Lu Heli, Liu Guifang
Institute of Natural Resources and Environmental Science, and College of Environment and Planning, Henan University, Kaifeng, China ; Henan Collaborative Innovation Center for Coordinated Developments in Central China Economic Zone, Zhengzhou, China ; United Nations University-Institute of Advanced Studies, Yokohama, Japan.
Institute of Natural Resources and Environmental Science, and College of Environment and Planning, Henan University, Kaifeng, China.
PLoS One. 2014 Jan 29;9(1):e81535. doi: 10.1371/journal.pone.0081535. eCollection 2014.
Like urban heat islands (UHI), human-induced land degradation (HLD) is a phenomenon attributed to human activities, but this phenomenon occurs in non-urban areas. Although a large body of work has demonstrated that land-cover change influences local climate systems, little work has been done on separating the impact of HLD from naturally-occurring fluctuations in very high-altitude areas. We developed an innovative NDVI-difference method in order to evaluate HLD effects upon the climate system in the central Tibet Plateau. The results show that the minimum temperature increased at a significantly faster pace than the maximum temperature in the growing season at HLD meteorological stations, but this was reversed at stations with natural forces only. Further analysis revealed that abrupt changes of minimum temperature occurred five years earlier and amplitudes of these changes were 1.4 times larger than at stations with natural forces only. Therefore, our results complement other evidence that points to the fact that local effects from UHI contribute to climatic asymmetry observed between minimum and maximum temperature trends. Accordingly, we stress the need for consideration of non-urban factors from anthropogenic activities, such as human-induced land degradation, in understanding these asymmetric diurnal changes.
与城市热岛效应（UHI）一样，人为导致的土地退化（HLD）是一种归因于人类活动的现象，但这种现象发生在非城市地区。尽管大量研究表明土地覆盖变化会影响当地气候系统，但在高海拔地区，将HLD的影响与自然发生的波动区分开来的研究却很少。我们开发了一种创新的归一化植被指数差异方法，以评估HLD对青藏高原中部气候系统的影响。结果表明，在HLD气象站，生长季节的最低温度升高速度明显快于最高温度，但在仅受自然因素影响的气象站情况则相反。进一步分析发现，最低温度的突变比仅受自然因素影响的气象站早五年出现，且变化幅度是其1.4倍。因此，我们的研究结果补充了其他证据，这些证据表明城市热岛效应的局部影响导致了最低温度和最高温度趋势之间的气候不对称。相应地，我们强调在理解这些不对称的昼夜变化时，需要考虑人为活动产生的非城市因素，如人为导致的土地退化。
