Clearcutting and Forest Fragmentation: Dismantling the cycle.
Sawyer cutting down Pau Amarelo in an experimental harvest plot
at a Low Impact Logging research site in the Amazon Basin, Para, Brasil.
Photo Chas Zartman
Deforestation rates in tropical areas are estimated at 15 x 106
hectares annually , and nowhere are forests being cut at a faster rate
than in the Amazon Basin (Whitemore 1997). Although research has
pointed to the numerous impacts of tropical deforestation on global Carbon
cycles , native biodiversity, population structure and community composition
of forest taxa (see Laurance et al., 1997), little is known as to its global
impact on nitrogen fixation rates . As mentioned in the Introduction,a
recent research conducted in a tropical rainforest estimated that for the
average understory leaf index presented in the study, annual nitrogen input
per year ranges between 2 and 5 kg of Nitrogen per hectare (Freiberg 1998).
At present rates of deforestation, loss of Nitrogen fixed above ground
per year could range between
30 x 106 to 75 x 106 kilograms. Although
this should be considered a rough estimate, such values illustrate the
potential importance that epiphyllous organisms contribute to nitrogen
cycling, as well as the necessity to manage forests to sustain such life
forms.
The Amazon Basin harbors the world's largest remaining contiguous tropical
forests in the world. Pictured above is a Brazilian forester at Sede
Cauaxi near the logging town of Paragominas, Para, Brasil.
Photo Chas Zartman
