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. Physical Environment Subalpine Environment Alpine/Tundra 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

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??
In all ecosystems, the significance of material transport from uphill or upwind sites is important for nutrient dynamics. In aquatic environments, minerals and nutrients are transported through fluvial means. However, in alpine ecosystems, fluvial means are not available for transport processes, and therefore, must be accomplished by other ways.

4. Alpine and subalpine ecosystems are connected through groundwater and wind processes.
Because strong winds and heavy snowpack dominate high-elevation environments, the alpine and subalpine ecosystems are connected through groundwater and wind. Materials in high-elevation ecosystems are transported through subsurface groundwater and the movement of snow due to winds. Snow and organic materials are picked up in the tundra and redistributed in the subalpine. This results in a net decrease of nutrients and organic matter in the tundra, and an increase in the subalpine.

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.
The alpine ecosystem of meadows and fellfields are important sources of water, nutrients and organic matter to the subalpine community. The greatest intake of these organic materials and nutrients is going to be along treeline where the interception of trees collects the wind-blown snow and much of the groundwater. As a result, the production rates of the subalpine ecosystem should increase and be maximized at treeline.

6. Ecological Differences
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
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

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.
In alpine and subalpine ecosystems, subsurface runoff can account for up to 90% of the total flow of the basin. Due to high permeability, short flow paths and shallow soils in alpine and subalpine basins, water has little opportunity to react with the soils and vegetation. In addition, this limits the ability of vegetation to uptake atmospherically deposited nitrogen. When plants are not able to consume all of the atmospherically deposited nitrogen, nitrogen saturation may occur, causing surface water acidification. Because of this, it is important that the hydrological interactions (redistribution of snow) between the alpine and subalpine ecosystems is occurring and bringing a new source of 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.
Productivity rates in the alpine ecosystem are decreasing due to the removal of snow and organic material.
Productivity rates in the subalpine ecosystem are increasing because there is an increase of nutrients into the system

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