Compact vs. Linear: Effects of Forest Structure, Patch Shape and Landscape Configuration on Black Alder Macromoth Communities

Landscape configuration and forest structure assume an increasing importance as determinants of animal communities. This paper focused on nocturnal Lepidoptera inhabiting alder patches in the Sila National Park, Italy. According to their shapes, patches were divided into linear and compact ones to disentangle the roles of forest structure and landscape configuration in determining the composition of nocturnal Lepidopteran communities at different observation scales. We used the Mann–Whitney test for medians and Shannon diversity, equitability, Fisher’s alpha, and nestedness to test differences among moth communities. We found that compact patches inhabited richer and more abundant communities. The abundance-based Correspondence Analysis showed moth communities clustered according to woodlot shape, except a compact woodlot with a linear-like moth community because it was entirely surrounded by grasslands. Percentage of forested area and abundance and composition of communities were positively correlated at 50 and 200 m buffers, while correlations were absent at smaller and larger buffers. Our results demonstrated that a width of 50 m may not be sufficient to give proper functionality to the wooded area, at least for moths. As a consequence, planning of forest restorations should consider the importance of increasing the structural habitat continuity at larger scales.