在中国西南有许多关于过去环境及其变化原因的观点，但这些观点缺乏直接证据的支持，这在关于西南干旱河谷生态系统方面最为典型，而且目前干旱河谷地区的生物多样性保护和生态恢复计划主要都是基于这些主观的认识而不是科学的理解。该文的目的是通过对干旱河谷环境变化的描述及其诠释，提供干旱河谷的一个历史面貌，用以验证是否支持当前对于干旱河谷环境变化的认识和理解，该文研究的干旱河谷范围包括滇西北及其临近的四川和西藏。28份1868～1949年间刊行的出版物中有关研究地区干旱河谷植被的历史资料和56幅清晰反映干旱河谷植被范围和状况的照片形成研究这种变化的历史基础，通过与2001～2005年间相同地区和范围的植被现状以及56幅与上述照片取景完全相同的重复照片的比较，研究了干旱河谷植被的变化。研究结果发现，在过去约150年间，研究地区的干旱河谷植被范围并没有显著的变化，在垂直方向没有向较高海拔扩展；耕地面积减少；滑坡主要是由当地本身的地质不稳定性和基础设施建设活动引起的。1868～2005年间文献资料和重复景观照片的对比研究，并不支持国内外许多有关干旱河谷环境退化的看法和观点以及以造林为主的干旱河谷生态恢复策略。
In southwestern China, there are many opinions about past environmental conditions and the historical drivers of change, but little direct evidence. Such is the case in Dry Valley ecosystems, where current conservation programs appear to be based more on subjective perceptions than scientific understanding. Our research objective was to develop an historical profile— the description and explanation of environmental change —for the Dry Valleys to see if today’s perceptions about past change are supported by data. Our study area encompassed n orthwestern Yunnan and adjacent Sichuan and Tibet. Specifically, we assessed vegetation dynamics by comparing historical records from 1868-1949 to conditions in 2001-2005. We used two sources to establish baseline conditions from which to assess change: 28 historical publications and 56 old photographs for which we rephotographed the modern scene. Our major finding is that there has been no substantial change in the cover of Dry Valley vegetation during the last 150 years. We also found that the aerial coverage of crop fields has decreased and major land slide activity was caused by chronic geological instability and infrastructure development. Overall, we found that comparisons of written and photographic records between 1868 and 2005 do not support many common assumptions regarding environmental degradation in the Dry Valleys, upon which current ecological restoration programs are based.