Do eucalypt plantations provide habitat for native forest biodiversity?
Faculty of Computing, Health and Science
School of Natural Sciences / Centre for Ecosystem Management
Plantation forestry contributes to the economic growth of many regions, but may also produce ecological impacts (e.g. on biodiversity) that can be reduced with proper management. We assessed the value of eucalypt plantations to favor habitat connectivity at the landscape scale by determining their ability to provide habitat for species associated with the natural vegetation. For this purpose, we compared diversity and composition of understory vegetation in low-management eucalypt plantations in young, intermediate (ready for harvest) and mature stages with pine plantations, native forests and shrublands. We estimated the true species richness with Chao2 estimators and compared among habitats the average species richness (at two different local scales: per plot and per site), Shannon indices and biovolume of herbs, shrubs and trees in the understory using ANOVAs or GLZs, depending on data distributions. Differences among habitats in understory species composition and functional types were compared with PERMANOVA, and were graphically represented using NMDS ordinations. At local scales, diversity tended to be higher in native communities (native forests and shrublands) and lower in plantations (lowest in intermediate eucalypt plantations). Diversity across all study sites was again lowest in eucalypt plantations in intermediate age, but was relatively high in other plantations, due to a high species turnover in young and mature eucalypt plantations. Eucalypt plantations were similar to shrublands in understory species composition and functional types when young, becoming more distant to them when older, and more similar to pine plantations and native forests. Native forests were the most distinctive community, with pine plantations being the most similar to them. Native forests harbored the rarest species and were also associated with seed dispersal by vertebrates (internally). Ant- and wind dispersal were the most common in shrublands and eucalypt plantations. Given the prevalence of eucalypt plantations in some regions, determining (and improving, if feasible) their ability to harbor biodiversity of native communities becomes a crucial goal, in order to increase landscape connectivity and favor species persistence at regional scales. In the study region, eucalypt plantations provide habitat for species typical of shrublands when young but do not contribute significantly to the maintenance of the understory biodiversity associated with native forests. Considering the distinctiveness of native forests, we favor protection and, where feasible, restoration of native forests over managing eucalypt plantations for biodiversity to best improve conservation outcomes.