Do Eucalyptus plantation forests support biodiversity conservation?

Abstract

The viewpoints concerning the impacts of Eucalyptus on biodiversity remain divergent. Here, we conducted a comparative ecological analysis by assessing the floristic compositions of understorey and soil seed bank, bird diversity and soil nutrient status in Eucalyptus plantation and natural forests, respectively. For this, three Eucalyptus plantations and natural forests were selected in a pairwise design at three sites in central Ethiopia having similar ecological conditions. In total, data were collected using 90 main plots and 450 subplots arranged on 18 transects laid out in forest types of the three sites. The dissimilarity in floristic species compositions, the differences in understorey floristic (including soil seed bank) and bird species richness and the status of soil nutrients were analyzed between Eucalyptus plantation and natural and forests using Adonis2 function, one-way ANOVA and GLMM, respectively. The results denoted that floristic family and species compositions were significantly dissimilar between the forest types. The floristic and bird species richness were higher in natural forests than in Eucalyptus plantation forests. The contributions of the soil seed bank to the understorey species was significantly lower in Eucalyptus plantations when compared with natural forests across the study sites. Natural forests support higher diversities of floristic life forms, endemicity and bird functional guilds than Eucalyptus plantations. Moreover, the statuses of soil organic carbon, total nitrogen, available potassium and phosphorus were lower in Eucalyptus plantation forests. Our overall results highlight that Eucalyptus plantation forests weakly support biodiversity and thus, maintaining heterogeneity landscapes and biodiversity hotspot areas are suggested instead of expanding homogeneous plantations.