População de Heteropsis Spp. Kunth (Cipó Titica) na Floresta Nacional do Tapajós.

Abstract

The present study aimed to analyze the ecological aspects of Heteropsis spp. Kunth, titica vine, in an area submitted to forest management. The study was conducted at Tapajós National Forest (FLONA Tapajós), in two Work Units (UTs 3 and 15), of the Annual Production Unit (UPA 11). Each UT is divided into blocks of 250 m x 250 m, which are the sample units. For the inventory of titica vine host trees, a total of 14 blocks were performed in UT 3 (87.5 ha) and 19 blocks in UT 15 (118.75 ha). The parameters recorded were: diameter at 1.30 m of soil (DBH), total height (Ht), stem quality (QF1 - straight, QF2 - slightly tortuous, QF3 - tortuous), regional name and geographical coordinates. The mature and immature aerial roots of titica vine were counted. The mature roots were collected and the mass measured, in kilograms, per host tree. After the collection was finished, the bark was removed from the roots and the mass was gauged in order to obtain the yield of the raw material. All host trees were counted and grouped according to their botanical families. Density of host trees in different DBH and Ht class centers was related. The titica vine production was determined by the root count (mature and immature) present in each host and by the mass of the mature roots. The ratio of DBH and Ht of host trees was determined with the mass of mature roots with bark, considering 15 trees of different sizes of diameter and height, per class of DBH and Ht, which were classified into three size classes: small (10 cm ≤ DBH <40 cm and 5 m ≤ Ht <15 m), medium (40 cm ≤ DBH <70 cm and 15 m ≤ Ht <25 m) and large (DBH ≥ 70 cm and Ht ≥ 25 m ). It was evaluated as to the difference in the amount of titica vine, in kilograms, in each type of stem. The Pearson correlation (r) was used to infer about the host tree variable that most influences the production of titica vine, in order to use it in the fitting of mathematical models to estimate its production. Five mathematical models were adjusted using CurveExpert Professional version 2.6.5, in which the criteria for choosing the best model were: adjusted coefficient of determination in percentage (R²aj%), standard error in percentage (Sy.x%) and residual graphical distribution. The spatial distribution of titica vine was made based on the Ripley K function using R version 3.1.2. A total of 337 host trees for titica vine were identified and measured, with a mean density of 1.65 tree-1, distributed in 88 species belonging to 35 families. Trees with DBH < 30 cm are the ones that host more titica vine plants (p-value = 9.9488 x 10-8). Trees with 10 m ≤ Ht <15 m host more titica vine plants, when compared to Ht trees ≥ 25 m (p-value = 0.0059). Trees with higher DBH and Ht are the ones with the highest amount of titica vine roots. No difference was observed in the production of titica vine mature roots, expressed in kilograms, in the different categories of stem quality (p-value = 0.160). The individuals of titica vine showed 585 roots.ha-1, leading to an average yield of 2.1 kg.ha-1 of titica vine with bark, after moisture loss and bark removal the production declined to 0.6 kg .ha-1. The density of host trees was the variable that presented the highest Pearson correlation (r = 0.88). The simple linear equation was the one that presented the best results to estimate the production of roots with bark, with R²aj% = 96.03, Sy.x% = 24.50 and the graphical distribution of the residues behaved uniformly around the axes of the abscissa. The spatial distribution of the titica vine tends to be aggregated.