Measuring fractions of beta diversity of plants along a cronosequence of eucalypt plantations in the pampas of Argentina

ESTELA RODRIGUEZ; PAIRO PAMELA; M. ISABEL BELLOCQ; ACEÑOLAZA, PABLO

Budapest

Conferencia; 1st International conference on community ecology; 2017

akademiai kiadó

Human activities produce landscape with natural and modified habitats (Vallejo et al. 2016). Typically, the majority of studies on the effects of eucalypt plantations on biodiversity consider mature plantations (Zhang et al 2014). However, they experience changes in environmental conditions related to age (e.g. canopy closure, increased depth of the leaf litter). Thus, these changes affect species differently, according to their habitat preferences, and may result in differences in diversity, structure and species composition between ages (Bunn et al., 2010). In addition, studies on the effects of eucalypt plantations on biodiversity in grassland are surprisingly scarce in Argentina, considering the spread of these plantations in Mesopotamic pampean. The aim of this study is to assess beta diversity (nestedness and turnover components) between plant communities in natural habitats (grasslands) and each age along eucalypt chronosequence (Eucalyptus grandis) and their relationship with environmental variables. The study was carried out from December 2015 to January 2016. To represent chronosequence, nine ages were chosen and grassland sites in Entre Ríos Province, Argentina. At each age and grassland, there were 3 replicates. We established at each replicate 3 plots (16m2) to record all plant species present. Plots were placed at least 15m away from the edge of the communities to avoid edge effect. In each replicate, we estimated environmental variables that we thought would change with age (pH, N, P, wood density, humidity, %canopy, depth of the leaf litter and average height of eucalypt tree).We have selected grassland as habitat reference and calculated βsor (dissimilarity in terms of the Sorensen index) into two additive fractions, βsim (dissimilarity due to species replacement) plus βnes (dissimilarity due to nestedness). In addition, we performed a principal component analysis (PCA) on the environmental variables measured in eucalypt plantations and calculated Pearson coefficient between age and PCA axis. Then, we calculated the linear regression between dissimilarity (βsor and their components) and PCA axis 1. This axis ordered replicates according eucalypt chronosequence (Fig. 1) and positively correlated with age (r=0.88, p