A model of northern treeline dynamics in response to transient changes in climate
- Univ. of California, Berkeley, CA (United States)
In order to predict the future distribution of boreal vegetation, we developed what, to our knowledge, is the first model of ecosystem change in response to transient changes in climate and disturbance regime over the next 50-500 yr. The model develops scenarios of change in disturbance regime and ecosystem type in what is currently arctic tundra in response to GCM-based scenarios of climate change. Seed availability, tree growth rate, and probability of fire were the model parameters that most strongly influenced the balance between tundra and boreal forest during transitional climates. The rate of climatic warming strongly affected the time lag between climate change and the simulated ecosystem response but had less effect on the rate or pattern of ecosystem change. The model calculated that a ramped change of 3[degrees] in the next century (corresponding to average rate of warming predicted by GCMs) would lead to a 150 yr lag preceeding any change from tundra to forest, followed by rates of forestation of up to 6-12% per decade. The model predicted that tundra would first be invaded by conifer forests, but that the proportion of broad-leafed deciduous forest would increase as climate continued to warm due to increased fire frequency. The pattern of climatic warming had strong effects on simulated rates of conversion from tundra to forest. Rapid step changes in climate or increases in climatic variability both promoted more rapid ecosystem change than did ramped change in climate or climatic oscillations, particularly when oscillations were long relative to the time required for tree growth to reproductive maturity.
- OSTI ID:
- 7264620
- Report Number(s):
- CONF-940894--
- Journal Information:
- Bulletin of the Ecological Society of America; (United States), Journal Name: Bulletin of the Ecological Society of America; (United States) Vol. 75:2; ISSN BECLAG; ISSN 0012-9623
- Country of Publication:
- United States
- Language:
- English
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