Toshimori Takahashi

Effects of stand, landscape, and spatial variables on bird communities in larch plantations and deciduous forests in central Japan

We examined the effects of stand, landscape, and spatial variables on bird communities in deciduous forests and Japanese larch (Larix leptolepis (Sieb & Zucc.) Gord.) plantations in a montane region of Nagano Prefecture, central Japan. We used plot-transect methods at 97 sites: 33 in winter 2003 and 18 sites were added in the 2004 breeding season in deciduous forests, and 32 in winter 2004 and 14 sites were added in the 2005 breeding season in larch plantations. Bird–environment relationships were explored using partial redundancy analysis and partial regression analysis. We used spatial variables derived from principal coordinates of neighbor matrices as explanatory variables to detect nonrandom spatial structure of bird communities. Variation in bird communities was mainly explained by stand and spatial variables for both forest types, whereas the effects of landscape variables were small. In plantations, important stand variables for both seasons included stand height, elevation, and the basal area of ...

Deciduous habitat fragmentation caused by a larch plantation matrix matters to birds in deciduous habitats

ABSTRACT Few studies have examined the relative importance of habitat loss and fragmentation caused by structurally complex matrices such as plantations. We examined the effects of the loss and fragmentation of the original deciduous habitat (secondary deciduous broadleaf forest) caused by a larch plantation matrix on bird occurrences in deciduous habitats in both the winter and breeding seasons in Chikuma Highland, Nagano prefecture, central Japan. Birds were counted using the plot-count method in 33 (winter) and 51 (breeding) deciduous habitats with a range of surrounding habitat loss and fragmentation at a 1600-m scale. Three species groups, for which larch plantations are likely to function as low-quality matrices, were analyzed. Effects of landscape structure were found only for flycatchers, which were negatively affected by habitat fragmentation. Flycatchers frequently occurred in habitats surrounded by elongated habitat patches in which between-patch distances were short. This effect was significant after the confounding effects of habitat structure were removed. Because habitat fragmentation was more important than habitat loss, the destruction of habitat connectivity, i.e., isolation and contraction of habitat patches, may not be compensated by the amount of habitat and may primarily be considered in low-contrast landscapes.