亚高山草甸华灰早熟禾对气候变化的响应

Responses of subalpine meadow Poa botryoides to climate change

利用亚高山草甸华灰早熟禾生长发育的定位观测资料和相应的气象观测资料,分析了1985—2005年甘肃省玛曲县气候变化对牧草生长发育的影响.结果表明,研究期间,玛曲县降水量的年际变化呈下降趋势,其线性拟合倾向率为-9.895mm·(10a)-1,降水量存在3a的周期变化;气温的年际变化呈上升趋势,其线性拟合倾向率为0.341℃·(10a)-1;华灰早熟禾生长季的干燥指数呈显著上升趋势,其线性拟合倾向率为0.036·(10a)-1,20世纪90年代初至2005年明显趋于干旱化.华灰早熟禾返青到籽实成熟约需140～150d,期间对≥0℃积温、降水量、日照时数的要求分别为1000℃～1200℃、400～450mm和1000～1100h;华灰早熟禾在返青后54d开始由缓慢生长转为迅速生长阶段,返青后第80天的生长速度达最大,返青后104d开始由迅速生长又转为缓慢生长.受气候变暖的影响,华灰早熟禾抽穗期、开花期、成熟期、黄枯期每10年分别提前15d、7～8d、8～9d、3d.研究区的气候变化使该区华灰早熟禾产量变幅明显加大,产量的不稳定性增加.

Based on the field plot observation and related meteorological data, the effects of climate change in 1985-2005 on the growth and development of subalpine meadow Poa botryoides in Maqu County of Gansu Province were analyzed. The results showed that during study period, the annual precipitation in the Maqu County had a decreasing trend, with a rate of -9. 895 mm · （10 a）^ -1 and a cycle of 3 yeats, while the annual air temperature had an increasing trend, with a rate of 0. 341 ℃ · （10 a）^ -1. The aridity index of P. botryoides in growth season had an obvious increasing trend, with a rate of 0. 036 · （ 10 a）^ -1, and the tendency was more markedly from the beginning of the 1990s to 2005. The period from reviving to ripeness of P. botryoides was 140-150 d, and the requirements of accumulated temperature above 0 ℃, precipitation, and sunshine duration in this period were 1000 ℃-1200 ℃, 400--450 mm, and 1000-1100 h, respectively. The growth rate of P. botryoides turned to higher at 54 d after reviving, reached the highest at 80 d after reviving, and became lower at 104 d after reviving. Under the effects of climate warming, the phenophase of P. botryoides was advanced by 15 d · （10 a）^ -1 at heading stage, 7-8 d · （10 a）^ -1 at flowering stage, 8-9 d · （10 a） ^-1 at ripeness stage, and 3 d · （10 a） ^-1 at withering stage. Climate change made the P. botryoides yield in study area have greater variation and higher unsteadiness.