient in West Africa. Differential patterns in SOM dynamics in C3/C4 mixed ecosystems occurred at various spatial scales. Relative changes in C / N ratios between two contrasting SOM fractions were used to evaluate potential site-scale differences in SOM dynamics between C3- and C4-dominated locations. These differences were strongly controlled by soil texture across the precipitation gradient, with a function driven by bulk δ13C and sand content explaining 0.63 of the observed variability. The variation of δ13C with soil depth indicated a greater accumulation of C3-derived carbon with increasing precipitation, with this trend also being strongly dependant on soil characteristics. The influence of vegetation thickening on SOM dynamics was also assessed in two adjacent, but structurally contrasting, transitional ecosystems occurring on comparable soils to minimise the confounding effects posed by climatic and edaphic factors. Radiocarbon analyses of sand-size aggregates yielded relatively short mean residence times (τ) even in deep soil layers, while the most stable SOM fraction associated with silt and clay exhibited shorter τ in the savanna woodland than in the neighbouring forest stand. These results, together with the vertical variation observed in δ13C values, strongly suggest that both ecosystems are undergoing a rapid transition towards denser closed canopy formations. However, vegetation thickening varied in intensity at each site and exerted contrasting effects on SOM dynamics. This study shows that the interdependence between biotic and abiotic factors ultimately determine whether SOM dynamics of C3- and C4-derived vegetation are at variance in ecosystems where both vegetation types coexist. The results highlight the far-reaching implications that vegetation thickening may have for the stability of deep SOM.
Publisher: Wiley
Date: 12-2018
DOI: 10.1002/ECE3.4601
Publisher: Copernicus GmbH
Date: 19-12-2014
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/FP16035
Abstract: We measured a erse range of foliar characteristics in shrub and tree species in temperate rainforest communities along a soil chronosequence (six sites from 8 to 120 000 years) and used multilevel model analysis to attribute the proportion of variance for each trait into genetic (G, here meaning species-level), environmental (E) and residual error components. We hypothesised that differences in leaf traits would be driven primarily by changes in soil nutrient availability during ecosystem progression and retrogression. Several leaf structural, chemical and gas-exchange traits were more strongly driven by G than E effects. For leaf mass per unit area (MA), foliar [N], net CO2 assimilation and dark respiration rates and foliar carbohydrate concentration, the G component accounted for 60–87% of the total variance, with the variability associated with plot, the E effect, much less important. Other traits, such as foliar [P] and N : P, displayed strong E and residual effects. Analyses revealed significant reductions in the slopes of G-only bivariate relationships when compared with raw relationships, indicating that a large proportion of trait–trait relationships is species based, and not a response to environment per se. This should be accounted for when assessing the mechanistic basis for using such relationships in order to make predictions of responses of plants to short-term environmental change.
Publisher: Wiley
Date: 02-03-2012
Publisher: Wiley
Date: 05-08-0008
DOI: 10.1111/NPH.13253
Abstract: Leaf dark respiration ( R dark ) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of R dark and associated leaf traits. Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed‐effects models were used to disentangle sources of variation in R dark . Area‐based R dark at the prevailing average daily growth temperature ( T ) of each site increased only twofold from the Arctic to the tropics, despite a 20°C increase in growing T (8–28°C). By contrast, R dark at a standard T (25°C, R dark 25 ) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher R dark 25 at a given photosynthetic capacity ( V cmax 25 ) or leaf nitrogen concentration ([N]) than species at warmer sites. R dark 25 values at any given V cmax 25 or [N] were higher in herbs than in woody plants. The results highlight variation in R dark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of R dark in terrestrial biosphere models (TBMs) and associated land‐surface components of Earth system models (ESMs).
Publisher: Copernicus GmbH
Date: 21-05-2015
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: Wiley
Date: 10-07-2012
Publisher: Copernicus GmbH
Date: 24-03-2014
Publisher: Wiley
Date: 13-05-2010
Publisher: American Geophysical Union (AGU)
Date: 22-01-2002
DOI: 10.1029/2000GB001374
Publisher: Wiley
Date: 25-01-2013
DOI: 10.1111/NPH.12104
Abstract: The rate of CO 2 assimilation by plants is directly influenced by the concentration of CO 2 in the atmosphere, c a . As an environmental variable, c a also has a unique global and historic significance. Although relatively stable and uniform in the short term, global c a has varied substantially on the timescale of thousands to millions of years, and currently is increasing at seemingly an unprecedented rate. This may exert profound impacts on both climate and plant function. Here we utilise extensive datasets and models to develop an integrated, multi‐scale assessment of the impact of changing c a on plant carbon dioxide uptake and water use. We find that, overall, the sensitivity of plants to rising or falling c a is qualitatively similar across all scales considered. It is characterised by an adaptive feedback response that tends to maintain 1 − c i / c a , the relative gradient for CO 2 diffusion into the leaf, relatively constant. This is achieved through predictable adjustments to stomatal anatomy and chloroplast biochemistry. Importantly, the long‐term response to changing c a can be described by simple equations rooted in the formulation of more commonly studied short‐term responses. Contents Summary 1077 I. Introduction 1078 II. Atmospheric CO 2 concentrations through time 1079 III. Plant sensitivity to CO 2 at geological timescales 1080 IV. Plant sensitivity to CO 2 over the last 200 yr 1081 V. Increased water‐use efficiency? 1084 VI. Simple formulation of stomatal conductance in land surface models for simulating long‐term CO 2 response 1087 VII. Conclusions 1088 Acknowledgements 1089 References 1089
Publisher: Copernicus GmbH
Date: 13-06-2014
Publisher: Wiley
Date: 19-06-2019
Abstract: If we are to ensure the persistence of species in an increasingly warm world, of interest is the identification of drivers that affect the ability of an organism to resist thermal stress. Underpinning any organism's capacity for resistance is a complex interplay between biological and physical factors occurring over multiple scales. Tropical coral reefs are a unique system, in that their function is dependent upon the maintenance of a coral-algal symbiosis that is directly disrupted by increases in water temperature. A number of physical factors have been identified as affecting the biological responses of the coral organism under broadscale thermal anomalies. One such factor is water flow, which is capable of modulating both organismal metabolic functioning and thermal environments. Understanding the physiological and hydrodynamic drivers of organism response to thermal stress improves predictive capabilities and informs targeted management responses, thereby increasing the resilience of reefs into the future.
No related organisations have been discovered for Jonathan Lloyd.
Start Date: 2010
End Date: 12-2012
Amount: $330,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2009
End Date: 10-2012
Amount: $503,000.00
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: 2008
End Date: 12-2011
Amount: $570,000.00
Funder: Australian Research Council
View Funded Activity