Abstract:
Abstract: Farmland reforestation can exert some positive impacts on the biodiversity conservation in forests. It is very necessary to evaluate the response of ecosystem services to biodiversity conservation in recent years. Particularly, the ecosystem assessment of biodiversity conservation can greatly contribute to the decision-making on returning farmland to forests for future ecological benefits. There is a heterogeneous spatial distribution of biodiversity conservation functions, depending mainly on habitat fragmentation, corridors, and ecological connectivity. Among them, a key indicator of biodiversity conservation function can be the response process of ecological connectivity to the policy of returning farmland to forests. In previous studies, the equivalence method was widely employed to calculate the ecosystem service value of biodiversity conservation. However, the spatially explicit assessment of ecosystem service values cannot be performed without considering the effect of different woodland categories on the equivalence coefficients. Furthermore, farmland reforestation can benefit from the balance of economic development and ecological conservation during the spatial land allocation, especially in a fluctuating terrain with a large probability of natural disasters. Taking Shidian County, Yunnan Province, China as the study area, this study aims to clarify the effect of three farmland reforestation scenarios on the biodiversity conservation values of forest land. The morphological analysis model and ecological connectivity index were integrated to identify the ecological importance of the forest patches. The spatial relationship with the local physical factors (slope and forest coverage) was selected to adjust the coefficients of ecological service value for the biodiversity conservation in the various types of forest land. The changing trend of values was used to determine the maximum benefit and the feasibility of returning farmland to forests under different scenarios. The results showed that the farmland reforestation significantly altered the land use structure and pattern. The ecological source areas of the four scenarios were 21 425.20, 32 266.15, 27 838.22, and 28 507.13 hm2, respectively. The ecological connectivity showed a significant increase in the diffusion distance from 1500 to 10000 m. There was an upward trend in the ecological service value of forest biodiversity conservation under the different scenarios, increasing by 3.02×107, 4.7×106, and 1.57×107 Yuan, respectively, with the increase of species dispersal distance. There was a high significance between the biomass with the slope and altitude in the different types of forest land. Therefore, the maximum revised equivalence factor was obtained as Scenario II, according to the revised equivalence factor formula and the average forest biomass density in China. Scenario II presented the least conversion of farmland to forest. In the value assessment of biodiversity conservation, the maximum and minimum were Scenario II, and III, respectively. Correspondingly, Scenario II can be expected to increase the ecological service value of biodiversity conservation. Anyway, the spatial structure and distribution of forest habitats can also provide solid guidelines for the decision making on reforestation policies and ecological compensation, as well as the intensity of farmland reforestation.