Monitoring Of Crop Phenology And Sensitivity Analysis In China

Crop phenological information plays an important role in food security,climate change and protect the ecological environment.In this paper,with the main origin of rice and winter wheat in China as study area,monitoring key phenological parameters and analyzing sptial-temporal variations based on the 500 m 8 day composite MODIS-OSAVI data from 2001 to 2014.The main achievements are as follows:(1)A smooth sequence curve is the precondition of monitoring phenology,while exist-ing methods difficult to balance the fidelity and smoothness.In this article,based on continu-ous wavelet transform time-frequency localization property of wavelet to find the best ap-proximation of the original signal,a simple Smooth method based on Continuous Wavelet Transform(SCWT)was proposed.And this method is better in fidelity and smoothness.(2)According to the characteristics of rice and winter wheat phenological parameters in time series,one integrated phenological monitoring method based on time series was pro-posed.Monitoring results obtained by this method,and compared with agro-meteorological station data,the proportion within 8 days,16 days,and 32 days reached 39.81%,39.81%and39.81%respectively.The results indicate that this phenological monitoring method had cer-tain rationality.(3)Based on the results of rice phenology in Northeast and Southeast provinces,three conclusions could be found.1)The change of phenological space pattern in northeast China is not significant,meanwhile the phenology of rice presented an advance trend for nearly 14 years.2)In southeast China,the spatial pattern of greening season,tillering season,earing season and maturing season emerged a great difference from north to south.Specifically,the phenological parameters of single rice of in Poyang Lake area was latest,the phenology of double rice was advanced from south to north,and the phenological parameters of mid-dle-season rice was gradually postponed from southwest to northeast.3)In general,the phe-nological variation of rice in southeast was stable for nearly 14 years.(4)Based on the inversion phenology of winter wheat in North China,the characteris-tics of spatial pattern and temporal variation were studied,and the sensitivity of meteorologi-cal factors were analyzed respectively.The results showed that:1)The spatial pattern of win-ter wheat phenology was postponed from southeast to northeast.2)The characteristics of the spatial pattern of winter wheat phenology were closely related to the climatic conditions in different region.Phenological parameters showed significant negative correlation with tem-perature,positive correlation with sunshine,and little correlation with rainfall.3)The phe-nology of winter wheat presented a delaying trend for nearly 14 years,especially in greening season and filling season,about 0.5 to 2 days each year.And the rate of change for earing season and maturing season was less than 1 day per year.4)Made correlation analysis with meteorological factors,the results indicated that the phenological parameters showed signifi-cant negative correlation with temperature,and with a lag about 2 to 3 months.Especially filling season showed significant correlation with temperature,but little correlation with rain-fall and sunlight.