Winter Ecological Interactions between Alpine and Subalpine Ecosystems

1. Winter Ecological Interactions between Alpine and Subalpine Ecosystems Kate Samelson 12 March 2006 EBIO 4120 Winter Ecology – Spring 2006 Mountain Research Station – University of Colorado, Boulder

2. Subalpine Environment Elevation: 10,000 to 11,500 ft Dominated mostly by Englemann’s spruce and subalpine fir Precipitation: 30-35in/yr, mostly as snow Lingering snowpacks keep forest floor moist for much of the year Deer mice, snowshoe hare, bobcats and Steller’s jays amongst other inhabit the subalpine environment Alpine/Tundra Environment Elevation: 11,500 ft and above Vegetation includes lichens, grasses, sedges, shrubs and mosses. Precipitation: 6-10in/yr, including melted snow Winds can be stronger than 100mph Pikas, marmots, mountain goats, sheep, elk and beetles all live in the tundra environment Physical Environment

3. Organic materials and nutrients are transported via fluvial means in aquatic systems. Fluvial processes are not present in alpine environments. How are alpine and subalpine ecosystems connected if not by fluvial processes, and how does this change affect the communities??

4. Alpine and subalpine ecosystems are connected through groundwater and wind processes.

5. Wind Organic materials and nutrients are transported downwind from the alpine to the subalpine. The greatest intake of organic materials and nutrients is going to be along treeline.

6. Alpine The tundra ecosystem is losing organic materials and nutrients downwind, and therefore the amount of organic matter being decomposed decreases. This lowers respiration rates in the community. Primary productivity to respiration ratios are >1 Subalpine The ecosystem is uptaking organic matter and nutrients from upwind, and therefore the amount organic matter being decomposed is increased. This raises respiration rates. Primary productivity to respiration ratios are <1 Ecological Differences

7. Subsurface Groundwater In alpine and subalpine ecosystems, subsurface runoff from snow can account for up to 90% of the total flow of the basin. The short residence time of water in the basin limits the ability of biota to uptake atmospherically deposited nitrogen.

8. Conclusions Alpine and subalpine ecosystems are connected through wind processes and subsurface groundwater. Wind scouring blows nutrient and nitrogen rich snow and organic materials from the tundra into the subalpine. Productivity rates in the alpine ecosystem are decreasing, while productivity rates in the subalpine ecosystem are increasing. Groundwater interactions between the alpine and subalpine communities are often minimal and ecologically less significant. Interactions between alpine and subalpine ecosystems is of great importance to the biota of both communities and without such, the two ecosystems would be drastically different.

9. Bibliography Liptzin, Daniel, Seastedt, Timothy, University of Colorado, Boulder, CO, USA Heterogenity in soil nutrients in the forest-alpine tundra ecotone.