Ecological Impacts
INTRODUCTION: AN OVERVIEW OF CLIMATE AND LAND USE EFFECTS ON ECOSYSTEMS
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Climate change has the potential to alter sensitive marine, freshwater, and terrestrial ecosystems in the CARA region, due to possible temperature increases, changes in precipitation, sea-level rise, and the increased frequency of extreme events. Important ecological changes that could occur as a result of climate change include:
- Changes in the timing of seasonal and life-cycle events for particular species, such as earlier flowering of trees or egg-laying in birds
- Lengthening of the growing season and changes in plant distribution
- Migration of species as they adapt to climate change impacts (e.g., gradual movements of animals or plant species northward and/or to higher altitudes),
- Long-term changes in ecosystem structure or shifts in the geographic distribution and extent of major ecosystem types
- Inundation of coastal wetlands as a result of sea-level rise, and
- Sea-water intrusion into wetlands and fresh or brackish marshes.
Such changes could lead to changes in abundance and/or diversity of plant and animal species. An in-depth review of the relationship between climate change and ecosystem conditions on a global scale can be found in the Intergovernmental Panel on Climate Change (IPCC) technical paper on climate change and biodiversity (IPCC, 2002): http://www.ipcc.ch/pub/tpbiodiv.pdf
A summary of some of the most recent studies in North America is provided in a US Geological Survey (USGS) report at: http://biology.usgs.gov/s+t/SNT/noframe/cl110.htm
The changes that could occur in ecosystems in turn could affect the goods and servicesthat ecosystems provide to society. Goods that ecosystems provide include food, fiber, fuel, pharmaceutical products, recreation and tourism, and wildlife. Services include nutrient cycling, enhanced water quality, capture of excess water runoff, controlling soil erosion, provision of wildlife habitat, detoxification of pollutants that are emitted to the environment, and the regulation of local climate and weather. The schematic diagram below, from the July 2003 U.S. Strategic Plan for the Climate Change Science Program, shows the key linkages between ecological, human, and climate systems. This report also provides an excellent discussion of the goods and services that are provided to society by ecosystems: http://www.climatescience.gov/Library/stratplan2003/final/ccspstratplan2003-chap8.htm
As with many other effects of climate change, impacts on ecosystems can be made worse, or in many cases completed overshadowed by, future changes in land use. For example, if the migration of species northward or to higher elevations in response to a warmer climate is blocked by major highways or suburban sprawl, then the ability of these species to adjust and survive could be threatened in the future. Even without climate change, land use changes can have direct (and many times very obvious) impacts on the natural ecosystems that they disturb or displace; or less direct, but still significant impacts e.g. by blocking seasonal migration routes. Such impacts have led to increased recognition of the importance of maintaining corridors that interconnect wildlife habitat in urban and suburban areas.
The Maryland Department of Natural Resources highlights the importance of green corridors in its 2004 report, Restoration Targeting in Maryland’s Green Infrastructure
Open-space acquisition is key part of the New Jersey Department of Environmental Protection’s Green Acres Program : http://www.state.nj.us/dep/greenacres/
As an example of a green corridor that is important for one of the CARA case study areas, the Algonquin to Adirondacks corridor from Ontario to Northern New York State is recognized as a key area for wildlife and plant species migration. A study of the Algonquin to Adirondacks corridor was conducted to identify areas of high priority for conservation efforts aimed at maintaining connectivity: http://www.ancientforest.org/a2a.html
The Wilderness Society provides an interesting study of the effects on ecosystems of roads in the Monongahela National Forest, in West Virginia, adjacent to the Virginia boarder:
http://www.wilderness.org/Library/Documents/MonongahelaRoadsReport.cfm
And the Virginia Cooperative Extension reports on the importance of buffer zones along streams and rivers (referred to as “riparian buffer zones”) at: http://www.ext.vt.edu/pubs/forestry/420-152/420-152.html
As such, the effects of land use change and climate change must be considered together when evaluating impacts on the health and viability of ecosystems in the CARA region.
The following map shows different ecological regions in the Northeastern United States. Ecoregions are contiguous areas of common topography, climate, and soil type where similar (naturally-occurring) vegetation and wildlife species are expected. The US EPA uses these regions to determine the type of water quality and pollution problems it expects to find in streams and lakes. More information on ecoregions can be found at the following EPA website: http://www.epa.gov/maia/html/ecoregion.html
The following sections provide more information on different types of ecosystems in the CARA region and how they might be affected by climate and land use change. Following this, you have the opportunity to answer a few questions about ecosystems in your area, to help you learn more about how these ecosystems might respond to climate and land use changes in the future.