Vegetation greenness and photosynthetic spring phenology in Northeast China and their responses to water and thermal factors
Vegetation phenology is a critical indicator reflecting the impact of climate change on ecosystems.Northeast China boasts rich vegetation types and has experienced stronger warming than the national average,thus research on its vegetation phenological responses to climate change is particularly significant for providing scientific underpinnings for ecosystem management under global change scenarios.This study used the MODIS Enhanced Vegetation Index(EVI)and Solar-Induced Chlorophyll Fluorescence(SIF)data from 2000 to 2020 to extract greenness and photosynthetic phenology in Northeast China.It analyzed the spatial-temporal variations of spring phenology in the region and combined meteorological data to diagnose the dominant factors that affect spring phenology across different vegetation types.The results revealed that:1)From 2000 to 2020,the spring phenology of vegetation in Northeast China exhibited an advancing trend.Specifically,the start of growing season derived from the EVI data(SOSEVI)advanced significantly at an average rate of 0.657 days per year(P＜0.05).Similarly,the start of growing season derived from the SIF data(SOSSIF)showed a statistically significant advance at an average rate of 0.443 days per year.Spatially,76.8％and 88.5％of the pixels displayed an advancing trend for SOSEVI and SOSSIF,respectively.2)Among the environmental factors,spring temperature(temperature of air at 2 m above the surface)and soil moisture(volumetric soil water in the surface layer)content exerted a strong influence on the spring phenology in Northeast China.For SOSEVI,approximately 44.5％of the pixels were primarily dominated by spring temperature,while about 24.5％were governed by soil moisture content.For SOSSIF,spring temperature played a dominant role in around 61.5％of the pixels,and soil moisture content was the primary driver in about 20.0％pixels.Thus,rising spring temperatures and increased soil moisture levels were identified as the main factors driving the earlier onset of spring phenology.3)The dominant factors influencing spring phenology varied among different vegetation types.The spring phenology of deciduous broadleaf forests was mainly affected by spring temperature,whereas the spring phenology of grassland was predominantly more sensitive to soil moisture conditions.This study disclosed the spatial-temporal patterns and dominant factors of spring phenological changes of various vegetation types in Northeast China,providing robust evidence for the understanding of climate change impacts on regional vegetation dynamics.
vegetationspring phenologyremote sensingspatial-temporal changeenvironmental factorsNortheast China
万方数据
维普
