TROPHIC ORGANIZATION OF BIRD ASSEMBLAGES IN OAK FORESTS DURING POST-CLEARCUT SUCCESSION IN SOUTHWESTERN BELARUS

Abstract

Studying the trophic structure of bird assemblages is an important tool for assessing functional diversity and stability of forest ecosystems. To identify patterns of transformation in the trophic structure of bird communities during secondary (demutation) succession in oak forests of southwestern Belarus. Field studies were conducted from 1995 to 2017 using line transect surveys across six stages of restorative succession (from recent clear-cuts to mature forest). Data analysis was performed using cluster analysis (Morisita – Horn index) and the Mantel test. A characteristic feature of early successional stages (1–9 years) is the dominance of phytoentomophages and insectivores employing ground foraging strategies (78,2 – 90,9 % of total abundance). As the forest stand develops, the proportion of species foraging in tree and shrub canopies and on trunks increases to 41,3 and 6,9 %, respectively. During the breeding season, invertebrates constitute the primary component of the diet across all successional stages (54,6 – 93,6 % of total abundance). However, at early successional stages, phytoentomophages contribute substantially to total biomass. Cluster analysis revealed a clear separation of bird assemblages into two groups: early post-clearcut stages (1–9 years) and established forest communities (30–150 years). A strong positive correlation was detected between the trophic structure of bird assemblages and the distribution of species across foraging strata (r = 0,825, p = 0,003). The trophic structure of bird assemblages serves as a reliable indicator of the successional status of oak forests. The findings support the necessity of maintaining stand structural heterogeneity to preserve the functional diversity of avian fauna under sustainable forest management practices.