PROCEEDINGS: Index of Abstracts
ASSESSING THE ABILITY OF PLANTS TO RESPOND TO CLIMATIC
CHANGE THROUGH DISTRIBUTION SHIFTS
Assistant Research Scientist, Center for Population
Biology, University of California at Davis, Davis, CA 95616.
Predictions of future global warming suggest northward shifts of
up to 800 km in the equilibrium distributions of plant species.
Historical data estimating the maximum rate of tree distribution
shifts (migration) suggest that most species will not keep pace
with future rates of human-induced climatic change. Previous plant
migrations have occurred at rates typically ranging from 15-50 km
per century. A simulation model, which incorporates the effects
of forest fragmentation and habitat loss, predicts maximum potential
migration responses of trees may be only 1-10 km per century, or
two orders of magnitude below that required to keep pace with predicted
climatic warming. These predicted migration rates suggest that plants
will fail to respond adequately to even modest climatic changes.
Gauging the actual response of forest species to climatic change,
and then appropriately managing forest resources poses several problems.
First, we do not know the distribution limits of most forest species
with the degree of precision to detect migration events on a 1-10
km scale. Second, many species may become vulnerable to extinction
by their inability to migrate, leaving them geographically isolated
from regions within their climatic tolerance. Third, while the distributions
of species can be artificially expanded if climate does warm, this
is not currently part of acceptable conservation management practice.
Deciding whether or not to artificially enhance species ranges forces
a choice between species preservation and historical community composition
models for conservation. A pressing concern for forest management
is to discover how climate change, anthropogenic habitat change,
and doubled CO2 interact to alter forest species performance and
regeneration within habitats they currently occupy. Range edges
are the first place to look for key changes in these ecological