Advanced Search

projects

ITEX: International Tundra Experiment - impacts of experimental warming and climate variability

imageThe International Tundra Experiment is a network of researchers examining the impacts of climate change on tundra vegetation throughout the Arctic, Antarctic and Alpine regions of the world. The goals of the networks are to document, understand and forecast changes in the tundra biome. Most members of the network do research at sites established in the early 1990s using standardized measurement protocols and a common warming experiment. The power of the network allows researchers to pool their data and make statements about the fate of the tundra biome as a whole. The four main areas of activity as part of the International Polar Year are: 1 vegetation change; 2 changes in the timing of key biological events (phenology); 3 changes in nutrient cycling; and 4 changes in carbon balance. Each of these areas is described below with a photograph and caption.

1. Vegetation Change

image

The vegetation of the tundra has been changing in recent years.  Earlier synthesis activities suggest that shrubs and tall grasses will replace lichens and mosses.  These changes will lead to a short-term decline in species diversity and an increase in the height and complexity of the plant canopy which as the potential to significantly change the energy balance for the tundra biome.  Documenting and understanding these changes is critical to efforts to model the energy balance of the Arctic.

2. Changes in the timing of key biological events (phenology)

image

With warming we have seen earlier leaf and flower emergence of many species.  These changes in when plants become active have far reaching impacts on the animals and the energy balance of the tundra biome.  As researchers model these changes we are better able to predict the impacts on caribou herds and migrating birds.  The initiation of growth also has the potential to change the carbon balance of the region.

3. Changes in nutrient cycling

image

Soils of the tundra are generally rich in old organic matter.  As the region warms these soils are expected to release carbon in the form of carbon dioxide and methane due to increased microbial activity.  Estimates suggest that carbon release from tundra soils could equal annual emissions from fossil fuel burning.  However tundra plants are also expected to grow more and absorb more carbon from the atmosphere.  Thus understanding the balance of these two factors is critical to understand the carbon balance of the region.

Warming is believed to increase the breakdown of organic matter and increase the fertility of tundra soils.  Poor nutrient availability is widespread within the tundra biome and increasing soil fertility could explain observed increases in plant growth and changes in the abundance of some plant species including shrubs. 

4. Changes in carbon balance
image

Soils of the tundra are generally rich in old organic matter.  As the region warms these soils are expected to release carbon in the form of carbon dioxide and methane due to increased microbial activity.  Estimates suggest that carbon release from tundra soils could equal annual emissions from fossil fuel burning.  However tundra plants are also expected to grow more and absorb more carbon from the atmosphere.  Thus understanding the balance of these two factors is critical to understand the carbon balance of the region.