Do Eucalyptus Plantations Support Biodiversity Conservation?

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. The data were collected using five plots arranged on each three transects laid out in each forest type at each of the three sites. The dissimilarity in floristic species compositions between plantation and natural and forests were tested using Adonis2 function within vegan package. The overall understorey species richness data were pooled together from seedlings, saplings and the soil seed bank for each of the Eucalyptus plantation and natural forests. Before we ran the analyses, the floristic and bird species richness data were transformed using square-root transformation by adding 0.5 on each value. The differences in floristic and bird species richness and the status of soil nutrients between the forest types were tested employing one-way ANOVA in which the forest types and the study sites were considered as fixed and random factors (error terms) respectively within the car package. The results denoted that floristic species and family compositions are significantly dissimilar between the forest types (P<0.004). The floristic and bird species richness are higher in natural forests than in Eucalyptus plantation forests (P<0.001). The results of the soil nutrient analyses indicated lower organic carbon, total nitrogen, available potassium and phosphorus and cation exchange capacity in Eucalyptus plantation forests (P<0.001). Our overall results highlight that the Eucalyptus plantation forests weakly support biodiversity and hence, conservation strategies should be devised on how to halt particularly its expansion into the biodiversity hotspot areas