Genetic diversity of dominant plant species in tropical land-use systems in Sumatra, Indonesia.
Biodiversity hotspots like tropical lowland rainforests in Sumatra are threatened by the agricultural expansion, which increases the deforestation rate in Indonesia, which is highest worldwide. Main land-use change drivers in Indonesia include the production of rubber and palm oil, both of which lead to a high forest conversion rate. In the remaining and degraded forest patches, species diversity has declined and species composition has been altered. Effects of habitat fragmentation and land-use change on genetic structure were frequently investigated at the species level and compared across plant species, but not for plant communities. In addition, the effect of land-use change on the genetic structure of plants has not yet been investigated. Using Amplified Fragment Length Polymorphism marker, the genetic diversity of 112 dominant plant species was assessed in four different land-use systems in Sumatra: old growth tropical lowland rainforest, jungle rubber, rubber plantation, and oil palm plantation. The four systems were investigated in two regions with four replicates, respectively. Because of different species compositions, characterized by different life history traits, forest and jungle rubber plots showed the highest diversity level, while oil palm and rubber plantations showed the lower diversity levels. The two intensively managed plantation systems showed similar genetic diversity levels as the tree dominated systems but are dominated by mainly alien species. This indicates that oil palm and rubber plantations could not be identified as habitats of conservational value. The newly introduced collection and analysis approach presents a universally applicable method to investigate different ecosystems in their plant genetic diversity to support the identification of habitats with high conservational value.