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A
major focus of my work for the past 15 years has been understanding how
variation influences community ecology. I have worked with Peter Chesson
(UC Davis) to develop ideas and methods for studying the relationships
of environmental variability and biodiversity. We have used desert annual
plants as a test case, with the goal of understanding the nature of environmental
variation experienced by populations and its contribution to species coexistence
through creation of what can be thought of as regeneration or other
temporal niches. Our work with desert annuals involves understanding
seed bank dynamics, the phenology of plant germination and growth, soil
resource dynamics, and patterns of resource use and competition, all of
which potentially vary according to environmental conditions. We have
begun a parallel study of sage-steppe ecosystems, which extends the work
to perennial plants, trophic webs, and simultaneous consideration of both
spatial and temporal patterns of variation in the environment. The
theory and methods we are developing have broad application to the understanding
and preservation
of biodiversity.
I collaborate with an archaeologist
(Herb Maschner, ISU Anthropology) and several other colleagues to
understand the long-term interactions of people with the landscape they
inhabit and the resources they depend upon. Our study area is the Lower Alaska Peninsula region, which
has been inhabited by the Aleut for thousands of years. The archaeological
record from the Lower Alaska Peninsula suggest periods of strong
overexploitation of primary resources followed by collapse or movement of
societies, strong overexploitation of primary resources followed by
switching to alternative resources, and periods of long persistence within
an area. We want to better understand the ecological, geomorphic, and
sociological conditions that predispose to these different patterns of
resource use and persistence or lack of such. The contemporary landscape
shows strong influence of past (prehistoric and historic) villages on
composition, diversity, and productivity of the regional flora and fauna. We
want to understand the relationship of these patterns to success of human
habitation, as well as their continuing importance to people, trophic webs,
and landscape-level patterns of abundance and movement of organisms, and
abundance and exchanges of abiotic resources.
My lab has recently begun to work in detail with the trophic webs associated
with dominant
vegetation in sage-steppe and maritime
tundra ecosystems. The work in sage-steppe and tundra will
test ideas of how food webs (and their component species) vary among habitat
patches with different landscape attributes (size, isolation, history
of exposure to land development and invasive species). The work also considers
the influence of temporal variation in the environment on dynamics
of trophic webs. We plan this work to include comparison with temperate
and tropical food webs now under study by colleagues at Imperial College
of London and the NERC
Centre for Population Biology.
Additionally, a major focus of my work over the long-term has been
plant-herbivore interactions and there are always opportunities for students
to develop projects on this topic associated with one of the projects listed
above. In the past, we have studied the distribution and foraging behavior
of small and medium-sized mammals (pikas, jack rabbits, voles, pocket
gophers, kangaroo rats, and woodrats, and some insects) and the effects of
these animals on vegetation and ecosystem dynamics in alpine, subalpine,
montane, prairie, old-field, and desert ecosystems.
Curriculum
Vitae
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I
am interested in population and community ecology, especially the ecology
of coexisting populations and how it is influenced by spatial and temporal
patterns in the environment. My lab group studies the mechanisms
involved in community dynamics and diversity, with plants, herbivorous
mammals, and arthropods as the main subjects of study. We now working
mainly in two regions, sage
steppe/cold desert and Alaskan maritime
tundra, though we continue some work in hot
deserts and high
elevation ecosystems. My students have diverse interests
and our lab strives to be integrative in approach, drawing techniques
and perspectives from behavioral, population, landscape, and ecosystem
ecology. Our current major projects concern (1) the structure and dynamics
of trophic webs, (2) the roles of patterns of environmental
variability (e.g., spatial variation in soils, large-scale habitat
conformations, temporal variation in weather patterns within and among
years) in community
dynamics and diversity, and (3) long-term human-landscape-food
web interactions of the Lower Alaska Peninsula, which has been inhabited
by the Aleut for millennia. I am especially interested
in linking dynamical models with studies of actual ecosystems so as to
both develop better conceptual models and improve our understanding of
how ecosystems work.