------ Forwarded Message
From: Phillip Owen <owen@soft.co.za>
Date: Wed, 20 Sep 2006 07:44:24 +0200
To: <sawac@geasphere.co.za>
Subject: Advantages of Mixed Species in Forest Plantations


Source: Farmers Weekly, Issue # 96036
15 September 2006

Although most forest plantations are established as monocultures,
research has shown that there are potential advantages to be gained by
carefully selected species mixture instead of monocultures. Matthew
Kelty of the Department of Natural Resources Conservation of the
University of Massachusetts in the US reviewed recent studies comparing
stand development and productivity of monocultures and mixed species
(polyculture) plantations.

Higher productivity of mixed stands with two types of species can be
ascribed to two interactions: complimentary resource use by species
results from the development of a stratified canopy (and possibly root
stratification), and facilitative improvement in nutrition occurring
where timber species are grown with a nitrogen – fixing species – but
only in combination with complimentary resource use. These mixtures can
also improve economic returns through greater individual tree growth
rates and multiple commercial or subsistence products.

More complex plantation mixtures of between five and 70 species have
been used to restore the ecology of degraded lands. In this case,
different seccession stages of different species combine to reduce the
need for sequential plantings. Further research is needed to examine
many more tree species across a wider range of habitats. - Chris Nel


No MonoCulture!
Yes Biodiversity!


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