William Stanley Harpole

William Stanley Harpole
Helmholtz-Zentrum für Umweltforschung | UFZ · Department of Physiological Diversity

PhD University of Minnesota

About

159
Publications
83,635
Reads
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18,430
Citations
Additional affiliations
December 2014 - present
Martin Luther University Halle-Wittenberg
Position
  • Professor
August 2014 - June 2015
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig
Position
  • Professor (Full)
August 2014 - present
Helmholtz-Zentrum für Umweltforschung
Position
  • Head of Department

Publications

Publications (159)
Article
Full-text available
Environmental monitoring involves the quantification of microscopic cells and particles such as algae, plant cells, pollen, or fungal spores. Traditional methods using conventional microscopy require expert knowledge, are time‐intensive and not well‐suited for automated high throughput. Multispectral imaging flow cytometry (MIFC) allows measurement...
Preprint
1. Human impacts have led to dramatic biodiversity change which can be highly scale-dependent across space and time. A primary means to manage these changes is via passive or active ecological restoration. The recovery of biodiversity following the removal of disturbance (passive) is often incomplete. The magnitude of recovery can very much depend...
Article
Full-text available
Abstract The Decade on Ecosystem Restoration aims to provide the means and incentives for upscaling restoration efforts worldwide. Although ecosystem restoration is a broad, interdisciplinary concept, effective ecological restoration requires sound ecological knowledge to successfully restore biodiversity and ecosystem services in degraded landscap...
Article
1. To evaluate how increased anthropogenic nutrient inputs alter carbon cycling in grasslands, we conducted a litter decomposition study across 20 temperate grasslands on three continents within the Nutrient Network, a globally distributed nutrient enrichment experiment 2. We determined the effects of experimental nitrogen (N), phosphorus (P), and...
Article
Full-text available
Cheating in microbial communities is often regarded as a precursor to a “tragedy of the commons,” ultimately leading to over-exploitation by a few species and destabilization of the community. While current evidence suggests that cheaters are evolutionarily and ecologically abundant, they can also play important roles in communities, such as promot...
Preprint
Full-text available
Global change drivers such as anthropogenic nutrient inputs simultaneously alter biodiversity, species composition, and ecosystem functions such as above ground biomass. These changes are interconnected by complex feedbacks among extinction, invasion, and shifting relative abundance. Here, we use a novel temporal application of the Price equation t...
Article
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The effects of altered nutrient supplies and herbivore density on species diversity vary with spatial scale, because coexistence mechanisms are scale dependent. This scale dependence may alter the shape of the species–area relationship (SAR), which can be described by changes in species richness (S) as a power function of the sample area (A): S = c...
Article
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Ecological stability refers to a family of concepts used to describe how systems of interacting species vary through time and respond to disturbances. Because observed ecological stability depends on sampling scales and environmental context, it is notoriously difficult to compare measurements across sites and systems. Here, we apply stochastic dyn...
Article
Spatial rarity is often used to predict extinction risk, but rarity can also occur temporally. Perhaps more relevant in the context of global change is whether a species is core to a community (persistent) or transient (intermittently present), with transient species often susceptible to human activities that reduce niche space. Using 5‐12 years of...
Article
Full-text available
Mitigating and adapting to climate change requires an understanding of the magnitude and nature by which climate change will influence the diversity of plants across the world’s ecosystems. Experiments can causally link precipitation change to plant diversity change, however, these experiments vary in their methods and in the diversity metrics repo...
Article
Full-text available
The niche dimensionality required for coexistence is often discussed in terms of the number of limiting resources. N and P limitation are benchmarks for studying phytoplankton interactions. However, it is generally agreed that limitation by small numbers of resources cannot explain the high phytoplankton diversity observed in nature. Here, we param...
Article
Full-text available
The cover image is based on the Letter Beyond nitrogen: phosphorus – estimating the minimum niche dimensionality for resource competition between phytoplankton by Peter Hofmann et al., https://doi.org/10.1111/ele.13695. Image Credit: Petra Hoffmann.
Article
Anthropogenic nitrogen (N) inputs are causing large changes in ecosystems worldwide. Many previous studies have examined the impact of N on terrestrial ecosystems; however, most have added N at rates that are much higher than predicted future deposition rates. Here, we present the results from a gradient of experimental N addition (0‐10 g N m‐2) in...
Preprint
Cheating in microbial communities is often regarded as a precursor to a “tragedy of the commons”, ultimately leading to over-exploitation by a few species, and destabilisation of the community. However, this view does not explain the ubiquity of cheaters in nature. Indeed, existing evidence suggests that cheaters are not only evolutionarily and eco...
Article
Quantifying the relative contributions of microbial species to ecosystem functioning is challenging, because of the distinct mechanisms associated with microbial phylogenetic and metabolic diversity. We constructed bacterial communities with different diversity traits and employed exoenzyme activities (EEAs) and carbon acquisition potential (CAP) f...
Article
Full-text available
A Correction to this paper has been published: https://doi.org/10.1038/s41467-021-20985-z.
Article
Full-text available
Human activities are transforming grassland biomass via changing climate, elemental nutrients, and herbivory. Theory predicts that food-limited herbivores will consume any additional biomass stimulated by nutrient inputs (‘consumer-controlled’). Alternatively, nutrient supply is predicted to increase biomass where herbivores alter community composi...
Poster
Full-text available
Cheating in microbial communities is often regarded as a precursor to a “tragedy of the commons” ultimately leading to over-exploitation by a few to the detriment of the community and destabilization of the system. However, existing evidence suggests that cheaters are not only evolutionarily and ecologically inevitable, but that they also play impo...
Article
Full-text available
To understand ecosystem responses to anthropogenic global change, a prevailing framework is the definition of threshold levels of pressure, above which response magnitudes and their variances increase disproportionately. However, we lack systematic quantitative evidence as to whether empirical data allow definition of such thresholds. Here, we summ...
Article
Human activities are enriching many of Earth’s ecosystems with biologically limiting mineral nutrients such as nitrogen (N) and phosphorus (P). In grasslands, this enrichment generally reduces plant diversity and increases productivity. The widely demonstrated positive effect of diversity on productivity suggests a potential negative feedback, wher...
Article
Full-text available
Seed dispersal limitation, which can be exacerbated by a number of anthropogenic causes, can result in local communities having fewer species than they might potentially support, representing a potential diversity deficit. The link between processes that shape natural variation in diversity, such as dispersal limitation, and the consequent effects...
Article
Full-text available
Many global changes take the form of resource enhancements that have potential to transform multiple aspects of ecosystems from slower to faster cycling, including a suite of both above‐ and belowground variables. We developed a novel analytic approach to measure integrated ecosystem responses to resource‐enhancing global changes, and how such whol...
Preprint
Quantifying the relative contributions of microbial species to ecosystem functioning is challenging, because of the distinct mechanisms associated with microbial phylogenetic and metabolic diversity. We constructed bacterial communities with different diversity traits and employed exoenzyme activities (EEAs) and total available carbon (TAC) from su...
Article
Full-text available
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Article
Aim Climate variability threatens to destabilize production in many ecosystems. Asynchronous species dynamics may buffer against such variability when a decrease in performance by some species is offset by an increase in performance of others. However, high climatic variability can eliminate species through stochastic extinctions or cause similar s...
Preprint
Full-text available
The ecological models of Alfred J. Lotka and Vito Volterra have had an enormous impact on ecology over the past century. Some of the earliest - and clearest - experimental tests of these models were famously conducted by Georgy Gause in the 1930's. Although well known, the data from these experiments are not widely available, and are often difficul...
Article
Full-text available
Nutrient enrichment is associated with plant invasions and biodiversity loss. Functional trait advantages may predict the ascendancy of invasive plants following nutrient enrichment but this is rarely tested. Here, we investigate (a) whether dominant native and non‐native plants differ in important morphological and physiological leaf traits, (b) h...
Article
What will plant communities of the future look like in the face of climate change? Answering this question is critical if we are to understand novel ecosystems, and their potential services. De Boeck and colleagues (2019) suggest that our conclusions (Korell et al. 2019) were too “gloomy” when we indicated that the majority of climate manipulations...
Article
Experiments that alter local climate and measure community‐ and ecosystem‐level responses are an important tool for understanding how future ecosystems will respond to climate change. Here, we synthesized data from 76 studies that manipulated climate and measured plant community responses, and find that most climate change experiments do not corres...
Article
Full-text available
Ensuring ecosystem resilience is an intuitive approach to safeguard the functioning of ecosystems and hence the future provisioning of ecosystem services (ES). However, resilience is a multi‐faceted concept that is difficult to operationalize. Focusing on resilience mechanisms, such as diversity, network architectures or adaptive capacity, has rece...
Article
Full-text available
Aims The abundance of a plant species in a diverse community may depend on two aspects of a plant’s resource niche: its ability to garner limiting resources for its own growth, and its ability to reduce resources available for other species. Given that these two aspects of niche can be quantified in monoculture, we tested whether plant growth or pl...
Article
Full-text available
Anthropogenic activities are increasing nutrient inputs to ecosystems worldwide, with consequences for global carbon and nutrient cycles. Recent meta-analyses show that aboveground primary production is often co-limited by multiple nutrients; however, little is known about how root production responds to changes in nutrient availability. At twenty-...
Article
Full-text available
Soil nitrogen mineralisation (Nmin), the conversion of organic into inorganic N, is important for productivity and nutrient cycling. The balance between mineralisation and immobilisation (net Nmin) varies with soil properties and climate. However, because most global-scale assessments of net Nmin are laboratory-based, its regulation under field-con...
Article
Full-text available
Models of natural processes necessarily sacrifice some realism for the sake of tractability. Detailed, parameter‐rich models often provide accurate estimates of system behaviour but can be data‐hungry and difficult to operationalise. Moreover, complexity increases the danger of “over‐fitting”, which leads to poor performance when models are applied...
Article
Full-text available
Stochasticity is a core component of ecology, as it underlies key processes that structure and create variability in nature. Despite its fundamental importance in ecological systems, the concept is often treated as synonymous with unpredictability in community ecology, and studies tend to focus on single forms of stochasticity rather than taking a...
Article
Understanding the links between intraspecific trait variability and environmental gradients is an important step towards unravelling the mechanisms that link species performance to environmental variation. Here, we performed a comparative, experimental study to investigate variability of cellular traits in three prokaryotic and three eukaryotic fre...
Article
Identifying stable coexistence in empirical systems is notoriously difficult. Here, we show how spatiotemporal structure and complex system dynamics can confound two commonly used stability metrics in empirical contexts: response to perturbation and invasion rate when rare. We use these metrics to characterize stable coexistence across a range of s...
Article
Full-text available
Declines in global biodiversity have inspired a generation of studies that seek to characterize relationships between biodiversity and ecosystem functioning. The metrics for complementarity and selection effects derived by Loreau and Hector in 2001 remain some of the most influential and widely used statistics for studying these relationships. Thes...
Article
Full-text available
Leaf traits are frequently measured in ecology to provide a ‘common currency’ for predicting how anthropogenic pressures impact ecosystem function. Here, we test whether leaf traits consistently respond to experimental treatments across 27 globally distributed grassland sites across 4 continents. We find that specific leaf area (leaf area per unit...
Preprint
Full-text available
Ensuring ecosystem resilience is an intuitive approach to safeguard future provisioning of ecosystem services (ES). However, resilience is an ambiguous concept and difficult to operationalize. Focusing on resilience mechanisms, such as diversity, network architectures or adaptive capacity, has recently been suggested as means to operationalize resi...
Article
Full-text available
One of the unifying goals of ecology is understanding the mechanisms that drive ecological patterns. For any particular observed pattern, ecologists have proposed varied mechanistic models. However, in spite of their differences, all of these mechanistic models rely on either abiotic conditions or biotic conditions, our “ecological first principles...
Poster
Full-text available
Biodiversity can have a positive impact on ecosystem functions because greater numbers of species, and their associated genetic and functional differences, can contribute at different times and contexts to overall ecosystem functioning. The relative contributions in microbial communities due to phylogenetic versus functional diversity is challengin...
Chapter
One of the unifying goals of ecology is understanding the mechanisms that drive ecological patterns. For any particular observed pattern, ecologists have proposed varied mechanistic models. However, in spite of their differences, all of these mechanistic models rely on either abiotic conditions or biotic conditions, our “ecological first principles...
Poster
Full-text available
First findings on how intraspecific size variability of phytoplankton along gradients of temperature and nitrogen : phosphorous ratio may affect the overall predicitability when using fixed trait models.
Poster
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Fateful meetings of unicellular green algae with cyanobacteria and their consequences – Surveillance of biotic interactions with (image) flow cytometry Massive growth of single species of cyanobacteria is a common phenomenon in many eutrophicated waters worldwide. Allelopathic growth control of phytoplankton species is one suggested mechanism, but...
Article
Full-text available
Environmental change can result in substantial shifts in community composition. The associated immigration and extinction events are likely constrained by the spatial distribution of species. Still, studies on environmental change typically quantify biotic responses at single spatial (time series within a single plot) or temporal (spatial beta dive...
Conference Paper
Full-text available
Grassland ecology experiments in remote locations requiring quantitative analysis of the biomass in defined plots are becoming increasingly widespread, but are still limited by manual sampling methodologies. To provide a cost-effective automated solution for biomass determination, several photogrammetric techniques are examined to generate 3D point...
Article
Full-text available
Background and aims Arbuscular mycorrhizal fungi (AMF) are important for plant nutrient and water acquisition. Much is known about how nutrient addition and environment affect AMF, but little is known about nutrient by environment interactions. We measured AMF colonization with nutrient additions and along an environmental gradient to assess these...
Article
Full-text available
Plant stoichiometry, the relative concentration of elements, is a key regulator of ecosystem functioning and is also being altered by human activities. In this paper we sought to understand the global drivers of plant stoichiometry and compare the relative contribution of climatic vs. anthro-pogenic effects. We addressed this goal by measuring plan...
Article
Full-text available
Biodiversity is declining in many local communities while also becoming increasingly homogenized across space. Experiments show that local plant species loss reduces ecosystem functioning and services, but the role of spatial homogenization of community composition and the potential interaction between diversity at different scales in maintaining e...
Article
Full-text available
The research of a generation of ecologists was catalysed by the recognition that the number and identity of species in communities influences the functioning of ecosystems. The relationship between biodiversity and ecosystem functioning (BEF) is most often examined by controlling species richness and randomising community composition. In natural sy...
Poster
Full-text available
Resilience in ecological communities can be expressed as a combination of different responses to a perturbation: Persistence (presence or absence of species), resistance (ability to withstand change) and recovery (return to reference/equilibrium conditions). Resilience components can be investigated with respect to species richness and composition,...
Poster
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We explored how the the functioning of bacterial communities, grouped based on the phylogenetic and functional similarity of their constituent bacteria, shifts throughout time, as well as in comparison to the functions of the bacteria in isolate cultures, due to species interactions.
Poster
Full-text available
The microcosm approach allows to monitor phytoplankton growth along environmental gradients. Growth performance of assembled communities will be analyzed based on community-, population-, species- and single cell-level to investigate morphological and physiological adaptations at different temporal scales. High throughput flow cytometry allows a de...
Article
Full-text available
The paradigmatic hypothesis for the effect of fertilisation on plant diversity represents a one-dimensional trade-off for plants competing for below-ground nutrients (generically) and above-ground light: fertilisation reduces competition for nutrients while increasing biomass and thereby shifts competition for depleted available light. The essentia...
Article
Full-text available
Global concern about human impact on biological diversity has triggered an intense research agenda on drivers and consequences of biodiversity change in parallel with international policy seeking to conserve biodiversity and associated ecosystem functions. Quantifying the trends in biodiversity is far from trivial, however, as recently documented b...
Article
Reductions in community evenness can lead to local extinctions as dominant species exclude subordinate species; however, herbivores can prevent competitive exclusion by consuming otherwise dominant plant species, thus increasing evenness. While these predictions logically result from chronic, gradual reductions in evenness, rapid, temporary pulses...
Article
Full-text available
Earth's biodiversity and carbon uptake by plants, or primary productivity, are intricately interlinked, underlie many essential ecosystem processes, and depend on the interplay among environmental factors, many of which are being changed by human activities. While ecological theory generalizes across taxa and environments, most empirical tests of f...
Article
Species diversity is commonly hypothesized to result from trade-offs for different limiting resources, providing separate niches for coexisting species. As soil nutrients occur in multiple chemical forms, plant differences in acquisition of the same element derived from different compounds may represent unique niche dimensions. Because plant produc...