HR: 0800h
AN: B51B-0377 [Abstracts]
TI: Modeling the Emergent Impacts of Harvesting Acadian Forests over 100+ Years
AU: * Luus, K A
EM: niinaluus@gmail.com
AF: Department of Earth Sciences and Environmental Programmes, Dalhousie University,
Oxford Street, Halifax, NS B3V1H3, Canada
AU: Plug, L J
EM: ljp@dal.ca
AF: Department of Earth Sciences and Environmental Programmes, Dalhousie University,
Oxford Street, Halifax, NS B3V1H3, Canada
AB:
Harvesting strategies and policies for Acadian forest in Nova Scotia,
Canada,
presently are set using Decision Support Models (DSMs) that aim to
maximize the
long-term (>100y) value of forests through decisions implemented over
short time
horizons (5-80 years). However, DSMs typically are aspatial, lack
ecological
processes and do not treat erosion, so the long-term (>100y) emergent
impacts of
the prescribed forestry decisions on erosion and vegetation in Acadian
forests
remain poorly known. To better understand these impacts, we created an
equation-based model that simulates the evolution of a ≥4 km2
forest in
time steps of 1 y and at a spatial resolution of 3 m2, the footprint
of a
single mature tree. The model combines 1) ecological processes of
recruitment,
competition, and mortality; 2) geomorphic processes of hillslope
erosion; 3)
anthropic processes of tree harvesting, replanting, and road
construction under
constraints imposed by regulations and cost/benefit ratio. The model
uses
digital elevation models, parameters (where available), and calibration
(where
measurements are not available) for conditions presently found in
central Cape
Breton, Nova Scotia. The model is unique because it 1) deals with the
impacts of
harvesting on an Acadian forest; and 2) vegetation and erosion are
coupled. The
model was tested by comparing the species-specific biomass of long-term
(40 y)
forest plot data to simulated results. At the spatial scale of
individual 1 ha
plots, model predictions presently account for approximately 50% of
observed
biomass changes through time, but predictions are hampered by the
effects of
serendipitous "random" events such as single tree windfall. Harvesting
increases the cumulative erosion over 3000 years by 240% when
compared to
an old
growth forest and significantly suppresses the growth of Balsam Fir
and Sugar Maple. We discuss further tests of the model, and how it
might be
used to investigate the long-term sustainability of the recommendations
made by DSMs
and to better understand the relationship between vegetation, erosion,
and
forest management strategies.
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0466 Modeling
SC: Biogeosciences [B]
MN: 2007 Fall Meeting