Pothole Creek
Study Area
Home Page
Background
On-Site Projects
Related Work
Stand Modelling
Demonstration Area
Site Map
TASS simulation of Pothole Creek - aerial view.
TASS simulation of Pothole Creek - side view.
|
Forest managers are faced with rapid changes in the forest resource and the
expectations of the public, making forest management in British Columbia increasingly complex. Experience and long-term field trials based on traditional approaches from Europe and other countries can no longer guide their decisions as they have
in the past. We now have to rely on our ability to understand and model the biology
of the resource, then incorporate the needs and aspirations of the public in terms of
environmental resilience and a sustained flow of benefits.
Growth and yield models have been essential tools in forest
management. These decision support tools have evolved to become very complex. They not
only provide estimates of the future yield of forests, but can estimate the financial
return and wood quality of a particular harvest, as well as the effects of
silvicultural practices, insect infestations, differing site index and natural variation
in the growth characteristics of trees on future harvests.
The Stand Development Modelling Group (SDMG) of the B.C.
Ministry of Forests and Range developed the yield model TASS (Tree and Stand Simulator) to model the
growth and yield of even-aged stands. It is a spatially explicit model which simulates the growth
of individual trees in a
three-dimensional space in the computer. Tree height, bole diameter, branch length,
crown form and foliage are updated annually. These measures can be affected by intertree competition
(characterised by the proximity and size of neighbours), thinning, pruning, animal damage,
site characteristics, defoliation, mortality, fertilization and natural variation in tree
growth. It has been calibrated to model growth and yield for even-aged stands of coastal
(Douglas-fir, hemlock, western redcedar, Sitka spruce) and interior (white spruce, lodgepole pine Douglas-fir hemlock) species of commercial importance.
SDMG is currently expanding TASS to include uneven-aged
and mixed species
stands. The new model will incorporate sub-models designed to simulate components of
uneven-aged systems that are not included in the even-aged model. This version
of TASS will provide decision support for foresters responsible for managing these
structurally diverse
stands and developing new methods of harvesting. It will also give them insight into the biology of
uneven-aged forests.
The development of TASS to incorporate more complex stands like uneven-aged
dry Douglas-fir requires new approaches in stand modelling and a great deal of new programming.
Modelling Uneven-Aged Stands |
