Large areas of rubber monoculture and high-intensity management have already been established in Xishuangbanna ((21°08′–22°36′ N, 99°56′–101°50′E) for half a century. Rubber monoculture now covers more than 400,000 ha, or 20% of land in Xishuangbanna. Previous studies demonstrated that, compared to primary tropical forests, rubber plantations significantly decrease diversity of plant species, birds, bats, insects and spiders. However, little is known about effects of this widespread rubber monoculture on soil ecosystems.
Dr. XIAO Haifeng of Xishuangbanna Tropical Botanical Garden (XTBG) and his colleagues used soil nematodes as indicator species to assess effects of different rubber plantation types on soil ecosystems. They compared soil nematode communities in different rubber plantations (rubber monoculture, rubber and tea mixture, rubber polyculture) and natural forest.
They studied effects of rubber plantation types on nematode communities at three different sites. They used spatial patterns instead of temporal sequences assuming that local site conditions before rubber planting were similar. Nematode communities were distinctly different among the four land-use types and significantly correlated with all the examined environmental factors except litter quantity, which suggested that rubber management practices significantly affected soil C, N, pH, soil moisture and vegetation (including plant diversity and quantity of plant litter and roots) and thus affected soil nematode communities.
Their results provided evidence to the local government and plantation managers that vegetation diversity had positive effects such as relatively high soil nutrient (N) levels and biodiversity in rubber plantations. They advised local government and plantation managers to: 1) plant various cash crops such as tea, coffee, and cocoa into rubber monocultures, which is consistent with the local government recently proposing environmentally friendly rubber plantations; 2) decrease the management intensity and adjust strategies to restore surface vegetation, and ultimately convert rubber monoculture to rubber polyculture.
The study entitled “Intensive rubber cultivation degrades soil nematode communities in Xishuangbanna, southwest China” has been published online in Soil Biology and Biochemistry.
