Article

Taking the pulse of Earth's tropical forests using networks of highly distributed plots ☆

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Abstract

Tropical forests are the most diverse and productive ecosystems on Earth. While better understanding of these forests is critical for our collective future, until quite recently efforts to measure and monitor them have been largely disconnected. Networking is essential to discover the answers to questions that transcend borders and the horizons of funding agencies. Here we show how a global community is responding to the challenges of tropical ecosystem research with diverse teams measuring forests tree-by-tree in thousands of long-term plots. We review the major scientific discoveries of this work and show how this process is changing tropical forest science. Our core approach involves linking long-term grassroots initiatives with standardized protocols and data management to generate robust scaled-up results. By connecting tropical researchers and elevating their status, our Social Research Network model recognises the key role of the data originator in scientific discovery. Conceived in 1999 with RAINFOR (South America), our permanent plot networks have been adapted to Africa (AfriTRON) and Southeast Asia (T-FORCES) and widely emulated worldwide. Now these multiple initiatives are integrated via ForestPlots.net cyber-infrastructure, linking colleagues from 54 countries across 24 plot networks. Collectively these are transforming understanding of tropical forests and their biospheric role. Together we have discovered how, where and why forest carbon and biodiversity are responding to climate change, and how they feedback on it. This long-term pan-tropical collaboration has revealed a large long-term carbon sink and its trends, as well as making clear which drivers are most important, which forest processes are affected, where they are changing, what the lags are, and the likely future responses of tropical forests as the climate continues to change. By leveraging a remarkably old technology, plot networks are sparking a very modern revolution in tropical forest science. In the future, humanity can benefit greatly by nurturing the grassroots communities now collectively capable of generating unique, long-term understanding of Earth's most precious forests.

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... ar national forest assessment programmes, our survey often identified substantial numbers of research plots. Developing cooperation between researchers who manage these plots, who often study distinct topics, can provide powerful information, even if their research does not address systematic sampling in space. Initiatives, such as ForestPlots.net (ForestPlots.net et al., 2021), the Tropical managed Forests Observatory (TmFO) (Sist et al., 2015) and ForestGEO (Anderson-Teixeira et al., 2015) that connect researchers to facilitate standardising protocols and metadata and to curate data, provide examples of how to fill major data gaps in mortality trends (Hubau et al., 2020). Many such plots exist with one or tw ...
... d intensity of ground sampling, particularly in tropical regions where fieldwork is more challenging (see the 'Bringing it all togetherdata integration across scales' section). Even where new NFIs are currently being established, research plots remain crucial because of their long-term record, often stretching back decades (Phillips & Gentry, 1994;ForestPlots.net et al., 2021), which provide necessary context for the rates that are observed in the present day. However, relying on these research plots raises questions of research equity and the fair share of research rewards (see the 'A comprehensive and fair global network' section). ...
... f working in systems of high species diversity, which requires highly qualified professionals in species identification. Different initiatives have tried to fill these gaps by implementing long-term monitoring sites in tropical regions (e.g. ForestGEO, LTER Brasil, PPBio), as well as integrating and supporting existing local monitoring initiatives (ForestPlots.net et al., 2021). Although these efforts have led to invaluable advancement in our understanding of these forests, data gaps remain, and the lack of investment in long-term monitoring efforts and integration of monitoring into government policies, especially in less wealthy countries, remains a shortcoming. ...
Article
Full-text available
Rates of tree mortality are increasing globally, with implications for forests and climate. Yet, how and why these trends vary globally remain unknown. Developing a comprehensive assessment of global tree mortality will require systematically integrating data from ground-based long-term forest monitoring with large-scale remote sensing. We surveyed the metadata from 466 865 forest monitoring plots across 89 countries and five continents using questionnaires and discuss the potential to use these to estimate tree mortality trends globally. Our survey shows that the area monitored has increased steadily since 1960, but we also identify many regions with limited ground-based information on tree mortality. The integration of existing ground-based forest inventories with remote sensing and modelling can potentially fill those gaps, but this requires development of technical solutions and agreements that enable seamless flows of information from the field to global assessments of tree mortality. A truly global monitoring effort should promote fair and equitable collaborations, transferring funding to and empowering scientists from less wealthy regions. Increasing interest in forests as a natural climate solution, the advancement of new technologies and world-wide connectivity means that now a global monitoring system of tree mortality is not just urgently needed but also possible.
... ar national forest assessment programmes, our survey often identified substantial numbers of research plots. Developing cooperation between researchers who manage these plots, who often study distinct topics, can provide powerful information, even if their research does not address systematic sampling in space. Initiatives, such as ForestPlots.net (ForestPlots.net et al., 2021), the Tropical managed Forests Observatory (TmFO) (Sist et al., 2015) and ForestGEO (Anderson-Teixeira et al., 2015) that connect researchers to facilitate standardising protocols and metadata and to curate data, provide examples of how to fill major data gaps in mortality trends (Hubau et al., 2020). Many such plots exist with one or tw ...
... d intensity of ground sampling, particularly in tropical regions where fieldwork is more challenging (see the 'Bringing it all togetherdata integration across scales' section). Even where new NFIs are currently being established, research plots remain crucial because of their long-term record, often stretching back decades (Phillips & Gentry, 1994;ForestPlots.net et al., 2021), which provide necessary context for the rates that are observed in the present day. However, relying on these research plots raises questions of research equity and the fair share of research rewards (see the 'A comprehensive and fair global network' section). ...
... f working in systems of high species diversity, which requires highly qualified professionals in species identification. Different initiatives have tried to fill these gaps by implementing long-term monitoring sites in tropical regions (e.g. ForestGEO, LTER Brasil, PPBio), as well as integrating and supporting existing local monitoring initiatives (ForestPlots.net et al., 2021). Although these efforts have led to invaluable advancement in our understanding of these forests, data gaps remain, and the lack of investment in long-term monitoring efforts and integration of monitoring into government policies, especially in less wealthy countries, remains a shortcoming. ...
Article
Full-text available
Rates of tree mortality are increasing globally, with implications for forests and climate. Yet, how and why these trends vary globally remain unknown. Developing a comprehensive assessment of global tree mortality will require systematically integrating data from ground-based long-term forest monitoring with large-scale remote sensing. We surveyed the metadata from 466 865 forest monitoring plots across 89 countries and five continents using questionnaires and discuss the potential to use these to estimate tree mortality trends globally. Our survey shows that the area monitored has increased steadily since 1960, but we also identify many regions with limited ground-based information on tree mortality. The integration of existing ground-based forest inventories with remote sensing and modelling can potentially fill those gaps, but this requires development of technical solutions and agreements that enable seamless flows of information from the field to global assessments of tree mortality. A truly global monitoring effort should promote fair and equitable collaborations, transferring funding to and empowering scientists from less wealthy regions. Increasing interest in forests as a natural climate solution, the advancement of new technologies and world-wide connectivity means that now a global monitoring system of tree mortality is not just urgently needed but also possible.
... ar national forest assessment programmes, our survey often identified substantial numbers of research plots. Developing cooperation between researchers who manage these plots, who often study distinct topics, can provide powerful information, even if their research does not address systematic sampling in space. Initiatives, such as ForestPlots.net (ForestPlots.net et al., 2021), the Tropical managed Forests Observatory (TmFO) (Sist et al., 2015) and ForestGEO (Anderson-Teixeira et al., 2015) that connect researchers to facilitate standardising protocols and metadata and to curate data, provide examples of how to fill major data gaps in mortality trends (Hubau et al., 2020). Many such plots exist with one or tw ...
... d intensity of ground sampling, particularly in tropical regions where fieldwork is more challenging (see the 'Bringing it all togetherdata integration across scales' section). Even where new NFIs are currently being established, research plots remain crucial because of their long-term record, often stretching back decades (Phillips & Gentry, 1994;ForestPlots.net et al., 2021), which provide necessary context for the rates that are observed in the present day. However, relying on these research plots raises questions of research equity and the fair share of research rewards (see the 'A comprehensive and fair global network' section). ...
... f working in systems of high species diversity, which requires highly qualified professionals in species identification. Different initiatives have tried to fill these gaps by implementing long-term monitoring sites in tropical regions (e.g. ForestGEO, LTER Brasil, PPBio), as well as integrating and supporting existing local monitoring initiatives (ForestPlots.net et al., 2021). Although these efforts have led to invaluable advancement in our understanding of these forests, data gaps remain, and the lack of investment in long-term monitoring efforts and integration of monitoring into government policies, especially in less wealthy countries, remains a shortcoming. ...
... ar national forest assessment programmes, our survey often identified substantial numbers of research plots. Developing cooperation between researchers who manage these plots, who often study distinct topics, can provide powerful information, even if their research does not address systematic sampling in space. Initiatives, such as ForestPlots.net (ForestPlots.net et al., 2021), the Tropical managed Forests Observatory (TmFO) (Sist et al., 2015) and ForestGEO (Anderson-Teixeira et al., 2015) that connect researchers to facilitate standardising protocols and metadata and to curate data, provide examples of how to fill major data gaps in mortality trends (Hubau et al., 2020). Many such plots exist with one or tw ...
... d intensity of ground sampling, particularly in tropical regions where fieldwork is more challenging (see the 'Bringing it all togetherdata integration across scales' section). Even where new NFIs are currently being established, research plots remain crucial because of their long-term record, often stretching back decades (Phillips & Gentry, 1994;ForestPlots.net et al., 2021), which provide necessary context for the rates that are observed in the present day. However, relying on these research plots raises questions of research equity and the fair share of research rewards (see the 'A comprehensive and fair global network' section). ...
... f working in systems of high species diversity, which requires highly qualified professionals in species identification. Different initiatives have tried to fill these gaps by implementing long-term monitoring sites in tropical regions (e.g. ForestGEO, LTER Brasil, PPBio), as well as integrating and supporting existing local monitoring initiatives (ForestPlots.net et al., 2021). Although these efforts have led to invaluable advancement in our understanding of these forests, data gaps remain, and the lack of investment in long-term monitoring efforts and integration of monitoring into government policies, especially in less wealthy countries, remains a shortcoming. ...
Article
Full-text available
Rates of tree mortality are increasing globally, with implications for forests and climate. Yet, how and why these trends vary globally remain unknown. Developing a comprehensive assessment of global tree mortality will require systematically integrating data from ground‐based long‐term forest monitoring with large‐scale remote sensing. We surveyed the metadata from 466 865 forest monitoring plots across 89 countries and five continents using questionnaires and discuss the potential to use these to estimate tree mortality trends globally. Our survey shows that the area monitored has increased steadily since 1960, but we also identify many regions with limited ground‐based information on tree mortality. The integration of existing ground‐based forest inventories with remote sensing and modelling can potentially fill those gaps, but this requires development of technical solutions and agreements that enable seamless flows of information from the field to global assessments of tree mortality. A truly global monitoring effort should promote fair and equitable collaborations, transferring funding to and empowering scientists from less wealthy regions. Increasing interest in forests as a natural climate solution, the advancement of new technologies and world‐wide connectivity means that now a global monitoring system of tree mortality is not just urgently needed but also possible.
... uturo , también de cómo las especies arbóreas poco conocidas van enfrentarse a cambios y escenarios críticos en el presente siglo y como estas van tener capacidad de resiliencia particularmente a eventos de sequias mucho más severas y frecuentes (Phillips et al. 2009;Brienen et al. 2015;Feldpausch et al. 2016;Hubau et al. 2020;Sullivan et al. 2020;ForestPlots.net et al. 2021). Los bosques de la región de los Andes-Amazónicos, son un buen escenario para explorar los vínculos entre la diversidad alfa, el cambio estructural, composición y la biomasa (Lieberman et al. 1996;Báez et al. 2015;Gentry, 1988;Feeley et al. 2011;Silman, 2014;Girardin et al. 2014;Duque et al. 2015;Malhi et al. 2017;Fadrique et al. 2018; ...
... de suma importancia y de mucha necesidad. En una escala más amplia los inventarios son también críticos para el desarrollo y planicación de áreas protegidas, lo que requiere referencia geográca, muestras replicadas y comparables para soportar decisiones o donde enfocar la conservación de recursos o actividades de desarrollo (Phillips et al. 2002;ForestPlots.net et al. 2021). En estas circunstancias, las parcelas permanentes son notables entre los instrumentos de medición que permiten directamente, una visión a gran escala y largo plazo de los procesos de los ecosistemas de los bosques tropicales en toda su área de distribución geográca. Desde el año 2002, el Jardín Botánico de Missouri y la Red Amazónica ...
... Esta información fue compilada en una matriz organizada por especies y número de individuos para cada parcela y extraída de la base de datos: http://www.forestplots.net (Lopez-Gonzalez et al. 2011ForestPlots.net et al. 2021). Los nombres cientícos fueron revisados y actualizados usando los especímenes de herbario, listados base de datos TROPICOS (http://www.tropicos.org/). ...
Article
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Los bosques pre-montanos y montanos son poco estudiados y su composición florística es muy poco conocida, aunque últimamente aquí se han descubierto nuevas especies de árboles. Describimos la diversidad, composición florística y estructura del bosque en 13 parcelas permanentes de 1 ha, evaluadas en el 2018 en el Transecto Yanachaga en el centro del Perú (400 a 3170 msnm). Registramos un total de 6998 árboles, 617 especies, 249 géneros y 82 familias. Existe unas altas correlaciones entre la altitud, la riqueza y diversidad de especies. La mayor riqueza ocurre en la parcela PNY-05 a 470 msnm con 202 especies y la menor con 43 especies en la parcela PNY-01 a 3170 mnsm. La altura promedio del dosel es mayor entre los 400 y 800 msnm, y disminuye progresivamente a medida que se va subiendo, presentando alturas mínimas entre 2800 y 3170 msnm. Este mismo comportamiento ocurre con respecto al área basal y volumen de madera. Los individuos muestreados están representados por especies de árboles (88%), palmeras (4%), helechos arborescentes (6.5%), lianas (1.5%) y hemiepífitos leñosos (0.03%). Las formas de vida varían notablemente en el transecto altitudinal, los árboles y palmeras son más abundantes y diversos en la parte baja, mientras los helechos arborescentes son abundantes por encima de los 1800 m. Existen diferencias en la diversidad, composición y estructura de árboles entre parcelas y también si se compara al llano amazónico. Los bosques del Transecto Yanachaga juegan un papel importante, puesto que conservan una alta diversidad de especies y hábitats.
... organised way 20 years ago, partly building on earlier initiatives (Malhi et al. 2002). The Amazon Forest Inventory Network (RAINFOR; http://www.rainfor.org/en) was established to record and interpret ecological and biogeochemical changes across the Amazon basin over precipitation and temperature gradients and in response to their temporal changes (ForestPlots.net et al. 2021). The objectives included relating forest dynamics, i.e. growth and mortality, to spatio-temporal variation in environmental drivers, e.g. dry season length, soil nutrients, to increasing atmospheric CO 2 concentrations, and forest fragmentation owing to deforestation (Malhi et al. 2002), the latter principally occurring at the southern ...
... has made a significant contribution to our understanding of oldgrowth (but see McMichael (2021) on the ecological legacies of past human activities) lowland rain forest dynamics in the Amazon basin (Phillips et al. 2009;Quesada et al. 2012). Subsequently, the network expanded, and after 20 years, it encompasses a worldwide network (Qie et al. 2017;ForestPlots.net et al. 2021) that today allows to make complex analyses of forest biomass patterns, and relate them to multiple causes such as climate (past and present) and biogeography (Sullivan et al. 2020). The RAINFOR network and its current extended version, ForestPlots.net (ForestPlots.net et al. 2021), have served as a solid empirical witness of evidence-b ...
... after 20 years, it encompasses a worldwide network (Qie et al. 2017;ForestPlots.net et al. 2021) that today allows to make complex analyses of forest biomass patterns, and relate them to multiple causes such as climate (past and present) and biogeography (Sullivan et al. 2020). The RAINFOR network and its current extended version, ForestPlots.net (ForestPlots.net et al. 2021), have served as a solid empirical witness of evidence-based science using its extensive network of on-the-ground local experts. It has also been providing useful information for ground-truthing of remote-sensing based approaches, not always without contradiction between ground and space-based approaches (Mitchard et al. 2014;Saatchi et ...
Article
Background Plot-based monitoring has yielded much information on the taxonomic diversity and carbon (C) storage in tropical lowland forests of the Amazon basin. This has resulted in an improved understanding of the relationship between lowland forest biomass dynamics and global change drivers, such as climate change and atmospheric CO2 concentration. Much less attention has been paid to the mountain ecosystems of South America that comprise montane forests and alpine vegetation (páramo, puna, high Andean grasslands, wetlands, and alpine heath). This vegetation complex provides a variety of ecosystem services and forms a natural laboratory along various physiographic, geological and evolutionary history/biogeography, and land use history gradients. Aims Here we review existing empirical understanding and model-based approaches to quantify the contribution of mountain ecosystems to ecosystem service provision in the rapidly changing socioecological setting of the South American mountains. The objective of this paper is to outline a broad road map for the implementation of mountain vegetation into dynamic global vegetation models (DGVM) for use in Earth System Models (ESM), based on our current understanding of their structure and function and of their responsiveness to global change drivers. We also identify treeline processes, critical in mountain ecosystems, as key missing elements in DGVMs/ESMs, and thus explore in addition a treeline model. Methods A stocktaking of availability of empirical data was undertaken from eight research sites along the Andes and in south-eastern Brazil. Out of eight sites, two (one each in Venezuela and Brazil) had some climate, ecological and ecophysiological data potentially suitable to parametrise a DGVM. Tree biomass data were available for six sites. A preliminary assessment of the Joint UK Land Environment Simulator (JULES) DGVM was made to identify gaps in available data and their impacts on model parametrisation and calibration. Additionally, the potential climate-determined elevation of the treeline was modelled to check the DGVM for its ability to identify the transition between the montane forest and alpine vegetation. Results Outcomes of the evaluation of the JULES land surface model identified the following key processes in montane forests: temperature-related decrease in net primary production, respiration, and allocation to above-ground biomass and increase in soil C stocks with elevation. There was a variable agreement between simulated biomass and those derived from field measurements via allometric equations. Conclusions We identified major gaps between data availability and the needs of process-based modelling of South American mountain vegetation and its dynamics in DGVMs. To bridge this gap, we propose a transdisciplinary network, composed of members of the theoretical/modelling and empirical scientific communities to study the natural dynamics of mountain ecosystems and their responses to global change drivers locally, regionally and at the continent scale, within a social-ecological system framework. The work presented here forms the basis for the design of data collection from field measurements and instrumental monitoring stations to parametrise and verify DGVMs. The network is designed to collaborate with and complement existing long-term research initiatives in the region and will adopt existing standard field protocols. Complementary protocols will ensure compatibility between field data collection and data needs for process-based and empirical models.
... d disturbed forests, their quantification is riddled with uncertainties Le Quéré et al., 2016). Therefore, attempting to do so requires building on several years of knowledge in tropical forest ecology, collaborating with research networks that estimate and study carbon stocks and sinks at different locations whilst employing similar methodologies (ForestPlots.net et al., 2020;Pennington and Baker, 2021) To obtain forest carbon stocks and sink estimates for a given site, tree-by-tree biomass is estimated in ground forest plots. According to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories (IPCC, 2006), forest biomass is assessed by measuring 5 carbon pools: aboveground live biomass (AGB), below ...
... Currently, undisturbed forests remain the most studied forests in the tropics, with several research networks carrying out long-term studies within them for decades (Davies et al., 2021;ForestPlots.net et al., 2020). Disturbed forests have also been extensively studied in the pantropics (Becknell et al., 2012;Chazdon et al., 2016;Poorter et al., 2016;Sist et al., 2015), with plot networks located mostly in North and South America. ...
... Research consortia have established measurement protocols and best practices, and have made their data publicly available. In addition, AGB and ∆AGB data from various networks have been integrated into datasets which can be publicly accessed (Anderson-Teixeira et al., 2018b;ForestPlots.net et al., 2020). At the same time, national forest monitoring efforts have increased: by 2020, approximately 57% of countries in the tropics were using NFI data (Nesha et al., 2021). ...
... Multiple methods exist to monitor the productivity of tropical forests 17 . Plot (re-)censusing is the most direct way to coincidently measure forest woody productivity and mortality 17 but requires extensive networks of large plots to be accurately representative of a vast biome like the Amazon rainforests, which makes this technique particularly labour-intensive and time-consuming. ...
... Multiple methods exist to monitor the productivity of tropical forests 17 . Plot (re-)censusing is the most direct way to coincidently measure forest woody productivity and mortality 17 but requires extensive networks of large plots to be accurately representative of a vast biome like the Amazon rainforests, which makes this technique particularly labour-intensive and time-consuming. In addition, plot recensusing has typically a low periodicity (e.g. 5 years) which prevents observations of inter-annual variability 14 . ...
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In the Amazon, the dry season of 2023 as well as the beginning of the wet season in 2024 were marked by unprecedented high temperatures and large precipitation deficits. While the tropical forests in the Amazon play a crucial role in the global carbon cycle and are a biodiversity hotspot, they were also shown to suffer from El-Niño related droughts in the past, leading to legitimate concerns about the ecological consequences of the recent climate conditions. To this day, while there is a growing effort to make remote sensing products available close to real-time, land surface models that are critical tools to understand the interactions between the biosphere and the environment have lagged behind the present due to the complexity to run and process large model ensembles. In this study, we employed advanced machine learning models trained on state-of-the-art remote sensing and dynamic global vegetation model estimates of gross primary productivity (GPP). The models provide near real-time GPP estimates, revealing significant productivity reductions during the 2023/2024 drought. Negative GPP anomalies were more widespread across the Amazon than during any other recent major drought event. The Climate-GPP relationships that emerged from the models suggest that future temperature increases and changes in precipitation will severely challenge Amazon forest resilience.
... ;Enuoh and Ogogo, 2018). The species composition data used for the study comprised single census tree-by-tree samples collected between 2002 and 2019 from five plots established in Nigeria (Asuk et al., 2022(Asuk et al., , 2023 and 61 plots established in Nigeria and Cameroon, accessed from the ForestPlots.net database (Lopez-Gonzalez et al., 2009;ForestPlots.net et al., 2021). The selected plots in Cameroon all measured 100m x 100m except for one plot that measured 40m x 100m (see Appendix S1, Table S1). The plots in Nigeria were smaller than those in Cameroon, measuring 40m x 120m (see Appendix S1, Table S1). ...
... 9; Enuoh and Ogogo, 2018). The species composition data used for the study comprised single census tree-by-tree samples collected between 2002 and 2019 from five plots established in Nigeria(Asuk et al., 2022(Asuk et al., , 2023 and 61 plots established in Nigeria and Cameroon, accessed from the ForestPlots.net database(Lopez-Gonzalez et al., 2009;ForestPlots.net et al., 2021). The selected plots in Cameroon all measured 100m x 100m except for one plot that measured 40m x 100m ...
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Human activities exert pronounced influence on forest ecosystems, impacting biodiversity and functions across multiple scales. However, the consequences of low-intensity human activities on tropical forest ecosystems are difficult to assess and remain poorly explored. The influence of human activities and other site-specific variables on forest tree assemblages in central-west Africa was investigated. The greatest impact of human activity was expected to be seen on edible tree species. Tree species in the forest were divided into edible (consumed by humans) and inedible species to assess the differential impacts of human resource use on species. Tree data from 66 plots in Nigeria and Cameroon (collected between 2002 and 2019) were analysed using Generalized Dissimilarity Models (GDMs) to assess pairwise beta-diversity between plots. Human activity significantly affected beta-diversity within the Nigeria-Cameroon forest region. Total beta-diversity was shaped by geographical distance between plots, plot elevation, stem density, proximity to human presence, and forest species composition. The forest species composition (monodominant or mixed forest) appeared to influence dissimilarity in beta-diversity for edible tree species only, likely linked to cultural practices in the region. Influence of elevation was significant for inedible species only, due to access restriction. These findings underscore the role of human influence in shaping tree species assemblages in African tropical forests and stress the necessity for further research in this area.
... Multiple methods exist to monitor the productivity of tropical forests 17 . Plot (re-)censusing is the most direct way to coincidently measure forest woody productivity and mortality 17 but requires extensive networks of large plots to be accurately representative of a vast biome like the Amazon rainforests, which makes this technique particularly labour-intensive and time-consuming. ...
... Multiple methods exist to monitor the productivity of tropical forests 17 . Plot (re-)censusing is the most direct way to coincidently measure forest woody productivity and mortality 17 but requires extensive networks of large plots to be accurately representative of a vast biome like the Amazon rainforests, which makes this technique particularly labour-intensive and time-consuming. In addition, plot recensusing has typically a low periodicity (e.g. 5 years) which prevents observations of inter-annual variability 14 . ...
Preprint
Full-text available
In the Amazon, the dry season of 2023 as well as the beginning of the wet season in 2024 were marked by unprecedented high temperatures and large precipitation deficits. While the tropical forests in the Amazon play a crucial role in the global carbon cycle and are a biodiversity hotspot, they were also shown to suffer from El-Niño related droughts in the past, leading to legitimate concerns about the ecological consequences of the recent climate conditions. To this day, while there is a growing effort to make remote sensing products available close to real-time, land surface models that are critical tools to understand the interactions between the biosphere and the environment have lagged behind the present due to the complexity to run and process large model ensembles. In this study, we employed advanced machine learning models trained on state-of-the-art remote sensing and dynamic global vegetation model estimates of gross primary productivity (GPP). The models provide near real-time GPP estimates, revealing significant productivity reductions during the 2023/2024 drought. Negative GPP anomalies were more widespread across the Amazon than during any other recent major drought event. The Climate-GPP relationships that emerged from the models suggest that future temperature increases and changes in precipitation will severely challenge Amazon forest resilience.
... Establishing a fixed window for analysis based on 5 years of growth should also reduce the bias caused by trees growing under different environmental conditions. To estimate the proportion of the core to use in the NSC analyses we calculated the growth rate of each species using inventory data from TAM-05, TAM-07, VCR-01 and VCR-02 plots (Lopez-Gonzalez et al. 2011, ForestPlot.net et al. 2021. When possible, we used the growth Tree Physiology Volume 00, 2023 rate of the sampled individual trees to estimate the amount of material for NSC analysis. ...
... The inventory data to estimate species growth rate at the study site are from the RAINFOR network, available upon request at ForestPlots.net (Lopez-Gonzalez et al. 2011, ForestPlot.net et al. 2021). Wood density from species occurring in the dry site are from Soares Jancoski et al. (2022), for species in the moist site, we used mean species WD for the Amazon Basin from Chave et al. (2009) and Zanne et al. (2009). ...
Article
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LLianas (woody vines) are important components of tropical forests and are known to compete with host trees for resources, decrease tree growth and increase tree mortality. Given the observed increases in liana abundance in some forests and their impacts on forest function, an integrated understanding of carbon dynamics of lianas and liana-infested trees is critical for improved prediction of tropical forest responses to climate change. Non-structural carbohydrates (NSC) are the main substrate for plant metabolism (e.g., growth, respiration), and have been implicated in enabling tree survival under environmental stress, but little is known of how they vary among life-forms or of how liana infestation impacts host tree NSC. We quantified stem xylem total NSC concentrations and its fractions (starch and soluble sugars) in trees without liana infestation, trees with >50% of the canopy covered by lianas, and the lianas infesting those trees. We hypothesized that (i) liana infestation depletes NSC storage in host trees by reducing carbon assimilation due to competition for resources; (ii) trees and lianas, which greatly differ in functional traits related to water transport and carbon uptake, would also have large differences in NSC storage. As water availability has a significant role in NSC dynamics of Amazonian tree species, we tested these hypotheses within a moist site in western Amazonia and a drier site in southern Amazonia. We did not find any difference in NSC, starch or soluble sugar concentrations between infested and non-infested trees, in either site. This result suggests that negative liana impact on trees may be mediated through mechanisms other than depletion of host tree NSC concentrations. We found lianas have higher stem NSC and starch than trees in both sites. The consistent differences in starch concentrations, a long-term NSC reserve, between life forms across sites reflect differences in lianas and trees carbon gain and use. Soluble sugar concentrations were higher in lianas than in trees in the moist site but indistinguishable between life forms in the dry site. The lack of difference in soluble sugars between trees and lianas in the dry site emphasizes the importance of this NSC fraction for the metabolism of plants occurring in water-limited environments. Abstracts in Portuguese and Spanish are available in the supplementary material.
... The Lähteenoja ForestPlots.net, 2021). ...
... tion. All identifications and morphospecies were applied consistently across all plots. The dataset included 5180 individuals of which 0.7% did not have a determination and were excluded from analyses of floristic composition. Fisher's alpha was used as an index of species diversity(Fisher et al., 1943). The plot data are managed at ForestPlots.net(ForestPlots.net, 2021;Lähteenoja & Page, 2011;Lopez-Gonzalez et al., 2009;Lopez-Gonzalez et al., 2011; ...
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The peat‐forming wetland forests of Amazonia are characterised by high below‐carbon stocks and supply fruit, fibres and timber to local communities. Predicting the future of these ecosystem services requires understanding how hydrological conditions are related to tree species composition and the presence, or absence, of peat. Here, we use continuous measurements of water table depth over 2.5 years and manual measurements of pore‐water pH and electrical conductivity to understand the ecohydrological controls of these variables across the large peatland complex in northern Peruvian Amazonia. Measurements were taken in permanent forest plots in four palm swamps, four seasonally flooded forests and four peatland pole forests. All trees ≥10 cm diameter were also measured and identified in the plots to assess floristic composition. Peat occurs in eight of these twelve sites; three seasonally flooded forests and one palm swamp are not associated with peat. Variation in tree species composition among forest types was linked to high flood levels (maximum flooding height) and pH: seasonally flooded forests experience high flood levels (up to 3.66 m from the ground surface) and have high pH values (6–7), palm swamps have intermediate flood levels (up to 1.34 m) and peatland pole forests experience shallow flooding (up to 0.28 m) and have low pH (4). In contrast, the presence of peat was linked to variation in maximum water table depth (ie the depth to which the water table drops below the ground surface). Surface peat is found in all forest types where maximum water table depth does not fall >0.55 m below the ground surface at any time. Peat formation and variation in tree species composition therefore have different ecohydrological controls. Predicted increases in the frequency and strength of flooding events may alter patterns of tree species composition, whereas increases in drought severity and declines in minimum river levels may pose a greater risk to the belowground carbon stores of these peatland ecosystems. This article is protected by copyright. All rights reserved.
... -term research program aiming at understanding vegetation development, understanding species autecology, and interactions between flora and fauna. Compared with tropical Americas and West Africa, there are few long-term vegetation plots in East Africa from which an understanding of species and vegetation can be developed (Cuni-Sanchez et al., 2021;ForestPlots.net et al., 2021). ...
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Forest and landscape restoration are increasingly popular nature‐based solutions to mitigate climate change and safeguard biodiversity. Restoration planning and monitoring implies that a reference ecosystem has been defined to which the restored site can be compared, but how to best select such reference? We tested three different potential natural vegetation (PNV) maps of the same areas in Kenya and Uganda for their utility as ecological references with independent data that were not used when those maps were made. These independent datasets included presence observations of woody species from 76 sites in forest reserves in Kenya and Uganda, and classification of surveyed species into a system that included “forest‐only” and “nonforest‐only” ecological types. Our tests show that (1) the three vegetation maps largely agree on the environmental envelopes/ranges within which forests occur. (2) There are large differences in how well the maps predict the presence of forest‐only species. (3) Two maps, based on empirical observations (V4A and White), predict forest types well, whereas the third, based on climate envelopes only (NS), performs poorly. (4) A large area in Uganda is potentially in one of two alternative stable states. We conclude that it is possible to evaluate the utility of PNV maps at a more detailed scale than the level of biome and ecoregion. This indicates that it is possible to map PNV at scales required for reference for restoration and management of forest vegetation. We recommend that empirically based maps of potential natural vegetation are used in restoration planning (biome and PNV maps based on climate envelopes alone may be unreliable tools) as a baseline model for predicting the distribution of reference ecosystems under current and future conditions. It could conveniently be done by deconstructing the existing biome maps, supported by rapid botanical surveys.
... Enuoh and Ogogo, 2018). The species composition data used for the study comprised single census tree-by-tree samples collected between 2002 and 2019 from five plots established in Nigeria (Asuk et al., 2022(Asuk et al., , 2023 and 61 plots established in Nigeria and Cameroon, accessed from the ForestPlots.net database (Lopez-Gonzalez et al., 2009;ForestPlots.net et al., 2021). ...
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Human activities exert a pronounced influence on forest ecosystems, impacting both biodiversity and function across multiple scales. Despite this, the consequences of low-intensity human activities on tropical forest ecosystems are difficult to assess and, therefore, remain poorly explored. Here, the influence of human activities and other site-specific variables on forest tree assemblages in central-west Africa was investigated. By dividing forest tree species into edible (from the perspective of humans) and inedible species, we aimed to assess the differential impacts of human resource use on different species; in particular, the greatest impact of human activity was expected to be seen on edible tree species. Tree data from 66 plots across Nigeria and Cameroon collected between 2002 and 2019 and Generalized Dissimilarity Models (GDMs) were used to assess pairwise beta-diversity between plots, accounting for candidate factors including proximity to human presence, elevation, and stem density. The analysis revealed that human activity significantly affects beta-diversity within the Nigeria-Cameroon forest region. The key variables that shape total beta-diversity included geographical distance between plots, plot elevation, stem density, proximity to human presence, and forest species composition. The forest species composition (monodominant or mixed forest) appeared to influence dissimilarity in beta-diversity, specifically for edible tree species. This pattern was not observed for inedible species, likely linked to the cultural practices in the region. While stem density contributed to the edible species models, elevation was more relevant for inedible species. These findings underscore the critical role of human influence in shaping tree species assemblages in African tropical forests and stress the necessity for further research in this area.
... have an emphasis on arguing from a Northern hemispherical, more specifically from a European perspective. However, the challenges of forest inventories in the Global South are different to those in the North. In tropical rainforests, the work is generally considered more expensive, and it requires a particularly profound knowledge of the ecosystem (ForestPlots.net et al., 2021). Yet, most countries in Latin America and the Caribbean stated that financial sustainability is a common concern for NFIs (Brandeis et al., 2022). Meanwhile, institutions requesting open access to forest data are often wellfunded and situated in the Global North (de Lima et al., 2022). The imbalance in funding and equity highlights the ...
... ots in white sand dry forest) and 8 plots for RRQ (all in palm swamp forest). The woody plant species sampled in the plots were already identified in species as part of a previous floristic project, when each individual received a permanent metal tag, whose related data were downloaded via ForestPlots.net online database (Lopez-Gonzalez et al. 2011, ForestPlots.net et al. 2021. Data on the conservation status and endemism of each host plant species were retrieved from the IUCN Red List of Threatened Species (IUCN 2023) and Leon et al. (2006). ...
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An insect gall inventory was carried out in two reserves of the Peruvian Amazon, Allpahuayo-Mishana National Reserve and Quistococha Regional Reserve, both situated in Iquitos, northeastern Peru. Four vegetation types were surveyed between December, 2021 and December, 2022: terra firme forest, white-sand wet forest, and white-sand dry forest in Allpahuayo-Mishana National Reserve, and palm swamp forest in Quistococha Regional Reserve. Overall, we found 262 gall morphotypes, distributed across 75 host species representing 66 plant genera and 30 families. Fabaceae was the plant family with the greatest number of gall morphotypes (n = 48), followed by Calophyllaceae (n = 21) and Euphorbiaceae (n = 20). The plant genera that supported the highest diversity of galls were Caraipa (n = 17), Eschweilera (n = 16), Tapirira (n = 16), Micrandra (n = 14), and Iryanthera (n = 10). The plant species Tapirira guianensis (n = 16), Caraipa utilis (n = 14), Micrandra elata (n = 14), Eschweilera coriacea (n = 11), and Sloanea parvifructa (n = 10) exhibited the highest richness of galls. Among the host plants, C. utilis stands alone as the only species noted as both endemic to the Amazonian region and bearing a Vulnerable (VU) conservation status. The leaves were the most attacked organs (90% of all galls). Most morphotypes are glabrous (89%), green (67%), globoid (53%), and one-chambered (91%). We found galling insects belonging to the orders Diptera, Thysanoptera, Lepidoptera, and Hemiptera. The galling insects of Cecidomyiidae (Diptera) were the most common, inducing 22% of the gall morphotypes. In addition to the gallers, we also observed the presence of successors, cecidophages, and parasitoids. Among the sampled vegetation types, the terra firme forest presented the highest richness of gall morphotypes and host plant species. This is the first systematic inventory of insect galls in this part of the Peruvian Amazon.
... Modern botanical surveys record species and trait composition within forests (Figure 4), and there are over 400 forest plots that have been repeatedly surveyed to capture changes in vegetation and carbon dynamics (Anderson-Teixeira et al., 2015;ForestPlots.net et al., 2021;Lopez-Gonzalez et al., 2009). Forest resilience has also been estimated based on field-collected data at some of these sites. ...
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People have modified landscapes throughout the Holocene (the last c . 11,700 years) by modifying soils, burning forests, cultivating and domesticating plants, and directly and indirectly enriched and depleted plant abundances. These activities also took place in Amazonia, which is the largest contiguous piece of rainforest in the world, and for many decades was considered to have very little human impact until the modern era. The compositional shift caused by past human disturbances can alter forest traits, creating ecological legacies that may persist through time. As the lifespan of most Amazonian tree species is more than 200 years, forests that were modified over the last centuries to millennia are likely still in a mid‐successional state. Ecological legacies resulting from past human activity may also affect modern forest resilience to ongoing anthropogenic and climatic changes. Current estimates of resilience assume that forests are in equilibrium, and long‐term successional trajectories are not considered. We suggest that disturbance histories, generated through palaeoecological and archaeological surveys, should be paired with field‐based and remotely sensed estimates of forest resilience to recent drought events, to determine whether past human activities affect modern forest resilience. We have outlined how this can be accomplished in future research. Read the free Plain Language Summary for this article on the Journal blog.
... Permanent forest dynamics plots have been established worldwide to investigate ecological questions, such as understanding the mechanisms behind species coexistence, forest dynamics, and ecosystem functioning (Hubbell et al., 1999;Anderson-Teixeira et al., 2015;Baker et al., 2017;ForestPlots.net, 2021). The shared census and monitoring protocols of these plots made such biodiversity monitoring platforms an ideal system in which to conduct our research. Here, we investigated the relationship between bird acoustic indices and various environmental factors including vegetation and topographic characteristics in a network of tropical fore ...
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The soundscape of different habitats can be discriminated by multiple acoustic indices as they have previously been related to vegetation characteristics. However, the relationship between acoustic indices and topography still needs to be thoroughly evaluated, as well as the variance in the relationship at different spatial scales within the same research system. Networks of forest dynamics plots constructed under the same protocol provide an ideal research platform for addressing the above issue. Our study investigated the relationship between acoustic indices, vegetation, and topographic characteristics at two spatial scales. We recorded soundscapes using autonomous recorders across a tropical forest dynamics plot network consisting of 22 plots in Xishuangbanna, Yunnan Province, southwest China. To exclude recordings with geophony and with biotic sounds from non-avian species, especially from cicadas and frogs, the recordings were previewed aurally and visually, with 9110 min of “clear” bird acoustic recordings chosen for final analysis. We assessed the relative importance of tree species richness, six vegetation characteristics, and three topographic characteristics for five acoustic signal complexity indices, and three statistical indices which describe the properties of frequency spectrum, at 25 m and 50 m spatial scales. We found that topographic complexity was the most significant factor influencing acoustic indices. The variation explained by topographic complexity ranged from 13.2 % to 47.2 % for the seven best-fitted models at both spatial scales. Horizontal vegetation characteristics, including tree density and basal area, were also important variables related to acoustic indices. The Acoustic Diversity Index (ADI) and Bioacoustic Index (BIO) were not associated with vegetation or topographic characteristics at either spatial scale. Three out of seven significant relationships between acoustic indices and vegetation or topographic characteristics disappeared as the spatial scale increased from 25 m to 50 m. In contrast, the significant relationship between Acoustic entropy (H), the centroid (CENT) and skewness (SKEW) and topographic complexity remained stable. Our results suggest that both acoustic signal complexity indices and acoustic statistical indices showed a different relationship to vegetation and topographic characteristics in tropical forests, and the strength of these relationship was scale-dependent. This study revealed that topographic complexity might be an effective predictive variable for further ecoacoustic research.
... Another approach towards consolidating land-cover classification with ecosystem functioning is the establishment of long-term plots within diverse savannas globally [195] such as the ones that have been instituted in forest science (e.g., http://forestplots.net [196]). A widely distributed global network will be able to capture climatic and edaphic gradients as well as community biogeography and vegetation structure. ...
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Savannas cover a wide climatic gradient across large portions of the Earth’s land surface and are an important component of the terrestrial biosphere. Savannas have been undergoing changes that alter the composition and structure of their vegetation such as the encroachment of woody vegetation and increasing land-use intensity. Monitoring the spatial and temporal dynamics of savanna ecosystem structure (e.g., partitioning woody and herbaceous vegetation) and function (e.g., aboveground biomass) is of high importance. Major challenges include misclassification of savannas as forests at the mesic end of their range, disentangling the contribution of woody and herbaceous vegetation to aboveground biomass, and quantifying and mapping fuel loads. Here, we review current (2010–present) research in the application of satellite remote sensing in savannas at regional and global scales. We identify emerging opportunities in satellite remote sensing that can help overcome existing challenges. We provide recommendations on how these opportunities can be leveraged, specifically (1) the development of a conceptual framework that leads to a consistent definition of savannas in remote sensing; (2) improving mapping of savannas to include ecologically relevant information such as soil properties and fire activity; (3) exploiting high-resolution imagery provided by nanosatellites to better understand the role of landscape structure in ecosystem functioning; and (4) using novel approaches from artificial intelligence and machine learning in combination with multisource satellite observations, e.g., multi-/hyperspectral, synthetic aperture radar (SAR), and light detection and ranging (lidar), and data on plant traits to infer potentially new relationships between biotic and abiotic components of savannas that can be either proven or disproven with targeted field experiments.
... Yet, for many regions, particularly in countries with a large coverage of primary forests, such inventories are not available or have been initiated only recently; for example, the first National Forest Inventory of Brazil started in 2009 (46,64). Particularly in the tropics, research-led monitoring initiatives (e.g., RAINFOR, ForestGeo) are our only gateway to track the fate of these globally important forests (62). Because it takes several decades until data series are long enough to capture dynamics in forest condition, continuing the current forest-monitoring initiatives is essential. ...
Article
Recent observations of elevated tree mortality following climate extremes, like heat and drought, raise concerns about climate change risks to global forest health. We currently lack both sufficient data and understanding to identify whether these observations represent a global trend toward increasing tree mortality. Here, we document events of sudden and unexpected elevated tree mortality following heat and drought events in ecosystems that previously were considered tolerant or not at risk of exposure. These events underscore the fact that climate change may affect forests with unexpected force in the future. We use the events as examples to highlight current difficulties and challenges for realistically predicting such tree mortality events and the uncertainties about future forest condition. Advances in remote sensing technology and greater availably of high-resolution data, from both field assessments and from satellites, are needed to improve both understanding and prediction of forest responses to future climate change. Expected final online publication date for the Annual Review of Plant Biology, Volume 73 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
... ss story in this context is the network of plots in tropical forests (24 plot networks from 54 countries) integrated via Forest-Plots.net cyber-infrastructure. This network encompasses thousands of long-term plots, where researchers have measured forests tree-by-tree to understand how forest carbon and biodiversity are responding to climate change (ForestPlots.net et al., 2021). ...
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Unprecedented amounts of analysis‐ready Earth Observation (EO) data, combined with increasing computational power and new algorithms, offer novel opportunities for analysing ecosystem dynamics across large geographic extents, and to support conservation planning and action. Much research effort has gone into developing global EO‐based land‐cover and land‐use datasets, including tree cover, crop types, and surface water dynamics. Yet there are inherent trade‐offs between regional and global EO products pertaining to class legends, availability of training/validation data, and accuracy. Acknowledging and understanding these trade‐offs is paramount for both developing EO products and for answering science questions relevant for ecology or conservation studies based on these data. Here we provide context on the development of global EO‐based land‐cover and land‐use datasets, and outline advantages and disadvantages of both regional and global datasets. We argue that both types of EO‐derived land‐cover datasets can be preferable, with regional data providing the context‐specificity that is often required for policy making and implementation (e.g., land‐use and management, conservation planning, payment schemes for ecosystem services), making use of regional knowledge, particularly important when moving from land cover to actors. Ensuring that global and regional land‐cover and land‐use products derived based on EO data are compatible and nested, both in terms of class legends and accuracy assessment, should be a key consideration when developing such data. Open access high‐quality training and validation data derived as part of such efforts are of utmost importance. Likewise, global efforts to generate sets of essential variables for climate change, biodiversity, or eventually land use, which often require land‐cover maps as inputs, should consider regionalized, hierarchical approaches to not sacrifice regional context. Global change impacts manifest in regions, and so must the policy and planning responses to these challenges. EO data should embrace that regions matter, perhaps more than ever, in an age of global data availability and processing.
... ing, in particular the CTFS-ForestGEO network established repeatedlycensused plots, typically 50 ha (Anderson-Teixeira et al., 2015, Davies et al., this volume), and the RAINFOR forest inventory plot network (Malhi et al., 2002;Peacock et al., 2007) focused on 1-ha tree census plots across Amazonia, which later spawned the Forest Plots metanetwork (ForestPlots.net et al., 2021). These networks built on a long tradition and expertise in assessment of tropical forest structure and biomass, and taxonomic expertise, and, by integrating these plots across regions and countries, provided new insights into spatial variability of forest structure, tree communities and dynamics, as well as revealing evidence for change ...
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A rich understanding of the productivity, carbon and nutrient cycling of terrestrial ecosystems is essential in the context of understanding, modelling and managing the future response of the biosphere to global change. This need is particularly acute in tropical ecosystems, home to over 60% of global terrestrial productivity, over half of planetary biodiversity, and hotspots of anthropogenic pressure. In recent years there has been a surge of activity in collecting data on the carbon cycle, productivity, and plant functional traits of tropical ecosystems, most intensively through the Global Ecosystems Monitoring network (GEM). The GEM approach provides valuable insights by linking field-based ecosystem ecology with the needs of Earth system science. In this paper, we review and synthesize the context, history and recent scientific output from the GEM network. Key insights have emerged on the spatial and temporal variability of ecosystem productivity and on the role of temperature and drought stress on ecosystem function and resilience. New work across the network is now linking carbon cycling to nutrient cycling and plant functional traits, and subsequently to airborne remote sensing. We discuss some of the novel emerging patterns and practical and methodological challenges of this approach, and examine current and possible future directions, both within this network and as lessons for a more general terrestrial ecosystem observation scheme.
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NASA's Global Ecosystem Dynamics Investigation (GEDI) mission one of the objectives is to estimate global forest aboveground biomass (AGB) using full waveform (WF) LiDAR data. GEDI's relative height (RH) metrics, derived from vertical energy distributions, serve as key predictors in AGB modeling, with energy quantiles ranging from 0 % to 100 %. Despite extensive studies on RH metrics, the selection of optimal RH metrics for AGB estimation remains inconsistent, and using fewer metrics can result in a loss of vertical structural complexity. This study explores the potential of dense sampling of RH metrics (RH5 to RH100, in 5 % increments) to retain forest structural complexity, even across diverse forest regimes. Using noise-free simulated GEDI WF data, we developed machine learning models (Cubist, Random Forest, and XGBoost) to estimate AGB across 174 forest plots in the Brazilian Amazon. Results showed that dense RH sampling outperformed models using fewer recommended RH metrics. Our proposed suite of mean RH (mRH) metrics (R² = 0.71, RMSE = 65.88 Mg/ha, nRMSE = 0.36) – derived at plot level from an extensive suite of RH metrics (RH5 to RH100, in 5 % increments) at sub-plot level, and vertical mean RH (vmRH) RH metrics within the 20 % waveform vertical energy distribution (vmRH20, vmRH40, vmRH60, vmRH80, and vmRH100) approach showed similar performance, at the plot level of an average size of 50 m by 50 m. The single vmRH metrics versus plot-level AGB estimates – vmRH80 consistently gives the best results for all ML models and Ordinary Least Square (OLS) regression with R² ranges from (0.65–0.68), RMSE (53.18 – 70.51) Mg/ha – highest RMSE reported for OLS regression. All model’s performances were comparable giving similar RMSE, nRMSE, and coefficient of determination (R²) for derivative RH metrics – mRH and vmRH – compared with the traditional approach of selective RH metrics at GEDI footprint level estimates. The trained model provided AGB estimates at 30 m resolution for entire ALS survey areas of sites (n = 174) in the Brazilian Legal Amazon (BLA) region. Overall, this approach retains GEDI waveform information effectively and offers a scalable solution for regional and potentially global AGB modeling. full length access: https://lnkd.in/e-sFzkp9
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Tropical moist forests are not the homogeneous green carpet often illustrated in maps or considered by global models. They harbour a complex mixture of forest types organized at different spatial scales that can now be more accurately mapped thanks to remote sensing products and artificial intelligence. In this study, we built a large‐scale vegetation map of the North of Congo and assessed the environmental drivers of the main forest types, their forest structure, their floristic and functional compositions and their faunistic composition. To build the map, we used Sentinel‐2 satellite images and recent deep learning architectures. We tested the effect of topographically determined water availability on vegetation type distribution by linking the map with a water drainage depth proxy (HAND, height above the nearest drainage index). We also described vegetation type structure and composition (floristic, functional and associated fauna) by linking the map with data from large inventories and derived from satellite images. We found that water drainage depth is a major driver of forest type distribution and that the different forest types are characterized by different structure, composition and functions, bringing new insights about their origins and successional dynamics. We discuss not only the crucial role of soil–water depth, but also the importance of consistently reproducing such maps through time to develop an accurate monitoring of tropical forest types and functions, and we provide insights on peculiar forest types (Marantaceae forests and monodominant Gilbertiodendron forests) on which future studies should focus more. Under the current context of global change, expected to trigger major forest structural and compositional changes in the tropics, an appropriate monitoring strategy of the spatio‐temporal dynamics of forest types and their associated floristic and faunistic composition would considerably help anticipate detrimental shifts.
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The increase in Earth observations from space in recent years supports improved quantification of carbon storage by terrestrial vegetation and fosters studies that relate satellite measurements to biomass retrieval algorithms. However, satellite observations are only indirectly related to the carbon stored by vegetation. While ground surveys provide biomass stock measurements to act as reference for training the models, they are sparsely distributed. Here, we addressed this problem by designing an algorithm that harnesses the interplay of satellite observations, modeling frameworks and field measurements, and generated global estimates of above-ground biomass (AGB) density that meet the requirements of the scientific community in terms of accuracy, spatial and temporal resolution. The design was adapted to the amount, type and spatial distribution of satellite data available around the year 2020. The retrieval algorithm estimated AGB annually by merging estimates derived from C-and L-band Synthetic Aperture Radar (SAR) backscatter observations with a Water Cloud type of model and does not rely on AGB reference data at the same spatial scale as the SAR data. This model is integrated with functions relating to forest structural variables that were trained on spaceborne LiDAR observations and sub-national AGB statistics. The yearly estimates of AGB were successively harmonized using a cost function that minimizes spurious fluctuations arising from the moderate-to-weak sensitivity of the SAR backscatter to AGB. The spatial distribution of the AGB estimates was correctly reproduced when the retrieval model was correctly set. Over-predictions occasionally occurred in the low AGB range (<50 Mg ha − 1) and under-predictions in the high AGB range (>300 Mg ha − 1). These errors were a consequence of sometimes too strong generalizations made within the modeling framework to allow reliable retrieval worldwide at the expense of accuracy. The precision of the estimates was mostly between 30% and 80% relative to the estimated value. While the framework is well founded, it could be improved by incorporating additional satellite observations that capture structural properties of vegetation (e.g., from SAR interferometry, low-frequency SAR, or high-resolution observations), a dense network of regularly monitored high-quality forest biomass reference sites, and spatially more detailed characterization of all model parameters estimates to better reflect regional differences.
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Across tropical and subtropical forests and savannas, variation in temperature, precipitation, and edaphic preferences is related to functional characteristics turnover across space. Here we use a unique dataset of 133 woody community sites (127 ha sample and 1351 species included) covering six forest and savanna vegetation types, to reexamine structural and functional patterns and their environmental drivers. Furthermore, we evaluated whether vegetation types (identified by floristic and environmental characteristics) consistently exhibited structural and functional distinctions. We also assessed the importance of vegetation type identity by quantifying the additional contribution of vegetation type in explaining vegetation patterns when compared to environmental models that include temperature, climate, soil and fire. Our variables included fundamental structural characteristics such as number of trees, basal area and average diameter, alongside functional attributes such as aboveground carbon stock, wood density and representativity of multi-stemmed trees. We also include the innovative approach to representativeness of species with compound leaves, which is a proxy for ecological patterns. We found that vegetation types have consistent differentiation for most structural and functional variables, so that vegetation types exist as distinct units beyond floristic differentiation. In addition, environmental variables play an important role in vegetation patterns, but associated with differences between vegetation types for most variables. Overall, vegetation types attributes serve as important drivers of most vegetation variables, contributing up to 30% to the explanation of variable patterns. Our work is the first to explore structural and functional variations among Brazilian tropical and subtropical vegetation types in a broad scale, reviewing ecological patterns previously defined by specific work or carried out using other approaches.
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Long-term experiments are essential in understanding the ecological consequences of global land use and climate change. Further, it is well established that long-term data sets are prerequisites for effective management of forest resources and biodiversity conservation. In view of this, the present study attempts to contribute to major global long-term ecological monitoring (LTEM) networks and the status of LTEM studies in India with a special focus on Indian Himalayan Region. Over the last 40 years, around 103 countries from the America, Europe, Africa, Asia and Australia have been engaged in LTEM studies on various aspects of biodiversity, monitoring and predicting climate change impacts in a range of ecosystems, including the mountains. The temporal distribution of past studies on the subject shows a gradual increasing pattern (3 papers in 1992) with a peak during 2021 (105 papers). The established LTEM networks across the globe provide a significant empirical basis for understanding ecosystem structure and dynamics. Literature indicates plenty of permanent monitoring plots from India, mostly from southern India, and their significant contribution to ecosystem understanding. Himalayan regions are important sites for monitoring biological and socio-ecological responses to environmental perturbations, including climate change. LTEM studies are lacking in the IHR; only a few sites have been established, mostly in alpine ecosystems. This review identifies research gaps, opportunities with respect to LTEM studies, and the possibilities for strengthening long-term research and observation in India in general and the Himalaya in particular.
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We review the history of plot-based studies of forests in Singapore and their contribution to our understanding of tropical forest ecology, especially of the regenerative capabilities of forest remnants after fragmentation, land-use change, and other disturbances. With this, we describe the establishment of the Long-Term Forest Ecological Monitoring plot network that includes the continued utilisation of sets of recently established, standardised plots along with the re-establishment of a historical set of plots surveyed by a team led by Wong Yew Kwan in 1992, ensuring the plot design is harmonised across the network.
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The present study evaluates the potential of airborne hyperspectral and space-borne multispectral satellite datasets to determine alpha (α) and beta (β) diversity combining in-situ floristic composition in tropical deciduous forests (TDFs) of Mudumalai Tiger Reserve (MTR), India. 43 forest plots (each of 0.04 ha) were sampled to record the species diversity in MTR. The very high-resolution AVIRIS-NG hyperspectral images and temporal Sentinel-2 multispectral images were used to extract spectral variables by associating each field plot with corresponding pixels of the satellite images. A high positive correlation of field-based α-diversity (Shannon-Wiener diversity index (H′)) with AVIRIS-NG based α-diversity (R²: 0.83 (2016); R²: 0.82 (2018)) was observed compared to Sentinel-2 based α-diversity (R²: 0.50 to 0.63) with high correlation during post-monsoon (R²: 0.63). Principal coordinate analysis of AVIRIS-NG based β-diversity signifies a low diversity (H′: <1.00) in the eastern parts (0.13% of MTR) in contrast to moderate (H′: 1.00 to 2.00; 13.39% of MTR) to high diversity (H′ >2.00; 86.49% of MTR) in the remaining parts of MTR. The study highlights the application of high spectral-spatial AVIRIS-NG images for precise tree diversity mapping and the high temporal-spatial Sentinel-2 satellite images for assessing the phenological variations of the forest species. The integration of high spatial-hyperspectral and temporal multispectral satellite datasets with field-based observations for fine-scale tree species diversity mapping at geographical and temporal scales is the novelty of the study that may effectively contribute in devising effective forest management plans for biodiversity conservation.
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It is often difficult to compile and synthesise evidence across multiple studies to inform policy and practice because different outcomes have been measured in different ways or datasets and models have not been fully or consistently reported. In the case of peatlands, a critical terrestrial carbon store, this lack of consistency hampers the evidence-based decisions in policy and practice that are needed to support effective restoration and conservation. This study adapted methods pioneered in the medical community to reach consensus over peatland outcomes that could be consistently measured and reported to improve the synthesis of data and reduce research waste. Here we report on a methodological framework for identifying, evaluating and prioritising the outcomes that should be measured. We discuss the subsequent steps to standardise methods for measuring and reporting outcomes in peatland research and monitoring. The framework was used to identify and prioritise sets of key variables (known as core domain sets) for UK blanket and raised bogs, and for tropical peat swamps. Peatland experts took part in a structured elicitation and prioritisation process, comprising two workshops and questionnaires, that focused on climate (32 and 18 unique outcomes for UK and tropical peats, respectively), hydrology (26 UK and 16 tropical outcomes), biodiversity (8 UK and 22 tropical outcomes) and fire-related outcomes (13, for tropical peatlands only). Future research is needed to tackle the challenges of standardising methods for data collection, management, analysis, reporting and re-use, and to extend the approach to other types of peatland. The process reported here is a first step towards creating datasets that can be synthesised to inform evidence-based policy and practice, and contribute towards the conservation, restoration and sustainable management of this globally significant carbon store.
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Although tropical forests differ substantially in form and function, they are often represented as a single biome in global change models, hindering understanding of how different tropical forests will respond to environmental change. The response of the tropical forest biome to environmental change is strongly influenced by forest type. Forest types differ based on functional traits and forest structure, which are readily derived from high resolution airborne remotely sensed data. Whether the spatial resolution of emerging satellite-derived hyperspectral data is sufficient to identify different tropical forest types is unclear. Here, we resample airborne remotely sensed forest data at spatial resolutions relevant to satellite remote sensing (30 m) across two sites in Malaysian Borneo. Using principal component and cluster analysis, we derive and map seven forest types. We find ecologically relevant variations in forest type that correspond to substantial differences in carbon stock, growth, and mortality rate. We find leaf mass per area and canopy phosphorus are critical traits for distinguishing forest type. Our findings highlight the importance of these parameters for accurately mapping tropical forest types using space borne observations.
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Long-term vegetation plots represent one of the largest types of research investments in ecology, but efforts to interrelate data on plants with that on animals is constrained because of the disturbance produced by human observers. Recent advances in the automated identification of animal sounds on large datasets of autonomously collected audio recordings holds the potential to describe plant-animal interactions, such as between frugivorous birds and fruiting trees, without such disturbance. We deployed an array of nine autonomous recording units (ARUs) on the 400 x 500 m Bubeng Forest Dynamics Plot, in Xishuangbanna, southwest China, and collected a total of 1965 hours of recordings across two seasons. Animal Sound Identifier (ASI) software was used to detect the vocalizations of five frugivorous bird species, and the probability of detection was related to the number of mature fruiting trees within a 50 m radius of the ARUs. There were more significant positive relationships than would be expected by chance in analyses that investigated bird/tree interactions across three months, both in the wet season and the dry season, as well as in short-term analyses within the dry season months of October and November. The analysis identified 54 interactions between bird and tree species with significant positive relationships. Follow-up observations of birds on the plot validated that such interactions were more likely to be observed than other interactions. We demonstrate that ARUs and automated voice identification can map the distribution and/or movement of vocal animals across large vegetation plots, allowing this data on animals to be inter-related to that on plants. We suggest that ARUs be added to the standardized protocols of the plot network, leveraging their vast amount of information about vegetation to describe plant-animal interactions currently, and monitor changes in the future.
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Lianas are quintessential components of tropical forests competing strongly with trees for resources. Yet, their role in the structure and functioning of forests is rarely studied. Here, we investigate the impact of lianas on the carbon stocks and sink potential of an intact moist tropical forest in Panama using 3D terrestrial laser scanning. We find that liana-infested trees are significantly shorter with smaller crown areas, thereby resulting in a significant liana-induced reduction in stand-level carbon stocks (5.3%) and coarse woody productivity (24.5%). The widely used pantropical allometric model overestimates the carbon stocks by 10% and underestimates the liana impact on woody productivity by 1.5% at the study site with current infestation level. Increasing liana abundance across Neotropics will further worsen this impact. We show that by ignoring liana impact in carbon estimation, we are currently overestimating the potential of nature-based climate solutions to lock up atmospheric carbon.
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Tree mortality rates and the modes of tree death have recently been extensively investigated in the Amazon. However, efforts to describe these processes have not been well distributed across the basin. No study has yet investigated in depth tree mortality process in the unique low, open, bamboo-dominated forests of southwestern Amazonia, a region with a distinct climate and the epicenter of recent severe drought events. Here, we investigated the leading ways that trees die in the terra-firme forests of the southwestern Brazilian Amazon, to understand whether the dynamics of mortality differ from those recorded in other parts of the basin. Using data from six permanent plots located in southwestern Amazonia, we calculated the mortality rate for three main modes of tree death: standing, broken and uprooted. We thus identified the predominant mode of death over a 14 year period (2002-2016). We found that trees in the southwestern Amazon died mainly standing (325 trees, 0.8% year−1) and broken (362 trees, 0.8% year− 1); significantly fewer trees died uprooted (156 trees, 0.4% year−1, equivalent to less than one in five of all trees dying). During the study period, the tree mode of death with the greatest proportion in the region alternated between standing and broken trees. Forest characteristics of the southwestern Amazon, like presence and high density of bamboo culms, and the fact that the region was subject to severe droughts in 2005 and 2010, may be affecting how trees die in southwestern Amazon. The presence of these factors makes the forest dynamics of the southwestern Amazon different from other regions of the Amazon basin.
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Extensive networks of large plots have the potential to transform knowledge of avian community dynamics through time and across geographical space. In the Neotropics, the global hotspot of avian diversity, only six 100-ha plots, all located in lowland forests of Amazonia, the Guianan shield and Panama, have been inventoried sufficiently. We review the most important lessons learned about Neotropical forest bird communities from those big bird plots and explore opportunities for creating a more extensive network of additional plots to address questions in ecology and conservation, following the model of the existing ForestGEO network of tree plots. Scholarly impact of the big bird plot papers has been extensive, with the papers accumulating nearly 1,500 citations, particularly on topics of tropical ecology, avian conservation, and community organization. Comparisons of results from the plot surveys show no single methodological scheme works effectively for surveying abundances of all bird species at all sites; multiple approaches have been utilized and must be employed in the future. On the existing plots, abundance patterns varied substantially between the South American plots and the Central American one, suggesting different community structuring mechanisms are at work and that additional sampling across geographic space is needed. Total bird abundance in Panama, dominated by small insectivores, was double that of Amazonia and the Guianan plateau, which were dominated by large granivores and frugivores. The most common species in Panama were three times more abundant than those in Amazonia, whereas overall richness was 1.5 times greater in Amazonia. Despite these differences in community structure, other basic information, including uncertainty in population density estimates, has yet to be quantified. Results from existing plots may inform drivers of differences in community structure and create baselines for detection of long-term regional changes in bird abundances, but supplementation of the small number of plots is needed to increase generalizability Frontiers in Ecology and Evolution | www.frontiersin.org 1 October 2021 | Volume 9 | Article 697511 Robinson et al. Benchmarking Tropical Birds on Plots of results and reveal the texture of geographic variation. We propose fruitful avenues of future research based on our current synthesis of the big bird plots. Collaborating with the large network of ForestGEO tree plots could be one approach to improve understanding of linkages between plant and bird diversity. Careful quantification of bird survey effort, recording of exact locations of survey routes or stations, and archiving detailed metadata will greatly enhance the value of benchmark data for future repeat surveys of the existing plots and initial surveys of newly established plots.
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This special issue focuses on long‐term ecological monitoring in the tropics, with a particular focus, appropriate to Plants, People, Planet, on what it can offer both to local people and decision makers in tropical countries. Two of the contributed papers emphasise the role that long‐term, permanent monitoring plots can play in bringing together researchers, policymakers and communities, based on examples from Peru and Colombia (Baker et al., Norden et al.). The articles also highlight new plot‐based methods for monitoring the neglected tropical dry biomes of savannas and dry forests (The SEOSAW Partnership; Moonlight et al.) and new methods for field‐based monitoring of habitat degradation (Ahrends et al.) and the distribution of large trees (Harris et al.). Overall, the issue demonstrates that sustainable management of tropical environments requires long‐term, ground‐based monitoring that engages with the communities and institutions that manage these landscapes.
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Societal Impact Statement The sustainable management of the southern African woodlands is closely linked to the livelihoods of over 150 M people. Findings from the Socio‐Ecological Observatory for the Southern African Woodlands (SEOSAW) will underpin the sustainability of two of the largest industries on the continent: woodfuels and timber. SEOSAW will also improve our understanding of how human use shapes the biogeography and functioning of these ecosystems. Summary Here we describe a new network of researchers and long‐term, in situ , measurements that will characterize the changing socio‐ecology of the woodlands of southern Africa. These woodlands encompass the largest savanna in the world, but are chronically understudied, with few long‐term measurements. A network of permanent sample plots (PSPs) is required to: (a) address management issues, particularly related to sustainable harvesting for energy and timber; (b) understand how the woodlands are responding to a range of global and local drivers, such as climate change, CO 2 fertilization, and harvesting; and (c) answer basic questions about biogeography, ecosystem function, and the role humans play in shaping the ecology of the region. We draw on other successful networks of PSPs and adapt their methods to the specific challenges of working in southern African woodlands. In particular we suggest divergences from established forest monitoring protocols that are needed to (a) adapt to a high level of ecosystem structural diversity (from open savanna to dry forest); (b) quantify the chronic disturbances by people, fire, and herbivores; (c) quantify the diversity and function of the understory of grasses, forbs, and shrubs; (d) understand the life histories of resprouting trees; and (e) conduct work in highly utilized, human‐dominated landscapes. We conclude by discussing how the SEOSAW network will integrate with remote sensing and modeling approaches. Throughout, we highlight the challenges inherent to integrating work by forest and savanna ecologists, and the wide range of skills needed to fully understand the socio‐ecology of the southern African woodlands.
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Se describe e ilustra a Virola pseudosebifera Vásquez & Soto-Shareva (Myristicaceae), una nueva especie proveniente de la Selva Alta, proveniente del Parque Nacional Cordillera Azul, Sector PV-15 Mishquiyaquillo, distrito Pampa Hermosa, provincia de Ucayali, región Loreto, Perú, a los 1497 m de elevación. Se caracteriza porque, el indumento de las ramitas terminales y de las hojas por el envés es uniformemente persistente, las inflorescencias estaminadas son estrechas 1.8-6.5(-7) cm de largo, las flores estaminadas con perigonio partido casi hasta la mitad de su longitud; las inflorescencias pistiladas, 1.0-3.0 (-3.5) cm de largo; las infrutescencias con, (1-)2(-3) frutos maduros, elipsoides, 2.8-3.6 × 1.8-2.4 cm, con pericarpio 2-3 mm de espesor y con indumento persistente. Adicionalmente se discuten sus relaciones con la especie afín, e incluye su ilustración y datos sobre su distribución geográfica y ecología, fenología, y su estado actual.
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Societal Impact Statement The approach that we take to our science is as important as the questions that we address if we would like our research to inform management. Here, we discuss our experience of using networks of permanent forest inventory plots to support sustainable management and conservation of intact tropical forests. A key conclusion is that to maximize the use of data from such large international networks within policymaking, it is crucial that leadership is widely shared among participants. Such an approach helps to address ethical concerns surrounding international collaborations and also achieves greater policy impact. Summary Long‐term data from permanent forest inventory plots have much to offer the management and conservation of intact tropical forest landscapes. Knowledge of the growth and mortality rates of economically important species, forest carbon balance, and the impact of climate change on forest composition are all central to effective management. However, this information is rarely integrated within the policymaking process. The problem reflects broader issues in using evidence to influence environmental management, and in particular, the need to engage with potential users beyond the collection and publication of high‐quality data. To ensure permanent plot data are used, (a) key “policy windows”—opportunities to integrate data within policy making—need to be identified; (b) long‐term relationships need to be developed between scientists and policy makers and policymaking organizations; and (c) leadership of plot networks needs to be shared among all participants, and particularly between institutions in the global north and those in tropical countries. Addressing these issues will allow permanent plot networks to make tangible contributions to ensuring that intact tropical forest persists over coming decades.
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Societal Impact Statement Tropical dry forests (TDF) underpin the wellbeing of millions, mostly rural populations; yet have suffered from severe clearing in Colombia, triggering cascading effects such as desertification. By engaging scientists, society, and institutions in the establishment of platforms for monitoring biodiversity and ecosystem functioning, crucial knowledge gaps will be bridged, helping to find a path toward sustainable development. Science‐led but socially and economically anchored information on biodiversity will help to incorporate nature's contributions to people into the society's cultural values. Ultimately, these transformative actions will translate into the comprehensive management of TDF through a greater impact in decision making. Summary Thousands of permanent plots have been established across the tropics with the purpose of monitoring tree communities. Research outcomes from these platforms, however, have been mainly directed toward the academic community, and their contribution to society has been limited so far. Here, we show how generating robust data on biodiversity has supported decision making in Colombian tropical dry forests (TDF), where less than 8% of their original cover remains. As a first step to build a national dialogue around the critical status of this ecosystem, a national collaborative network on TDF research and monitoring was born in 2014, the Red de Investigación y Monitoreo del Bosque Seco Tropical en Colombia (Red BST‐Col). Our main goal is to generate scientifically sound information that feeds into the comprehensive management of this ecosystem. To do so, a set of biodiversity monitoring platforms has been established across the country, which have already served to answer socio‐ecological questions related with deforestation drivers, citizen science, or the valuation of ecosystem services. Overall, this research agenda has nurtured the four lines that underpin the Program for the comprehensive management of dry forests in Colombia (knowledge management, preservation, restoration, and sustainable use), formulated by the Humboldt Institute, the United Nations Development Programme, and the Ministry of Environment in 2019. Many challenges are ahead, however, for a complex territory where multiple social actors and productive sectors coexist. The ultimate goal is to integrate all the dimensions of biodiversity to achieve a synthetic understanding of the functioning of the most endangered ecosystem in Colombia, and its relationship with local communities' wellbeing.
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Tropical ecosystems adapted to high water availability may be highly impacted by climatic changes that increase soil and atmospheric moisture deficits. Many tropical regions are experiencing significant changes in climatic conditions, which may induce strong shifts in taxonomic, functional and phylogenetic diversity of forest communities. However, it remains unclear if and to what extent tropical forests are shifting in these facets of diversity along climatic gradients in response to climate change. Here, we show that changes in climate affected all three facets of diversity in West Africa in recent decades. Taxonomic and functional diversity increased in wetter forests but tended to decrease in forests with drier climate. Phylogenetic diversity showed a large decrease along a wet-dry climatic gradient. Notably, we find that all three facets of diversity tended to be higher in wetter forests. Drier forests showed functional, taxonomic and phylogenetic homogenization. Understanding how different facets of diversity respond to a changing environment across climatic gradients is essential for effective long-term conservation of tropical forest ecosystems. Different aspects of biodiversity may not necessarily converge in their response to climate change. Here, the authors investigate 25-year shifts in taxonomic, functional and phylogenetic diversity of tropical forests along a spatial climate gradient in West Africa, showing that drier forests are less stable than wetter forests.
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Aim Amazonian forests predominantly grow on highly weathered and nutrient poor soils. Anthropogenically enriched Amazonian Dark Earths (ADE), traditionally known as Terra Preta de Índio , were formed by pre‐Columbian populations. ADE soils are characterized by increased fertility and have continued to be exploited following European colonization. Here, we evaluated the legacy of land‐use and soil enrichment on the composition and structure in ADE and non‐ADE (NDE) forests. Location Eastern and southern Amazonia. Time period Pre‐Columbia – 2014. Methods We sampled nine pairs of ADE and adjacent NDE forest plots in eastern and southern Amazonia. In each plot, we collected soil samples at 0–10 and 10–20 cm depth and measured stem diameter, height, and identified all individual woody plants (palms, trees and lianas) with diameter ≥ 10 cm. We compared soil physicochemical properties, vegetation diversity, floristic composition, aboveground biomass, and percentage of useful species. Results In the nine paired plots, soil fertility was significantly higher in ADE soil. We sampled 4,191 individual woody plants representing 404 species and 65 families. The floristic composition of ADE and NDE forests differed significantly at both local and regional levels. In southern Amazonia, ADE forests had, on average, higher aboveground biomass than other forests of the region, while in eastern Amazonia, biomass was similar to that of NDE forests. Species richness of both forest types did not differ and was within the range of existing regional studies. The differences in composition between large and small diameter tree recruits may indicate long‐term recovery and residual effects from historical land‐use. Additionally, the proportion of edible species tended to be higher in the ADE forests of eastern and southern Amazonia. Main conclusions The marked differences in soil fertility, floristic composition and aboveground biomass between ADE and NDE forests are consistent with a small‐scale long‐term land‐use legacy and a regional increase in tree diversity.
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The sensitivity of tropical forest carbon to climate is a key uncertainty in predicting global climate change. Although short-term drying and warming are known to affect forests, it is unknown if such effects translate into long-term responses. Here, we analyze 590 permanent plots measured across the tropics to derive the equilibrium climate controls on forest carbon. Maximum temperature is the most important predictor of aboveground biomass (−9.1 megagrams of carbon per hectare per degree Celsius), primarily by reducing woody productivity, and has a greater impact per °C in the hottest forests (>32.2°C). Our results nevertheless reveal greater thermal resilience than observations of short-term variation imply. To realize the long-term climate adaptation potential of tropical forests requires both protecting them and stabilizing Earth’s climate.
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Our knowledge about the structure and function of Andean forests at regional scales remains limited. Current initiatives to study forests over continental or global scales still have important geographical gaps, particularly in regions such as the tropical and subtropical Andes. In this study, we assessed patterns of structure and tree species diversity along ~ 4000 km of latitude and ~ 4000 m of elevation range in Andean forests. We used the Andean Forest Network (Red de Bosques Andinos, https://redbosques.condesan.org/) database which, at present, includes 491 forest plots (totaling 156.3 ha, ranging from 0.01 to 6 ha) representing a total of 86,964 identified tree stems ≥ 10 cm diameter at breast height belonging to 2341 identified species, 584 genera and 133 botanical families. Tree stem density and basal area increases with elevation while species richness decreases. Stem density and species richness both decrease with latitude. Subtropical forests have distinct tree species composition compared to those in the tropical region. In addition, floristic similarity of subtropical plots is between 13 to 16% while similarity between tropical forest plots is between 3% to 9%. Overall, plots ~ 0.5-ha or larger may be preferred for describing patterns at regional scales in order to avoid plot size effects. We highlight the need to promote collaboration and capacity building among researchers in the Andean region (i.e., South-South cooperation) in order to generate and synthesize information at regional scale.
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Structurally intact tropical forests sequestered about half of the global terrestrial carbon uptake over the 1990s and early 2000s, removing about 15 per cent of anthropogenic carbon dioxide emissions. Climate-driven vegetation models typically predict that this tropical forest ‘carbon sink’ will continue for decades. Here we assess trends in the carbon sink using 244 structurally intact African tropical forests spanning 11 countries, compare them with 321 published plots from Amazonia and investigate the underlying drivers of the trends. The carbon sink in live aboveground biomass in intact African tropical forests has been stable for the three decades to 2015, at 0.66 tonnes of carbon per hectare per year (95 per cent confidence interval 0.53–0.79), in contrast to the long-term decline in Amazonian forests. Therefore the carbon sink responses of Earth’s two largest expanses of tropical forest have diverged. The difference is largely driven by carbon losses from tree mortality, with no detectable multi-decadal trend in Africa and a long-term increase in Amazonia. Both continents show increasing tree growth, consistent with the expected net effect of rising atmospheric carbon dioxide and air temperature. Despite the past stability of the African carbon sink, our most intensively monitored plots suggest a post-2010 increase in carbon losses, delayed compared to Amazonia, indicating asynchronous carbon sink saturation on the two continents. A statistical model including carbon dioxide, temperature, drought and forest dynamics accounts for the observed trends and indicates a long-term future decline in the African sink, whereas the Amazonian sink continues to weaken rapidly. Overall, the uptake of carbon into Earth’s intact tropical forests peaked in the 1990s. Given that the global terrestrial carbon sink is increasing in size, independent observations indicating greater recent carbon uptake into the Northern Hemisphere landmass reinforce our conclusion that the intact tropical forest carbon sink has already peaked. This saturation and ongoing decline of the tropical forest carbon sink has consequences for policies intended to stabilize Earth’s climate.
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The intensity and frequency of severe droughts in the Amazon region have increased in the recent decades. These extreme events are associated with changes in forest dynamics, biomass and floristic composition. However, most studies of drought response have focused on upland forests with deep water tables, which may be especially sensitive to drought. Palms, which tend to dominate the less well‐drained soils, have also been neglected. The relative neglect of shallow water tables and palms is a significant concern for our understanding of tropical drought impacts, especially as one‐third of Amazon forests grow on shallow water tables (<5 m deep). We evaluated the drought response of palms and trees in forests distributed over a 600 km transect in central‐southern Amazonia, where the landscape is dominated by shallow water table forests (SWTF). We compared vegetation dynamics before and following the 2015–2016 El Nino drought, the hottest and driest on record for the region (−214 mm of cumulative water deficit). We observed no change in stand mortality rates and no biomass loss in response to drought in these forests. Instead, we observed an increase in recruitment rates, which doubled to 6.78% year‐1 ± 4.40 (M ± SD) during 2015–2016 for palms and increased by half for trees (to 2.92% year‐1 ± 1.21), compared to rates in the pre‐El‐Nino interval. Within these SWTF, mortality and recruitment rates varied as a function of climatic drought intensity and water table depth for both palms and trees, with mortality being greatest in climatically and hydrologically wetter environments and recruitment greatest in drier environments. Across our transect, there was a significant increase over time in tree biomass. Synthesis. Our results indicate that forests growing over shallow water tables—relatively under‐studied vegetation that nonetheless occupies one‐third of Amazon forests—are remarkably resistant to drought. These findings are consistent with the hypothesis that local hydrology and its interactions with climate strongly constrain forest drought effects, and has implications for climate change feedbacks. This work enhances our understanding of integrated drought effects on tropical forest dynamics and highlights the importance of incorporating neglected forest types into both the modelling of forest climate responses and into public decisions about priorities for conservation.
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Despite the mounting threats that tropical ecosystems face, conservation in the tropics remains severely under‐researched relative to temperate systems. Efforts to address this knowledge gap have so far largely failed to analyze the relationship between an author's choice of study site and that author's country of origin. We examined factors that motivate both foreign and domestic scientists to conduct research in tropical countries, based on a sample of nearly 3000 tropical conservation research articles. Many barriers that have historically deterred foreign research effort appear to have been overcome, although US scientists still respond negatively to safety concerns and distance. The productivity of local scientists is affected by corruption and lack of institutional support. Both foreign and in‐country scientists are increasingly working in places with more listed threatened species, but many regions still lack adequate conservation research. Although foreign scientists could be attracted to less‐studied areas through targeted grants, the long‐term solution must be to train and employ more local scientists.
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Tropical forests hold 30% of Earth’s terrestrial carbon and at least 60% of its terrestrial biodiversity, but forest loss and degradation are jeopardizing these ecosystems. Although the regrowth of secondary forests has the potential to offset some of the losses of carbon and biodiversity, it remains unclear if secondary regeneration will be affected by climate changes such as higher temperatures and more frequent extreme droughts. We used a data set of 10 repeated forest inventories spanning two decades (1999–2017) to investigate carbon and tree species recovery and how climate and landscape context influence carbon dynamics in an older secondary forest located in one of the oldest post‐Columbian agricultural frontiers in the Brazilian Amazon. Carbon accumulation averaged 1.08 Mg·ha⁻¹·yr⁻¹, and species richness was effectively constant over the studied period. Moreover, we provide evidence that secondary forests are vulnerable to drought stress: Carbon balance and growth rates were lower in drier periods. This contrasts with drought responses in primary forests, where changes in carbon dynamics are driven by increased stem mortality. These results highlight an important climate change–vegetation feedback, whereby the increasing dry‐season lengths being observed across parts of Amazonia may reduce the effectiveness of secondary forests in sequestering carbon and mitigating climate change. In addition, the current rate of forest regrowth in this region was low compared with previous pan‐tropical and Amazonian assessments—our secondary forests reached just 41.1% of the average carbon and 56% of the tree diversity in the nearest primary forests—suggesting that these areas are unlikely to return to their original levels on politically meaningful time scales.
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Higher levels of taxonomic and evolutionary diversity are expected to maximize ecosystem function, yet their relative importance in driving variation in ecosystem function at large scales in diverse 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 diversity and two key measures of ecosystem function: aboveground wood productivity and biomass storage. While taxonomic and phylogenetic diversity were not important predictors of variation in biomass, both emerged as independent predictors of wood productivity. Amazon forests that contain greater evolutionary diversity 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 diversity of tree species in diverse 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 diversity translates into higher levels of ecosystem function: tropical forest communities with more distantly related taxa have greater wood productivity.
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Vegetation greenness has been increasing globally since at least 1981, when satellite technology enabled large-scale vegetation monitoring. The greening phenomenon, together with warming, sea-level rise and sea-ice decline, represents highly credible evidence of anthropogenic climate change. In this Review, we examine the detection of the greening signal, its causes and its consequences. Greening is pronounced over intensively farmed or afforested areas, such as in China and India, reflecting human activities. However, strong greening also occurs in biomes with low human footprint, such as the Arctic, where global change drivers play a dominant role. Vegetation models suggest that CO2 fertilization is the main driver of greening on the global scale, with other factors being notable at the regional scale. Modelling indicates that greening could mitigate global warming by increasing the carbon sink on land and altering biogeophysical processes, mainly evaporative cooling. Coupling high temporal and fine spatial resolution remote-sensing observations with ground measurements, increasing sampling in the tropics and Arctic, and modelling Earth systems in more detail will further our insights into the greening of Earth.
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Forest biomass is an essential indicator for monitoring the Earth’s ecosystems and climate. It is a critical input to greenhouse gas accounting, estimation of carbon losses and forest degradation, assessment of renewable energy potential, and for developing climate change mitigation policies such as REDD+, among others. Wall-to-wall mapping of aboveground biomass (AGB) is now possible with satellite remote sensing (RS). However, RS methods require extant, up-to-date, reliable, representative and comparable in situ data for calibration and validation. Here, we present the Forest Observation System (FOS) initiative, an international cooperation to establish and maintain a global in situ forest biomass database. AGB and canopy height estimates with their associated uncertainties are derived at a 0.25 ha scale from field measurements made in permanent research plots across the world’s forests. All plot estimates are geolocated and have a size that allows for direct comparison with many RS measurements. The FOS offers the potential to improve the accuracy of RS-based biomass products while developing new synergies between the RS and ground-based ecosystem research communities. Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.9850571
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