BEN # 44
aceska at CUE.BC.CA
Sun Jan 24 03:00:00 EST 1993
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No. 44 October 5, 1992
Address: aceska at cue.bc.ca Victoria, B.C.
BIODIVERSITY IN THE MANAGED LANDSCAPE: THEORY AND PRACTICE
CONFERENCE IN SACRAMENTO JULY 13-17, 1992 (PART 4 of 5)
From: Evelyn Hamilton <ehamilton at galaxy.gov.bc.ca>
V. COMMUNITY DIVERSITY
Biological and ecological processes
Mary Willson, USFS Juneau, AK
Her main point was that units of conservation should be the
interactions between organisms, rather than the specific or-
ganisms. Our research has been limited in terms of time and
space. Evolutionary processes have been ignored. Correlation has
been the focus rather than causation.
We need to understand and conserve interactions including:
1. plant and animal interactions, e.g.
a) bears, salmon and berries,
b) treefall gaps where vegetation structure influences pol-
2. plant and fungi interactions,
3. fungi and tree interactions.
Ariel Lugo, Univ. Puerto Rico Agr. Exp. Stn. Rio Piedras, PR
Many of our problems are social and economic. We need to:
1. use natural resilience and manage sustainably,
2. manage the landscape, using natural succession to aid res-
Tom Spies, USFS, Corvallis, OR
Old growth is ecologically diverse. Disturbance is important at
the patch, mosaic and landscape levels.
Different types of old growth include:
1. Coarse grained type - where wind or fire is the agent of
disturbance. Disturbances are large with patches > 0.1 ha in
a) short lived trees < 250 years e.g. aspen, red alder
b) intermediate lived trees > 250 years e.g. Douglas-fir
2. Fine grained type - more stable systems where the disturbance
is more localized with patches < 0.1 ha. in size -
a) short lived trees <250 years balsam fir, white spruce,
b) intermediate to long lived trees >250 years
Aquatic systems - freshwater and marine
Jack Williams, BLM, Washington, D.C.
In Canada there were 22 threatened or endangered species of fish
in 1989. All of the fish species in the Colorado River are endan-
gered. Over 67% of the fish species in Illinois have declined
significantly. On the west coast 214 salmon stocks are endan-
gered. In the Columbia Basin 19% of the fish species are at high
risk, > 1/3 have become extinct; < 1% of marine habitats are
Introduced species and habitat loss are critical factors con-
tributing to this species declines. In the US less than 2% of the
rivers are in a high quality state.
VI. LANDSCAPE DIVERSITY
Biological conservation at the landscape scale
Reed Noss, Corvallis, OR
Landscapes have pattern of repeated components. Pattern has
effect on species composition. He discussed disturbance regime,
fragmentation and reserve network design and the concepts of
coarse and fine filter. Protection of representative communities
(coarse filter) would protect 80% of the species.
Species are distributed along environmental gradients. Since
plant species migrated at different rates after the ice age,
using communities defined by vegetation to capture all components
of diversity may not be the best approach in times of rapid
We need to consider whole landscape management. Core areas and
linkages are likely important although these ideas have not been
adequately tested. Some moderate level of disturbance will likely
maximize diversity. We need to develop an optimal mix of seral
stages. Reserves should be large enough to be in a steady state.
We need to determine:
1. How big do reserves need to be?
2. How wide should corridors be?
3. What type of human use is acceptable?
4. What are the best habitat mosaics at regional scales?
Scaling issues for biodiversity protection
Scott Pearson, Oak Ridge National Lab, Oak Ridge, TN.
His summary was:
1. Don't focus on a single concept like corridors or patches,
view the landscape as a whole.
2. Don't destroy the natural heterogeneity of the landscape.
3. Don't destroy landscape connectivity.
4. Don't ignore the effects of critical thresholds.
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