Abstract
The magnitude of export of nutrients with forest harvest depends on the adopted waste management and, above all, on the distribution of biomass and nutrients in the trees, which is conditioned by the genetic potential and the species composition of forest stand. The objective of this study was to quantify the biomass and nutrients of the trees and evaluate the effect of the management of harvest residues on the removal of nutrients from pure and mixed plantations of Pinus sp.. The study areas are located in the Southwest region of Bahia State, Brazil. Twenty trees per species were selected and felled under both planting conditions. The biomass quantification was performed by the destructive method. Samples of the tree components were analyzed for N, P, K, Ca and Mg contents. The total biomass was 75 Mg ha-1 for pure planting, and 81 Mg ha-1 for mixed planting, with wood and bark as the most representative compartments. Removal of the wood with bark led to too much nutrient removal, reaching a further 50% of the total contained in the biomass. Mixed planting has been shown more prone to export P, K and Mg. For both plantations, 64% of the N, P, K, Ca and Mg are in other components of the aerial part of the tree, and not in the wood. The elements that represent the highest risk for maintaining productivity are Ca and Mg.
Highlights
Brazilian forestry sector has become recently one of the most relevant in the global scenario in economic terms, with 7.8 million hectares of planted forests
The biomass distribution in different compartments of trees showed greater participation of the stem, which represented more than 56% and less contribution of the needles, which constituted 5 to 7% of the total biomass (Table 3)
The biomass results in Mg ha-1 observed in both plantations are lower than those found by Sette Júnior et al (2006) for Pinus taeda with 12 years of age in Santa Catarina State - Brazil (148 Mg.ha-1), and Corrêa and Bellote (2011) for Pinus caribaea with 11 years of age in the state of São Paulo - Brazil (264 Mg.ha-1)
Summary
Brazilian forestry sector has become recently one of the most relevant in the global scenario in economic terms, with 7.8 million hectares of planted forests. Species of the genus Pinus are among the most used in the country, occupying 1.6 million hectares (IBÁ, 2017). Much of this representativeness is linked to the genus' rusticity and tolerance, making possible its adaptation to low fertility soils and wide use of wood. Growing forest species, such as those of the genus Pinus, show intense absorption of nutrients from the soil and, as a consequence, accumulate large amounts of biomass. For these reasons, the total or large-
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
