Necromassa e fauna de insetos saproxílicos associada a Floresta Ombrófila Mista

Abstract

The objective of this research was to evaluate the stock, methods of estimation and to describe spatial patterns distribution of coarse woody debris and its relation with the presence of saproxylic Coleoptera in a Atlantic Forest fragment biotype, Araucaria Forest typology located in the Irati National Forest (FLONA), south-central of Paraná, Brazil. For that, 10 ha were selected, inserted in a 25 ha plot of permanent plots installed in the forest fragment in 2002, in which all pieces of fallen dead wood and standing dead tree with diameter ≥ 10 cm and length ≥ 1 m were sampled. Volume, mass and carbon were estimated for different woody residues types (log, brunches, whole downed dead tree and standing dead tree) and decomposition classes by fixed area and line intercept methods. The spatial distribution patterns of dead wood were analyzed using the Ripley K function. The relationship between dead wood quantity and quality and saproxylic beetles abundace, were analyzed with the application of generalized linear models (GLM) and multivariate analysis of Non-Metric Multidimensional Scheduling (NMDS). For suchanalyzes, the Coleoptera were captured during a period of 25 months using flight interception traps allocated in pieces of downed dead logs and standing dead tree. The main results were: Dead wood stocks in the analyzed fragment were 189 pieces.ha-¹, 24.96 m³.ha-¹ (Volume), 9.23 Mg.ha-¹ (Mass) and 3.94 Mg.ha-¹ (Carbon); Most of the woody detritus were represented by whole fallen dead tree and log of small diameter (less than 25 cm), and about 40% presented intermediate stage of decomposition; downed dead wood with diameter ≤ 25 cm and total showed small aggregate spatial distribution pattern, and standing dead trees and downed dead wood with diameter ≥ 25 cm showed random pattern; The most abundant saproxylic Coleoptera identified were Nitidulidae, Scarabaeidea, Cerambycidae and Staphylinidae. The abundance of these families showed significant relation with meteorological variables and quantity characteristics (m³.ha-1, m³ and N), size (diameter) and quality (degree of decomposition) of dead wood. In view of the presented results it is possible to conclude that: the fixed area method of 0.25 ha size proved to estimate the Dead wood variables with precision (CV around 50% and sample error below 25%); The line intercept sampling method was efficient for the estimation of the volume, mass and carbon variables of dead wood in the sampled area, in the operational aspects requiring a smaller sampling effort, as well as a shorter sampling time, compared to the fixed area method, However the method also tended to overestimate stocks; The evaluated fragment presents potential capacity to store significant amounts of carbon; Dead wood do not present a single distribution pattern and express a close relation with the distribution pattern of their dynamics in the analyzed fragment; The quantity and quality of dead wood influences the abundance of saproxylic beetles in the Irati FLONA Araucaria Forest Fragment.