蒙古国西部地区植被物候变化特征及其对气候因子的响应

Characteristics of Vegetation Phenological Changes and Its Response to Climate Factors in Western Mongolia

对陆上生态体系而言,植物生理季节性变化是衡量其对气候转变反响的关键度量尺度,尤其对全球气温上升现象极为敏感的高纬度与高海拔地带的植物生理季节性。本研究借助MOD13A1卫星遥感资料,叠加温度与降水数据,剖析2000~2021年间蒙古国西部地区植被生长季始期(Start of growing season,SOS)、生长季长度(Length of growing season,LOS)以及生长季末期(End of growing season,EOS)的时空变化特征和海拔依赖性变化机制。结果如下:(1)蒙古国西部地区的SOS主要集中在第90~125 d,近22 a来SOS呈微弱的提前趋势,提前幅度为0.23 d/a。(2)植被物候与气象要素的关系表明,2月的气温和降水与SOS显著负相关(P<0.05),1月的气温和降水与SOS显著正相关(P<0.05),而EOS主要受8月气温和降水的影响。(3)草甸草原和典型草原SOS主要受降水影响,高山草原、荒漠草原以及针叶林的SOS主要受气温影响,所有植被类型的EOS对温度的响应更大。总的来说,研究区植被物候与气候因子表现出季节性的差异,响应规律复杂。

Vegetation phenology is an important indicator of terrestrial ecosystem response to climate change,especially in high latitude and high-altitude areas where vegetation phenology is highly sensitive to global warming.Based on MOD13A1 remote sensing products and combined with temperature and precipitation data,this paper studied the spatiotemporal characteristic and altitude-dependent variation mechanism of vegetation phenology,including the start of growing season(SOS),the length of growing season(LOS),and the end of growing season(EOS)in western Mongolia from 2000 to 2021.The results were as follows:(1)SOS in western Mongolia mainly concentrated in the 90th to 125th day,and showed a week advance trend in recent 22 years,with an advance amplitude of 0.23 d/a.(2)The relationship between vegetation phenology and meteorological factors showed that the temperature and precipitation in February were significantly negatively correlated with SOS(P<0.05),while the temperature and precipitation in January were significantly positively correlated with SOS(P<0.05),and EOS was mainly affected by the temperature and precipitation in August.(3)the SOS of meadow steppe and typical steppe was mainly affected by precipitation,while SOS of alpine steppe,desert steppe and coniferous forest was mainly affected by temperature.The EOS of all vegetation types had a greater response to temperature.In general,the vegetation phenology and climate factors in the study area showed seasonal differences and com‑plex response laws.