Nathan Swenson

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Verified

Nathan verified their affiliation via an institutional email.

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• PhD
• Professor at University of Notre Dame

In tropical forests, trees often have damage in the form of visible cavities. However, the impacts of these cavities on tropical tree growth and survival are unknown, despite potential implications for the global carbon cycle. Here, we integrate 10 years of forest dynamics data with a survey of cavity presence on 25,450 rainforest trees (> 5 cm in...

Abiotic environments and biotic neighbourhoods interact to influence plant growth and community assembly. However, the nature of this interaction depends very much on how biotic neighbourhoods are measured, including their relatedness to focal plants. In a tropical seasonal rainforest, we examine the growth of a dominant canopy species in response...

Typical characters of plants, such as the size and shape of leaves, photosynthetic rate, seed production, body mass, body length, and depth of roots influence the growth, fitness, and performance of plants. At the same time, how plants will respond to the changing environment is also governed by such characteristics which ultimately shapes the stru...

Despite the progress in the measurement and accessibility of plant trait information, acquiring sufficiently complete data from enough species to answer broad‐scale questions in plant functional ecology and biogeography remains challenging. A common way to overcome this challenge is by imputation, or ‘gap‐filling' of trait values. This has proven a...

All species must partition resources among the processes that underly growth, survival, and reproduction. The resulting demographic trade‐offs constrain the range of viable life‐history strategies and are hypothesized to promote local coexistence. Tropical forests pose ideal systems to study demographic trade‐offs as they have a high diversity of c...

Leaf dark respiration (Rdark), an important yet rarely quantified component of carbon cycling in forest ecosystems, is often simulated from leaf traits such as the maximum carboxylation capacity (Vcmax), leaf mass per area (LMA), nitrogen (N) and phosphorus (P) concentrations, in terrestrial biosphere models. However, the validity of these relation...

The ecology of forest ecosystems depends on the composition of trees. Capturing fine-grained information on individual trees at broad scales provides a unique perspective on forest ecosystems, forest restoration, and responses to disturbance. Individual tree data at wide extents promises to increase the scale of forest analysis, biogeographic resea...

The structure and dynamics of forest ecosystems are the outcome of differential performance playing out at the individual level. Interactions between the traits of an organism and its environment determine performance. Thus, our ability to understand and, ultimately, model forest dynamics critically relies on knowledge regarding the functional biol...

A long-standing but poorly tested hypothesis in plant ecology and evolution is that biotic interactions play a more important role in producing and maintaining species diversity in the tropics than in the temperate zone. A core prediction of this hypothesis is that tropical plants deploy a higher diversity of phytochemicals within and across commun...

Ecologists have historically sought to identify the mechanisms underlying the maintenance of local species diversity. High-dimensional trait-based relationships, such as alternative phenotypes, have been hypothesized as important for maintaining species diversity such that phenotypically dissimilar individuals compete less for resources but have si...

Transcriptomics provides a versatile tool for ecological monitoring. Here, through genome-guided profiling of transcripts mapping to 33 042 gene models, expression differences can be discerned among multi-year and seasonal leaf samples collected from American beech trees at two latitudinally separated sites. Despite a bottleneck due to post-Columbi...

Tropical tree communities are among the most diverse in the world. A small number of genera often disproportionately contribute to this diversity. How so many species from a single genus can co‐occur represents a major outstanding question in biology. Niche differences are likely to play a major role in promoting congeneric diversity, but the mecha...

The ecology of forest ecosystems depends on the composition of trees. Capturing fine-grained information on individual trees at broad scales allows an unprecedented view of forest ecosystems, forest restoration and responses to disturbance. To create detailed maps of tree species, airborne remote sensing can cover areas containing millions of trees...

Understanding the mechanisms that promote the coexistence of hundreds of species over small areas in tropical forest remains a challenge. Many tropical tree species are presumed to be functionally equivalent shade tolerant species but exist on a continuum of performance trade‐offs between survival in shade and the ability to quickly grow in sunligh...

Forest trees provide critical ecosystem services for humanity that are under threat due to ongoing global change. Measuring and characterizing genetic diversity is key to understanding adaptive potential and developing strategies to mitigate negative consequences arising from climate change. In the area of forest genetic diversity, genetic divergen...

Metabolomics provides an unprecedented window into diverse plant secondary metabolites that represent a potentially critical niche dimension in tropical forests underlying species oexistence. Here, we used untargeted metabolomics to evaluate chemical composition of 358 tree species and its relationship with hylogeny and variation in light environme...

Functional trait variation measured on continuous scales has helped ecologists to unravel important ecological processes. However, forest ecologists have recently moved back toward using functional groups. There are pragmatic and biological rationales for focusing on functional groups. Both of these approaches have inherent limitations including bi...

Identifying the drivers of community structure and dynamics is a major pursuit in ecology. Emphasis is typically placed on the importance of local scale interactions when attempting to explain these fundamental ecological patterns. However, regional scale phenomena are also important predictors. The importance of regional scale context should be mo...

Metabolomics provides an unprecedented window on diverse plant secondary metabolites that represent a potentially critical niche dimension in tropical forests underlying co-existence. Here, we used untargeted metabolomics to evaluate the chemical composition of 358 tree species and its relationship to phylogeny and variation in light environment, s...

Forest trees provide critical ecosystem services for humanity that are under threat due to ongoing global change. Measuring and characterizing genetic diversity is key to understanding adaptive potential and developing strategies to mitigate negative consequences arising from climate change. In the area of forest genetic diversity, genetic divergen...

Forest tree communities are largely structured by interactions between phenotypes and their environments. Functional traits have been popularized as providing key insights into plant functional tradeoffs. Similarly, tree crown—stem diameter and tree height—stem diameter allometric relationships are likely to be strongly coordinated with functional...

Background and aims Understanding shifts in demographic and functional composition of forests after major natural disturbances has become increasingly relevant given the accelerating rates of climate change and elevated frequency of natural disturbances. Although plant demographic strategies are often described across a slow-fast continuum, severe...

Researchers have a history of seeking explanation for and understanding of diversity patterns. High-dimensional trait-based trade-offs have been hypothesized as important for maintaining species and functional diversity. These relationships have primarily been investigated at the community-level, despite the importance of intraspecific variation to...

Understanding the mechanisms that promote the coexistence of hundreds of species over small areas in tropical forest remains a challenge. Many tropical tree species are presumed to be functionally equivalent shade tolerant species that differ in performance trade-offs between survival in shade and the ability to quickly grow in sunlight. Variation...

Transcriptomics, the quantification of gene expression, provides a versatile tool for ecological monitoring. Here, we show that through genome-guided profiling of transcripts mapping to 33,042 loci, gene expression differences can be discerned among multi-year and seasonal leaf samples collected from American beech trees at two latitudinally separa...

Here we provide the ‘Global Spectrum of Plant Form and Function Dataset’, containing species mean values for six vascular plant traits. Together, these traits –plant height, stem specific density, leaf area, leaf mass per area, leaf nitrogen content per dry mass, and diaspore (seed or spore) mass – define the primary axes of variation in plant form...

An important mechanism promoting species coexistence is conspecific negative density dependence (CNDD), which inhibits conspecific neighbors by accumulating host-specific enemies near adult trees. Natural enemies may be genotype-specific and regulate offspring dynamics more strongly than non-offspring, which is often neglected due to the difficulty...

Plant communities in mountainous areas shift gradually as climatic conditions change with altitude. How trait structure in multivariate space adapts to these varying climates in natural forest stands is unclear. Studying the multivariate functional trait structure and redundancy of tree communities along altitude gradients is crucial to understandi...

Lianas, climbing woody plants, influence the structure and function of tropical forests. Climbing traits have evolved multiple times, including ancestral groups such as gymnosperms and pteridophytes, but the genetic basis of the liana strategy is largely unknown. Here, we use a comparative transcriptomic approach for 47 tropical plant species, incl...

The study of community spatial structure is central to understanding diversity patterns over space and species co‐occurrence at local scales. Although most analytical approaches consider horizontal and vertical dimensions separately, in this study we introduce a three‐dimensional spatial analysis that simultaneously includes horizontal and vertical...

Maples (the genus Acer) represent important and beloved forest, urban, and ornamental trees distributed throughout the Northern hemisphere. They exist in a diverse array of native ranges and distributions, across spectrums of tolerance or decline, and have varying levels of susceptibility to biotic and abiotic stress. Among Acer species, several st...

Tropical dry forests (TDFs) have experienced pronounced droughts and increased temperatures for the last century. To assess whether these climatic shifts have influenced dry forest vegetation and ecosystem functioning, we integrated ground observations from a Costa Rican long‐term forest dynamics monitoring plot with remotely sensed measures of for...

Unravelling the drivers of forests dynamics is one of the main challenges in tree community ecology. These drivers include niche differentiation, dispersal limitation and stochasticity. Previous work has demonstrated that these mechanisms likely interact such that no one process is responsible for forest dynamics. One possibility is that the functi...

Predicting species abundance is one of the most fundamental pursuits of ecology. Combining the information encoded in functional traits and metacommunities provides a new perspective to predict the abundance of species in communities. We applied a community assembly via trait selection model to predict quadrat-scale species abundances using functio...

Despite important progress in understanding the impacts of forest clearing and logging on above‐ground communities, how these disturbances affect soil microbial β‐diversity and the ecological processes driving microbial assemblages are poorly understood. Furthermore, whether and how the microbial shifts affect vegetation composition and diversity d...

Large scale disturbances are known to impact the alpha and beta diversity of communities. However, whether these disturbances increase or decrease diversity is often debated. The goal of this study was to quantify how the diversity of the seedling community was impacted within and across elevation in the El Yunque forest of Puerto Rico following a...

Lianas, climbing woody plants, influence the structure and function of tropical forests. Climbing traits have evolved multiple times, including ancestral groups such as gymnosperms and pteridophytes, but the genetic basis of the liana strategy is largely unknown. Here, we use a comparative transcriptomic approach for 47 tropical plant species, incl...

Trait‐based approaches have been extensively used in community ecology to provide a mechanistic understanding of the drivers of community assembly. However, a foundational assumption of the trait framework, traits relate to performance, has been mainly examined through univariate relationships that simplify the complex phenotypic integration of org...

Aim Here we examine the functional profile of regional tree species pools across the latitudinal distribution of Neotropical moist forests, and test trait–climate relationships among local communities. We expected opportunistic strategies (acquisitive traits, small seeds) to be overrepresented in species pools further from the equator, but also in...

Quantifying the functional trait space of natural assemblages could help ecologists understand the underlying mechanisms that sustain species richness. In this study, we investigated the functional trait space patterns of six forest passerine bird assemblages, with species richness increasing to lower latitudes. Further, we examined the underlying...

At local scales, it has been suggested that high levels of resources lead to increased tree growth via trait optimization (highly peaked trait distribution). However, this contrasts with (1) theories that suggest that trait optimization and high growth occur in the most common resource level and (2) empirical evidence showing that high trait optimi...

Predicting drought responses of individual trees in tropical forests remains challenging, in part because trees experience drought differently depending on their position in spatially heterogeneous environments. Specifically, topography and the competitive environment can influence the severity of water stress experienced by individual trees, leadi...

ForestGEO is a network of scientists and long-term forest dynamics plots (FDPs) spanning the Earth's major forest types. ForestGEO's mission is to advance understanding of the diversity and dynamics of forests and to strengthen global capacity for forest science research. ForestGEO is unique among forest plot networks in its large-scale plot dimens...

Individual‐level demographic outcomes should be predictable upon the basis of traits. However, linking traits to tree performance has proven challenging likely due to a failure to consider physiological traits (i.e. hard‐traits) and the failure to integrate organ‐level and whole plant‐level trait information. Here, we modelled the survival rate and...

Plants allocate biomass to different organs in response to resource variation for maximizing performance, yet we lack a framework that adequately integrates plant responses to the simultaneous variation in above‐ and below‐ground resources. Although traditionally, the optimal partition theory (OPT) has explained patterns of biomass allocation in re...

One of the important goals in plant ecology is to form a mechanistic link between the underlying processes driving the dynamics and structure of communities and the observed demography (i.e., growth, survival, and recruitment) and assembly (i.e., distribution of species) in a community via traits. Although the importance of traits to performance is...

Understanding tree species responses to biotic and abiotic factors is fundamental for stronger predictions of community assembly and dynamics. However, several challenges remain. These include a failure to investigate whether there is evidence for key hypothesized life‐history trade‐offs and to link these trade‐offs to functional traits. In this st...

Functional traits are expected to provide insights into the abiotic and biotic drivers of plant demography. However, successfully linking traits to plant demographic performance likely requires the consideration of important contextual and individual‐level information that is often ignored in trait‐based ecology. Here, we modelled 8 years of growth...

Despite several decades of study in community ecology, the relative importance of the ecological processes that determine species co‐occurrence across spatial scales remains uncertain. Some of this uncertainty may be reduced by studying the scale dependency of community assembly in the light of environmental variation. Phylogenetic information and...

Many studies have tried to assess the role of both deterministic and stochastic processes in community assembly, yet a lack of consensus exists on which processes are more prevalent and at which spatial scales they operate. To shed light on this issue, we tested two nonmutually exclusive, scale‐dependent hypotheses: (1) that competitive exclusion d...

Background and aims: The composition and dynamics of plant communities arises from individual-level demographic outcomes, which are driven by interactions between phenotypes and the environment. Functional traits that can be measured across plants are frequently used to model plant growth and survival. Perhaps surprisingly, species average trait v...

Over the past three decades, there has been a concerted effort to study the long‐term dynamics of tropical forests throughout the world. Data regarding temporal trends in species diversity, species composition, and species‐specific demographic rates have now been amassed. Such data can be utilized to test predictions regarding the roles the environ...

Questions We asked: (a) whether the strength of conspecific and heterospecific neighborhood crowding effects on focal tree survival and growth vary with neighborhood radii; and (b) if the relative strength of the effect of neighborhood interactions on tree growth and survival varies with neighborhood scale. Location Luquillo Forest Dynamics Plot,...

The functional trait values that constitute a whole‐plant phenotype interact with the environment to determine demographic rates. Current approaches often fail to explicitly consider trait × trait and trait × environment interactions, which may lead to missed information that is valuable for understanding and predicting the drivers of demographic r...

The geographic distribution of plant form and function has been studied for over a century for purposes ranging from vegetation classification to global vegetation modeling. Despite this attention we have surprisingly few studies that have actually mapped the distribution and diversity of quantitative plant traits on continental scales and quantifi...

Forest community composition is the outcome of multiple forces, including those that increase taxonomic and functional divergence and those that promote convergence in traits. The mechanisms underlying these forces may not operate homogenously within communities; individuals of different species are never perfectly mixed, and thus, species tend to...

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research sp...

Disentangling the processes that drive population, community and whole forest structure and dynamics is a challenge. It becomes a grand challenge in the tropics where there are a large number of species, small population sizes, less research infrastructure, and a relatively smaller number of researchers compared to the temperate zone. Tackling this...

The fields of ecology, evolution and biogeography were neatly intertwined over a century ago. However, they became more compartmentalized approximately mid-way through the twentieth century. In the last few decades, there has been a renewed interest in the integration of evolutionary history into ecology and vice versa. Running throughout this lite...

Ecologists have traditionally made their first analytical encounter with phylogenies as something that must be considered when conducting comparative analyses. Over the past decade this has become less and less true where phylogenetic information is utilized for measuring biodiversity and inferring ecological mechanisms. However, before delving int...

This chapter aims to provide some historical background beginning with the development of phylogenetic diversity metrics in the 1990s and how the concepts and metrics from this literature have impacted community ecology and macroecology and vice versa. In acknowledging up front that the phylogenetic diversity literature is large at this point, I ha...

The perspective I have attempted to outline in this book is that phylogenies are not a magical cure for all that ails ecology nor are they part of some passing fad. Rather, they are useful in many instances and less than useful other instances. Furthermore, I have argued that phylogenies are, at present, often utilized in ecology in ways that do no...

Here, I first discuss the recent advances that have made phylogenetic information available to ecologists across scales. Ideally, phylogenetic ecology would leverage a highly resolved tree of life. Though, despite the optimism of some, I fear such a tree is not likely to materialize in the near future as present sequence repositories are very spars...

Here, I begin with a discussion of the hypothesized role of phylogenetic niche conservatism and the latitudinal gradient as well as the cradles versus museums dichotomy regarding the origins of tropical diversity. Lastly, I will discuss priority effects, ecological opportunity and how phylogenetic information may be used in these contexts to unders...

Functional phylogenomics can be defined as the use of functional genomic (i.e. transcriptomic) information for phylogenetic inference. As I will describe below, in many cases, the inference of a species tree is the primary goal of a functional phylogenomic investigation. However, the approach has a great range of possibilities that are potentially...

This chapter is designed to push community ecologists to re-consider how they are using phylogenetic information in their research. The research path that I present as a much more interesting, valuable and viable phylogenetic approach to community ecology is not novel. It has been running in parallel with occasional cross-pollination with the phylo...

The investigation of the implications of historical, biogeographic or evolutionary events and processes for community structure combined with the investigation of the processes dictating species coexistence constitutes the study of community assembly. Thus, the study of community assembly is informed by, but not limited to, an understanding of the...

Transpiration in humid tropical forests modulates the global water cycle and is a key driver of climate regulation. Yet, our understanding of how tropical trees regulate sap flux in response to climate variability remain elusive. With a progressively warming climate, atmospheric evaporative demand (i.e., vapor pressure deficit, VPD) will be increas...

Fungal influence on density dependence Tree species in highly diverse tropical forests tend to exhibit conspecific negative density dependence, a phenomenon whereby individuals of the same species tend to grow at a distance from one another. This is understood to be a key driver of species coexistence. The strength of negative density dependence va...

The relationship between plant functional traits and demographic performance forms the foundation of trait-based ecology. It also serves as the natural linkage between trait-based ecology and much of evolutionary biology. Despite these important aspects, plant trait–demographic performance relationships reported in the literature are typically weak...

A conspicuous feature of natural communities is that individuals within species exhibit broad variation in their phenotype. While the phenotypic differences among species are prominent and have received considerable attention in earlier studies, recent findings suggest that about 40% of the trait variation is found within species. How this intraspe...

Acer (the maple genus) is one of the diverse tree genera in the Northern Hemisphere with about152 species, most of which are in eastern Asia. There are roughly a dozen of species in Europe/western Asia and a dozen in North America. Several phylogenetic studies of Acer have been conducted since 1998, but none have provided a satisfactory resolution...

Although populations are phenotypically diverse, the majority of trait‐based studies have focused on examining differences among species. The justification for this broadly applied approach is based on the assumption that differences among species are always greater than within species. This is likely true for local communities, but species are oft...

Species composition and community structure in Neotropical forests have been severely affected by increases in climate change and disturbance. Among the most conspicuous changes is the proliferation of lianas. These increases have affected not only the carbon storage capacity of forests but also tree dynamics by reducing tree growth and increasing...

Much ecological research aims to explain how climate impacts biodiversity and ecosystem-level processes through functional traits that link environment with individual performance. However, the specific climatic drivers of functional diversity across space and time remain unclear due largely to limitations in the availability of paired trait and cl...

Investigations of forest community structure and dynamics have been facilitated by the use of neighbourhood models that examine the interactions between a focal tree and its neighbours using a fixed radius. However, different studies have chosen different radii without clear reasons, hampering the understanding of mechanisms structuring tree commun...

Disturbance plays a key role in shaping forest composition and diversity. We used a community phylogeny and long-term forest dynamics data to investigate biotic and abiotic factors shaping tropical forest regeneration following both human and natural disturbance. Specifically, we examined shifts in seedling phylogenetic and functional (i.e., seed m...

Survival rates of large trees determine forest biomass dynamics. Survival rates of small trees have been linked to mechanisms that maintain biodiversity across tropical forests. How species survival rates change with size offers insight into the links between biodiversity and ecosystem function across tropical forests. We tested patterns of size-de...

Over the past two decades, biodiversity assessments have moved beyond simply measuring species diversity and toward the utilization of phylogenetic information. Despite these major advances toward holistically estimating the similarity of species, challenges remain. Specifically, the large phylogenies utilized for such analyses often contain multip...

As cyclonic wind storms (hurricanes and typhoons) increase in frequency and intensity with climate change, it is important to understand their effects on the populations and communities of tropical trees they impact. Using tree demographic data from four large, tropical forest dynamics plots that differ in cyclonic storm frequency, we compare tree...

The nutrient demands of regrowing tropical forests are partly satisfied by nitrogen-fixing legume trees, but our understanding of the abundance of those species is biased towards wet tropical regions. Here we show how the abundance of Leguminosae is affected by both recovery from disturbance and large-scale rainfall gradients through a synthesis of...