Influences of forest structure and landscape features on spatial variation in species composition in a palm community in central Amazonia

Abstract

The mechanisms that maintain palm species diversity in tropical rain forests are still debated. Spatial variation in forest structure produces small-scale environmental heterogeneity, which in turn can affect plant survival and reproductive performance. An understanding of how palms respond to variation in forest heterogeneity may help to explain the diversity and structure of their assemblages. We used multivariate ordination statistics and multiple linear models to analyse how palm assemblages are affected by forest structure and landscape features in central Amazonia. In 72 (250 × 4 m) forest plots distributed over an area of 64 km 2 , we recorded all seedling and adult palms, and measured topographic and soil variables, and components of forest structure and tree abundance. We found 16 976 adults and 18 935 seedlings of 46 palm species and five varieties including two morphological forms making a total of 50 botanical entities. Results show that landscape features (altitude, slope, proportions of soil sand and clay) and various components of forest structure (such as degree of forest openness, abundance of forest trees, logs and snags, and leaf litter mass), influence spatial variation in richness, abundance and species composition of palms, creating ecological gradients in palm community composition. Despite the statistically significant effects of environmental variables, most species occurred throughout the full range of the ecological gradients we studied, indicating that there is either relatively weak niche specialization in the palms, or that the competition between the species is mediated by diffuse demographic processes that cannot be evaluated only through studies of species distributions.

Understory host plant and insect gall diversity changes across topographic habitats differing in nutrient and water stress in the Brazilian Amazon rainforest

“…Topographic gradients have also been shown to explain the variation in the species composition of palms (Rodrigues et al 2014), as well as variation in the species richness and density of herbs and pteridophytes (Costa 2006). The importance of plant species richness in determining galling insect species richness has also been indicated in several previous studies (e.g., Fernandes and Price 1988, Fernandes 1992, Araújo et al 2013.…”

Synthesis of the first 10 years of long-term ecological research in Amazonian Forest ecosystem – implications for conservation and management

“…Studies demonstrate that the composition of plants in many functional groups studied in RFD (herbs, palms, shrubs, trees and lianas), as well as fungi, is strongly associated with edaphic conditions, changing gradually along the topographic gradient that extends from sandy, poor and poorly-drained soils of valleys to more clay-rich and well-drained soils of plateaus (Costa et al, 2005(Costa et al, , 2009Kinupp and Magnusson, 2005;Braga-Neto et al, 2008;Drucker et al, 2008;Schietti et al, 2013;Rodrigues et al, 2014). Similarly, studies from non-fragmented areas of the PDBFF reserves show that topography and soil fertility affect the distribution of understory plants (Harms et al, 2004), lianas , arboreal successional species (Laurance et al, 2006a), and the composition of the tree community (Bohlman et al, 2008;Laurance et al, 2010).…”

Subtle changes in elevation shift bat‐assemblage structure in Central Amazonia

“…In Ducke Reserve, terrain elevation influences soil texture, which in turn is related to palm and shrub species composition (Kinupp & Magnusson , Rodrigues et al . ) and to the woody vegetation structure (Castilho et al . ).…”