The biodiversity benefit of native forest over Grain-for-Green plantations

Abstract

ABSTRACTAimChina’s Grain-for-Green Program (GFGP) is the largest reforestation program in the world and has been operating since 1999. The GFGP has promoted the establishment of tree plantations over the preservation of diverse native forest. In a previous study (Hua et al. 2016, Nat Comms 7:12717), we showed that native forest supports higher species richnesses of birds and bees than do GFGP plantations. We also showed that ‘mixed-plantation’ GFGP plantations, which are mostly made up of two to five neighboring monoculture stands of different tree species, planted in checkboard fashion, support a level of bird (but not bee) species richness that is higher than any of the individual GFGP monocultures, although still below that of native forest. To better protect terrestrial biodiversity, which is an important objective of China’s land-sustainability spending, we recommended that the GFGP should firstly prioritize native forest conservation and regeneration and secondly promote checkerboard planting arrangements over monocultures. Here, we use metabarcoding of arthropod biodiversity to test the generality of these results and policy recommendations.LocationSichuan, ChinaMethodsWe used COI-amplicon sequencing (‘metabarcoding’) of bulk samples of arthropods that were collected with pan traps in native forest, cropland, mixed plantations, and monocultures.ResultsNative forest supports the highest overall levels of arthropod species richness and diversity, followed by cropland and mixed plantations, followed by bamboo monoculture, followed by the other monocultures. Also, the arthropod community in mixed plantations shares more species with native forest than do any of the monocultures. Together, these results show a biodiversity value of mixed plantations for arthropods that is higher than that previously indicated by bees alone.Main conclusionThese results strengthen our original policy recommendations of (1) promoting the conservation and expansion of native forest and (2) promoting mixed-plantation arrangements. The value of this added metabarcoding-based analysis is that these policy prescriptions are now also based on a dataset that includes over 500 species-resolution taxa, ranging across the Arthropoda.