柑橘园扩张对生态系统服务和景观格局的影响——以江西省信丰县为例

柑橘园扩张是我国柑橘主产区较典型的土地利用/覆盖变化过程之一。但柑橘园扩张对区域生态系统服务和景观格局的影响尚不清楚，探明柑橘园种植的生态效应对柑橘主产区实现生态-经济协同发展具有重要的理论和现实意义。以江西省信丰县为研究区，基于第二次、第三次全国国土调查数据，借助InVEST模型、景观格局指数、图谱分析等方法，结合地形梯度和相关性分析，对柑橘园扩张所致的生态系统服务和景观格局变化及其权衡与关联进行分析。结果表明：①2010-2019年，柑橘园扩张方向以占用林地和耕地为主，柑橘园面积从9961.29 hm²增至12633.84 hm²，其中新增柑橘园7504.72 hm²，退出柑橘园4832.16 hm²，区域内柑橘园转换频繁。②柑橘园扩张导致信丰县景观格局总体呈现破碎化趋势，景观连通性降低，并对土壤保持服务和碳储量服务产生负向影响，对柑橘供给服务产生正向影响，对产水服务几乎无影响。③不同类型柑橘园在不同地形梯度上的扩张对生态系统服务的影响方向和程度存在差异。④在权衡与协同分析中，供给服务与支持服务呈权衡关系，碳储量-产水、碳储量-土壤保持等支持服务之间呈协同关系；景观破碎化与生态系统服务显著关联。研究结果可为经济作物大规模种植区的园地合理开发利用和生境保护提供科学依据。

Effects of citrus orchard expansion on ecosystem services and landscape pattern: A case study of Xinfeng County, Jiangxi Province, China

The conversion of natural forest and cultivated land to citrus orchard has become one of the typical land use/cover change processes in major citrus producing areas in China. Enlarging citrus cultivation can bring promising profitability to smallholders. However, the ecological consequences of enlarging citrus cultivation on ecosystem services (ES) and landscape patterns remain unclear. It is of great significance to explore the ecological effects of citrus orchard scale planting on the eco-economic synergistic development of major citrus producing areas. This paper focuses on analyzing the changes of ESs and landscape pattern, their correlation and the tradeoff/synergy of ESs change caused by citrus orchard expansion, using a case of Xinfeng County, Jiangxi Province. First, we used TUPU analysis methods to characterize the spatial and temporal variation of citrus orchard expansion from 2010 to 2019, based on the data of the secondly and thirdly national land survey. Second, InVEST model was employed to evaluate critical ES dynamics caused by citrus orchard expansion, and then we analyzed its differences in different terrain gradients. Third, we applied correlation analysis to examine the tradeoffs between ESs and the relationships between ESs and landscape patterns. The results showed that:(1) from 2010 to 2019, the expansion direction of citrus orchards was mainly converted from forest land and cultivated land, and the area of citrus orchards increased from 9961.29 hm² to 12633.84 hm², with 7504.72 hm² newly transferred in and 4832.16 hm² transferred out. The contradiction among forest land, cultivated land and citrus orchard is prominent in Xinfeng County. (2) The expansion of citrus orchards has boosted the supply of citrus supply services, whereas it had a negative impact on soil conservation services and carbon storage services. Soil conservation and carbon storage services decreased by 67.19% and 35.98%, respectively, from 2010 to 2019 throughout the region as a whole. Surprisingly, its impact on water yield services was not significant, with only a 5% reduction over the research period. Moreover, citrus orchard expansion has also resulted in a decrease in landscape connectivity and a trend of fragmentation in Xinfeng County. (3) The expansion of different citrus orchards on different terrain gradients had different effects on ESs. (4) In the tradeoff and synergy analysis, there was a tradeoff relationship between supply services and support services, and there was a synergy relationship between carbon storage-water yield and carbon storage-soil conservation. It is found that landscape fragmentation is significantly correlated with ESs. These results can provide scientific evidence for the rational development and utilization of gardens and habitat protection in large-scale cash crop planting areas.