April 4, 2005
Ecologist Erika Zavaleta receives prestigious Mellon Foundation
By Jennifer McNulty
Erika Zavaleta, an assistant professor of environmental studies
at UCSC, has received a prestigious grant from the Andrew W.
Mellon Foundation to investigate the ecological impacts of the
loss of plant species in California ecosystems.
Erika Zavaleta describes California as a global hotspot
for threatened plant diversity.
Photo: Jim MacKenzie
Through a program that supports the research projects of outstanding
junior faculty, Zavaleta has been awarded a three-year, $200,000
grant. A maximum of only three such awards are presented each
Zavaleta, who joined the UCSC faculty in 2003, conducts research
on the ecological impacts of biodiversity change. She is particularly
interested in understanding the ecosystem effects of a decline
in the number of plant species, including impacts on nutrient
cycling and retention, productivity, and community and ecosystem
The grant will support observational field research and an
experimental study of the effects of removing vulnerable species
from two key ecosystems: vernal pool and grassland habitats
in central California.
Zavaletas work fills a gap that persists because most
studies on the ecology of species decline and extinction have
focused on vertebrate animals, not plants.
Despite the fact that plant species are declining and
disappearing at an alarming rate around the world, we have only
a marginal understanding of the ecological consequences of these
declines, said Zavaleta, who described California as a
global hotspot for threatened plant diversity.
Zavaletas project will focus on non-random loss of rare
and vulnerable plants.
"Most species in ecosystems, and most at-risk species,
are relatively uncommon, said Zavaleta. They exert
what influence they have in relatively small numbers.
In a pilot study in 2003-04, Zavaleta found that losses of
even very rare species have a large impact on ecosystem productivity,
colonization by other species, and water consumption. Her finding
that declining biodiversity greatly reduced resistance to invasive
species has important implications for resource managers. The
new grant will enable Zavaleta to improve and expand on the
pilot study to explore the mechanisms underlying the documented
The observational study will compare approximately 500 currently
threatened plant species and their nonthreatened relatives to
explore whether they possess, as a group, unique or distinct
characteristics, such as size, structure, life history, and
defenses. This will be the first phylogenetically controlled
study of plant species vulnerability that we know of,
In the experimental study, Zavaleta will manipulate a small
number of species in a single type of ecosystem to measure the
ecological consequences of removing or reducing species. UCSC
doctoral candidate Kristin B. Hulvey and a postdoctoral researcher
will collaborate with Zavaleta, who will also work with colleagues
at other universities.
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