黑河源头天然牧草生长特征及对气候变化的响应

Growth Characteristics of Natural Herbage and Its Response to Climate Change in the Headwaters of Heihe River

为更好地了解黑河源头天然牧草生长特征及气候变化对天然牧草的影响,采用2003—2021年黑河源头腹地的央隆、阿柔生态监测点天然牧草数据及气候资料,采用线性趋势法、相关性分析和气温回升系数计算方法,研究黑河源头天然牧草的高度、覆盖度、产量、返青期和枯黄期以及影响的气象因子。结果表明:天然牧草的高度和覆盖度均以不同的速率呈现上升趋势,天然牧草产量以不同的速率呈现上升趋势。返青期以-1.65 d/10 a的速率提前,枯黄期以1.70 d/10 a的速率推迟,天然牧草生长期延长;从气象因子对天然牧草生长的影响分析结论得出:水热条件是影响天然牧草生长的主要因子,天然牧草返青期与≥0℃初日和≥3℃初日有显著相关关系,降水量呈现增多趋势与天然牧草高度、覆盖度呈现上升的趋势有明显的对应关系,而上年秋季多雨可能致使天然牧草返青期推迟,少雨可能使返青期提前;除水热条件外,日照、地温、冻土、风速对天然牧草的生长有一定的影响,但影响甚微。

To better understand the characteristics of natural forage growth in the source of the Heihe and the impact of climate change on natural forage,this paper used natural forage data and climatic data from 2003 to 2021 from the ecological monitoring sites of Yanglong and Arou in the hinterland of the source of the Heihe,and employed the linear trend method,correlation analysis and temperature rebound coefficient calculation to study the height,cover,yield,re-greening and yellowing periods of natural forage in the source of the Heihe and the meteorological factors affecting them.The results showed that both the height and cover of natural forage grasses showed increasing trends at different rates,and the yield of natural forage grasses showed increasing trend at different rates.The greening period was advanced at a rate of-1.65 d/10 a,the wilting period was delayed at a rate of 1.70 d/10 a,and the growth period of natural forage was extended.From the analysis of the influence of meteorological factors on the growth of natural forage,it was concluded that water and heat conditions were the main factors affecting the growth of natural forage,and there was a significant correlation between the re-greening period of natural forage and the first day of≥0℃and the first day of≥3℃,and there was a significant correspondence between the trend of increasing precipitation and the trend of increasing the height and cover of natural forage,more rain in the previous autumn might delay the re-greening period of natural forage,and less rain might make the re-greening period earlier.In addition to water and heat conditions,sunshine,ground temperature,frozen soil and wind speed had certain effects on the growth of natural grass,but the effects were minimal.