城郊生态系统土壤安全:问题与挑战

土壤作为地球表层系统物质和能量迁移转化的关键节点,其生态功能受到城市化快速发展的严重影响,土壤安全面临严峻的挑战。城郊生态系统受到城市和乡村的双重影响,具有复杂的景观结构和剧烈的动态变化,土壤安全问题更为突出和复杂。基于文献计量学方法,对1990—2017年发表的相关文献进行了统计,梳理和总结了城郊生态系统土壤安全研究的趋势和热点问题,对城郊生态系统中土壤安全面临的问题,及其特殊性、复杂性进行了重点论述,明确了当前快速城市化发展过程中城郊土壤安全研究面临的问题和挑战。建议今后的城郊生态系统土壤安全研究应加强区域尺度上的综合和不同城市发展模式下地区之间的比较,明确城市扩张对城郊生态系统土壤安全的影响机制;建立和完善基于"土壤安全"的城郊生态系统服务评价框架,深入研究城郊生态系统格局-过程-服务之间的关系;明确解析城郊土壤主要污染物来源及其复合污染状况,并结合区域特征,因地制宜开展科学的生态规划,优化城郊景观格局,提升城郊地区土壤安全与生态系统服务功能;明确土壤安全在城郊生态系统可持续发展目标中的重要性,建立科学合理的管理政策。

Soil security in peri-urban ecosystems: problems and challenges

Soil is considered the key connection for material and energy transfer and transformation in the Earth''s surface layer. Soil''s components and ecological functions have been dramatically affected by rapid urbanization in recent decades. This is especially true for peri-urban ecosystems. A peri-urban ecosystem comprises the interaction and transition zones between urban and rural or natural ecosystems. Soils in peri-urban ecosystems are identified with both urban and rural/natural ecosystems'' structural and functional features, and are prone to being affected by urbanization pressures. Soils in peri-urban ecosystems provide essential life-support functions and ecosystem services for urban and rural residents, including food supply, water purification, water conservation, contamination interception, leisure and entertainment services, cultural services, and more. Under rapid urbanization, a large area of agricultural and natural landscapes are converted to urban landscapes. Soils in peri-urban ecosystems therefore tend to be significantly disturbed because of increasing human activities, which change the soil processes and reduce the quality and diversity of soil functions such as food production, pollution attenuation, hydrological cycling, and energy balance. The inherent conflicts between urbanization and soil security have been studied for a long time. As urbanization levels in peri-urban ecosystems have increased, soil security problems in peri-urban ecosystems have been a key issue in recent studies. This study reviews published literature concerning soil security in peri-urban ecosystems and aims to contribute to scientific understanding of the interrelations between soil security and urbanization. Statistical analysis showed that the number of published papers concerning peri-urban ecosystems rapidly increased after 2000, especially in the past 5 years. Many studies concerning soil security were focused on urbanization''s influence on soil processes in urban areas, including cropland loss, food production, climate change, and other processes linked with soils. However, only a limited number of studies that focused on peri-urban areas were found. The soil security problems in peri-urban ecosystem areas were often ignored by both rural and urban ecosystems research. In this review, the particularity and complexity of soil security in peri-urban ecosystems are discussed. In summary, we suggest that future peri-urban studies should focus on the following issues: (1) exploring comparative studies at a large scale under different urban sprawl modes, (2) exploring the tradeoff of ecosystem services in the framework of soil security in peri-urban ecosystems, and perspectives on current solutions for soil security in peri-urban ecosystems are proposed, (3) exploring the sources of contaminants in soil and their co-contamination in peri-urban ecosystems, and optimizing landscape patterns to promote soil security and ecosystem services, and (4) considering the sustainable development goals of peri-urban ecosystems and highlighting the multi-dimensional role of soil security in sustainable policy and management. Because soils in peri-urban ecosystems have their own unique set of socioeconomic and ecological features, soil security should be emphasized for understanding the environmental response to global urbanization.