气候变化对亚高山草甸类草地牧草生长发育的影响

Impacts of Climate Change on Pasture Growth in Subalpine Meadows

利用亚高山草甸类草地牧草生长发育定位观测资料和对应气象观测资料，分析气候变化对牧草生长发育的影响。结果表明，研究区域降水量年际变化呈下降趋势，降水量变化曲线线性拟合倾向率玛曲为-9．90mm／10年，降水量存在3年的年际周期变化。气温年际变化趋势呈上升趋势，气温变化曲线线性拟合倾向为0．341℃／10年。草地年干燥指数呈显著上升趋势，干燥指数变化曲线线性拟合倾向率为0．036／10年，20世纪90年代初至2005年明显趋于干旱化。主要禾本科牧草返青到籽实成熟约需140～150天，需≥0℃积温1000～1200℃，需降水量400～450mm，需日照时数1000～1100h。牧草在返青后64天开始，由缓慢生长转为迅速生长阶段，在返青后的第88天，生长速度最大，返青后112天开始，其生长从迅速生长又转为缓慢生长。对牧草生长发育全生育期而言，受气候变暖，气温增高的影响，近20年牧草开花期提前10～14天，成熟期提前20～24天。从返青到抽穗期，气温对牧草产量形成为正效应，拔节到抽穗期牧草产量形成对气温变化十分敏感，开花到籽实成熟期，热量对牧草的影响由正效应转向负效应，在籽实成熟期牧草产量形成对气温变化进入第二个敏感期。除籽实成熟期降水量对牧草产量形成为负效应外，其余时段降水量对牧草产量形成均为正效应，在禾本科牧草分蘖拔节期牧草产量形成对降水量变化十分敏感，旬降水量每增加1mm，牧草产量可增加（150～200）kg／hm2，籽实成熟期降水量的影响由正效应转向负效应。从返青到分蘖期，日照时数对牧草产量形成为正效应；拔节到开花期日照时数对牧草产量形成为负效应；抽穗期牧草产量形成对日照时数变化十分敏感，籽实成熟期到黄枯期日照时数的影响为正效应。研究区域气候变异系数增大，降水量和气温共同影响，导致该区域牧草产量呈波动变化，牧草产量的变幅明显加大，产量的不稳定性增加。

This paper uses data on grass growth and meteorological factors to analyze the impacts of climate change on pasture growth in subalpine meadows. The restdts show that precipitation declined at the rate of -9.90 mm/10a. The interannual change of temperature displayed a marked increase, at the rate of 0.341℃/10a. The aridity index of grassland increased at the rate of 0.036/10a, with a significant trend from 1990 to 2005. The period from reviving to ripeness of gramineous pasture was 140 - 150 days, requiring an accumulated temperature above 0℃ of around 1 000 ~ 1 200℃, precipitation of around 400 ~ 450 mm, and sunshine duration of around 1 000 - 1 100 hours. The pasture growth changed from low- speed growth to high-speed growth 64 days after reviving and changed back to low-speed growth 112 days after reviving. The pasture grows at the peak rate 88 days after reviving. The temperature rise enables the period of inflorescence to be extended by 10 ~ 14 days and the ripeness period to be extended by 20 - 24 days over the past 20 years. The effects of temperature on grass yields were positive for the period from revival to heading, with the most sensitivity during the jointing and tillering stage. The effects of temperature on grass yields were negative for the period from inflorescence to ripeness, which had the second highest sensitivity during the ripeness period. The effects of precipitation on grass yields were positive except for during the ripeness period, which was sensitive during the jointing and tillering stage. The grass yields increase 150 ~ 200kg/hm2 when precipitation increases by lmm per ten days. The effects of precipitation on grass yields were negative in the ripeness stage. The effects of sunshine duration on grass yields were positive from the stages of reviving to tillering. The effects of sunshine duration on grass yields were negative during the jointing and tillering period, which was sensitive in the heading period. The effects of sunshine duration on grass yields were positive during the ripeness stage. The increase in climate variability causes variation and an unsteady increase in pasture output.