CRESCIMENTO E PRODUÇÃO EM POVOAMENTOS DE Pinus taeda L. DANIFICADOS POR MACACOSPREGO E SEUS IMPACTOS ECONÔMICOS

Abstract

The objective of this research was to evaluate the growth losses and the economic consequences produced by Capuchin monkeys (Sapajus nigritus) in Pinus taeda plantations. The data were collected in two stands of this species of the same age, 18 years old, planted in the Center-South region of the Paraná state, Brazil which received similar silvicultural treatment and belonged to the same site class, one of them being damaged and the other not damaged by the Capuchin monkeys. In a first phase of the field work, two plots with area of one hectare each were installed and measured in the two stands, measuring the diameters and height of all the trees. In a second phase, 80 trees (40 trees damaged and 40 trees not damaged by the Capuchin monkeys) were selected and felled, contemplating all the diametric variability. In these trees, the volumes were obtained by the Smalian formula, generating data for adjustments of volume equations, identifying and measuring the extent of damages on the 40 trees damaged, classifying them as ringed and windowed. In the same trees, 663 discs (8 discs in each non-damaged tree and 9 discs in ringed trees) were used for the application of the complete stem analysis in order to reconstitute the past growth of the variables diameter, individual basal area, height and volume, common form factor at the various ages, besides generating data of the profiles of the stem at the various ages, with which the fifth degree polynomial were adjusted to evaluate the evolution of the assortment. With these taper functions, assortment grouped by classes of age were estimated for the first thinning (8-11 years), second thinning (12-15 years) and with a clear cutting (16-18 years). The ChapmanRichards model was used to describe the production curves and the current annual increment curves (CAI) and mean annual increment (MAI) curves. The Regazzi test (2013) was applied to the production curves to verify the possibility of grouping or not the data of non-damaged and damaged trees (two groups: ringed and windowed). The assortment of wood at 18 years of age for non-damaged trees was compared to the assortment for damage trees, as well as the income produced. To adjust the volume equations in trees damaged by Capuchin monkeys, different groupings of the data were tested according to the type of damage (ringed and windowed). The identity test (Graybill test, 1976) was used to verify the possibility of adjustment of damaged and undamaged trees by single-pronged Capuchin monkeys in a single model or whether there is a need to adjust them separately, as well as to verify the possibility of adjustment of trees with windowing-type damages and ring-type damages in a single model. The models tested to estimate the individual volume of Pinus taeda trees damaged and undamaged by monkey-monkeys proved to be adequate, with some advantage for the Meyer model. The identity test indicated that it is necessary to adjust the volume equations specific to damaged and undamaged trees. He also pointed out that, for damaged trees, adjustments should be made, separately, for ringed and windowed trees. The results generated by Complete stem analysis indicated that the first damage occurred between 5-6 years of age, but most occurred between 7-8 years. Height was the variable most affected by the damage of the Capuchin monkeys, reducing its growth potential by approximately 50% for ring-like damages and, consequently, affecting volume. The windowed trees presented a higher individual medium volume compared to not damaged group. This happened due to the cicatrization process of the fissure caused by the monkeys as well as due the excentricity of the section where the damage occurred. The Regazzi test (2013) showed a difference between the growth curves for the variables diameter (dbh), height (h) and volume (v), and it was not possible to use the same equation for the three groups of trees evaluated (ringed, windowed and non-damaged).The curves produced with the taper functions at various ages, as well as the form factor by age, allowed to describe the average evolution of the stem taper to nondamaged, windowed and ringed trees, and it was verified that the damaged trees became more cylindrical with the age than the trees not damaged. The damages to the wood were mainly concentrated in the assortments destined to pulpwood (8-18 cm) and sawmill 2 (18-25 cm). In the clear cutting, the main product obtained for the damaged and non-damaged stands was assigned to sawmill 1 (25-35 cm). The difference between the income obtained for the damaged stand and for the non-damaged stand was 12%, which is equivalent to R$ 5,426.48.ha-1.