江河源区高寒草甸退化序列秃斑热岛效应研究

Study on the“Heat Island Effect”of Barren Patch on Degradation Sequences of Alpine Meadow in the Source Region of the Yangtze and Yellow River,Qinghai-Tibetan Plateau,China

秃斑是江河源区高寒草甸退化序列普遍存在的地理景观,以江河源区高寒草甸退化序列秃斑为对象,分析表土5cm处温度日动态、月动态和季节动态及土壤有机碳与全年、生长季>0℃积温的关系,结果表明:温度日动态为黑土滩退化样地中坡最高温、升温(降温)速率和温差最大,分别是未退化样地中坡的3.52倍、8.33(7.11)倍和8.21倍。生长季黑土滩退化样地中坡9月温差最大,未退化样地低坡6月温差最大,前者是后者的3.96倍;各样地8月>0℃月积温最高,其中黑土滩退化样地中坡是未退化样地低坡的1.5倍;非生长季各样地最大温差和>0℃月积温相差较小。全年、生长季>0℃积温与土壤有机碳呈极显著负相关,全年、生长季>0℃积温增加1000℃有机碳含量分别减少6.2%和7.3%。秃斑呈现突出的热岛现象,其热岛效应表现为土壤有机碳流失和水分蒸散,继而土壤可蚀性增大,或是高寒草甸退化的内在动力。

The barren patch is distributed throughout alpine meadow in the source region of the Yangtze and Yellow River,Qinghai-Tibetan Plateau.The barren patch was taken as research object,the dynamic of diurnal,monthly and seasonal temperature of surface soil in 5cm in depth and relationship between organic carbon and〉 0℃ annual accumulative temperature,〉0℃ growth season＇s accumulative temperature were analyzed.The results showed that the highest temperature,heating（cooling）rate,and temperature range were the highest in middle slope of black beach degraded meadow in a day,which were respectively 3.52,8.33（7.11）and 8.21 times higher than ones of middle slope of non-degraded meadow.In the growth season,the difference in temperature of middle slope of black beach degraded meadow was the highest in September,which was 3.96 times as many as one of low slope of non-degraded meadow in June.Besides,〉0℃ monthly accumulative temperature was the highest in August,and one of middle slope of black beach degraded meadow was 1.5times as many as one of low slope of non-degraded meadow.In contrast,the difference in temperature range and 〉0℃ accumulative temperature on Black beach degraded meadow and non-degraded meadow was very small in the non-growth season.〉0℃annual accumulative temperature and〉0℃ growth season＇s accumulative temperature were significantly negative correlation with organic carbon.With increasing〉 0℃ annual accumulative temperature by 1000℃in a year and in growth season,organic carbon decreased by 6.2%and 7.3%respectively.The barren patch showed the conspicuous heat island phenomenon.Besides,heat island effect;such as,organic carbon loss,water transpiration and soil erosion,may be the major reason why alpine meadow was degraded.