Plant Community Structure and Conservation of a Northern Peru Sclerophyllous Forest

Abstract

ABSTRACTThe vegetation near El Bosque Petrificado Piedra Chamana, in the northern Peruvian Andes, is evergreen sclerophyllous forest with significant shrub, epiphyte, and mat components. Important/characteristic genera include Dodonaea, Polylepis, Oreopanax, Oreocallis, Myrcianthes, and the mat‐forming orchid Pleurothallis. A vegetation survey including 12 transects and 240 plots in high‐ and low‐grazed areas documented 96 plant species. Compared with low‐grazed areas, high‐grazed areas had significantly fewer tree species, more herbs, and higher density of individuals. Both grazing categories exhibited high connectedness (as seen in network metrics) and positive biotic associations (nestedness), suggesting facilitation of some species by others, but high‐grazed areas showed greater indications of positive associations (as seen in the C‐score and V‐ratio). These positive biotic associations may relate to the harsh environment and the role of keystone taxa such as Dodonaea viscosa, canopy trees, and mat‐forming elements in moderating conditions and promoting species establishment. Only in the low‐grazed areas was there any indication of competitive interactions (negative C‐score/ less than expected species‐pair occurrence). The shift in sign of the C‐score, from negative in low‐grazed areas to positive in high‐grazed areas, indicates a loss of competitive interactions as a factor influencing community structure where grazing pressure is higher. Conservation of the area's natural resources would be advanced by protection of areas where the vegetation structure is more intact, better controls on grazing animals, and identification of development alternatives that would reduce pressure on the area's unique vegetation.