Protecting primary forests requires protecting secondary forests too!

“I want to convince you we need to go beyond primary forests to
preserve biodiversity”, Robin Chazdon told an audience at the National
Natural History Museum during a symposium on the tropics. Chazdon, a
professor of ecology and evolutionary biology at the University of
Connecticut, has been studying secondary growth forests for over
eighteen years. Secondary forests are those forests in the process of
regrowth after being used for agriculture or logging. In her study
area of NE Costa Rica, many of these forests were converted to
pastures in the 1970s and 1980s, but have since been abandoned.

In her
presentation Chazdon argued that to preserve biodiversity numerous
types of human-impacted landscapes, such as secondary forest, require
attention by the conservation community. Such a statement may seem
obvious when Chazdon points out that 90 percent of the world’s
tropical forests exist outside of protected reserves, but so far there
have been few conservation initiatives focusing on secondary forests,
agroforestry, or other human-modified areas. Perhaps that is because
most human-modified areas in the tropics have largely been considered
hostile to biodiversity. However, a series of studies done in the last
few years have painted a very different picture. In a large sample of
secondary forests from 10-45 years old in Costa Rica, scientists
discovered 90 percent of tree species found in old-growth forest areas
were represented either by seedlings, small trees, or large trees.
Chazdon describes such forests as “works in progress”—the number of
species increase as time goes by, allowing biodiversity to recover
faster than many expected.

A similar study in Jari, Brazil of
secondary forest found less diversity of trees—35 percent of mature
forest species—however Chazdon points out that the study only counted
trees and not seedlings. In addition the study area was relatively
young. Currently, 42 tropical nations have higher areas of secondary
and degraded forest than primary forest, creating urgency as to how
conservation groups and governments should respond to this new trend
of regeneration. While secondary forests are becoming increasingly
important for biodiversity, agroforestry has also proven effective in
retaining biodiversity while in addition serving human needs.
Agroforestry combines tree planting or forest components with the
growth of products for human consumption. In many parts of the world
this is the traditional style of agriculture, practiced for millennia
before modern clear-cutting and industrial agriculture became the
norm. http://news.mongabay.com/2009/0118-hance_secondaryforest.html