气候变化对不同海拔高山嵩草物候期的影响

利用三江源两个不同海拔高度区牧业气象观测站1989-2010年高山嵩草(Kobresia pygmaea)物候观测资料及同期日、月、年气象资料，通过回归、相关和非参数检验方法，就青海省海拔相差较大的曲麻莱和河南的气候变化及其对高山嵩草物候的影响差异进行对比研究。结果显示，22年来两站年平均气温增速相当，高海拔区的平均最低气温增幅大于低海拔区，而高海拔区的平均最高气温增幅小于低海拔区，生长季（4―9月）与全年的气温变化有相同趋势。两站全年及生长季气温变化均显著相关，其差异主要受海拔影响。两站高山嵩草的返青期、黄枯期和生长季均存在明显的年际波动，高海拔区的波动大于低海拔区。海拔每升高100 m，高山嵩草的返青期推迟3.3 d,生长期缩短2.5 d。1989―1999年与2000―2010年两个时间段平均物候期高海拔区提前6~25 d，生长期延长3 d。低海拔区返青期提前1 d，其余物候期推迟1~9 d，生长期延长6 d。高海拔区高山嵩草的生长更容易受气候变化的影响，其生境更为脆弱。

Impacts of climate change on Kobresia pygmaea phenophase at different altitude regions in Qinghai Plateau

Impacts of climate change on phenophase of Kobresia pygmaea at high(4 175.0 m) and low(3 500.0 m) altitude regions in the Qinghai Plateau were studied by analyzing the observation data obtained from Qumalai and Henan meteorological stations from 1989 to 2010.The results showed that during the past 22 years the air temperature had an increasing trend at both high and low altitudes,the warming amplitude of mean minimum temperature was larger at high altitude than that at low altitude,while the warming amplitude of mean maximum temperature was larger at low altitude than that at the high altitude.The air temperature change in growth season(April to September) showed a same trend at two meteorological stations.There was a significant correlation between air temperature of the growth season and annual air temperature.It was found that days of green stage,growth period and withering period of K.pygmaea at two meteorological stations showed interannual fluctuations,the fluctuations at high altitude were bigger than those at low altitude.The first day of green stage had a delaying tendency with increasing altitude,3.3 d per 100 m.In contrast,the growth period had a shortening tendency with increasing altitude,2.5 d per 100 m.At high altitude regions,average phenophase of K.pygmaea was advanced 6-25 d,and growth period was prolonged 3 d.At low altitude regions,withering period was advanced 1 d,while other phenophase was delayed 1-9 d,and growth period was prolonged 6 d.The growth of K.pygmaea at high altitude was influenced easier than that at low altitude by climate change.Its habitat was more fragile at the high altitude region.