农业空间半自然生境内涵、特征与识别

维护农业空间生态安全是国土综合整治与生态修复的重要目标,处于自然生境和人工生境过渡性地带的半自然生境是自然要素与人工要素强烈交互作用下形成的人与自然"共享空间",其以自然发展规律为核心,又依靠人类活动延续独特的结构、过程和功能,具有资源类型多样化、景观格局复杂化和生态功能多元化的特征,是保障和提升农业空间生态系统健康的关键区域。通过对半自然生境内涵与特征的解析,以四川省罗江区为例,基于格局视角对农业空间半自然生境进行识别,结果表明：（1）罗江区半自然生境比例达27.28%,主要聚集于农林混交区,城乡交错带次之,农业集中区半自然生境比例偏低,其内部存在生境面积微小、斑块细碎、连通阻断等问题;（2）生态型半自然生境比例为17.28%,主要分布于农业集中区边缘地带,人工型半自然生境比例为10.00%,主要分布于大型居民聚集区周边和用地混杂山区;（3）从整体空间上看,区域形成农业集中区-生态型半自然生境-人工型半自然生境-人工/自然生境的渐进分布格局,其景观格局可总结为"片核-环屏-廊道-斑块"4种模式;（4）在国土空间规划新时代,农业空间半自然生境研究需联动城镇空间与生态空间实现系统化保护修复,为我国当前粮食安全保障国策和生态文明建设战略约束下的国土空间管控提出适应性策略。

Connotation, characteristics and recognition of semi-natural habitats in agricultural space

Maintaining the ecological security of agricultural space is an important goal of comprehensive land remediation and ecological restoration. The semi-natural habitats (SNHs) in the transitional zone between natural and artificial habitats can be called "shared space", which are formed under the strong interaction of natural elements and artificial elements. SNHs have ecological assemblages which have been substantially modified in their composition, balance or function by human activities. They have evolved through traditional agricultural, pastoral or other human activities and depended on their continuation to retain their characteristic composition, structure and function. Despite not being natural, these habitats and ecosystems often have the characteristics of diversification of resource types, complex landscape pattern and diversification of ecological functions, providing high value in terms of biodiversity and other ecosystem services. There is no gainsaying that it is a key area to ensure and improve the ecosystem health of agricultural space. By analyzing the connotation and characteristics of SNHs, taking Luojiang District of Sichuan Province as an example, the SNHs in agricultural space were identified from the perspective of pattern. The results showed that:(1) the proportion of SNHs in Luojiang District was 27.28%, mainly concentrated in the mixed agricultural and forestry areas, followed by the urban and rural areas. The agricultural concentration areas had a relatively low proportion of SNHs, and there had problems such as small habitat area, fragmented patches, and blocked connectivity. (2) The proportion of ecological SNHs was 17.28%, that was mainly distributed in the fringes of agricultural concentration areas. And the proportion of artificial SNHs was 10.00%, which was mainly distributed in the surrounding areas of large residential areas and in mountainous areas with mixed land use. (3) From the perspective of overall space, the region formed a gradual distribution pattern of agricultural concentration areas-ecological SNHs-artificial SNHs-artificial habitats or natural habitats. And the landscape pattern could be summarized as four patterns of "sheet core-environmental screen-corridor-patch". (4) In the new era of territorial space planning, the research on semi-natural habitats in agricultural space needs to link urban space and ecological space to achieve systematic protection and restoration, so as to provide adaptability for the management and control of territorial space under the constraints of China''s current national policy of food security and ecological civilization construction strategy.