Joint Laboratory for GIS Application

Nanning, China

Joint Laboratory for GIS Application

Nanning, China
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Chen Y.-L.,China Agricultural University | Chen Y.-L.,Guangxi Meteorological Disaster Mitigation Institute | Chen Y.-L.,Joint Laboratory for GIS Application | Feng L.-P.,China Agricultural University | And 6 more authors.
Acta Agronomica Sinica | Year: 2016

Sugarcane stalk elongation is the most important factor for the development evaluation and yield estimation, on which meteorological factors have significant effects. Differences between new planting sugarcane and ratooning sugarcane in development and response to meteorological factors need to be analyzed for promoting agricultural production. In this paper, taking new-planting sugarcane and ratooning sugarcane of Guangxi as the research materials, observed sugarcane agronomic data and meteorological information at four agro-meteorological experimental stations from 2000 to 2011 were used to analyze the relationship between stalk elongation and meteorological factors that were precipitation, relative humidity, maximum temperature, minimum temperature, mean temperature, air pressure, and sunshine hours at different stages. The results show that there was an obvious difference between new-planting sugarcane and ratooning sugarcane in stalk height. During the sugarcane stem elongation, compared with ratooning sugarcane, new-planting sugarcane had a higher stalk height with a lower background in most of years, besides, its total stem elongation amount was much more but elongation duration was short. There was a significant correlation between stalk elongation and most meteorological factors in both new-planting sugarcane and ratooning sugarcane. The effect of most meteorological variables was larger in new-planting sugarcane than in ratooning sugarcane. The correlation between new-planting sugarcane and meteorological factors are obviously higher than that of ratoon sugarcane. Minimum temperature, relative humidity and maximum temperature played a direct positive role on stalk elongation in both new-planting sugarcane and ratooning sugarcane, and average temperature and air pressure played a direct negative role, meanwhile, accumulated temperature and rainfall play a significant indirect effect through other meteorological factors. There was a significant lag in the response of stem elongation to rainfall for both new-planting sugarcane and ratooning sugarcane. Compared with ratooning sugarcane, lag of new-planting sugarcane was longer. The total lag time was about 20 days for new-planting sugarcane and 10 days for ratooning sugarcane. There was also a lag in response to sunshine hours for new-planting sugarcane, but no lag to temperature for both sugarcanes.


Chen Y.,Guangxi Meteorological Disaster Mitigation Institute Remote Sensing Application and Validation Base of NSMC | Chen Y.,Joint Laboratory for GIS Application | Chen Y.,China Agricultural University | Mo W.,Guangxi Meteorological Disaster Mitigation Institute Remote Sensing Application and Validation Base of NSMC | And 9 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2015

In this paper, taking the vegetation in Karst rocky area as the research subject, MODIS enhanced vegetation index (EVI) series and climatic information during 2001-2010 are used to analyze the relationship between vegetation and climate factors. Vapor pressure, precipitation, relative humidity, maximum temperature, minimum temperature, mean temperature, dew point temperature, wind speed and sunshine hours are taken as climatic variables to explore their relationships with EVI series in different stages using correlation analysis method and path analysis method. Then, climatic factors are selected to establish EVI simulation models of Karst vegetation by stepwise regression analysis method. The results show that: There are significant positive correlations between EVI of Karst vegetation and most climatic factors. The correlation coefficients between EVI and the climatic factors including vapor pressure, mean temperature, dew point temperature, minimum and maximum temperature are higher and show better consistency than other factors, and all the values are over 0.8. The response of EVI to climatic factors has obvious hysteresis nature except sunshine hours and wind speed. The lag time is about 16 days for most climatic factors. Minimum and maximum temperature and mean temperature play a most significant direct effect on vegetation EVI; vapor pressure, precipitation and relative humidity play a significant indirect effect on EVI although their direct effect are not obvious. According to the correlations between EVI and climatic factors, 2 EVI simulation models are established including the same-time model and mixed-time model. The same-time model means the stages of the climatic factor series used in the model are the same to the EVI series. But, in the mixed-time model, climatic factors and EVI series in different stages are used. Vapor pressure, sunshine hours and dew point temperature are used to build the same-time model, and vapor pressure (one stage before), maximum temperature (one stage before), precipitation (one stage before), dew point temperature (one stage before) and sunshine hours (same stage) are used to build the mixed-time model. Two models' efficiencies in total Guangxi Karst area and single station are tested using data series from 2000 to 2010 and data in 2011. The simulation precisions for total Guangxi Karst area are higher than each single station for both models. From 2000 to 2010, the R2 of the same-time model and the mixed-time model are 0.843 and 0.892, respectively, while 0.765±0.033, 0.801±0.021, respectively for single station. Meanwhile, in the year of 2011, the R2 of the same-time model and the mixed-time model are 0.797 and 0.873 while 0.716±0.073, 0.746±0.064 for single station respectively. For most stations, the efficiency of mixed-time model is higher than the same-time model. As the climatic factors used in the model are different and the relationships between climatic factors and vegetation vary among the stations, the efficiency of the same-time model for some stations is higher than the mixed-time model's. ©, 2015, Chinese Society of Agricultural Engineering. All right reserved.


Chen Y.L.,Guangxi Meteorological Disaster Mitigation Institute | Chen Y.L.,Joint Laboratory for GIS Application | Zhong S.Q.,Guangxi Meteorological Disaster Mitigation Institute | Zhong S.Q.,Joint Laboratory for GIS Application | And 4 more authors.
Applied Mechanics and Materials | Year: 2013

TM/ETM data as the base information combined with a digital elevation model are used to analyze the spatial distribution and temporal variation of soil erosion in Guangxi. The results shows that light, medium and strong are the main three levels of soil erosion in Guangxi. The proportions of light and medium soil erosion are higher which are 6.18% and 4.76% respectively. The total area of soil erosion and its degrees exhibit an upward trend since the 1980s. The area of soil erosion in Guangxi increases 4% in the past 20 years. The five levels of soil erosion performance an upward trend mostly. Medium soil erosion is of the biggest change with an increase of 1.29% while acute soil erosion exhibits a smallest change with an increase of 0.49%.

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