gregory r. houseman, phd - wichita state university · gregory r. houseman, phd gregory r....
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Gregory R. Houseman, PhD
Gregory R. Houseman, PhD
Assistant Professor of Biology
Office: 519 Hubbard Hall
Phone: (316) 978-5841
Email: [email protected]
Education Degree Year Field of Study
Michigan State University PhD 2004 Plant Biology / EEBB
Illinois State University MS 1998 Biology
AuSable Institute 1992 Naturalist Certificate
Cornerstone University BA 1990 Biology
Professional Experience
Research Interests
External Research Grants
Peer-Reviewed Publications
Courses Taught
Professional Experience 2008-present. Assistant Professor, Wichita State University
2006-2008. Post-doctoral Fellow, University of Kansas
2004-2006. Research Associate, Kellogg Biological Station, Michigan State University
2006. Adjunct Professor, Kalamazoo College
Research Interests I am broadly interested in the processes that control the development and maintenance of
ecological communities, with emphasis on patterns of species diversity, invasion, and the
ecosystem production. I approach these topics by testing ecological theory and look for new
ideas that can be used to guide the management and restoration of ecosystems. Below are some
specific examples my research:
Effects of Soil Heterogeneity on Plant Diversity
Environmental heterogeneity is one of the most intuitive explanations for variation in diversity.
For example, plant diversity is expected to increase with soil heterogeneity. A large number of
observational studies that have measured resources such as light, soil moisture, soil nitrogen or
other soil variables report an increase in plant diversity with increased heterogeneity of these
resources. Surprisingly, experimental field experiments have found little support for this
relationship. Using a novel approach, Brandon Williams and I have found that plant diversity
increases with experimentally created soil heterogeneity at least during the early phases of
community assembly (see images and citation below). Currently, we monitoring whether these
patterns are maintained over time and tracking how community assembly develops from initially
homogeneous or heterogeneous conditions.
Vertical soil profile illustrating different
rooting activity
Example of soil patch structure allocated to
heterogeneous and homogeneous plots (type
for is a mixture of strata 1-3)
see Williams & Houseman 2013 Journal of Plant Ecology
Williams, B. M. and G. R. Houseman. 2013. Experimental evidence that soil heterogeneity
enhances plant diversity during community assembly. Journal of Plant Ecology
DOI:10.1093/jpe/rtt056. Abstract
Effects of Seed Arrival Patterns on Plant Diversity
Stratum2
Stratum1
Mixed StratumCombination of
all 3 strata
Stratum3
Heterogeneous soils
4 4 4 4 4 4
4 4 4 4 4 4
4 4 4 4 4 4
4 4 4 4 4 4
4 4 4 4 4 4
4 4 4 4 4 4
Homogeneous soils
It is now well-documented that species pools limit plant diversity in grasslands (see publications
list). However, nearly all these studies use uniform seed addition patterns. In nature, seed
dispersal is very patchy depending on the size and density of the focal species. The
consequences of patchy dispersal are relatively unknown and have potentially important
implications for restoration approaches, which often use uniform application. Currently, I am
testing these ideas in a large field experiment in a species-poor, Kansas prairie. Early results
from this work suggest that weaker seedling competitors may benefit from patchy seed arrival
leading to an increase in species evenness and potentially richness (depending on scale). Work
on this project continues!
Houseman, G. R. 2013. Aggregated seed arrival alters plant diversity in grassland communities.
Journal of Plant Ecology DOI:10.1093/jpe/rtt044. Abstract
Invasive Species: searching for an Achilles’ heel
Although invasive species can have large negative effects on the structure and function of native
ecosystems, they do provide an interesting opportunity to test underlying ecological principles
while trying to find ways to minimize their effects. Currently, we are testing how propagule
pressure (immigration rate) influences the probability of invasion among systems that vary in
soil fertility and disturbance regimes. We are also testing in the field and lab several potential
competitive mechanisms by which Lespedeza cuneata (sericea) invades native grasslands in
Kansas.
Coykendall, K. E. and G. R. Houseman. 2013. Lespedeza cuneata invasion alters oils
facilitating its own growth. Biological Invasions DOI:10.1007/s10530-013-0623-8. Abstract
Houseman, G. R., B. L. Foster and C. E. Brassil. 2013 Propagule pressure-invasibility
relationships: Testing the influence of soil fertility and disturbance with Lespedeza cuneata.
Oecologia DOI:10.1007/s00442-013-2781-x. Abstract
Wong, B. M., G. R. Houseman, S. E. Hinman and B. L. Foster. 2013. Invasive Plant Science
and Management 5:487-493. Abstract
Community Assembly and the Development of Diversity
While species pools and immigration are likely to influence diversity, it is unclear whether the
results are sensitive to the sequence of colonization events (community assembly). If
communities are structured by the interaction between species traits and environmental
conditions, community assembly is predicted to be a deterministic process. However, neutral
theory predicts that community assembly is a stochastic process driven by births, deaths,
immigration and evolution. Currently, Bryan Foster and I are testing the relative importance of
these neutral and niche based processes on community assembly in northeast Kansas. In this
experiment, we are manipulating species diversity and composition of plant species. After
removing extant species, we seeded 240 plots in various combinations of plant species diversity
and species traits. We are monitoring changes in diversity through time as a function of initial
species composition (note differences among plots marked by the white posts in the pictures
below) In addition to providing a strong test of ecological theory, the results will quantify how
initial diversity and species composition impact the development and maintenance of plant
diversity in grassland restorations.
Community Responses to Perturbations
Because the outcome of species interactions is dependent on environmental conditions, climate
change—including alteration of atmosphere deposition of N—may alter the structure of
communities. One interesting way to test this for communities is to quantify the variability
(dispersion) of communities in response to perturbations. For example, in a long-term nutrient
addition experiment in low-productivity sand prairie, we found that increased fertility reduced
diversity at small scales, but also led to greater variability in plant community composition than
unfertilized plots. This increased variability following perturbation suggests that it may be
difficult to predict the response of communities to human alteration of environmental conditions.
Currently, we have an experiment underway to test how initial conditions may influence the
community dispersion in grassland systems.
Houseman, G. R., G. G. Mittelbach, H. L. Reynolds, and K. L. Gross. 2008. Perturbations alter
community convergence, divergence, and formation of multiple community states Ecology
89:2172-2180. Abstract
Effects of herbivore diversity on native plant communities
Herbivores can have strong effects on native plant biomass, but little is known about how
different herbivore groups may independently or interactively effect plant species. Leland
Russell and I are testing this idea by reducing the access by insect and non-bovine mammals in a
restored Kansas grassland (see below). Additionally, fertilizer is applied to half of the plots to
test whether the effects of these herbivore groups vary with soil fertility.
Community
State
Community
State
Community
State
1 community
state
1 community
state
A
multiple
community
states
D
B
Initial Perturbed
Community
State
C
1 or no clear
community state
Convergence
Divergence
(Alternate States)
Peer-Reviewed Publications Shah, M. A., R. M. Callaway, T. Shah, G. R. Houseman, R. W. Pal, S. Xiao, W. Luo, C.
Rosche, Z. A. Reshi, D. P. Khasa and S. Chen. 2014. Conyza canadensis suppresses plant
diversity in its nonnative ranges but not at home: A transcontinental comparison. New
Phytologist DOI:10.1111/nph.12733 . Abstract
Williams, B. M. and G. R. Houseman. 2013. Experimental evidence that soil heterogeneity
enhances plant diversity during community assembly. Journal of Plant Ecology
DOI:10.1093/jpe/rtt056. Abstract
Houseman, G. R., B. L. Foster and C. E. Brassil. 2013 Propagule pressure-invasibility
relationships: Testing the influence of soil fertility and disturbance with Lespedeza cuneata.
Oecologia DOI:10.1007/s00442-013-2781-x. Abstract
Houseman, G. R. 2013. Aggregated seed arrival alters plant diversity in grassland communities.
Journal of Plant Ecology DOI:10.1093/jpe/rtt044. Abstract
Coykendall, K. E. and G. R. Houseman. 2013. Lespedeza cuneata invasion alters oils
facilitating its own growth. Biological Invasions DOI:10.1007/s10530-013-0623-8. Abstract
Wong, B. M., G. R. Houseman, S. E. Hinman and B. L. Foster. 2013. Invasive Plant Science
and Management 5:487-493. Abstract
Houseman, G. R. and K. L. Gross. 2011. Linking grassland plant diversity to species pools,
sorting and plant traits. Journal of Ecology 99:464-472. Abstract
B. L. Foster, K. Kindscher, G. R. Houseman, C. A. Murphy. 2009. Effects of hay management
and native species sowing on grassland community structure, biomass, and restoration.
Ecological Applications 19:1884-1896. Abstract
Houseman, G. R., G. G. Mittelbach, H. L. Reynolds, and K. L. Gross. 2008. Perturbations alter
community convergence, divergence, and formation of multiple community states Ecology
89:2172-2180. Abstract
Reynolds, H. L., G. G. Mittelbach, T. Darcy-Hall and G. R. Houseman, K. L. Gross. 2007. No
effect of varying soil resource heterogeneity on plant species richness in a low fertility grassland.
Journal of Ecology 95:723-733. Abstract
Houseman, G. R. and K. L. Gross. 2006. Does ecological filtering across a productivity gradient
explain variation in species pool-richness relationships? Oikos 115:148-154. Abstract
Suding, K. N., K. L. Gross, and G. R. Houseman. 2004. Alternative states and positive
feedbacks in restoration ecology. Trends in Ecology and Evolution 19:46-53. Abstract
Houseman, G. R. and R. C. Anderson. 2002. Effects of jack pine plantations on Kirtland’s
warbler nest habitat and barrens flora. Restoration Ecology 10:27-36. Abstract
Anderson, R. C., R. M. Anderson and G. R. Houseman. 2002 American Ginseng. Native Plants
Journal 3:93-97, 100-105. Abstract
External Research Grants NSF Kansas EPSCoR (2010) “Can spatial variability created by dispersal explain the
accumulation of biodiversity” ($39,000)
USDA-NRI (2006) “Does propagule pressure change invasion risk under different agricultural
management regimes” ($125,000)
NSF Doctoral Dissertation Improvement Grant 0308856 with Kay Gross (2003) “Species pools
and plant traits as constraints on species diversity across productivity gradients” ($10,000)
Courses Taught at Wichita State University BIOL211 General Biology II
BIOL503 Taxonomy and Geography of Flowering Plants
BIOL560-561 Plant Ecology
BIOL610 Ecosystem Management and Restoration