Abstract
Long-term studies of the dynamics of managed forests in tropical regions are lacking. This study aimed to evaluate the dynamics of a tropical forest, over a 25-year period, that was experimentally logged in 1987 and 1988 and submitted to three different cutting intensities. All trees with diameter at breast height (DBH) ≥ 10 cm have been measured annually since 1990. The three logging intensities that were applied were: light (T1)-trees harvested with DBH ≥ 55 cm; medium (T2)-DBH ≥ 50 cm; and heavy (T3)-DBH ≥ 40 cm. Control plots (T0) were also monitored. The highest mean annual mortality rates (1.82% ± 0.38), recruitment rates (2.93% ± 0.77) and diameter increments (0.30 ± 0.02 cm) occurred in the T3 treatment. Shifts in dynamics of the forest were mainly caused by a striking increase in a fast-growing pioneer species and their high mortality rates. The loss in stocking caused by mortality was greater than to that of replacement by recruitment. The results demonstrated that selective logging altered the natural dynamics of the forest through increased: mortality rates, recruitment and growth rates of the residual trees.
Highlights
The Amazon forest is known as the largest tropical forest in the world [1,2], and is characterized by its different types of vegetation and elevated floristic diversity [3,4,5]
Despite the fact that T1 subjected to low intensity logging, the mortality rate was higher in this treatment than mortality rates in the medium intensity logging
The results demonstrated that the application of different logging intensities to the forest altered the dynamics, increasing mortality rates, recruitment and adding to the increment of the remaining trees
Summary
The Amazon forest is known as the largest tropical forest in the world [1,2], and is characterized by its different types of vegetation and elevated floristic diversity [3,4,5]. The process of forest degradation often begins with poorly planned selective logging, of just a few tree species, known as “high grading.”. These logging operations target high value trees that are more attractive to the timber market. After depleting the stocking of the previously forested site, the remaining vegetation is replaced by non-productive pasture and/or agricultural crops [9], followed by land abandonment. This dynamic of deforestation has led to Forests 2019, 10, 89; doi:10.3390/f10020089 www.mdpi.com/journal/forests
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