塞罕坝木质部生长物候与植被物候的差异及影响因素

Differences and influencing factors between xylem growth phenology and vegetation phenology in Saihanba area

为探究塞罕坝地区木质部生长物候与植被物候变化规律及其影响因子,基于塞罕坝样点数据的木质部生长物候监测数据及NDVI数据利用最佳阈值提取方法获得预测木质部生长物候的最佳阈值,并基于该阈值预测塞罕坝地区2010-2021年木质部起止生长物候。利用动态阈值法基于遥感数据提取植被物候,对比分析木质部生长物候与植被物候空间变化差异及其影响因子。结果表明,塞罕坝地区木质部生长始期主要集中在每年第111~150天,木质部生长末期主要集中在每年第235~257天。植被木质部生长季长度大约为96~130 d。塞罕坝地区木质部生长物候比植被物候起始期提前3~21 d,该差异主要受温度降水和坡度影响,而生长结束期延后3~43 d,该差异主要受植被覆盖度影响。木质部生长季长度比植被物候长9~64 d,主要受降水的影响。由于木质部生长比植被物候更能反映树木碳汇的形成时期,因此更长的木质部生长物候表明更多的碳积累。

In order to explore the changes and influencing factors of xylem growth phenology and vegetation phenology in Saihanba area,based on xylem growth phenology monitoring data and NDVI data from Saihanba sample point,the optimal threshold value extraction method was used to obtain the optimal threshold value for predicting xylem growth phenology.Based on the threshold,the start and end growth phenology of xylem in Saihanba area from 2010 to 2021 was used to predict.The dynamic threshold method was used to extract vegetation phenology based on remote sensing data,and the difference of xylem growth phenology and vegetation phenology in spatial change and its influencing factors were compared and analyzed.The results showed that the beginning of xylem growth was mainly concentrated in the 111150 days,and the end growth stage of xylem was mainly concentrated in the 235257 days.The xylem growing season of vegetation was about 96130 days long.The xylem growth phenology in the Saihanba area was 321 days earlier than the vegetation phenology start,which was mainly affected by temperature,precipitation and slope,while the growth end period was delayed by 343 days,and the difference was mainly affected by vegetation coverage.The length of the xylem growing season was 964 days longer than that of vegetation phenology,which was mainly affected by precipitation.Since xylem growth was more reflective of the formation period of the tree's carbon sink than vegetation phenology,longer xylem growth phenology indicated more carbon accumulation.