1991—2015年三江源河曲高寒草甸干湿状况及牧草产量变化的气候归因研究

以三江源东部河曲高寒草甸为研究对象，通过分析1991—2015年气温、降水、潜在蒸散、湿润指数和牧草产量变化特征，探讨了地区干湿状况对牧草产量的影响。研究表明：1991—2015年河曲高寒草甸潜在蒸散以3.5 mm·a^-1的速率增加（P<0.01），在年降水量按2.3 mm·a^-1呈非显著性（P>0.05）增加的趋势下，地区干湿状况基本保持平稳（多年均值为0.52），隶属于半湿润气候区。25年来牧草干重产量平均为303.7 g·m^-2，并以3.0 g·m^-2·a^-1的速率下降。分析牧草产量与影响干湿状况的气候因素之间的相关性发现，气温对牧草产量影响不明显（P>0.05），降水量表现为正相关关系（P>0.10），说明该区域降水是牧草产量提高与否的主导因素；牧草产量与潜在蒸散表现为负相关关系（P>0.10），与湿润指数表现为正相关关系（P>0.10）；在生长季时期，牧草产量与降水量、潜在蒸散和湿润指数的相关性关系达到了显著水平（P<0.10），说明牧草产量在生长季对地区环境条件湿润与否较为敏感。

Analysis of surface humid level and climatic attribution of forage yield changes in Hequ alpine meadow from 1991 to 2015

Taking Hequ alpine meadow， which located in the east of Three-River Headwaters region， as the research object. Discussed the effect of humid level on forage yield by analyzed the changes of temperature， precipitation， potential evapotranspiration， humid index and forage yield from 1991 to 2015. The results shows that： （1） From 1991 to 2015， the potential evapotranspiration of Hequ alpine meadow was increased at a rate of 3.5 mm·a^-1 （P<0.01）； The precipitation was increased as a non-significant rate of 2.3 mm·a^-1 （P>0.05）， and the humid level remained stable as a semi-humid climate（mean value of years is 0.52 ）. （2） In the past 25 years， the average dry yield of forage was 303.7 g·m^-2 and decrease ratio was 3.0 g·m^-2·a^-1. （3） By analyzing the correlation between forage yield and climatic factors which affecting the humid level， it was found that air temperature has less impact on forage yield and precipitation showed a positive correlation （P>0.10） that indicating precipitation is the metal factor which influenced the forage yield. Forage yield showed a negative correlation with potential evapotranspiration （P>0.10） and a positive correlation with humid index （P>0.10）. During the growing season， forage yield showed a significant correlation with all factors except air temperature means production is quite sensitive to the wetness of regional environmental conditions.