From: aceska@CUE.BC.CA (Adolf Ceska)
Newsgroups: bionet.plants
Subject: BEN # 43
Date: 23 Jan 93 16:25:00 GMT
Distribution: bionet


BBBBB    EEEEEE   NN   N          ISSN 1188-603X
BB   B   EE       NNN  N
BBBBB    EEEEE    NN N N          BOTANICAL
BB   B   EE       NN  NN          ELECTRONIC
BBBBB    EEEEEE   NN   N          NEWS

No. 43                            October 1, 1992

Address: aceska@cue.bc.ca         Victoria, B.C.
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BIODIVERSITY IN THE MANAGED LANDSCAPE: THEORY AND PRACTICE
CONFERENCE IN SACRAMENTO JULY 13-17, 1992    (PART 3 of 5)
From: Evelyn Hamilton <ehamilton@galaxy.gov.bc.ca>


                     IV. SPECIES DIVERSITY

Species  expirations and extinction rates. Alwyn Gentry, Missouri
Botanical Garden, St. Louis, MO

He estimated that there are 10K species of  undescribed  vascular
plants.  In  North  America  60  plants  are thought to have gone
extinct in recent years. In the tropics 100K species/year may  be
going  extinct. This rate may be 1000 times background extinction
rates.

He discussed the situation in Rondonia in Brazil where only 2% of
the coastal forest remain,  and  the  application  theories  from
island  biogeography  to  tropical  deforestation. These theories
state that on smaller islands there will be fewer  species.  When
you  lose  90%  of  the area, you lose 50% of the species. On the
basis of this, projected extinction in the tropics is 12-15%  per
year with a loss of 2/3 of the tropical species by the end of the
next  century.  This rate will exceed the Cretaceous mass extinc-
tion rate.

Tropical species are more localized  in  their  distribution  and
endemism  is  common.  Evolution may be random because of the in-
fluence of founder effects and genetic drift rather  than  selec-
tion.  Speciation  may occur in 15 years. If speciation is rapid,
so likely is extinction.


Population viability
Bruce Marcot, USFS Portland, OR

He stated that 1/10 of the world's birds and 1/3 of  the  world's
parrots are threatened.

There  are legal mandates, such as the National Forest Management
Act which define a viable population. Questions about the  degree
of certainty, area and time frame exist.

He  outlined  a  process that could be used to ensure that viable
populations were sustained. Steps include:

 1. Identify species of concern, level  of  protection  required,
    extent of habitat, rarity, etc.

 2. Coordinate planning among agencies.

 3. Develop species-environment tools.

 4. Integrate models into the planning process.

 5. Develop range of management strategies.

 6. Conduct viability analysis.

 7. Evaluate results - effects of alternatives.

 8. Decide what to do.


Conservation of plant species diversity
Bruce Pavlik, Dept. Bot., Mills College, Oakland, CA

Globally,  there  are about 20K rare plants. Many of these are in
the tropics. Over 70% of all rare plants have less than 5 popula-
tions.

Reserves can be used to conserve plant species. There need to  be
clear  objectives  for  each reserve. Each reserve should be sub-
jected to manipulation experiments (e.g. fire, herbivory, etc) on
at least a small portion of the site. In the absence  of  manage-
ment and the knowledge upon which to base that management you may
lose the species you hope to protect in a reserve.

He  recommends  to  develop  a  program to monitor the management
practices. All monitoring must be demographic  (i.e.  focused  on
determining  what  is  happening  to the individuals). There is a
need for trend analysis  (which  is  mechanistic,  synthetic  and
predictive),  and  factor  resolution  (studies  of  competition,
mortality, effects of management activities)  to  determine  what
species are declining and what action is needed.


Conservation of forest vertebrates
Marty Raphael, USFS Olympia, WA

General trends in W. Oregon throughout forest development are:

 1. more  mammal  diversity  at  first  and  then it declines and
    increases in oldest stages,

 2. reptiles only in young forests,

 3. amphibian diversity increases with stand age.


We need to look at habitat availability in different seral stages
from the perspectives of historical, present, likely  future  and
worst case levels.

Alternative approaches that can be taken include:

 1. maximizing  the  minimum  abundance of all species (i.e. rare
    species will be sustained at their highest possible levels),

 2. maximizing the joint probability of occurrence of all species
    being viable,

 3. maximizing the sum of all these probabilities.


Creating policy on species diversity
Michael Bean, Environmental Defense Fund, Washington, D.C.

He gave a very interesting and clear talk that focussed primarily
on Endangered Species Act and made the following points:

 1. Most species conservation policy is still  focused  on  those
    species that are at risk of extinction.

 2. Only  plants  and  animals  are  covered  in legislation (not
    fungi, etc).

 3. Many more species are in peril that the 700  species  on  the
    threatened  and  endangered list. It is likely that 4-5x this
    number are eligible for protection.

 4. Recovery efforts are currently driven by the degree  of  con-
    flict and public support.

 5. Other  criteria  that should be considered in determining the
    need for species protection include whether the species is
    a) likely to play a key role in ecosystem functioning,
    b) has indicator value for ecosystem health,
    c) is related to crop species, or
    d) has traditional medicinal value.

 6. We need to determine when a species is endangered, i.e.  what
    the threshold is.

 7. The  current  legislation  requires  that listing be based on
    biological considerations not economic ones.

 8. There is evidence that protection is being withheld too long.
    Half of the plants added in the last 7 years  had  less  than
    100  individuals  when  listed and animals generally had less
    than 1000 individuals when listed. Probabilities  of  extinc-
    tions and timeframes are not articulated.

His  conclusion  was  that  we  need  to focus on the genetic and
community diversity as well as species diversity.