Roderick Jan Zagt

Tropenbos International

Amazonia’s floodplain system is the largest and most biodiverse on Earth. Although forests are crucial to the ecological integrity of floodplains, our understanding of their species composition and how this may differ from surrounding forest types is still far too limited, particularly as changing inundation regimes begin to reshape floodplain tree...

The density of wood is a key indicator of trees’ carbon investment strategies, impacting productivity and carbon storage. Despite its importance, the global variation in wood density and its environmental controls remain poorly understood, preventing accurate predictions of global forest carbon stocks. Here, we analyze information from 1.1 million...

Aim: Amazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated w...

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we inve...

ARTICLE Mapping density, diversity and species-richness of the Amazon tree flora Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by fore...

Understanding what controls global leaf type variation in trees is crucial for comprehending their role in terrestrial ecosystems, including carbon, water and nutrient dynamics. Yet our understanding of the factors influencing forest leaf types remains incomplete, leaving us uncertain about the global proportions of needle-leaved, broadleaved, ever...

Indigenous societies are known to have occupied the Amazon basin for more than 12,000 years, but the scale of their influence on Amazonian forests remains uncertain. We report the discovery, using LIDAR (light detection and ranging) information from across the basin, of 24 previously undetected pre-Columbian earthworks beneath the forest canopy. Mo...

The tropical forest carbon sink is known to be drought sensitive, but it is unclear which forests are the most vulnerable to extreme events. Forests with hotter and drier baseline conditions may be protected by prior adaptation, or more vulnerable because they operate closer to physiological limits. Here we report that forests in drier South Americ...

Durante los años con alta frecuencia de incendios, como 2015 y 2019, el distrito Ketapang al suroeste de la Provincia de Kalimantan Occidental fue objeto de atención nacional e internacional. El Kalimantan Occidental posee alrededor de 1,7 millones de ha de turberas, las cuartas en extensión de Indonesia, 253.000 de las cuales se localizan en el di...

1. Biodiversity is an important component of natural ecosystems, with higher species richness often correlating with an increase in ecosystem productivity. Yet, this relationship varies substantially across environments, typically becoming less pronounced at high levels of species richness. However, species richness alone cannot reflect all importa...

In a time of rapid global change, the question of what determines patterns in species abundance distribution remains a priority for understanding the complex dynamics of ecosystems. The constrained maximization of information entropy provides a framework for the understanding of such complex systems dynamics by a quantitative analysis of important...

During years with frequent fires in Indonesia, such as 2015 and 2019, Ketapang District in southwestern West Kalimantan Province received national and international attention. This article presents initial findings and lessons learned from Tropenbos Indonesia’s implementation of the Fire-smart landscape governance programme of the Working Landscape...

Aim To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser‐avail...

The formalization of community forest tenure rights is expected to promote sustainable community forest management, and is seen as a way to combine objectives related to environmental conservation, livelihood improvement, and local self-determination. However, the formalization of forest tenure rights by itself, does not automatically result in the...

Aim Water availability is the major driver of tropical forest structure and dynamics. Most research has focused on the impacts of climatic water availability, whereas remarkably little is known about the influence of water table depth and excess soil water on forest processes. Nevertheless, given that plants take up water from the soil, the impacts...

Rural landscapes in many parts of Indonesia are rapidly being transformed, due to the expansion of agrocommodity plantations—oil palm in particular. At the same time, communities in those landscapes face declining crop yields and ecosystem degradation as a result of both climate and non-climate factors. We assessed local perceptions on climate stre...

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...

In a time of rapid global change, the question of what determines patterns in species abundance distribution remains a priority for understanding the complex dynamics of ecosystems. The constrained maximization of information entropy provides a framework for the understanding of such complex systems dynamics by a quantitative analysis of important...

A Correction to this paper has been published: https://doi.org/10.1038/s41467-020-20537-x

The carbon sink capacity of tropical forests is substantially affected by tree mortality. However, the main drivers of tropical tree death remain largely unknown. Here we present a pan-Amazonian assessment of how and why trees die, analysing over 120,000 trees representing > 3800 species from 189 long-term RAINFOR forest plots. While tree mortality...

The carbon sink capacity of tropical forests is substantially affected by tree mortality. However, the main drivers of tropical tree death remain largely unknown. Here we present a pan-Amazonian assessment of how and why trees die, analysing over 120,000 trees representing > 3800 species from 189 long-term RAINFOR forest plots. While tree mortality...

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 contro...

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 contro...

Landscape governance refers to the combination of rules and decision-making processes of civic, private, and public actors with stakes in the landscape, that together shape the future of that landscape. As part of the Green Livelihoods Alliance, a program that supports civil society organizations (CSOs) to strengthen the governance of tropical fore...

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...

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...

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such “monodominant” forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tr...

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tr...

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tr...

2019, The Author(s), under exclusive licence to Springer Nature Limited. In this Letter, the middle initial of author G. J. Nabuurs was omitted, and he should have been associated with an additional affiliation: ‘Forest Ecology and Forest Management Group, Wageningen University and Research, Wageningen, The Netherlands’ (now added as affiliation 18...

A spatially explicit global map of tree symbioses with nitrogen-fixing bacteria and mycorrhizal fungi reveals that climate variables are the primary drivers of the distribution of different types of symbiosis.

Neutral models are often used as null models, testing the relative importance of niche versus neutral processes in shaping diversity. Most versions, however, focus only on regional scale predictions and neglect local level contributions. Recently, a new formulation of spatial neutral theory was published showing an incompatibility between regional...

Aim Large tropical trees form the interface between ground and airborne observations, offering a unique opportunity to capture forest properties remotely and to investigate their variations on broad scales. However, despite rapid development of metrics to characterize the forest canopy from remotely sensed data, a gap remains between aerial and fie...

Aim: Large tropical trees form the interface between ground and airborne observations, offering a unique opportunity to capture forest properties remotely and to investigate their variations on broad scales. However, despite rapid development of metrics to characterize the forest canopy from remotely sensed data, a gap remains between aerial and fi...

Integrated landscape initiatives typically aim to strengthen landscape governance by developing and facilitating multi-stakeholder platforms. These are institutional coordination mechanisms that enable discussions, negotiations, and joint planning between stak4eholders from various sectors in a given landscape. Multi-stakeholder platforms tend to i...

Aim: Large tropical trees form the interface between ground and airborne observations, offering a unique opportunity to capture forest properties remotely and to investigate their variations on broad scales. However, despite rapid development of metrics to characterize the forest canopy from remotely sensed data, a gap remains between aerial and fi...

If the world stays on its current development path, the state of biodiversity will continue to decline. This is due to projected further increases in pressures, most prominently habitat loss and climate change. In order to reduce these pressures, biodiversity conservation and restoration, as well as sustainable resource use, needs to be an integral...

Species distribution models (SDMs) are widely used in ecology and conservation. Presence-only SDMs such as MaxEnt frequently use natural history collections (NHCs) as occurrence data, given their huge numbers and accessibility. NHCs are often spatially biased which may generate inaccuracies in SDMs. Here, we test how the distribution of NHCs and Ma...

Belongs to paper Species Distribution Modelling: Contrasting presence-only models with plot abundance data by Gomes et al.

Comparing the results of modelling the area of occupancy with MaxEnt and with inverse distance weighting (IDW). Analysis results for the predicted area of occupancy as calculated by Maxent and IDW methods. The analyses were conducted for 170 of all 227 hyperdominant species that had MaxEnt’s predicted environmental suitability significantly differ...

Species distribution models (SDMs) are widely used in ecology and conservation. Presence-only SDMs such as MaxEnt frequently use natural history collections (NHCs) as occurrence data, given their huge numbers and accessibility. NHCs are often spatially biased which may generate inaccuracies in SDMs. Here, we test how the distribution of NHCs and Ma...

Species distribution models (SDMs) are widely used in ecology and conservation. Presence-only SDMs such as MaxEnt frequently use natural history collections (NHCs) as occurrence data, given their huge numbers and accessibility. NHCs are often spatially biased which may generate inaccuracies in SDMs. Here, we test how the distribution of NHCs and Ma...

Landscape governance relates to how decision making addresses overlapping claims and conflicting interests in the landscape. It also relates to how the rules encourage synergies among stakeholders and stimulate the sustainable management of the landscape. In order to achieve sustainable landscape development, it is crucial to understand how governa...

Land use decision making in the Upper Suriname River area knows a history of disempowerment and marginalization of the Saamaka communities inhabiting the area. Non-recognition of land rights is at the origin of this problem. This is aggravated by the increasing over-exploitation of timber resources by powerful stakeholders and the unfair distributi...

With many sophisticated methods available for estimating migration, ecologists face the difficult decision of choosing for their specific line of work. Here we test and compare several methods, performing sanity and robustness tests, applying to large-scale data and discussing the results and interpretation. Five methods were selected to compare fo...

Past human influences on Amazonian forest The marks of prehistoric human societies on tropical forests can still be detected today. Levis et al. performed a basin-wide comparison of plant distributions, archaeological sites, and environmental data. Plants domesticated by pre-Columbian peoples are much more likely to be dominant in Amazonian forests...

The extent to which pre-Columbian societies altered Amazonian landscapes is hotly debated. We performed a basin-wide analysis of pre-Columbian impacts on Amazonian forests by overlaying known archaeological sites in Amazonia with the distributions and abundances of 85 woody species domesticated by pre-Columbian peoples. Domesticated species are fiv...

Lineages tend to retain ecological characteristics of their ancestors through time. However, for some traits, selection during evolutionary history may have also played a role in determining trait values. To address the relative importance of these processes requires large-scale quantification of traits and evolutionary relationships among species....

Comparison between published values of phylogenetic signal and values found in the present study

List of plots encompassing the Floristic tree inventories for 577 plots compiled from RAINFOR database, with their respective coordinates in Latitude (Lat.) and Longitude (Long.) , area in hectare, number of individuals with diameter equal or superior to 10 cm, number of species, number of genera and data contributors. Plots with long term data and...

Phylogeny of 497 Amazonian tree and palm genera, with branches coloured according to wood density, potential tree size, maximum tree growth and mortality rates.

Comparison between published values of phylogenetic signal for traits of tropical forest trees measured by Blomberg's K statistic. Bar colour indicates the different studies [1-5]; bars in black are represented by traits calculated in the present study and shades of grey show values for published studies. Bars with negative values represent absence...

Phylogeny of 497 Amazonian tree and palm genera, with branches coloured according to wood density, potential tree size, maximum tree growth and mortality rates.

Description of the methods used to calculate intrinsic trait values to account for the effect of variation in environmental conditions among plots

Comparison between published values of phylogenetic signal for traits of tropical forest trees measured by Blomberg's K statistic. Bar colour indicates the different studies [1-5]; bars in black are represented by traits calculated in the present study and shades of grey show values for published studies. Bars with negative values represent absence...

Model comparison; Loadings for Phylogenetic Principal Componets Analysis (PPCA); Sensitivity analyses

Description of the methods used to calculate intrinsic trait values to account for the effect of variation in environmental conditions among plots

List of plots encompassing the Floristic tree inventories for 577 plots compiled from RAINFOR database, with their respective coordinates in Latitude (Lat.) and Longitude (Long.) , area in hectare, number of individuals with diameter equal or superior to 10 cm, number of species, number of genera and data contributors. Plots with long term data and...

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Estimates of extinction risk for Amazonian plant and animal species are rare, and not often incorporated into land-use policy and conservation planning. Here we overlay spatial distribution models with historical and projected deforestation to show that at least 40% and up to 64% of all Amazonian tree species are likely to qualify as globally threa...

Estimates of extinction risk for Amazonian plant and animal species are rare and not often incorporated into land-use policy and conservation planning. We overlay spatial distribution models with historical and projected deforestation to show that at least 36% and up to 57% of all Amazonian tree species are likely to qualify as globally threatened...

While Amazonian forests are extraordinarily diverse, the abundance of trees is skewed strongly towards relatively few ‘hyperdominant’ species. In addition to their diversity, Amazonian trees are a key component of the global carbon cycle, assimilating and storing more carbon than any other ecosystem on Earth. Here we ask, using a unique data set of...

While Amazonian forests are extraordinarily diverse, the abundance of trees is skewed strongly towards relatively few 'hyperdominant' species. In addition to their diversity, Amazonian trees are a key component of the global carbon cycle, assimilating and storing more carbon than any other ecosystem on Earth. Here we ask, using a unique data set of...

While Amazonian forests are extraordinarily diverse, the abundance of trees is skewed strongly towards relatively few â € hyperdominantâ €™ species. In addition to their diversity, Amazonian trees are a key component of the global carbon cycle, assimilating and storing more carbon than any other ecosystem on Earth. Here we ask, using a unique data...