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Analysis Of Vegetation Growing Season Changes In 13 Provinces Of Northern China In Recent 30 Years

Posted on:2017-04-26Degree:MasterType:Thesis
Country:ChinaCandidate:H B LiuFull Text:PDF
GTID:2310330488971005Subject:Cartography and Geographic Information System
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Vegetation is an extremely important part in the world's terrestrial ecosystems. Under the influence of global warming, vegetation activity significantly enhanced and vegetation phenology and its relationship between climatic factors has become the current hot issue of global change research. Both domestic and foreign scholars trends to use remote sensing methods to study vegetation growing season change and analyze the relationship between vegetation growing season factors in response to changes of climatic factors. Based on GIMMS 3g NDVI, land use, temperature and precipitation data, the paper fitted the vegetation growth curve and extracted the phenology parameters. They were the beginning of the growing season, the end of the growing and the length of the growing season in 13 provinces of northern China in recent 30 years(from 1983 to 2012) and also analyzed its temporal and spatial changes and also the relationship between temperature and precipitation. We used harmonic analysis of time series method to reconstruct vegetation NDVI, dynamic threshold and a six polynomial fitting method. Some general conclusions can be drawn as follows:(1) With longer time series features and better data quality, GIMMS 3g NDVI is very good to show the characteristic of vegetation growing season curve and can be used to future study of vegetation growing season after time series harmonic data analysis.(2) During the study period, most of the northern part of the beginning of the growing season mean mainly distributed among 90 to 150 d, the average value of the region for 30 years was 111.6 d, and showed a trend of advance. Mean value of the end of the growing season was 266 d, mainly distributed from 250 to 300 d, was postponed trend. The average value of end of the growing season for the region was 266 d, mainly between 250 to 300 d, was to extend the trend. In items of different vegetation types, there was also an advanced trend of the beginning of the growth season, a delayed end of growth season and an extension of the completely growing season. The growth season parameters change were not continuous and the type difference was bigger, the space characteristic was obvious.(3) Affected by global warming and rising temperatures in the region of China, the beginning of the growing season showed an overall trend of advance, the end of the growing season showed a postponed trend, the length of growing season showed a trend of extension, and the number of days in advance or postpone were various. Take different types of vegetation into consideration, there are also the beginning of the growing season ahead, and to postpone the end of the growing season to extend the length of the growing season trend;(4) The climate change response is sensitive to the vegetation phenology-growing season in 13 provinces of northern China. The beginning of growing season had a strong negative correlation with spring temperature and its relationship with precipitation was not obvious but maintained a generally same trend with precipitation. Spring temperature was the main factors affecting the beginning of growing season period. The rising of temperature and the increase of precipitation in autumn prolonged the period of the completely growing season and the effect of autumn air temperature on the beginning period of growing season is greater than that of precipitation. In terms of length of growing season, temperature and precipitation played a much more important role in grassland rather than woodland and the effect of the brush was very small.
Keywords/Search Tags:beginning of growing season(BOS), end of growing season(EOS), length of growing season(LOS), GIMMS 3g NDVI, harmonic analysis, polynomial fitting
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