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Clarification of land degradation phenomena and establishment of sustainable land use system in East Asia

阐明东亚土地退化现象并建立可持续土地利用体系

基本信息

批准号：
09660019
负责人：
TSUNEKAWA Atsushi
金额：
$ 1.79万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

1° x 1° grid cells in the Asia region were classified using the datasets of vegetation, elevation, soil type, mean annual temperature and annual precipitation. Correspondence analysis was used for plotting the samples on three-dimensional space, followed by the cluster analysis for classifying all samples into ten categories. As a result, those ten land types in Asia could be mapped and the relationship between the land types and natural conditions such as vegetation, elevation, soil, mean annual temperature and annual precipitation were grasped. The result of correspondence analysis indicates that temperature and precipitation are the most important factors causing remarkable spatial structures, that is, the concentric circle centering Tibetian Highlands and South to North change from tropics to subpolar. This land classification is verified by using χ Square test to highly correspond to cultivation intensity and distribution of soil degradation.Then taking a small catchment in Sichuan Province, China that had been exposed to massive deforestation and reafforestation as a case study of land degradation, further study was made. Land cover changes during the past 50 years and actual status of bio-resources utilization were analyzed to evaluate the agricultural sustainability in a small catchment area in Sichuan Province, Southern China. This study clarified massive deforestation in the 1950's was for fuel wood supply in this area. Afforestaion in the 1970's restored the forest resources quantitatively, which means the forest cover ratio became twice as large as the average in Sichuan Province. The analysis of bio-resources utilization suggested that the nitrogen input mainly consisting of chemical fertilizer remarkably exceeds the nitrogen output in the study area.

利用植被、海拔、土壤类型、年平均温度和年降水量等数据，对亚洲地区1° × 1°网格单元进行了分类。采用对应分析将样本在三维空间上作图，然后进行聚类分析，将所有样本分为10类。结果表明，亚洲10种土地类型都可以绘制成图，并掌握了这些土地类型与植被、海拔、土壤、年平均气温、年降水量等自然条件的关系。对应分析结果表明，气温和降水是造成青藏高原地区空间结构显著的主要因子，即以青藏高原为中心的同心圆由南向北由热带向副极地变化。利用χ 2检验验证了该土地分类方法与耕作强度和土壤退化分布的高度对应性，并以四川省一个遭受大规模毁林和退耕还林的小流域为例，对土地退化进行了进一步研究。以四川省某小流域为例，分析了该流域近50年来土地覆被变化和生物资源利用现状，评价了该流域农业可持续性。这项研究澄清了20世纪50年代大规模的森林砍伐是为了该地区的燃料木材供应。70年代的植树造林使森林资源得到了数量上的恢复，森林覆盖率比全省平均水平提高了一倍。生物资源利用分析表明，研究区以化肥为主的氮素输入明显大于氮素输出。