Trujillo et al. 2012 (Conference Paper) Brazil

Edge effects on understorey Orchidaceae and Bromeliaceae Epiphytes in two different microhabitats in a Atlantic Rainforest remnant in northeast Brazil.

Author(s):—J.S. Cabral, J.A.S. Filho & M. Tabarelli

Publication:— (2012).

Abstract:—Tropical forests are under intense human impact, including fragmentation. Whereas most studies on the effects of fragmentation and resulting edges have been conducted for a wide variety of organisms, vascular epiphytes have been largely neglected. The aim of this study was characterize the edge effects (edge length) on understorey Orchidaceae and Bromeliaceae epiphytes. Sixteen transects (10 m wide, 350 m long) from the edge towards the core were used to sample epiphytic understorey orchids and bromeliads. We counted and identified all individuals. We further differentiated microhabitats, distinguishing dry (no water streams) vs moist (along streams) transects. The study site was the largest remnant of the Pernambuco endemism center of the Atlantic rainforest, in Alagoas State, Brazil. For the analysis, we calculated Shannon-Wiener diversity index for different classes regarding their distance to the edge. We assumed that edge effects were characterized by changes in diversity compared to the core region. Twenty three species (417 individuals) of Orchidaceae and 14 (77 individuals) of Bromeliaceae were sampled. Edge effects were characterized by lower diversity towards the edge. However, the length of the edge depended on the family and microhabitat. Orchidaceae diversity displayed edge effects in both habitats (ca. 50 and 250 m at the moist and dry microhabitats, respectively). Moreover, the edge at the dry microhabitat had few Orchidaceae of long life-cycles compared to the core. Bromeliaceae diversity did not show an evident edge at the moist microhabitat, whereas the edge was ca. 150 m long at the dry microhabitat. Both Orchidaceae and Bromeliaceae were subject to edge effects. Conservation strategies can use both families as bioindicators and should include them in conservation policies. Differences between both families and microhabitats indicate that the mechanisms generating edge effects on epiphytes may vary, suggesting the need for further studies.