退耕还林过程中旱地—林地景观梯度时空变化分析以西北旱区陕西耀州为例

SPATIAL-TEMPORAL CHANGE ANALYSIS OF LANDSCAPE GRADIENT IN THE PROCESS OF REVERTING FARMLAND TO FOREST IN NORTHWEST ARID REGION——A CASE STUDY OF YAOZHOU, SHAANXI PROVINCE

关键词:  西北旱区  退耕还林  旱地—林地  动态变化  景观梯度

Key words:  northwest arid region  reverting farmland to forest  arid land-forest land  dynamic change  landscape gradient

摘要:

目的 研究掌握退耕还林政策实施过程中的土地动态变化程度和景观梯度空间分布，促进区域土地政策优化调整，实现土地资源可持续和集约化利用。方法 文章以西北旱区关中平原典型县域陕西耀州为研究区域，采用土地利用动态度模型、土地利用扩展程度综合指数和土地景观梯度模型，充分利用土地景观空间信息，研究分析 2000—2015年陕西耀州主要地类旱地、林地动态变化程度和景观梯度空间信息。结果 退耕还林政策实施效果明显。该政策直接影响研究区域旱地和林地的数量和空间分布，林地和旱地在2000—2008年间的动态变化程度较2008—2015年均表现更为剧烈，2000—2015年间旱地景观梯度空间分布为西北向东南方向递增和聚集，即东南区域以旱地景观聚集区为主，林地景观梯度空间分布为南部向北部方向递增和聚集，即中部和北部以林地景观聚集区为主，旱地退化过程也是向东南方向逐渐推进，旱地和林地景观经历了2000—2008年急速变化期和2008—2015年持续稳定期两个阶段。结论 提出的分析方法能快速、客观反映研究区域旱地和林地的动态变化程度和景观变化空间信息，为土地政策调控和优化土地利用结构提供科学的参考依据。

Abstract:

Policy regulating is the main cause of changes and spatiotemporal differences to land use. Studying and mastering the degree of land dynamic change and the spatial distribution of landscape gradient in the implementation process of land policy are practically meaningful for optimizing the land policy and realizing sustainable and intensive utilization of land resources. This paper took Yaozhou as a case study area, a typical county of the Guanzhong Plain in northwest arid region, studied and analyzed the degree of land dynamic change and the spatial distribution of landscape gradient by using land use dynamic attitude model, comprehensive index of land use extension and land landscape gradient model from 2000 to 2015. Results indicated that the implementation of the policy had a direct impact on the number and spatial distribution of arid land and forest in the study area. The dynamic change of arid land and forest in the period of 2000-2008 was more drastic than that in the period of 2008-2015. From 2000 to 2015, the spatial distribution of arid land landscape gradient increased and aggregated from northwest to southeast and the spatial distribution of forest landscape gradient was incremental and aggregated from south to north. The degradation process of arid land was advancing to the southeast. The landscape of arid land and forest experienced a period of rapid change from 2000 to 2008 and sustained stability from 2008 to 2015. The analysis method proposed in this study could quickly and objectively reflect the degree of dynamic change and spatial information of landscape change of arid and forest in the study area.