河套灌区农田植被物候和NDVI峰值对气候变化的响应

The impact of climatic factors on vegetation phenology and peak NDVI in the Hetao Irrigation District

【目的】研究河套灌区植被物候参数和NDVI峰值时空变化特征及对气候变化的响应。【方法】利用2001—2021年MOD13Q1数据和双logistic四参数模型,识别了河套灌区植被SOS、EOS、LOS、POS、NDVI峰值时空变化特征及对气候变化的响应。【结果】河套灌区植被SOS一般从5月下旬到6月中旬开始,到9月中旬至10月上旬结束,LOS主要介于95~116 d,POS主要介于200~220 d,NDVI峰值主要介于0.5~0.7。植被物候变化趋势主要体现在SOS的推迟、LOS的缩短和NDVI峰值的增加。SOS的推迟导致LOS的缩短。而EOS和POS呈提前和推迟趋势的像元比较接近。河套灌区SOS、EOS、POS与气温均以负敏感为主,与降水量以正敏感为主。NDVI峰值与气温和降水量均呈正敏感。【结论】河套灌区物候参数和NDVI峰值的变化趋势具空间异质性,对不同气候因子的响应也有所差异。

【Objective】The increase in atmospheric CO2 and the associated global warming is expected to affect plant growth and development.This paper investigates the spatiotemporal variation in vegetation phenological traits and peak NDVI of plants in Hetao Irrigation District in Inner Mongolia.【Method】The analysis was based on MOD13Q1 data from 2001 to 2021.The impact of climatic factors on spatiotemporal variation in the start of season SOS,the end of season(EOS),the length of season(LOS),the peak of season(POS),and the normalized difference vegetation index(NDVI)of the vegetations in the region was analyzed using the two-logistic and four-parameter model.【Result】The SOS started from the end of May to the middle of June,and ended from the middle of September to the beginning of October.The annual peak LOS and POS ranged from 95 to 116 days,and from 200 to 220 days,respectively.The annual peak NDVI ranged from 0.5-0.7.Climate change delayed the onset of SOS,reduced LOS,and elevated peak NDVI.Additionally,the delayed SOS contributed to the decrease in LOS.The changes in EOS and POS with climate were consistent.SOS,EOS and POS were negatively correlated to temperature and positively correlated to precipitation.The peak NDVI was positively correlated to temperature and precipitation.【Conclusion】The vegetation phenology and peak NDVI in the Hetao Irrigation District were spatially heterogeneous,and the impact of climatic factors on them also varied.