基于"质量-风险"的干旱区休耕空间布局及补偿策略

构建节水型休耕生态补偿机制是干旱地区农业可持续发展的必然选择,探讨符合干旱地区休耕地的空间布局方法是提高休耕生态补偿效率的关键。该研究以新疆开都-孔雀河流域为例,从土壤理化属性和耕作便利条件两方面建立耕地质量评价指标体系,利用综合评估法评估流域内耕地质量状况;基于MEDALUS-ESAs模型框架,从土壤、气候、植被和土地利用与管理4个方面评估全流域的土地退化风险;综合考虑耕地质量和土地退化风险,利用Z-score方法确定休耕空间布局,并提出不同分区的休耕补偿策略。结果表明：1）开都-孔雀河流域耕地质量"总体良好,局部较差",土地退化风险呈现"北低南高"的空间分布格局;2）流域内优先休耕区内耕地面积为67 814.60 hm2,次优先休耕区的耕地面积为71 784.94 hm2,限制休耕区内耕地面积为80 576.89 hm2,禁止休耕区内耕地面积为107 358.03 hm2;3）优先休耕区耕地的约束条件为耕地质量,可将休耕与耕地质量提升相结合,实施中长期休耕,依据农业收益损失和土地改良成本确定休耕补偿标准;次优先休耕区耕地质量较好,可与农业节水相结合,基于水资源短缺状况对耕地进行季节性休耕,依据农业收益损失确定休耕补偿标准;限制休耕区受耕地质量和生态安全的双重约束,应将休耕与耕地质量提升、生态保护相结合,实施年度休耕,依据农业收益损失、土地改良成本和生态保护成本确定休耕补偿标准。

Spatial distribution and compensation strategy of land fallow based on quality-risk in arid areas

Abstract: A diversified fallow ecological compensation is an inevitable choice for the sustainable development of agriculture in China. It is very necessary to explore the spatial distribution of fallow land for the higher efficiency of ecological compensation for fallow in arid areas. Taking the Kaidu-Kongque River basin in Xinjiang as an example, this article aims to propose different compensation strategies for different zones, thereby determining the spatial layout of fallow, considering the quality of cultivated land and risk of land degradation. The specific procedures were: 1) An evaluation index system of cultivated land quality was established to select the indicators from two aspects of soil physical and chemical properties, and cultivation convenience. A comprehensive evaluation was then made for the quality of cultivated land. 2) MEDALUS-ESAs model was selected to estimate potential risks of land degradation in the basin, where four indicators included soil, climate, vegetation and land use. 3) The Z-score was also applied for the quality score of cultivated land and risk index of land degradation. The standardized value was divided into four quadrants, according to the coordinate axis to determine the spatial distribution of fallow. Specifically, the cultivated land with "low quality and low risk" was classified as a priority fallow area, "high quality-low risk" was classified as a sub-priority fallow area, "low quality-high risk" was classified as restricted fallow areas, and "high-quality-high-risk" was classified as fallow area. 4) Different compensation strategies were finally proposed for fallow, according to different zones. The results showed that: 1) There was a fair overall quality of cultivated land in the whole Kaidu-Kongque River Basin, but slightly good in local areas. The spatial pattern of land degradation risk was "low in the northern, high in the southern". 2) The area of cultivated land located in the priority fallow area was 67 814.60 hm2, mainly distributed in the western part of Kongque River Oasis and the northeastern part of Bosten Lake. The area of cultivated land located in the sub-priority fallow was 71 784.94 hm2, mainly distributed in the northern part of the Kaidu River Oasis. The area of cultivated land located in the restricted fallow area was 80 576.89 hm2, mainly distributed in the central area of the Kongque River Oasis, the northern and southern part of Bosten Lake, and the eastern part of the Kaidu River Oasis. The area of cultivated land located in the forbidden fallow area was 107 358.03 hm2, mainly distributed in the southern part of Kaidu River and Kongque River Oases and the eastern Bosten Lake. 3) The cultivated land located in the priority fallow area was restricted by cultivated land quality. As such, the long-term fallow was necessary to combine with the quality improvement of cultivated land. The fallow compensation in the zone was determined, according to the loss of agricultural income and the cost of land improvement. Furthermore, the cultivated land located in the sub-priority fallow area was in good condition, where the fallow can be combined with agricultural water saving to implement seasonally fallow. More importantly, the fallow compensation depended mainly on the loss of agricultural income. The cultivated land in the restricted fallow area was restricted by cultivated land quality and ecological safety. Therefore, the fallow can be combined with cultivated land quality improvement and ecological protection to implement annual fallow, where the agricultural income loss, land improvement costs, and ecological protection costs standard should be considered into the fallow compensation.