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Context Allometric equations describing the relationships between tree height (H) and breast height diameter (D) should be both statistically efficient and biologically relevant. Aims To determine whether selected allometric equations can meet established criteria for both efficiency and relevance. Methods Nine equations were compared to define the H–D relationships of 1122 individuals and 18 species from an Australian subtropical rainforest. Key results Three-parameter asymptotic equations described initial slope (a), curvature (b), and asymptotic height (Ha). Each equation was evaluated for precision (root mean square error, RMSE) and bias in H estimates, and ease of interpretation of function parameters. For both individual species and all stems, a non-rectangular hyperbola (NRH) provided almost equally high precision and low bias as did the statistically most parsimonious generalised Michaelis–Menten function, plus linear parameter values easily relatable to tree structural and functional attributes. The value of NRH a increased linearly with wood density for canopy species, but not for understorey and subdominant species, whereas the value of NRH b decreased as Ha increased from understorey to canopy species. Conclusions Species within understorey, subdominant, and canopy structural groups shared similar ranges of parameter values within groups that reflect both intrinsic architectural and developmental patterns, and environmental limitations to Ha. Implications The NRH can be used to visualise both early and later tree development stages and differences among the growth patterns of species occupying different positions within a forest.

The relationships between climate and forest dynamics can help us to interpret patterns of ecosystem carbon and to predict how forests react to climatic changes. We report mass dynamics of deadwood (necromass) from tropical forest ecosystems subject to some of the highest frequency of tropical cyclones in the world and to regular, persistent seasonal monsoon winds. Plots that are influenced by typhoons but exposed to different degrees of monsoon winds were monitored. We expected that stocks and inputs of necromass would reflect the seasonal intensity of wind events and be higher in the high wind exposure forest than in the low wind exposure forest, especially for fallen woody debris. The results showed that necromass input was indeed influenced by the magnitude of typhoons and aggravated by monsoon winds. However, while there was no significant difference in stock of necromass between plots, inputs of standing necromass were significantly higher in the high wind exposure plot; these were mostly derived from dead resprouts. Both our forests had very low values of total necromass stocks (3.47–4.32 Mg C ha−1) and inputs (2.1–2.5 Mg C ha−1 y−1) compared with tropical forests worldwide. Our results show that both monsoon and typhoon winds shape these tropical forests, favouring low stature individuals and trees with ability to resprout and that these strategies provide these forests with remarkable resistance and resilience to wind disturbances. Our findings from some of the most wind-affected forests in the world indicate how woody carbon dynamics and forest structure in other regions may respond to future changes in the frequency and intensity of winds.

The spatial distribution of tree species in the forest is key to understanding species coexistence concerning their realized niche. Previous research has shown that forest community composition differs in Lanjenchi Forest Dynamics Plot (FDP) and is likely to be caused by the strength of the northeast monsoon wind. However, relationships between species and other environmental factors are not completely understood. We investigated tree species-habitat associations in Lanjenchi asking how topographic habitat affects forest structure and composition, and we classified the plot into topographic habitat using Multivariate Regression Trees based on the forest community composition and topography. Then, based on metrics of forest structure, we used the torus translation test to evaluate the degree of tree species-habitat association. Three habitats were identified in Lanjenchi and can be classified into windward, intermediate, and leeward habitats based on wind exposure value and aspect. Moreover, 81% of species had a strong positive association with one of the three habitats. Based on the strength of habitat association, the tree species can be divided into six categories. Among these categories, windward species are most abundant in Lanjenchi but are some of the rarest species in Taiwan. These results indicated that the northeast monsoon wind is an essential factor that shapes species distribution in the Lanjenchi, especially at the windward habitats. The northeast monsoon wind creates a unique niche allowing many regionally rare species to dominate these habitats in tropical Taiwan.

Made available in DSpace on 2022-04-28T19:40:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-05-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) CYTED Ciencia y Tecnología para el Desarrollo Natural Environment Research Council Newton Fund Understanding of tropical forests has been revolutionized by monitoring in permanent plots. Data from global plot networks have transformed our knowledge of forests’ diversity, function, contribution to global biogeochemical cycles, and sensitivity to climate change. Monitoring has thus far been concentrated in rain forests. Despite increasing appreciation of their threatened status, biodiversity, and importance to the global carbon cycle, monitoring in tropical dry forests is still in its infancy. We provide a protocol for permanent monitoring plots in tropical dry forests. Expanding monitoring into dry biomes is critical for overcoming the linked challenges of climate change, land use change, and the biodiversity crisis. Tropical Biodiversity Royal Botanic Garden Edinburgh School of Geography Faculty of Environment University of Leeds Fundación Ecosistemas Secos de Colombia School of Geosciences The University of Edinburgh Geography College of Life and Environmental Sciences University of Exeter Instituto de Pesquisas Jardim Botanico do Rio de Janeiro Centro de Ecologia Instituto Venezolano de Investigaciones Cientificas Ciencias Básicas de la Biodiversidad Instituto de Investigación de Recursos Biológicos Alexander von Humboldt Herbario Departamento Académico de Biología Universidad Nacional Agraria La Molina Center for Conservation and Sustainability Smithsonian Conservation Biology Institute Department of Life Sciences Imperial College London Laboratório de Ciências Ambientais Universidade Estadual do Norte Fluminense Instituto de Investigaciones en Ciencias Agrarias de Rosario (IICAR) Facultad Ciencias Agrarias UNR Universidad Nacional de Rosario Escuela de Biología Facultad de Ciencias Exactas Pontificia Universidad Católica del Ecuador Real Jardín Botánico CSIC Laboratório de Ciências Ambientas Universidade Estadual do Norte Fluminense Departamento de Biologia Faculdade de Filosofia Ciências e Letras de Ribeirão Preto Universidade de Sao Paulo Museo de Historia Natural Noel Kempff Mercado Universidad Autonoma Gabriel Rene Moreno Unidade Acadêmica de Garanhuns Universidade Federal Rural de Pernambuco Instituto de Biologia Universidade Federal da Bahia International Master Program of Agriculture National Chung Hsing University Departamento de Biologia Vegetal Universidade Federal do Ceará Centro de Tecnologia e Recursos Naturais (CTRN) Universidade Federal de Campina Grande Programa de Pós-Graduação em Ciências Biológicas (PPGCB) Centro Ciências Biológicas e da Saúde Universidade Estadual de Montes Claros Ciencias Biologicas Universidade Estadual de Feira de Santana Grupo de Ecología y Conservación de Fauna y Flora Silvestre Universidad Nacional de Colombia Facultad de Ciencias Instituto de Investigaciones sobre los Recursos Naturales Universidad Michoacana de San Nicolás de Hidalgo Universidade do Estado de Mato Grosso Herbario HOXA Jardín Botánico de Missouri Embrapa Semiárido Embrapa Biologia Vegetal Universidade Federal de Minas Gerais Faculdade de Ciências Farmacêuticas de Ribeirão Preto Universidade de Sao Paulo Laboratório de Fenologia Departamento de Botânica Instituto de Biociências Universidade Estadual Paulista Departamento de Biologia Vegetal Universidade Federal de Viçosa Departamento de Ciências Florestais Universidade Federal de Lavras Department of Forest Sciences Universidade Federal Rural de Pernambuco Departamento de Ciências Atmosféricas Instituto de Astronomia Geofífisica e Ciências Atmosféricas Universidade de São Paulo Plant Ecology and Nature Conservation Wageningen University and Research Laboratório de Fenologia Departamento de Botânica Instituto de Biociências Universidade Estadual Paulista FAPESP: 2015/50488-5 CYTED Ciencia y Tecnología para el Desarrollo: 418RT0554 Natural Environment Research Council: NE/I027797/1 Natural Environment Research Council: NE/I028122/1 Newton Fund: NE/N000587/1 Newton Fund: NE/N01247X/1 Newton Fund: NE/N012550/1

Arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) associations are critical for host-tree performance. However, how mycorrhizal associations correlate with the latitudinal tree beta-diversity remains untested. Using a global dataset of 45 forest plots representing 2,804,270 trees across 3840 species, we test how AM and EcM trees contribute to total beta-diversity and its components (turnover and nestedness) of all trees. We find AM rather than EcM trees predominantly contribute to decreasing total beta-diversity and turnover and increasing nestedness with increasing latitude, probably because wide distributions of EcM trees do not generate strong compositional differences among localities. Environmental variables, especially temperature and precipitation, are strongly correlated with beta-diversity patterns for both AM trees and all trees rather than EcM trees. Results support our hypotheses that latitudinal beta-diversity patterns and environmental effects on these patterns are highly dependent on mycorrhizal types. Our findings highlight the importance of AM-dominated forests for conserving global forest biodiversity., The relationship of mycorrhizal associations with latitudinal gradients in tree beta-diversity is unexplored. Using a global dataset approach, this study examines how trees with arbuscular mycorrhizal and ectomycorrhizal associations contribute to latitudinal beta-diversity patterns and the environmental controls of these patterns.

ForestGEO is a network of scientists and long-term forest dynamics plots (FDPs) spanning the Earth's major forest types. ForestGEO's mission is to advance understanding of the diversity and dynamics of forests and to strengthen global capacity for forest science research. ForestGEO is unique among forest plot networks in its large-scale plot dimensions, censusing of all stems ≥1 cm in diameter, inclusion of tropical, temperate and boreal forests, and investigation of additional biotic (e.g., arthropods) and abiotic (e.g., soils) drivers, which together provide a holistic view of forest functioning. The 71 FDPs in 27 countries include approximately 7.33 million living trees and about 12,000 species, representing 20% of the world's known tree diversity. With >1300 published papers, ForestGEO researchers have made significant contributions in two fundamental areas: species coexistence and diversity, and ecosystem functioning. Specifically, defining the major biotic and abiotic controls on the distribution and coexistence of species and functional types and on variation in species' demography has led to improved understanding of how the multiple dimensions of forest diversity are structured across space and time and how this diversity relates to the processes controlling the role of forests in the Earth system. Nevertheless, knowledge gaps remain that impede our ability to predict how forest diversity and function will respond to climate change and other stressors. Meeting these global research challenges requires major advances in standardizing taxonomy of tropical species, resolving the main drivers of forest dynamics, and integrating plot-based ground and remote sensing observations to scale up estimates of forest diversity and function, coupled with improved predictive models. However, they cannot be met without greater financial commitment to sustain the long-term research of ForestGEO and other forest plot networks, greatly expanded scientific capacity across the world's forested nations, and increased collaboration and integration among research networks and disciplines addressing forest science.

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., Tree mortality has been shown to be the dominant control on carbon storage in Amazon forests, but little is known of how and why Amazon forest trees die. Here the authors analyse a large Amazon-wide dataset, finding that fast-growing species face greater mortality risk, but that slower-growing individuals within a species are more likely to die, regardless of size.

The original version of this Article contained an error in Table 2, where the number of individuals in the “All Amazonia” row was reported as 11,6431 instead of 116,431. Also, the original version of this Article contained an error in the Methods, where the R2 for the proportion of broken/uprooted dead trees increase per year was reported as 0.12, the correct value being 0.06. The original version of this Article contained errors in the author affiliations. The affiliation of Gerardo A. Aymard C. with UNELLEZGuanare, Herbario Universitario (PORT), Portuguesa, Venezuela Compensation International Progress S.A. Ciprogress–Greenlife.

Background Abandoned human-modified forests are refuges for remnant biodiversity. However, there are very few studies on the biodiversity and regeneration of native species in human-modified forests which are rich in exotic trees. Our research aim is to evaluate the regeneration status and biodiversity of two adjacent human-modified forests. The two forests have distinct overstorey exotic species richness prior to abandonment: one is an exotic tree plantation low in species richness, and the other is an exotic arboretum high in species richness. The original management practices of the two forests have been neglected for more than 20 years. A primary forest was selected as a reference forest to compare their diversity and regeneration status. We asked: (1) Is there a structural difference among the three forests? (2) What are the proportions of native saplings in the human-modified forests? (3) Are the introduced exotic species able to naturalize? Results We recorded 1316 individuals from 88 species, belonging to 69 genera and 34 families in the three forests [each sampled 16 quadrats (10 m × 5 m)]. Both human-modified forests were similar in their height structure, diameter structure, and sapling density, but differed in species diversity (characterized by rarefaction curves) and floristic composition (indicated by a quantitative similarity index). In the arboretum, only 50% of the sapling individuals were native. Surprisingly, when sampling efforts were standardized, the arboretum had higher native sapling species richness than the exotic species-poor plantation. Moreover, both human-modified forests had conserved a few rare and endemic species. Nevertheless, some exotic species in the arboretum had escaped to the nearby plantation. Conclusions After 20 years of abandonment, the two human-modified forests had converged in structure, but not in diversity patterns of native saplings. This could be due to that the diversity of exotic overstorey composition can influence the natural regeneration of understorey plants. Our study also raised concerns about conserving native species and managing naturalized exotic species in these human-modified forests. Electronic supplementary material The online version of this article (doi:10.1186/s40529-017-0190-x) contains supplementary material, which is available to authorized users.

Carbon stored in woody debris is a key carbon pool in forest ecosystems. The most widely-used method to convert woody debris volume to carbon is by first multiplying field-measured volume with wood density to obtain necromass, and then assuming that a fixed proportion (often 50%) of the necromass is carbon. However, this crucial assumption is rarely tested directly, especially in the tropics. The aim of this study is to verify the field carbon concentration values of living trees and woody debris in two distinct tropical forests in Taiwan. Wood from living trees and woody debris across five decay classes was sampled to measure density and carbon concentrations. We found that both wood density and carbon concentration (carbon mass/total mass) declined significantly with the decay class of the wood. Mean (±SE) carbon concentration values for living trees were 44.6 ± 0.1%, while for decay classes one to five they were respectively 41.1 ± 1.4%, 41.4 ± 1.0%, 37.7 ± 1.3%, 30.5 ± 2.0%, and 19.6 ± 2.2%. Total necromass carbon stock was low, only 3.33 ± 0.55 Mg C ha −1 in the windward forest (Lanjenchi) and 4.65 ± 1.63 Mg C ha −1 in the lowland forest (Nanjenshan). Applying the conventional 50% necromass carbon fraction value would cause a substantial overestimate of the carbon stocks in woody debris of between 17% and 36%, or about 1 Mg of carbon per hectare. The decline in carbon concentration and the increase of variances in the heavily decayed class suggest that in high-diversity tropical forests there are diverse decomposition trajectories and that assuming a fixed carbon fraction across woody pieces is not justified. Our work reveals the need to consider site-specific and decay class-specific carbon concentrations in order to accurately estimate carbon stocks and fluxes in forest ecosystems. If the marked decline in carbon content with necromass decay is typical of tropical forests, the dead wood carbon pool in the biome needs revision and is likely to be overestimated.

Additional file 1: Figure S1. Relationship between the sky-canopy border length and mixed-pixel zone length in model canopy hemispherical photographs. Figure S2. Using linear models to fit the relationships between the grey pixel fraction and canopy gap fraction in model canopy hemispherical photographs. Figure S3. Using linear and second order polynomial models to fit the relationships between the grey pixel fraction and canopy gap fraction in model canopy hemispherical photographs. Figure S4. Relationships of canopy gap fraction, the camera-to-canopy distance and lensâ view angle to the sky-canopy border length. Figure S5. Effects of the exposure-thresholding mismatch extents (ETM extents) on estimated gap fraction. Text S1. The method for obtaining the correct gap fraction for model canopies. Text S2. The impreciseness of our control on the light intensity of the light source when taking photographs for model canopies.

Wood density and carbon concentration are the two major parameters needed for carbon pool estimation. However, the two parameters are rarely measured in tropical forests. In this dataset, physical properties (wood density) and chemical properties (i.e. carbon, nitrogen, and hydrogen concentration) of woody debris across decay classes in tropical Taiwan were presented. The decay classes of woody debris were subjectively classified into five classes. Based on the dataset, a more precise estimation of carbon stocks in woody debris across decay classes can be obtained. For further description, interpretation and discussion about the dataset please refer to Chao et al. (submitted).

Additional file 1: Appendix A. Native species recorded in the study plots. Appendix B. Non-native species recorded in the study plots.

Summary: Tropical forest above-ground wood production (AGWP) varies substantially along environmental gradients. Some evidence suggests that AGWP may vary between regions and specifically that Asian forests have particularly high AGWP. However, comparisons across biogeographic regions using standardized methods are lacking, limiting our assessment of pan-tropical variation in AGWP and potential causes. We sampled AGWP in NW Amazon (17 long-term forest plots) and N Borneo (11 plots), both with abundant year-round precipitation. Within each region, forests growing on a broad range of edaphic conditions were sampled using standardized soil and forest measurement techniques. Plot-level AGWP was 49% greater in Borneo than in Amazonia (9.73 ± 0.56 vs. 6.53 ± 0.34 Mg dry mass ha -1 a -1 , respectively; regional mean ± 1 SE). AGWP was positively associated with soil fertility (PCA axes, sum of bases and total P). After controlling for the edaphic environment, AGWP remained significantly higher in Bornean plots. Differences in AGWP were largely attributable to differing height-diameter allometry in the two regions and the abundance of large trees in Borneo. This may be explained, in part, by the greater solar radiation in Borneo compared with NW Amazonia. Trees belonging to the dominant SE Asian family, Dipterocarpaceae, gained woody biomass faster than otherwise equivalent, neighbouring non-dipterocarps, implying that the exceptional production of Bornean forests may be driven by floristic elements. This dominant SE Asian family may partition biomass differently or be more efficient at harvesting resources and in converting them to woody biomass. Synthesis. N Bornean forests have much greater AGWP rates than those in NW Amazon when soil conditions and rainfall are controlled for. Greater resource availability and the highly productive dipterocarps may, in combination, explain why Asian forests produce wood half as fast again as comparable forests in the Amazon. Our results also suggest that taxonomic groups differ in their fundamental ability to capture carbon and that different tropical regions may therefore have different carbon uptake capacities due to biogeographic history. North Bornean forests have much greater AGWP rates than those in north-western Amazon when soil conditions and rainfall are controlled for. Greater resource availability and the highly productive dipterocarps may, in combination, explain why these Asian forests produce wood half as fast again as comparable forests in the Amazon. Our results also suggest that taxonomic groups differ in their fundamental ability to capture carbon and that different tropical regions may therefore have different carbon uptake capacities due to biogeographic history.

High image discrimination threshold values tend to be given to canopy hemispherical photographs (CHPs) with high exposure (resulting in bright images), but the effects of exposure on image threshold have been overlooked. A model canopy system was developed to precisely manipulate exposure (in relation to reference exposure measured from an unobscured overcast model sky), canopy openness, gap fragmentation and sky illumination of CHPs. We showed that there was a numerical trade-off relationship between exposure and image threshold of CHPs, whereas the last three factors had negligible effects on image threshold. A new thresholding method based on this relationship was shown to be applicable in the field and to allow users of hemispherical photography (HP) to compensate for the effects of higher exposure on CHPs with higher empirical threshold values. The advantages of this method are as follows: (i) it is an objective method; (ii) its overall performance is better than that of automatic thresholding methods throughout a wide range of canopy openness and exposure; and (iii) its efficiency of image analysis is higher than that of conventional manual and automatic thresholding methods, because all CHPs can be analysed with a constant empirical threshold value. Our results highlight the necessity of integrating both exposure and thresholding for optimal CHP results and the contribution that model canopies can make to methodological studies of HP.

In order to reveal the characteristics of the vegetation affected by monsoons at the northern border of Paleotropics, a tree-by-tree census was conducted in the lowland forests in the southernmost Taiwan (Nanjenshan) and an adjacent islet (Lanyu). The census recorded a total of 109,060 individuals (≥1-cm diameter at breast height) belonging to 255 vascular tree species in 1330 quadrats (10 × 10 m). Two-way Indicator Species Analysis first classified forest types into two groups, Lanyu and Nanjenshan, reflecting biogeographical differences. Five subgroups were further classified, showing correlations with topographic position indices. Forests located on wind-exposed slopes, regardless of elevations, were characterised by low canopy height, high stem density, high proportion of small stems, and high proportion of warm-temperate-related species, compared with the wind-sheltered communities. However, there were no significant differences in basal area and species diversity. In comparison with other tropical forests, our forests are characterised by high stem density, low diversity and a lack of the pan-Paleotropical dominant Dipterocarpaceae. In conclusion, vegetation in the studied regions not only showed a transition characteristic between Paleotropics and Holarctic Kingdoms in terms of composition, but also showed differentiations caused by their biogeographical history and the interaction between topographic positions and wind stress from monsoons.

Question: How do trees die in high-mortality and low mortality Amazonian forest regions? Why do trees die in different ways? Location: Humid, lowland forests in Amazonian Peru and Venezuela.

Spatial patterns of trees in a lowland rainforest at Nanjen Lake, southern Taiwan were evaluated. Among the 91 species with more than 15 individuals in the 1.61-ha plot, 90.1% species showed an aggregated distribution pattern, and 8.8% species were randomly distributed at the 4 m scale. Along the distance scales, 71.4% species kept aggregated distribution pattern, and only one species remained randomly distributed at all distance scales. Rare species tended to be more aggregated than the common species. As for trees in different size classes, 40.9% highly aggregated species became less aggregated or even randomly distributed with the increase of tree size, while 9.1% species had an inverse pattern. As for trees in the size class ≥ 8 cm diameter, 68.2% species were randomly distributed and only 29.6% species were aggregated. No species displayed a regular pattern in any size class. There were four major habitat types in the study plot, including ridge, mid-slope, valley and streamside types. Our results suggested that the distribution patterns of most species within the Nanjen Lake plot were related to habitat heterogeneity, such that some species were only distributed along the streamside and some species could only be found on the ridge top. Other factors, such as dispersal limitation, might also play a role in determining the distribution patterns of trees.

Summary 1. Tree mortality is an important process in forest ecology. We explored the extent to which tropical tree death is a predictable outcome of taxon and individual level properties by means of mixedspecies logistic regression, for trees ≥ 10 cm in diameter. We worked in two lowland forest regions with markedly different floristic composition and dynamic regimes ‐ the high wood density, lowmortality northeastern (NE) Amazon (in eastern Venezuela), and the low wood density, highmortality northwestern (NW) Amazon (in northern Peru). 2. Among those genera that are shared between regions there were no detectable regional differences in mortality rates. This suggests that floristic compositional differences are a major driver of the twofold regional contrast in stand-level mortality. 3. In NE forests, mortality risk of individual trees is best predicted by low taxon-level wood density, slow relative growth, and large size, reflecting phylogenetically determined life-history strategy, physiological stress and senescence. 4. In NW forests, trees with low wood density and slow relative growth are also at most risk, but probability of death is independent of tree size, indicating that senescence is unimportant in this region. 5. Synthesis. This study shows that despite fundamental floristic and dynamic differences between the two Amazonian regions, mortality risk can be predicted with mixed-species, individual-based statistical models and that the predictors are remarkably similar, such that tree growth and wood density both play important roles.

Spatial patterns of trees in a lowland rainforest in the 5.88-ha Lanjenchi plot of the southernmost Taiwan were evaluated. Among the 88 species with more than 15 individuals, 87.5% had an aggregated distribution pattern, and 9.1% species were randomly distributed. Rare species tended to be more aggregated than common species at all distance scales. As for different DBH size classes, 35.5% species shifted from highly aggregated patterns to a low level of aggregation or random distribution with an increase in tree size, and 11.3% species had an inverse pattern. When comparing spatial patterns among different habitats within the plot, the aggregation intensity increased along a wind-stress gradient from the sheltered creek to the most exposed slopes. No species displayed a regular pattern in any size class or habitat type. This study revealed that distribution of most species within the Lanjenchi forest was related to habitat heterogeneity. Other factors, such as dispersal limitation, however, may also play a role in determining the distribution patterns.

The forest in Lanjenchi is a remnant patch of subtropical rainforests in southern Taiwan. In 1998, the previous Lanjenchi plot was enlarged from 3 ha to 5.88 ha in order to include more topographical variation and understand how the gradient of wind stress controls forest structure and species composition. All free-standing woody plants in these plots with diameter ≥ 1 cm were identified, measured, tagged and mapped. A total of 60,146 individuals belonging to 136 vascular tree species in 83 genera and 42 families was recorded. Families with the largest cumulative basal areas were Fagaceae, Theaceae, Araliaceae, Aquifollaceae, Lauraceae and Illiciaceae. The size-class distribution of all species showed that most species were in good recruitment patterns with the most stems in small size classes. The results of two-way indicator species analysis (TWINSPAN) classified the sampling plots into four forest and habitat types: 1. Rhaphiolepis indica var. hiiranensis - Illicium arborescens (Windward I) type; 2. Cinnamomum brevipedunculatum - Illicium arborescens (Windward II) type; 3. Sloanea formosana - Ilex cochinchinensis (Leeward) type; and 4. Glycosmis citrifolia - Helicia formosana (Creek) type. The forest composition changes formed a sequence on the topographic gradient from the most exposed windward ridges and north-east-facing slopes to more sheltered leeward footslopes and creeks. Further studies using detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) confirmed the results of TWINSPAN, and showed the important roles of the topographic variables in the distribution of most tree species.

Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades1, 2, with a substantial fraction of this sink probably located in the tropics3, particularly in the Amazon4. 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 longevity5. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale1, 2, and is contrary to expectations based on models.

Forest inventory plots are widely used to estimate biomass carbon storage and its change over time. While there has been much debate and exploration of the analytical methods for calculating biomass, the methods used to determine rates of wood production have not been evaluated to the same degree. This affects assessment of ecosystem fluxes and may have wider implications if inventory data are used to parameterise biospheric models, or scaled to large areas in assessments of carbon sequestration. Here we use a dataset of 35 long-term Amazonian forest inventory plots to test different methods of calculating wood production rates. These address potential biases associated with three issues that routinely impact the interpretation of tree measurement data: (1) changes in the point of measurement (POM) of stem diameter as trees grow over time; (2) unequal length of time between censuses; and (3) the treatment of trees that pass the minimum diameter threshold (‘‘recruits’’). We derive corrections that control for changing POM height, that account for the unobserved growth of trees that die within census intervals, and that explore different assumptions regarding the growth of recruits during the previous census interval. For our dataset we find that annual aboveground coarse wood production (AGWP; in Mg ha � 1

Forest structure and dynamics vary across the Amazon Basin in an east-west gradient coincident with variations in soil fertility and geology. This has resulted in the hypothesis that soil fertility may play an important role in explaining Basin-wide variations in forest biomass, growth and stem turnover rates. Soil samples were collected in a total of 59 different forest plots across the Amazon Basin and analysed for exchangeable cations, carbon, nitrogen and pH, with several phosphorus fractions of likely different plant availability also quantified. Physical properties were additionally examined and an index of soil physical quality developed. Bivariate relationships of soil and climatic properties with above-ground wood productivity, stand-level tree turnover rates, above-ground wood biomass and wood density were first examined with multivariate regression models then applied. Both forms of analysis were undertaken with and without considerations regarding the underlying spatial structure of the dataset. Despite the presence of autocorrelated spatial structures complicating many analyses, forest structure and dynamics were found to be strongly and quantitatively related to edaphic as well as climatic conditions. Basin-wide differences in stand-level turnover rates are mostly influenced by soil physical properties with variations in rates of coarse wood production mostly related to soil phosphorus status. Total soil P was a better predictor of wood production rates than any of the fractionated organic- or inorganic-P pools. This suggests that it is not only the immediately available P forms, but probably the entire soil phosphorus pool that is interacting with forest growth on longer timescales. A role for soil potassium in modulating Amazon forest dynamics through its effects on stand-level wood density was also detected. Taking this into account, otherwise enigmatic variations in stand-level biomass across the Basin were then accounted for through the interacting effects of soil physical and chemical properties with climate. A hypothesis of self-maintaining forest dynamic feedback mechanisms initiated by edaphic conditions is proposed. It is further suggested that this is a major factor determining endogenous disturbance levels, species composition, and forest productivity across the Amazon Basin.

The rich ecology of tropical forests is intimately tied to their moisture status. Multi-site syntheses can provide a macro-scale view of these linkages and their susceptibility to changing climates. Here, we report pan-tropical and regional-scale analyses of tree vulnerability to drought. We assembled available data on tropical forest tree stem mortality before, during, and after recent drought events, from 119 monitoring plots in 10 countries concentrated in Amazonia and Borneo. In most sites, larger trees are disproportionately at risk. At least within Amazonia, low wood density trees are also at greater risk of drought-associated mortality, independent of size. For comparable drought intensities, trees in Borneo are more vulnerable than trees in the Amazon. There is some evidence for lagged impacts of drought, with mortality rates remaining elevated 2 yr after the meteorological event is over. These findings indicate that repeated droughts would shift the functional composition of tropical forests toward smaller, denser-wooded trees. At very high drought intensities, the linear relationship between tree mortality and moisture stress apparently breaks down, suggesting the existence of moisture stress thresholds beyond which some tropical forests would suffer catastrophic tree mortality. © The Authors (2010). Journal compilation © New Phytologist Trust (2010).

Amazon forests are a key but poorly understood component of the global carbon cycle. If, as anticipated, they dry this century, they might accelerate climate change through carbon losses and changed surface energy balances. We used records from multiple long-term monitoring plots across Amazonia to assess forest responses to the intense 2005 drought, a possible analog of future events. Affected forest lost biomass, reversing a large long-term carbon sink, with the greatest impacts observed where the dry season was unusually intense. Relative to pre-2005 conditions, forest subjected to a 100-millimeter increase in water deficit lost 5.3 megagrams of aboveground biomass of carbon per hectare. The drought had a total biomass carbon impact of 1.2 to 1.6 petagrams (1.2 × 10 15 to 1.6 × 10 15 grams). Amazon forests therefore appear vulnerable to increasing moisture stress, with the potential for large carbon losses to exert feedback on climate change.

The Amazon basin, one of the most substantial biomass carbon pools on earth, is characterised by strong macroecological gradients in biomass, mortality rates, and wood density from west to east. These gradients could affect necromass stocks, but this has not yet been tested. This study aims to assess the stocks and determinants of necromass across Amazonian forests. Field-based and literature data were used to find relationships between necromass and possible determinants. Furthermore, a simple model was applied to estimate and extrapolate necromass stocks across terra firma Amazonian forests. In eight northwestern and three northeastern Amazonian permanent plots, volumes of coarse woody debris (≥10 cm diameter) were measured in the field and the density of each decay class was estimated. Forest structure and historical mortality data were used to determine the factors controlling necromass. Necromass is greater in forests with low stem mortality rates (northeast) rather than in forests with high stem mortality rates (northwest) (58.5±10.6 and 27.3±3.2 Mg ha−1, respectively). Using all published necromass values, we find that necromass across terra firma forests in Amazonia is positively related to both forest dynamics (mortality mass inputs and a surrogate for decomposition rate (average wood density of living trees)) and forest structure (biomass), but is better explained by forest dynamics. We propose an improved method to estimate necromass for plots where necromass has not been measured. The estimates, together with other actual measurements of necromass, were scaled-up to project a total Amazonian necromass of 9.6±1.0 Pg C. The ratio of necromass (on average weighted by forest region) to coarse aboveground biomass is 0.127. Overall, we find (1) a strong spatial trend in necromass in parallel with other macroecological gradients and (2) that necromass is a substantial component of the carbon pool in the Amazon.

© 2009 by the American Geophysical Union. All rights reserved. Long-term, on-the-ground monitoring of forest plots distributed across Amazonia provides a powerful means to quantify stocks and fluxes of biomass and biodiversity. Here we examine the evidence for concerted changes in the structure, dynamics, and functional composition of old-growth Amazonian forests over recent decades. Mature forests have, as a whole, gained biomass and undergone accelerated growth and dynamics, but questions remain as to the long-term persistence of these changes. Because forest growth on average exceeds mortality, intact Amazonian forests have been functioning as a carbon sink. We estimate a net biomass increase in trees > 10 cm diameter of 0.62 ± 0.23 t C ha -1 a -1 through the late twentieth century. If representative of the wider forest landscape, this translates into a sink in South American old-growth forest of at least 0.49 ± 0.18 Pg C a -1 . If other biomass and necromass components also increased proportionally, the estimated South American old-growth forest sink is 0.79 ± 0.29 Pg C a -1 , before allowing for possible gains in soil carbon. If tropical forests elsewhere are behaving similarly, the old-growth biomass forest sink would be 1.60 ± 0.58 Pg C a -1 . This bottom-up estimate of the carbon balance of tropical forests is preliminary, pending syntheses of detailed biometric studies across the other tropical continents. There is also some evidence for recent changes in the functional composition (biodiversity) of Amazonian forest, but the evidence is less comprehensive than that for changes in structure and dynamics. The most likely driver(s) of changes are recent increases in the supply of resources such as atmospheric carbon dioxide, which would increase net primary productivity, increasing tree growth and recruitment, and, in turn, mortality. In the future the growth response of remaining undisturbed Amazonian forests is likely to saturate, and there is a risk of these ecosystems transitioning from sink to source driven by higher respiration (temperature), higher mortality (drought), or compositional change (functional shifts toward lighterwooded plants). Even a modest switch from carbon sink to source for Amazonian forests would impact global climate, biodiversity, and human welfare, while the documented acceleration of tree growth and mortality may already be affecting the interactions of thousands of plant and millions of animal species.

Positive aboveground biomass trends have been reported from old-growth forests across the Amazon basin and hypothesized to reflect a large-scale response to exterior forcing. The result could, however, be an artefact due to a sampling bias induced by the nature of forest growth dynamics. Here, we characterize statistically the disturbance process in Amazon old-growth forests as recorded in 135 forest plots of the RAINFOR network up to 2006, and other independent research programmes, and explore the consequences of sampling artefacts using a data-based stochastic simulator. Over the observed range of annual aboveground biomass losses, standard statistical tests show that the distribution of biomass losses through mortality follow an exponential or near-identical Weibull probability distribution and not a power law as assumed by others. The simulator was parameterized using both an exponential disturbance probability distribution as well as a mixed exponential-power law distribution to account for potential large-scale blowdown events. In both cases, sampling biases turn out to be too small to explain the gains detected by the extended RAINFOR plot network. This result lends further support to the notion that currently observed biomass gains for intact forests across the Amazon are actually occurring over large scales at the current time, presumably as a response to climate change.

Forest structure and dynamics have been noted to vary across the Amazon Basin in an east-west gradient in a pattern which coincides with variations in soil fertility and geology. This has resulted in the hypothesis that soil fertility may play an important role in explaining Basin-wide variations in forest biomass, growth and stem turnover rates. To test this hypothesis and assess the importance of edaphic properties in affect forest structure and dynamics, soil and plant samples were collected in a total of 59 different forest plots across the Amazon Basin. Samples were analysed for exchangeable cations, C, N, pH with various P fractions also determined. Physical properties were also examined and an index of soil physical quality developed. Overall, forest structure and dynamics were found to be strongly and quantitatively related to edaphic conditions. Tree turnover rates emerged to be mostly influenced by soil physical properties whereas forest growth rates were mainly related to a measure of available soil phosphorus, although also dependent on rainfall amount and distribution. On the other hand, large scale variations in forest biomass could not be explained by any of the edaphic properties measured, nor by variation in climate. A new hypothesis of self-maintaining forest dynamic feedback mechanisms initiated by edaphic conditions is proposed. It is further suggested that this is a major factor determining forest disturbance levels, species composition and forest productivity on a Basin wide scale.

Long-term measurements of ecosystem-atmosphere exchanges of carbon, water, and energy, via eddy flux towers, give insight into three key questions about Amazonian forest function. First, what is the carbon balance of Amazon forests? Some towers give accurate site-specific carbon balances, as validated by independent methods, but decisive resolution of the large-scale question will also require integration of remote sensing techniques (to detect and encompass the distribution of naturally induced disturbance states across the landscape of old growth forests) with eddy flux process studies (to characterize the association between carbon balance and forest disturbance states). Second, what is the seasonality of ecosystem metabolism in Amazonian forests? Models have historically simulated dry season declines in photosynthetic metabolism, a consequence of modeled water limitation. Tower sites in equatorial Amazonian forests, however, show that photosynthetic metabolism increases during dry seasons ("green up"), perhaps because deep roots buffer trees from dry season water stress, while phenological rhythms trigger leaf flush, associated with increased solar irradiance. Third, how does ecosystem metabolism vary across biome types and land use patterns? As dry season length increases from equatorial forest, to drier southern forests, to savanna, fluxes show seasonal patterns consistent with increasing water stress, including a switch from dry season green up to "brown down." Land use change in forest ecosystems removes deep roots, artificially inducing the same trend toward brown down. In the final part, this review suggests that eddy tower network and satellitebased insights into seasonal responses provide a model for detecting responses to extreme interannual climate variations that can test whether forests are vulnerable to model-simulated Amazonian forest collapse under climate change.

Long-term monitoring of distributed, multiple plots is the key to quantify macroecological patterns and changes. Here we examine the evidence for concerted changes in the structure, dynamics and composition of old-growth Amazonian forests in the late twentieth century. In the 1980s and 1990s, mature forests gained biomass and underwent accelerated growth and dynamics, all consistent with a widespread, long-acting stimulation of growth. Because growth on average exceeded mortality, intact Amazonian forests have been a carbon sink. In the late twentieth century, biomass of trees of more than 10 cm diameter increased by 0.62±0.23 t C ha −1 yr −1 averaged across the basin. This implies a carbon sink in Neotropical old-growth forest of at least 0.49±0.18 Pg C yr −1 . If other biomass and necromass components are also increased proportionally, then the old-growth forest sink here has been 0.79±0.29 Pg C yr −1 , even before allowing for any gains in soil carbon stocks. This is approximately equal to the carbon emissions to the atmosphere by Amazon deforestation. There is also evidence for recent changes in Amazon biodiversity. In the future, the growth response of remaining old-growth mature Amazon forests will saturate, and these ecosystems may switch from sink to source driven by higher respiration (temperature), higher mortality (as outputs equilibrate to the growth inputs and periodic drought) or compositional change (disturbances). Any switch from carbon sink to source would have profound implications for global climate, biodiversity and human welfare, while the documented acceleration of tree growth and mortality may already be affecting the interactions among millions of species.

This research proposed lot release policies for color filter fabs based on iterative simulation. Heuristic lot release plan was first developed and used as the input of an AutoMod simulation model to generate the expected performance that was used to improve the release plan and then iteratively simulated.

This research proposes an Order Assignment Policy (OAP) to effectively and efficiently assign orders to color filter fabs. The objectives of this research is to minimize order tardiness and minimize the variance of fab utilization by taking into account fabs ' available capacity and orders ' due date, batch size, product type, and process routing. OAP consists of three modules: Order Priority Module (OPM), WIP-Pulling Module (WPM), and Order Release Module (ORM). OPM assigns different priorities to orders according different dispatching rules. WPM pulls WIP from the end of the process route to meet the orders in Master Production Schedule (MPS). If WIP cannot meet the MPS requirement, ORM is executed to select one of the fabs and release lots into this fab. An AutoMod simulation model is developed, and data of real color filter fabs are collected and used to evaluate OAP's performance based on the design of experiments. Preliminary simulation results show that the combination of OPM using Earliest Due Date (EDD) and ORM using Least Fab Utilization (LFU) leads to the least average lateness of orders, while OPM using Largest Batch Size (LBS) and ORM using LFU results in the least variance of fab utilization.