Can fertilization and stand uniformity affect the growth and biomass production in a Pinus taeda plantation in southern Brazil

Abstract

Silvicultural activities employed during stand development are used to manage the distribution of site resources (light, water and nutrients) to the trees within the stand. Because heterogeneity within forest plantations has been shown to increase the number of dominated trees and decrease stand productivity, the establishment of efficient and productive plantations should presumably include nutrient regimes which ensure readily available nutrients and tree-to-tree homogeneity. The study aimed to evaluate how fertilization and uniformity can affect growth and biomass production in a Pinus taeda plantation in southern Brazil. Clones of loblolly pine (Pinus taeda L; Arborgen GE34) were subjected to two factors: (i) uniformity (U) or heterogeneity (H) of planting; and (ii) fertilization (F) or no fertilization (W) to the plants. Trees were evaluated up to 11.2 years of age. Individual survival (%), diameter at breast height (DBH), total height (H), dominant height (Hdom), basal area (G), stem volume (Vol), mean annual increment (MAI), leaf area index (LAI), uniformity index (PV50), needles, branches, bark, trunk, thick roots, and total biomass were measured. Trees grown under uniform and fertilized conditions showed the highest values of the variable's uniformity index (PV50 index); growth (height, DBH, and LAI), productivity(MAI and stem volume), and biomass (stembark, stemwood, branches, coarse roots, and total) compared to trees grown under heterogeneous and unfertilized conditions. Our results show that the productivity of fast growing, genetically identical trees can be improved with silvicultural activities which promote uniformity and improve nutrient availability.