Data from: Effects of forest-use intensity on vascular epiphyte diversity along an elevational gradient

Aim: Understanding patterns of tropical plant diversity and their
vulnerability to anthropogenic disturbance at different spatial scales
remains a great challenge in ecology and conservation. Here, we study how
the effects of forest-use intensity on vascular epiphyte diversity vary
along a tropical elevational gradient. Location: 3500-m elevational
gradient along the eastern slopes of Cofre de Perote, Mexico. Methods: We
studied the effects of forest-use intensity on alpha, beta, and gamma
diversity of vascular epiphyte assemblages in old-growth, degraded, and
secondary forests at eight study sites at 500 m intervals along the
elevational gradient. At each elevation and in each of the three
forest-use intensity levels, we established five 400 m² plots yielding a
total of 120 plots. Results: Interactive effects of elevation and
forest-use intensity strongly impacted local-scale patterns of vascular
epiphyte diversity. We found a bimodal trend, with species diversity
peaking at 500 and 1500 m above sea-level, which deviates from the
previously reported humped-shaped pattern. In most cases alpha diversity
did not differ significantly among forest-use intensity levels. However,
gamma diversity was always lower in secondary forests compared to
old-growth forests across the entire elevational gradient. Within each
elevational belt, beta diversity was dominated by species turnover along
the forest-use intensity gradient in the lowlands and declined with
increasing elevation, where community composition became increasingly
nested. Along the elevational gradient, the spatial turnover of vascular
epiphyte community composition was similar among forest-use intensity
levels. Main conclusions: Our results reveal a strong interaction between
forest-use intensity and elevation, making it difficult to extrapolate
findings from one elevational belt to another. Our findings highlight the
value of old-growth forest for epiphyte diversity, but also show that
degraded and secondary forests –depending on the elevational belt– may
maintain a high species diversity, and thus play an important role in
conservation planning.