Bunker Lab: Community Ecology and Global Change


	Daniel E. Bunker Assistant Professor Department of Biological Sciences New Jersey Institute of Technology	433 Colton Hall University Heights Newark, NJ 07102 973.642.7537 email	Links TraitNet BioMERGE Rutgers Federated Department of Biological Sciences CV

Research Overview
Prospective Students
Research Initiatives
Publications
Tools
Links

Global change poses a strong challenge to ecologists, environmental scientists, and conservation biologists: even as our natural and managed ecosystems become more stressed by the forces of global change, humans require that they produce both a greater quantity and variety of ecosystem services. For instance, we may expect a forested ecosystem to produce timber, provide clean water, sequester carbon, support wildlife, and provide recreational opportunities, yet at the same time the forest community is being buffeted by climate change, invasive species, and land-use change. In order to ensure that our ecosystems provide the services society demands, we must be able to predict how ecological communities will respond to these global forces, and in turn how changes in community composition will affect ecosystem services. To develop this predictive framework, I employ a mix of observation, experimentation, modeling and synthesis, within a diverse array of biological communities.

Global change poses a strong challenge to ecologists, environmental scientists, and conservation biologists: even as our natural and managed ecosystems become more stressed by the forces of global change, humans require that they produce both a greater quantity and variety of ecosystem services. For instance, we may expect a forested ecosystem to produce timber, provide clean water, sequester carbon, support wildlife, and provide recreational opportunities, yet at the same time the forest community is being buffeted by climate change, invasive species, and land-use change. In order to ensure that our ecosystems provide the services society demands, we must be able to predict how ecological communities will respond to these global forces, and in turn how changes in community composition will affect ecosystem services. To develop this predictive framework, I employ a mix of observation, experimentation, modeling and synthesis, within a diverse array of biological communities.

I am always looking for smart, motivated graduate students. I am happy to advise students interested in developing their own dissertations fromscratch or contributing to the efforts that I have underway.

I encourage any prospective students to begin the process early, researching graduate programs and potential advisors, and contacting both advisors and progarms early in the process.

In addition to our small but growing Ecology and Evolution group in the Federated Department of Biology at Rutgers-Newark and NJIT, we are also affiliated with the Department of Ecology, Evolution, and Natural Resources at Rutgers-New Brunswick. Students at NJIT can seemlessly cross register for courses at all three campuses. Details on applying to the graduate program can be found here.

NJIT has outstanding faculty and resources in Mathematics and Computer Science, including the Center for Applied Mathematics and Statistics and a Ph.D. program in Applied Mathematics including Mathematical Biology. NJIT is particularly well suited to prospective students with interests in computational approaches to problems in Ecology and Evolution.

Interested candidates are encouraged to email me directly, early in the process of exploring graduate school options.

Global change and species composition in the Northeastern US

Global change poses a great challenge to ecologists. Changes in temperature and precipitation, the introduction of invasive species, increasing urbanization and habitat fragmentation - these forces will drive prevasive change throughout our ecological communities. Some speices will be favored while others will decline. Effective predictions of species and community responses to these forces will be critical to our management of our natural resourses.

We are pursuing these questions by integrating long term community dynamics data with detailed species trait observations and bioclimatic range envelopes to predict species and community responses. This project is just beginning. We are currently identifying field sites and potential colabortors.

Species traits and ecoinformatics

TraitNet, a research coordination network and biological database designed to foster the systematic collection and dissemination of species trait data Ideally, ecologists eventually will be able to predict many aspects of community interactions and ecosystem functioning from species traits. However, we have found that species trait data are at best widely scattered throughout the literature and at worse simply nonexistent. Many other types of data are currently online, including community composition data (e.g., VegBank, CTFS), the phylogenetic relationships of species (e.g., Tree of Life, Phylocom, TreeBASE), and the genetic sequences of species (e.g., GenBank). Yet, in spite of the fact that trait measurements are critical to much ecological and evolutionary research, we know relatively little about species traits. In response, Shahid Naeem and I are implementing an NSF Research Coordination Network and online database designed to bring together researchers who utilize species traits as a tool for myriad and diverse research efforts. The goal of TraitNet is to build an ecoinformatics backbone that will enable seamless data contributions to a fully searchable, geo-referenced database. This database will allow species trait data to be discovered and shared while protecting the intellectual property rights of data contributors. The network includes more than 40 founding participants, including ecologists and evolutionary biologists as well as ecoinformatics specialists and computer scientists. We believe that species traits are a critical compliment to community, phylogenetic and genetic data, and that TraitNet will foster substantial research that would be otherwise unattainable. More info on the TraitNet Website

TraitNet, a research coordination network and biological database designed to foster the systematic collection and dissemination of species trait data

Ideally, ecologists eventually will be able to predict many aspects of community interactions and ecosystem functioning from species traits.

However, we have found that species trait data are at best widely scattered throughout the literature and at worse simply nonexistent. Many other types of data are currently online, including community composition data (e.g., VegBank, CTFS), the phylogenetic relationships of species (e.g., Tree of Life, Phylocom, TreeBASE), and the genetic sequences of species (e.g., GenBank). Yet, in spite of the fact that trait measurements are critical to much ecological and evolutionary research, we know relatively little about species traits.

In response, Shahid Naeem and I are implementing an NSF Research Coordination Network and online database designed to bring together researchers who utilize species traits as a tool for myriad and diverse research efforts. The goal of TraitNet is to build an ecoinformatics backbone that will enable seamless data contributions to a fully searchable, geo-referenced database. This database will allow species trait data to be discovered and shared while protecting the intellectual property rights of data contributors. The network includes more than 40 founding participants, including ecologists and evolutionary biologists as well as ecoinformatics specialists and computer scientists. We believe that species traits are a critical compliment to community, phylogenetic and genetic data, and that TraitNet will foster substantial research that would be otherwise unattainable.

More info on the TraitNet Website

TraitNetLogo

Data Schema

Global change, tree species composition and ecosystem function in tropical forests

In collaboration with Shahid Naeem, Fabrice DeClerk and several other BioMERGE participants, I have been working to quantify the effects of tree species extinctions on ecosystem function. Prior efforts to quantify the effect of biodiversity on ecosystem function have used small-scale experiments in relatively simple systems and have also assumed random extinctions. However, most biological systems are far more complex and less amenable to wholesale manipulation, and species' responses will differ among extinction drivers. To evaluate the effects of tree species loss on carbon storage, we simulated several extinction scenarios within a diverse, well-studied tropical forest, and quantified the effects on above-ground carbon storage. We demonstrated that both the magnitude and variability of carbon storage differed greatly between global drivers of extinction such as fragmentation or climate change. We currently are elaborating on this approach by developing more mechanistic models of both extinction risk and ecosystem function. Because this approach requires substantial species trait data, I have recently begun working with the Species Traits Working Group at the Center for Tropical Forest Science, led by Joe Wright of the Smithsonian Tropical Research Institute, to collect species trait data from the 18 large forest dynamics plots maintained by CTFS.

In collaboration with Shahid Naeem, Fabrice DeClerk and several other BioMERGE participants, I have been working to quantify the effects of tree species extinctions on ecosystem function. Prior efforts to quantify the effect of biodiversity on ecosystem function have used small-scale experiments in relatively simple systems and have also assumed random extinctions. However, most biological systems are far more complex and less amenable to wholesale manipulation, and species' responses will differ among extinction drivers. To evaluate the effects of tree species loss on carbon storage, we simulated several extinction scenarios within a diverse, well-studied tropical forest, and quantified the effects on above-ground carbon storage. We demonstrated that both the magnitude and variability of carbon storage differed greatly between global drivers of extinction such as fragmentation or climate change. We currently are elaborating on this approach by developing more mechanistic models of both extinction risk and ecosystem function.

Because this approach requires substantial species trait data, I have recently begun working with the Species Traits Working Group at the Center for Tropical Forest Science, led by Joe Wright of the Smithsonian Tropical Research Institute, to collect species trait data from the 18 large forest dynamics plots maintained by CTFS.

The effects of land-use change on neotropical dung beetle communities and multiple ecosystem services

In collaboration with Elizabeth Nichols, Sacha Spector of the American Museum of Natural History, as well as numerous data contributors, I am working to quantify the effects of land use change on dung beetle communities and the ensuing effects on ecosystem function. Dung beetles perform several important ecosystem functions - in addition to dung removal, dung beetles recycle nutrients, disperse seeds, and suppress both flies and pathogens. Dung beetles are also highly diverse and respond differentially to land use change. Utilizing samples of dung beetle community composition collected across seven levels of land use intensity, including intact forest, secondary forests, clear cuts and pasture , we are identifying the traits that predispose dung beetle species to population declines. We also are independently building models of species' contributions to functioning via their functional traits. When combined, we will be able to assess broadly the effects of land use change on a suite of important ecosystem functions.

In collaboration with Elizabeth Nichols, Sacha Spector of the American Museum of Natural History, as well as numerous data contributors, I am working to quantify the effects of land use change on dung beetle communities and the ensuing effects on ecosystem function. Dung beetles perform several important ecosystem functions - in addition to dung removal, dung beetles recycle nutrients, disperse seeds, and suppress both flies and pathogens. Dung beetles are also highly diverse and respond differentially to land use change. Utilizing samples of dung beetle community composition collected across seven levels of land use intensity, including intact forest, secondary forests, clear cuts and pasture , we are identifying the traits that predispose dung beetle species to population declines. We also are independently building models of species' contributions to functioning via their functional traits. When combined, we will be able to assess broadly the effects of land use change on a suite of important ecosystem functions.

'Biodiversity, Ecosystem Functioning, and Human Wellbeing: An Ecological and Economic Perspective'

Naeem, S., D.E. Bunker, A. Hector, M. Loreau and C. Perrings, editors. In press. 2009. Biodiversity, Ecosystem Functioning, and Human Wellbeing: An Ecological and Economic Perspective. Oxford University Press, Oxford. --> Publishers website In collaboration with Shahid Naeem, Andy Hector, Charles Perrings, and Michel Loreau, we are currently finishing an edited volume intended to assess the current state of biodiversity and ecosystem functioning research. The volume is being produced in association with a joint BioMERGE - DIVERSITAS meeting, and will include both basic science and applied results. The volume will be published in July 2009.

Naeem, S., D.E. Bunker, A. Hector, M. Loreau and C. Perrings, editors. In press. 2009. Biodiversity, Ecosystem Functioning, and Human Wellbeing: An Ecological and Economic Perspective. Oxford University Press, Oxford. --> Publishers website

In collaboration with Shahid Naeem, Andy Hector, Charles Perrings, and Michel Loreau, we are currently finishing an edited volume intended to assess the current state of biodiversity and ecosystem functioning research. The volume is being produced in association with a joint BioMERGE - DIVERSITAS meeting, and will include both basic science and applied results. The volume will be published in July 2009.

Functional diversity quantified by convex hull volume

Ecosystems perform numerous functions and provide a wide variety of services. Maximizing the range and magnitude of functions and services requires that communities fill all available niches. We combine ideas about functional diversity with those of habitat filtering to quantify the proportion of trait space occupied by a given set of species. Advancing prior work using convex hulls, we employ a hulls-within-hulls approach that sums intraspecific hulls, and thus trait space, as a proportion of the total available trait space (the total hull volume of intact communities or of the candidate species pool). We find that while a reduced set of species may fill the available functional trait space, this may come at the price of both reduced redundancy and limited ability to respond to environmental change.	Click to animate

Ecosystems perform numerous functions and provide a wide variety of services. Maximizing the range and magnitude of functions and services requires that communities fill all available niches. We combine ideas about functional diversity with those of habitat filtering to quantify the proportion of trait space occupied by a given set of species. Advancing prior work using convex hulls, we employ a hulls-within-hulls approach that sums intraspecific hulls, and thus trait space, as a proportion of the total available trait space (the total hull volume of intact communities or of the candidate species pool). We find that while a reduced set of species may fill the available functional trait space, this may come at the price of both reduced redundancy and limited ability to respond to environmental change.

Click to animate

Identifying the mechanisms of invasive species success and biological control

For much of my dissertation work, I focused on testing the ability of three competing theories of plant competition to predict invasions and biological control. While many researchers have assumed that species successfully invade because escape from natural enemies has made them better resource competitors than the natives they displace, this assumption has never been tested rigorously in the field. Community ecology offers several models of plant competition that may predict invasions and biocontrol success, including Tilman's resource competition model, Goldberg's response to resource availability model, and the plant size model advocated by both Miller and Keddy. All three offer trait-based measures that, in theory, predict competitive ability and thus the invasive potential of an exotic species. In addition, all three models predict that a biocontrol agent (e.g., an insect herbivore) will succeed, short of killing its host outright, only by reducing the competitive ability of its host, for instance by limiting the invader's ability to reduce resource availability to lower levels than its native competitors. I have been testing these theories experimentally, in collaboration with Walter Carson, with the widespread invasive, Purple Loosestrife, its native competitor, Broad-leaved Cattail, and Galerucella calmariensis, a leaf-feeding beetle widely released in an effort to biologically control purple loosestrife. Our results suggest loosestrife is able to invade cattail through competition for light and possibly soil nitrogen. However, loosestrife also appears to facilitate cattail by allowing cattail to escape its insect herbivores. The mechanism of this facilitation could be either simple density dependent predation or 'apparent facilitation,' whereby cattail's insect herbivores share a predator with loosestrife's herbivores. Although I have completed my dissertation, I am continuing these long-term experiments as we seek definitive competitive outcomes as well as the mechanisms responsible for the facilitation of cattail by loosestrife.

For much of my dissertation work, I focused on testing the ability of three competing theories of plant competition to predict invasions and biological control. While many researchers have assumed that species successfully invade because escape from natural enemies has made them better resource competitors than the natives they displace, this assumption has never been tested rigorously in the field. Community ecology offers several models of plant competition that may predict invasions and biocontrol success, including Tilman's resource competition model, Goldberg's response to resource availability model, and the plant size model advocated by both Miller and Keddy. All three offer trait-based measures that, in theory, predict competitive ability and thus the invasive potential of an exotic species. In addition, all three models predict that a biocontrol agent (e.g., an insect herbivore) will succeed, short of killing its host outright, only by reducing the competitive ability of its host, for instance by limiting the invader's ability to reduce resource availability to lower levels than its native competitors.
I have been testing these theories experimentally, in collaboration with Walter Carson, with the widespread invasive, Purple Loosestrife, its native competitor, Broad-leaved Cattail, and Galerucella calmariensis, a leaf-feeding beetle widely released in an effort to biologically control purple loosestrife. Our results suggest loosestrife is able to invade cattail through competition for light and possibly soil nitrogen. However, loosestrife also appears to facilitate cattail by allowing cattail to escape its insect herbivores. The mechanism of this facilitation could be either simple density dependent predation or 'apparent facilitation,' whereby cattail's insect herbivores share a predator with loosestrife's herbivores. Although I have completed my dissertation, I am continuing these long-term experiments as we seek definitive competitive outcomes as well as the mechanisms responsible for the facilitation of cattail by loosestrife.

Cattail

Garerucella

loosestrife

mesocosms

Modeling competition for light among terrestrial plants

Resource competition theory was originally modeled under the assumption that resources, such as soil nitrogen, are distributed homogenously. However, many species compete primarily for light. Because light is directional and declines in availability with depth in a canopy, no single measure of light availability, for instance at the soil surface, adequately describes a species' ability to compete for light. To address this limitation, I have developed, in collaboration with Scott Stark and Walter Carson, a model of competition for light that makes no assumptions about the vertical foliage distribution of competing species, and thus can be applied to real-world species such as loosestrife and cattail. In addition, our model allows for the direct inclusion of effects such as herbivory and leaf litter on competitive dynamics.

Resource competition theory was originally modeled under the assumption that resources, such as soil nitrogen, are distributed homogenously. However, many species compete primarily for light. Because light is directional and declines in availability with depth in a canopy, no single measure of light availability, for instance at the soil surface, adequately describes a species' ability to compete for light. To address this limitation, I have developed, in collaboration with Scott Stark and Walter Carson, a model of competition for light that makes no assumptions about the vertical foliage distribution of competing species, and thus can be applied to real-world species such as loosestrife and cattail. In addition, our model allows for the direct inclusion of effects such as herbivory and leaf litter on competitive dynamics.

BOOKS

Naeem, S., D.E. Bunker, A. Hector, M. Loreau and C. Perrings, editors. In press. 2009. Biodiversity, Ecosystem Functioning, and Human Wellbeing: An Ecological and Economic Perspective. Oxford University Press, Oxford. --> OUP website

BOOK CHAPTERS

Naeem, S., D.E. Bunker, A. Hector, M. Loreau, and C. Perrings. In press. 2009. The ecological and social implications of changing biodiversity: An overview of a decade of biodiversity and ecosystem functioning research. In Naeem, et al, editors. Biodiversity, Ecosystem Functioning, and Human Wellbeing: An Ecological and Economic Perspective. Oxford University Press, Oxford.

Solan, M., J. Godbold, D.F.B. Flynn, A. Symstad, and D.E. Bunker. Biodiversity-ecosystem function research and biodiversity futures: Early bird catches the worm or a day late and a dollar short? In press. 2009. In Naeem, et al, editors. Biodiversity, Ecosystem Functioning, and Human Wellbeing: An Ecological and Economic Perspective. Oxford University Press, Oxford.

Engelhardt, K., A. Symstad, A. Prieur-Richard, M. Thomas, and D.E. Bunker. In press. 2009. Opening communities to colonization –The impacts of invaders on biodiversity and ecosystem functioning. In Naeem, et al, editors. Biodiversity, Ecosystem Functioning, and Human Wellbeing: An Ecological and Economic Perspective. Oxford University Press, Oxford.

Naeem, S., and D.E. Bunker. In press. 2009. TraitNet: Furthering biodiversity research through the curation, discovery, and sharing of species trait data. In Naeem, et al, editors. Biodiversity, Ecosystem Functioning, and Human Wellbeing: An Ecological and Economic Perspective. Oxford University Press, Oxford.

Naeem, S., D.E. Bunker, A. Hector, M. Loreau, and C. Perrings. In press. 2009. Can we predict the effects of global change on biodiversity loss and ecosystem functioning? In Naeem, et al, editors. Biodiversity, Ecosystem Functioning, and Human Wellbeing: An Ecological and Economic Perspective. Oxford University Press, Oxford.

JOURNAL ARTICLES

Carson, W. P., Hovick, S. M., Baumert, A. J., Bunker, D. E. and Pendergast, T. H. 2008. Evaluating the post-release efficacy of invasive plant biocontrol by insects: A comprehensive approach. Arthropod-Plant Interactions. 2, 77-86.

Bunker, D.E., and S. Naeem. 2006. Species diversity and ecosystem functioning. Letter to the editor in Science. 312: 846-847. PDF

Stark, S.C., D.E. Bunker, and W.P. Carson. 2006. A null model of exotic plant diversity tested with exotic and native species-area relationships. Ecology Letters. PDF

Bunker, D.E., F. DeClerck, J.C. Bradford, R.K. Colwell, I. Perfecto,O. L. Phillips, M. Sankaran and S. Naeem. 2005. Species Loss and Above-ground Carbon Storage in a Tropical Forest. Science 310:1029-1031. PDF and the Supplement

Bunker, D.E., and W.P. Carson. 2005. Drought stress and tropical forest woody seedlings: effect on community structure and composition. Journal of Ecology. 93: 794-806. PDF

Stevens, M.H.H, D.E. Bunker, S. Schnitzer, and W.P. Carson. 2004. Establishment limitation reduces species recruitment and species richness as soil resources rise. Journal of Ecology. 92: 339-347. PDF

Stevens, M., Z.T. Long, S.A. Schnitzer, D.E. Bunker, R. Collins, A. Bledsoe, W.P. Carson. 2003. Testing Ecological Theory - Lab manual for Ecology Laboratory. University of Pittsburgh. Pittsburgh, PA. PDF not available

D'Arrigo, R.D., C.M. Malmstrom, G.C. Jacoby, S.O. Los and D.E. Bunker. 2001. Correlation between maximum latewood density of annual tree rings and NDVI based estimates of forest productivity. International Journal of Remote Sensing. 21: 2329-2336. PDF

Yamaguchi, D.K., B.F. Atwater, D.E. Bunker, B.E. Benson, and M.S. Reid. 1997. Tree-ring dating the 1700 Cascadia earthquake. Nature 389: (6654) 922-923. PDF

Jacoby, G.C., D.E. Bunker, B.E. Benson. 1997. Tree-ring evidence for an AD 1700 Cascadia earthquake in Washington and northern Oregon. Geology 25: (11) 999-1002. PDF