Atlantic forest tree species responses to silvicultural practices in a degraded pasture restoration plantation: from leaf physiology to survival and initial growth.

摘要

Deforestation has led to ecosystem degradation in many tropical regions. Re-establishment of native tree species on degraded land presents challenges due to environmental stressors such as water and nutrient limitations, particularly from weed competition. Ecophysiological studies can help assess responses of native tree species to silvicultural practices and improve our understanding of processes that influence their establishment and growth. Silvicultural treatments borrowed from commercial tree plantations such as greater nutrient applications and complete weed control can improve best silvicultural practices in forest restoration. Two contrasting silvicultural treatments, "traditional" based on common management practices for reforestation of native trees and "intensive" based on commercial plantation silviculture, were evaluated based on tree mortality, biomass, photosynthesis, chlorophyll content, soluble proteins, and nutritional status of 20 native Brazilian species, 2.5 years after planting. Intensive silviculture increased tree survival by 20%, showed higher aboveground biomass from 13% to 7-fold and increased photosynthesis of ~20% from 15.8 micro mol m-2 s-1 to 18.7 micro mol m-2 s-1, compared to traditional silviculture. Total soluble proteins were 14% higher with 6.7 micro g cm-2 in intensive silviculture compared to 5.9 micro g cm-2 under traditional silviculture. Eighty percent of trees showed greater N content, with a 13% higher average than under traditional silviculture (2.60 g m-2 versus 2.92 g m-2). Average values of chlorophyll A, B, and total were ~8% higher under intensive silviculture, but not significantly different between treatments. Overall, intensive silviculture provided a positive impact on the restoration plantation. During the initial years of plantation establishment, intensive silviculture methods were effective in leading to significant increases in growth and survival.