David U Hooper

David U Hooper
Western Washington University | WWU · Department of Biology

Ph.D., Stanford University

About

68
Publications
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31,428
Citations

Publications

Publications (68)
Article
Full-text available
Selective grazing of livestock creates lightly and heavily grazed vegetation patches, which together contribute to the whole community in grazed grasslands. The intermediate disturbance hypothesis (IDH) predicts moderate grazing intensity can increase species diversity. However, grazing patchiness complicates predicted responses to grazing intensit...
Article
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Watershed nitrogen (N) budgets provide insights into drivers and solutions for groundwater and surface water N contamination. We constructed a comprehensive N budget for the transboundary Nooksack River Watershed (British Columbia, Canada, and Washington, USA) using locally derived data, national statistics, and standard parameters. Feed imports fo...
Article
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The role of plant diversity in reducing invasions has generated decades of debate. Diverse communities might be more resistant to invasion because the communities contain resident species that are functionally similar to the invader (limiting similarity), or multiple species use the range of available resources more effectively (complementarity) th...
Article
Plant diversity can increase biomass production in plot-scale studies, but applying these results to ecosystem carbon (C) storage at larger spatial and temporal scales remains problematic. Other ecosystem controls interact with diversity and plant production, and may influence soil pools differently from plant pools. We integrated diversity with th...
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Degradation of semiarid ecosystems from overgrazing threatens a variety of ecosystem services. Rainfall and nitrogen commonly co-limit production in semiarid grassland ecosystems; however, few studies have reported how interactive effects of precipitation and nitrogen addition influence the recovery of grasslands degraded by overgrazing. We conduct...
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Carbon storage by ecosystems is valuable for climate protection. Biodiversity conservation may help increase carbon storage, but the value of this influence has been difficult to assess. We use plant, soil, and ecosystem carbon storage data from two grassland biodiversity experiments to show that greater species richness increases economic value: I...
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Species diversity affects the functioning of ecosystems, including the efficiency by which communities capture limited resources, produce biomass, recycle and retain biologically essential nutrients. These ecological functions ultimately support the ecosystem services upon which humanity depends. Despite hundreds of experimental tests of the effect...
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Global species extinction rates are orders of magnitude above the background rate documented in the fossil record. However, recent data syntheses have found mixed evidence for patterns of net species loss at local spatial scales. For example, two recent data meta-analyses have found that species richness is decreasing in some locations and is incre...
Article
Context Many studies have examined how intensity of grazing and patterns of precipitation individually and interactively influence the spatial and temporal dynamics of grassland vegetation, such as dominance, succession, coexistence, and spatial heterogeneity. However existing models have rarely considered the diet preferences of grazers and how th...
Conference Paper
Background/Question/Methods Two decades of experimental research have shown that biodiversity can significantly alter ecosystem functioning, and that this trend is robust across organisms, habitats, and scenarios of global change. Many of these experiments have measured multiple ecosystem processes, but analyses have considered these processes in...
Conference Paper
Background/Question/Methods Tests of the effects of plant diversity on ecosystem processes have typically used synthetic communities, and only rarely have manipulated other state factors that also control ecosystem processes. Although ecosystem ecology has a long history of testing effects of plant traits on ecosystem processes, there is much rec...
Conference Paper
Background/Question/Methods While notable successes have helped turn the tide on environmental degradation, in many cases, problems persist despite regulations and restoration efforts. There is broad recognition that incentive-based frameworks, based on the concept of payments for ecosystem services, may help achieve goals for environmental prote...
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Stream conservation and restoration strategies commonly focus on preserving extant riparian forest and restoring riparian habitat. Though these practices are beneficial to stream habitat, they may not suffice to restore stream condition in catchments heavily influenced by intensive land use.To evaluate this hypothesis, we measured invertebrate popu...
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Extensive research shows that more species-rich assemblages are generally more productive and efficient in resource use than comparable assemblages with fewer species. But the question of how diversity simultaneously affects the wide variety of ecological functions that ecosystems perform remains relatively understudied, and it presents several ana...
Conference Paper
Background/Question/Methods Global environmental change helped drive the field of ecosystem ecology from descriptive to predictive science. Doing so required synthesis of a broad array of mechanisms into a conceptual framework that would be widely applicable to a variety of environmental changes, ecosystems and process responses. At the same time...
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Effects of anthropogenic nitrogen (N) deposition and the ability of terrestrial ecosystems to store carbon (C) depend in part on the amount of N retained in the system and its partitioning among plant and soil pools. We conducted a meta-analysis of studies at 48 sites across four continents that used enriched 15N isotope tracers in order to synthes...
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The most unique feature of Earth is the existence of life, and the most extraordinary feature of life is its diversity. Approximately 9 million types of plants, animals, protists and fungi inhabit the Earth. So, too, do 7 billion people. Two decades ago, at the first Earth Summit, the vast majority of the world's nations declared that human actions...
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Evidence is mounting that extinctions are altering key processes important to the productivity and sustainability of Earth's ecosystems. Further species loss will accelerate change in ecosystem processes, but it is unclear how these effects compare to the direct effects of other forms of environmental change that are both driving diversity loss and...
Conference Paper
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Background/Question/Methods Many experiments have shown that species richness of primary producers have significant effects on resource uptake and biomass production. While the effects of biodiversity are unequivocally significant, a key question remains: how do these effects compare in magnitude to other forms of environmental change. We used me...
Conference Paper
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Background/Question/Methods Streams and the biota that inhabit them are threatened by anthropogenic landuse via changes in hydrological dynamics, water chemistry, temperature, and substrate composition. To address stream degradation, stream conservation and restoration strategies focus on preserving extant riparian forest and reestablishing lost...
Data
Average soil moisture from the beginning and the end of growing seasons at 0-30 cm soil depth. Data were averaged across all nitrogen treatments (n = 12). (TIF)
Data
Average ten day temperature (oC) among experiment years. (TIF)
Article
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Long-term livestock over-grazing causes nitrogen outputs to exceed inputs in Inner Mongolia, suggesting that low levels of nitrogen fertilization could help restore grasslands degraded by overgrazing. However, the effectiveness of such an approach depends on the response of production and species composition to the interactive drivers of nitrogen a...
Article
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Over the past several decades, a rapidly expanding field of research known as biodiversity and ecosystem functioning has begun to quantify how the world's biological diversity can, as an independent variable, control ecological processes that are both essential for, and fundamental to, the functioning of ecosystems. Research in this area has often...
Article
Environmental changes, including elevated CO2, climate change, enhanced nutrient deposition, change in land use type and intensity, and species invasions, are contributing to worldwide loss of biodiversity. Ecosystem responses may either buffer or exacerbate these changes through various feedback loops, with important implications for the services...
Article
1. Recent debates about the role of biotic resistance in controlling invasion success have focused on effects of species richness. However, functional composition could be a stronger control: species already in the community with similar functional traits to those of the invaders should have the greatest competitive effect on invaders. Still, exper...
Conference Paper
Background/Question/Methods Diverse communities may be more resistant to invasion due to a lack of niche space for invaders. Negative native-exotic richness relationships (NERRs) could support this hypothesis, but results have been inconsistent at small spatial scales, and positive NERRs are observed at large scales. Also, absolute or relative cove...
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Predicting ecosystem responses to global change is a major challenge in ecology. A critical step in that challenge is to understand how changing environmental conditions influence processes across levels of ecological organization. While direct scaling from individual to ecosystem dynamics can lead to robust and mechanistic predictions, new approac...
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Humans are altering the composition of biological communities through a variety of activities that increase rates of species invasions and species extinctions, at all scales, from local to global. These changes in components of the Earth's biodiversity cause concern for ethical and aesthetic reasons, but they also have a strong potential to alter e...
Article
A recent debate among ecologists has focused on mechanisms by which species diversity might affect net primary productivity. Communities with more species could use a greater variety of resource capture characteristics, leading to greater use of limiting resources (complementarity) and therefore greater productivity (overyielding). Recent experimen...
Article
Climatic change may influence decomposition dynamics in arctic and boreal ecosystems, affecting both atmospheric CO2 levels, and the flux of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) to aquatic systems. In this study, we investigated landscape-scale controls on potential production of these compounds using a one-year labor...
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The LI-COR 6200 portable photosynthesis system (LI-6200) is commonly used in combination with large chambers to measure ecosystem level CO2 flux in ecosystems with small-statured canopies (agriculture, tundra, grasslands, forest understory, etc.). Two problems with the methodology lead to artifactually low estimates of rates of net ecosystem assimi...
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The ecological consequences of biodiversity loss have aroused considerable interest and controversy during the past decade. Major advances have been made in describing the relationship between species diversity and ecosystem processes, in identifying functionally important species, and in revealing underlying mechanisms. There is, however, uncertai...
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Ecological research is entering a new era of integration and collaboration as we meet the challenge of understanding the great complexity of biological systems. Ecological subdisciplines are rapidly combining and incorporating other biological, physical, mathematical, and sociological disciplines. The burgeoning base of theoretical and empirical wo...
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Ecological research is entering a new era of integration and collaboration as we meet the challenge of understanding the great complexity of biological systems. Ecological subdisciplines are rapidly combining and incorporating other biological, physical, mathematical, and sociological disciplines. The burgeoning base of theoretical and empirical wo...
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We assess the evidence for correlation between aboveground and belowground diversity and conclude that a variety of mechanisms could lead to positive, negative, or no relationship – depending on the strength and type of interactions among species.
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We identify the basic types of interactions between vascular plants and soil biota; describe the sensitivity of each type to changes in species composition; and, within this framework, evaluate the potential consequences of Global Change drivers on ecosystem processes.
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Human alteration of the global environment has triggered the sixth major extinction event in the history of life and caused widespread changes in the global distribution of organisms. These changes in biodiversity alter ecosystem processes and change the resilience of ecosystems to environmental change. This has profound consequences for services t...
Article
Assistant professor in the Department of Biology at Western Washington University, Bellingham, Washington 98225-9160 10: Professor at the Laboratoire d'Ecologie de Sols Tropicaux, ORSTOM/Université Paris VI, 32 Avenue Henri Varagnat, 93143 Bondy, France 11: Senior scientist at the Centre for Terrestrial Ecology, Netherlands Institute of Ecology, 66...
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We investigated the relationship between plant nitrogen limitation and water availability in dryland ecosystems. We tested the hypothesis that at lower levels of annual precipitation, aboveground net primary productivity (ANPP) is limited primarily by water whereas at higher levels of precipitation, it is limited primarily by nitrogen. Using a lite...
Article
We conducted plant species removals, air temperaturemanipulations, and vegetation and soil transplants inAlaskan wet-meadow and tussock tundra communities todetermine the relative importance of vegetation typeand environmental variables in controlling ecosystemmethane (CH4) and carbon dioxide (CO2) flux. Plastic greenhouses placed over wet-meadow t...
Article
To investigate how plant diversity affects ecosystem-level processes such as primary production and nutrient cycling, I established an experimental plant diversity gradient in serpentine grassland using four functional groups of plants: early season annual forbs (E), late season annual forbs (L), perennial bunchgrasses (P), and nitrogen fixers (N)....
Article
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We evaluated the effects of plant functional group richness on seasonal patterns of soil nitrogen and phosphorus cycling, using serpentine grassland in south San Jose, California. We established experimental plots with four functional types of plants: early-season annual forbs (E), late-season annual forbs (L), nitrogen-fixers (N), and perennial bu...
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T he earth is currently in the midst of the sixth major ex-tinction event in the history of life. The causes of earlier extinction events (e.g., the extinction of dino-F. Stuart Chapin (e-mail: fschapin@socrates. berkeley.edu) is a professor and David U. Hooper is a postdoctoral fellow in tbe
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The relative effects of plant richness (the number of plant functional groups) and composition (the identity of the plant functional groups) on primary productivity and soil nitrogen pools were tested experimentally. Differences in plant composition explained more of the variation in production and nitrogen dynamics than did the number of functiona...
Article
In the field, dark respiration rates are greatest in cores from more northerly locations. This is due in part to greater amounts of dwarf shrub biomass in the more northerly cores, but also to differences in soil organic matter quality. Laboratory incubations of these soils under common conditions show some evidence for greater pools of available c...
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Thesis (Ph. D.)--Stanford University, 1996. Submitted to the Department of Biological Sciences. Copyright by the author.
Article
The effect of biological diversity on ecosystem biogeochemistry has not been widely studied in recent years, due in part to widespread recognition that our understanding of population/ecosystem interactions was insufficient to sustain the pioneering discussions of the late 1960s (cf. Woodwell and Smith 1969). Indeed, the fields of population biolog...

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