Captive propagation (ex-situ cultivation and propagion) is a tool used
by some conservation programs, such as the Center for Plant Conservation
(CPC) program centered at the Missouri Botanical Garden and 25 participating
botanical gardens located across the USA. The Atlanta Botanical Garden is one
of these participating gardens. Each garden deals with conservation of a
select number of plants from their local phytogeographic region. The Atlanta
Botanical Garden therefore deals with several CP species. I have worked in
association with the CPC program at the Desert Botanical Garden, and have had
a chance to observe their techniques and priorities of ex-situ conservation.
While ex-situ conservation bears some similarities to commercial and hobby
plant cultivation, the CPC cultivation priorities differ markedly in many
important ways. The conservation program places a heavy emphasis on seed
banking and seed storage techniques. The program recognizes the importance
of genetic diversity, which is maintained by preserving the largest possible
number of genetically different individuals. Because the number of
individuals is maximized, the number of different taxa being conserved is
minimized. This differs from hobby collections, where the number of taxa
grown is maximized, at the expense of the number of individuals per taxon.
Controlled crosses are performed on growing plants to produce seed. Self-
fertile plants are also outcrossed, so as not to rely on self-pollination.
Wherever possible, the CPC plants are grown outdoors to minimize selection
for greenhouse growing conditions. The CPC gardens focus on local species,
while hobby and commerical growers tend to focus on interesting exotics.
For taxa with good seed longevity, the seed bank itself is considered the
primary conservation element, and the actively growing plants are
grown up as a test of seed viability. The growing collections are also
used for research, especially on pollination and seed set.
The CPC program is designed to "back up" wild populations, should catastrophe
decimate the wild stand(s). CPC is greared for reintroduction of plants to
the wild as the end goal. Reintroduction plans are not part of commercial
or hobby cultivation. Though some say commercial and hobby cultivated plants
are suitable stock for reintroduction, these plants have not been cultivated
in a manner that enhances their reintroduction potential. In fact, long-term
maintenance in cultivation is likely to reduce that potential. While it is
not impossible that a hobby-grown plant might be successfully reintroduced to
original habitat, any success would be due to luck, and not due to design.
For this reason, commercial and hobby collections cannot be regarded as
conservation of natural biodiversity.
> I'm still curious as to why there is a "one side thinks this, the
> other side thinks that" tone in this dialogue. Like the past
> "scientists vs. hobbyists" thread the artificial barriers some
> are trying to erect are quite inaccurate. My guess is the
> overwhelming majority of readers of this list, who have not
> yet written on this topic, favor both strategies for preservation
> as I do.
It is important for hobby growers to understand that commercially propagated
plants and hobby collections do not represent conservation material. I
realize many growers may be entertaining the idea that their collections
do have conservation value. Some may not wish to give up this idea because it
would seem to de-value their collection. Many people have gained an interest
in conservation as a result of exposure to plants through hobby collecting.
It is an important next step to realize that the collection itself is not an
important conservation resource, and that they may personally work for
conservation in other ways, which have real value. Techniques of ex-situ
cultivation do have promise for conservation. These techniques may in some
ways resemble hobby cultivation, but a closer examination shows a very
different set of procedures and priorities differ between conservation and
hobby collection. Again, I think it is important to understand how the
science and the hobby differ, and not be confused by the minor points
of similarity.
Cultivation of plants is valuable for keeping plants IN cultivation. If
desirable plants are available commercially and through trade, this has
promise to limit collection from the wild. To the extent that cultivated
plants are selected for cultivation, they become easier to grow and have
their own value for continued cultivation. Some people have bemoaned
the fact that some species of Nepenthes have gone extinct before they've
been brought into cultivation. Growers should worry about the species of
Nepenthes already in cultivation, and be sure they are not lost. It may
be more valuable to grow plants which are rare in cultivation (as opposed
to rare in the wild) to ensure these rarely grown plants are not lost
from cultivation. The wild sources may not always be available as a
source for replacements.
As a side note, I think it would be confusing to label the perpetuation
of cultivated material as "conservation", because this can lead to
confusion with the conservation of wild biodiversity. For example, I don't
think the preservation of rose cultivars is best called "conservation", but
perhaps some people are using that term. Concepts like "conservation" and
"endangered species" have been given high value and are now applied as labels
in many inappropriate ways, ie "lumbermen are an endangered species".
Michael Chamberland