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

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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 black legged 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

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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

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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

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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 4 th trophic level (piscivorus fish) can cause trophic cascades, leading to clearer water

Applied Community Ecology • Trophic cascades with and w/out top predators

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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

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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

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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

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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)

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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 CO 2 ) Many species went extinct Communities were not thoughtfully constructed

Applied Community Ecology

Applied Community Ecology