Multi-scalar spatial modeling of northern forest dynamics: Foundations, theories, and applications.

摘要

This dissertation describes the development and analysis of a new forest dynamics model. The NORTHern W&barbelow;oodland D&barbelow;ynamics S&barbelow;imulator (NORTHWDS) was designed to spatially model forest pattern and process for the northern Lake States, and to incorporate multiple spatial scales. While ecologically detailed, this stand table-based model is sufficiently parsimonious to be able to simulate 100s to 1000s of hectares for centuries. Processes like tree regeneration, growth, and mortality, herbaceous and shrubby competition, biogeochemistry, carbon cycling, edge effects, and climatic influences are incorporated in NORTHWDS. Wind disturbance and white-tailed deer browsing were also included to help forecast stand and landscape dynamics under managed and unmanaged scenarios. Preliminary results suggest that NORTHWDS can reliably predict long-term forest ecosystem responses to succession and disturbance. NORTHWDS was also applied to test the effectiveness of a managing-for-old-growth strategy, with results indicating that this type of management can provide improvements over traditional even- and uneven-aged harvest systems in desirable old-growth attributes like aboveground live biomass and coarse woody debris patterns. The results of the NORTHWDS developmental and application chapters were then synthesized to produce a new conceptual approach to landscape simulation that incorporated space, multiple scales, and a hierarchical design. A user's guide, the source code, and model defaults complete this dissertation.