Worldwide, large swaths of land lay barren in the
wake of agricultural expansion, and as global forest cover continues to
decline, carbon and water cycles, biodiversity, and human health are impacted.
But efforts to restore abandoned pastures and agricultural plots back into
functioning forest ecosystems are often hindered by high costs and time
requirements. Fortunately, scientists have developed a new method for a more
cost effective solution to forest restoration, the establishment of “tree
islands.”
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Typically, forest restoration involves planting
rows of trees, plantation style, which cover the entire restoration site.
However, a team of researchers led by Rakan A. Zahawi of Las Cruces Biological
Station in Costa Rica and Karen Holl of UC Santa Cruz recently tested an
innovative method known as applied nucleation or the “tree island
method” to facilitate forest recovery. In the tree island method, clusters
of trees are spread out across the site instead of covering the whole
deforested area. For this study, the researchers tested three different
treatments on abandoned pasture plots in Costa Rica: planting tree islands,
plantation style planting, and no planting or what is known as “passive
restoration.”
“We were surprised,” Karen Holl told
mongabay.com, “that the applied nucleation strategy was as effective in
facilitating the natural establishment of forest tree seedlings as planting the
entire area with trees, even though we only planted 27% of the trees in the
applied nucleation treatment.”
The establishment of tree islands, around the size
of 100m2, serves as “activation energy” of sorts. As the trees grow, they
shade out competitive pasture grasses and also attract frugivorous (i.e
fruit-eating) birds that spread the tree seeds around. Once the bird-dispersed
trees reach maturity, they provide habitat for more seed dispersing birds and
animals, which will bring more seeds. Once this ecological process is
jump-started successfully, it should proceed without further intervention.
“There are large areas of degraded lands in
the tropics that are in need of restoration and there simply aren’t enough resources
to do so,” says Holl. “The overarching goal for the tree island
method is that we will be able to restore forest in former agricultural lands
in
a more economical manner so larger areas can be restored with the added
benefit that this restoration approach will create habitat conditions that are
more similar to the forest than planting trees in straight lines.”
Read more at ENN affiliate Mongabay.
Restoring
farmlands image via Shutterstock.
