Response Of Typical Marsh Herbaceous Plant Phenology To Climate Change In Sanjiang Plain

In the context of global warming,the growing environment and growth conditions of herbaceous plants have been continuously affected.Plant phenology is one of the key indicators to study the extent to which plant growth is affected by climate,and the study of typical plant phenology in a given region is important for the stability of local ecosystems.Based on the phenofit package of R software and Moderate Spatial Resolution Imaging Spectroscopy(MODIS)imagery,this paper compares and analyses the most suitable dataset,the best curve fitting method and the phenological extraction method for the plant taxa of typical wetland marshes in the Sanjiang Plain.The main topics include NDVIand EVI datasets,five curve fitting methods(AG,Zhang,Beck,Elmore,Gu),TRS,Derivative,Klosterman,and Klosterman,Derivative,Klosterman,and GU methods.Pearson correlation analysis,MannKendall mutation test and trend test,ANOVA and multiple linear regression analysis were used to study the response of typical herbaceous plant phenology to climate change in the swampy wetlands of the Sanjiang Plain.The main findings are as follows:(1)the EVI dataset was more suitable than the NDVI dataset for the study of herbaceous plant phenology in the swampy wetlands of the Sanjiang Plain;the Gu curve fitting method was the best among the curve fitting methods;the TRS1.SOS parameter in the TRS1 phenology extraction method was suitable for extracting the SOS of Carex spp.,Sweetgrass spp.and Wild Greengrass spp.and the Klosterman phenology extraction method The Senescence parameter in the Klosterman method is suitable for extracting the EOS of Carex,Sweetgrass and Wild Cycads.(2)There is a trend towards a warmer and wetter climate in the Sanjiang Plain from 2000 to 2021.In the phenological monitoring of Carex,Sweetgrass and Wild Fescue,there is a high degree of continuity and no obvious mutation points in each genus;among them,there is an early trend in SOS of Carex and EOS of Sweetgrass.(3)In terms of interannual variation in temperature and precipitation,there was a tendency for sweetgrass spp.EOS to advance as temperature increased.In terms of seasonal variation,Carex LOS was positively correlated with spring maximum temperature;Sweetgrass LOS was positively correlated with spring minimum temperature;Wild fescue LOS was positively correlated with spring mean temperature and negatively correlated with autumn mean temperature;Carex EOS was negatively correlated with autumn minimum temperature;Sweetgrass EOS was negatively correlated with winter EOS was negatively correlated with mean winter temperature and minimum winter temperature.The EOS of the genus Wild Fescue was negatively correlated with mean autumn air temperature.SOS of all genera was not sensitive to meteorological factors;LOS and EOS of Carex were more sensitive to mean monthly temperature;LOS of Wild Fescue was more sensitive to mean monthly temperature,while the sensitivity of phenological parameters of other genera to meteorological factors was not significant.Both temperature and precipitation had a lagging effect on SOS and EOS in Carex,Sweetgrass and Wild Cycads,with varying lag times,but a single meteorological factor was not the determining factor.