Transcript Applied Community Ecology

Applied Community Ecology
• While we have focused on theory, patterns
and processes throughout much of the
semester, we will also consider how
community ecology may be applied to modern
ecological problems
Applied Community Ecology
• Some examples of applied community ecology
Applied Community Ecology
• Epidemiology
• Consider the interaction between native and
introduced insect pest species and Lyme
disease
Applied Community Ecology
• One of the interesting components to this
system is the apparent importance of acorn
production as a driver in the system
• Mast crops have positive effects on the
densities of white-tailed deer (congregate)
and white-footed mice (increase r)
Applied Community Ecology
• Deer are the primary host for adult blacklegged ticks and carry the bacterium Borrelia
burgdorferi.
• Juvenile ticks feed and mature on Peromyscus,
which serve as an important reservoir for the
spirochete
• Relationship has been experimentally shown
through manipulating acorn densities
Applied Community Ecology
• Interactions in NE forests
Applied Community Ecology
• A second chain reaction occurs with the
introduced gypsy moth, Lymantria dispar,
which undergoes outbreaks that can defoliate
many trees (including oaks)
• The high densities of Peromyscus that follow
large acorn crops have negavtive effects on
Lymantria, primarily through predation on the
Lymantria larvae
Applied Community Ecology
• While Peromyscus predation may not limit
Lymantria populations, large-scale defoliation
can suppress acorn production and
subsequent Peromyscus reproductive success
and population growth (which may then
create a positive feedback loop)
Applied Community Ecology
• Management of oak for reduced tick
abundance would lead to a greater likelihood
of gypsy moth outbreaks, whereas
management for reduced moth outbreaks
would lead to greater numbers of ticks and a
subsequent increase in Lyme’s disease
Applied Community Ecology
• Restoration of Composition and Function
• Restoring a community can potentially draw
from many of the principles and concepts we
have studied this semester
• Systems can be restored (or transformed) into
productive systems that can function in a
desirable manner
Applied Community Ecology
• In some cases we may
draw upon our
knowledge of primary
succession (e.g.
abandoned mine tailings
and closed landfill sites)
or even complete
establishment (e.g.
wetlands in mitigation)
Applied Community Ecology
Applied Community Ecology
• Another application may be removal of
species (e.g. exotics) and re-establishing
natives
Applied Community Ecology
• One of the primary goals of restoration
ecology is to not only establish a community,
but to accelerate the pace at which it is
established and direct it accordingly
• In some cases it may be somewhat difficult;
consider higher plants, mycorrhizal fungi and
pollinators are being necessary to perpetuate
the existence of the plant community
Applied Community Ecology
• Some of the important effects that we know
would be applicable include priority effects,
assembly rules, and successional pathways
• Restoration efforts also provide large-scale
and unique opportunities
for experimental
community ecology
Applied Community Ecology
• Biological Control of Invasive Species
• One of the components required to control
invasives is to either restore a functioning
food web or perhaps add a member (many
aspects of predator-prey dynamics at play
here)
• However, very little information exists that
food web theory is utilized in this manner
Applied Community Ecology
• Karban et al. (1994) used a predatory mite and
an alternative prey species on grapevines in an
attempt to control Pacific mites
• Of course, choice of alternative prey must be
made very, very carefully
Applied Community Ecology
• With alternative prey, largest population
reduction
Applied Community Ecology
• Biomanipulation of Water Quality
• We have many opportunities (unfortunately)
to experiment on ways to clean up waterways
• The idea that changes in food chain length, or
changes in the abundance of top predators,
may generate trophic cascades that have
desirable effects on lake ecosystems
Applied Community Ecology
• Typically, the desire is to improve water clarity
in systems that have become somewhat
eutrophic after a history of elevated nutrient
inputs, either from agricultural runoff or
sewage inputs
Applied Community Ecology
• Biomanipulation strategies use trophic
cascades to increase herbivory by
zooplankton on phytoplankton in lakes
• Lakes with algal blooms are assumed to have
essentially 3 trophic levels
• An increase in the abundance in the 4th
trophic level (piscivorus fish) can cause
trophic cascades, leading to clearer water
Applied Community Ecology
• Trophic cascades with and w/out top
predators
Applied Community Ecology
• Management of Multispecies Fisheries
• Most natural exploited fish populations are
components of more complex food webs
• Unfortunately, many fisheries managers tend
to be population biologists and typically focus
on the target species with little regard for the
web context
Applied Community Ecology
• Applying simple community theory addressing
how changes in one species may impact
competitors, as well as species above and
below themselves in the food web
• However, due to the scale and complexity of
the problem, this is not an easy issue to tackle
Applied Community Ecology
• Optimal Design of Nature Preserves
• Applying concepts generated from Island
Biogeography theory has been applied to
many conservation paradigms, although not
without some controversy (e.g. SLOSS)
Applied Community Ecology
• Many preserves are designated as such to
protect a single, high-profile species
• Consequently, the remaining community may
get little or no attention
• Species may persist through nonequilibrium
mechanisms in patchy habitats, multiple
habitat patches, or a natural disturbance
regime
Applied Community Ecology
• Predicting and Managing Responses to Global
Environmental Change
• As responses of communities to Pleistocene
glaciations show, the ranges of species shift,
expand, and contract in response to changing
regimes of temperature and rainfall
Applied Community Ecology
• The problems associated with climate change
may be exacerbated by habitat fragmentation
• E.g. species will need to move/disperse as one
area becomes unsuitable; if fragmentation is
severe, it may be very difficult to successfully
disperse and establish new populations
Applied Community Ecology
• One approach to better understand how
species may respond is to the ‘climate
envelop’ approach, which uses current
correlations between climate and distribution
to predict future movements
• Of course, species are modeled individually
and do not take into account any of the biotic
interactions that are so important
Applied Community Ecology
• Example of how a
climate envelope may
predict future
distributions
Applied Community Ecology
• Early experiments have also shown things may
not be so simple
• Looking at three Drosophila species in an
artificial system of connected population
cages that followed a temperature gradient
• Results: the distributions of single sp.
experiments were different than those from 3
sp. communities
Applied Community Ecology
• Maximization of Yield in Mixed-species
Agricultural Systems
• Most modern ag-systems tend to be
dominated as a monoculture, even if
polycultures are more productive. Why?
• Overyielding is typically attributed to
differences in resource utilization among
species
Applied Community Ecology
• In most cases, overyielding is a trial and error
experiment rather than a priori considerations
• Mixtures should take advantage of associated
defenses against natural enemies (as well as
minimize nutrient competition if possible)
Applied Community Ecology
• Assembly of Viable Communities in Novel
Environments
• Consider the common ‘terrarium’ experiment
done by kids in which producers, consumers,
and decomposers generate and recycle all of
the oxygen , carbon dioxide, and nutrients
needed to sustain the enclosed community
Applied Community Ecology
• Obviously such systems
are much simpler than
those found in nature,
but they resemble basic
properties and
problems encountered
in novel community
assembly
Applied Community Ecology
• In the future balanced
systems like these may be
scaled up and used to
create functioning
communities in novel
human-engineered
environments (e.g. space,
harsh environments)
Applied Community Ecology
• Biosphere 2 was an attempt at such an initial
large scale effort
Applied Community Ecology
• The Biosphere 2 quickly departed from
equilibrium (e.g. oxygen and CO2)
• Many species went extinct
• Communities were not thoughtfully
constructed
Applied Community Ecology
Applied Community Ecology