Forecasting Model of Agro-meteorological Disaster Grade Based on Decision Tree

Based on the discuss of the basic concept of data mining technology and the decision tree method,combining with the data samples of wind and hailstorm disasters in some counties of Mudanjiang region,the forecasting model of agro-meteorological disaster grade was established by adopting the C4.5 classification algorithm of decision tree,which can forecast the direct economic loss degree to provide rational data mining model and obtain effective analysis results.

Evaluation and Effect of Agro-meteorological Disasters on Agricultural Production in Liaoning Province

Based on statistic data of agricultural production and meteorological disasters in Liaoning Province from 1971 to 2008,the effect weight,disaster rate and variance value of main agro-meteorological disasters including drought,flood,wind,hail and frozen injury were calculated,and the variation characteristic of time series of agro-meteorological disasters was further analyzed,while the grade division and comprehensive evaluation of agro-meteorological disasters were carried out in our paper.The results showed that there was a negative correlation between grain yield and the degree of agro-meteorological disasters,and agro-meteorological disasters were relatively serious in 1989,1997 and 2000,with the reduction of grain yield.Meanwhile,the occurrence frequency of light disasters was highest,accounting for 39% of total years,and the adverse effect of agro-meteorological disasters on agricultural production became more and more severe decade by decade;the effect weight of drought reached 63%,so drought was the main agro-meteorological disaster influencing agricultural production.

Multiple Cropping Intensity in China Derived from Agro-meteorological Observations and MODIS Data

Double-and triple-cropping in a year have played a very important role in meeting the rising need for food in China.However,the intensified agricultural practices have significantly altered biogeochemical cycles and soil quality.Understanding and mapping cropping intensity in China′s agricultural systems are therefore necessary to better estimate carbon,nitrogen and water fluxes within agro-ecosystems on the national scale.In this study,we investigated the spatial pattern of crop calendar and multiple cropping rotations in China using phenological records from 394 agro-meteorological stations(AMSs)across China.The results from the analysis of in situ field observations were used to develop a new algorithm that identifies the spatial distribution of multiple cropping in China from moderate resolution imaging spectroradiometer(MODIS)time series data with a 500 m spatial resolution and an 8-day temporal resolution.According to the MODIS-derived multiple cropping distribution in 2002,the proportion of cropland cultivated with multiple crops reached 34%in China.Double-cropping accounted for approximately 94.6%and triple-cropping for 5.4%.The results demonstrat that MODIS EVI(Enhanced Vegetation Index)time series data have the capability and potential to delineate the dynamics of double-and triple-cropping practices.The resultant multiple cropping map could be used to evaluate the impacts of agricultural intensification on biogeochemical cycles.

Study on Agro-meteorological Conditions for Film Mulching Planting in Autum

The agro-meteorological conditions for film mulching planting in autumn in Xiji, Ningxia was studied by using the meteorological data from the national basic stations over the years, including the mulching planting of corn in autumn in differ- ent stages from 1985 to 1986, the mulching planting in different stages after the appearance of effective precipitation in October, and the wind simulation experimen- tal data of blower. Precipitation suitability analysis model before autumn film mulching and crop growth period was simulated to analyze the effective precipitation weather before mulching planting in autumn, and simulations were also made to temperature suitability analysis model during soil preparation and film mulching peri- ods in autumn, the suitability function of optimal sowing time about the soil moisture dynamic changes in autumn in different times, the best water conservation effect in film mulching period at different time after the appearance of effective precipitation, the wind resistance function of film mulching in autumn. All the simulation work was of high referential value to carry out meteorological service and agricultural weather forecast about film mulching in autumn.

Research Advances in Monitoring Agro-meteorological Disasters Using Remote Sensing

Remote sensing is an important method for rapidly obtaining farmland information. Once meteorological disaster occurs,using the remote sensing technology to extract disaster area of crops and monitor disaster level has great significance for evaluating disasters and making a timely remedy. This paper elaborated the importance of monitoring agro-meteorological disasters using remote sensing in current special historical period,overviewed remote sensing methods both at home and abroad,analyzed existing problems,made clear major problems to be solved in monitoring agro-meteorological disasters using remote sensing,and discussed the development prospect of the remote sensing technology.

Spatial pattern and decadal change of agro-meteorological disasters in the main wheat production area of China during 1991-2009

Agro-meteorological disasters （AMD） have become more frequent with climate warming. In this study, the temporal and spatial changes in the occurrence frequency of major meteorological disasters on wheat production were firstly explored by analyzing the observed records at national agro-meteorological stations （AMS） of China from 1991 to 2009. Fur- thermore, impact of climate change on AMD was discussed by comparing the warmer decade （2000-2009） with another decade （1991-2000）. It was found that drought was the most fre- quent disaster during the last two decades, with a highest proportion of 79%. And the fre- quency of AMD increased significantly with climate change. Specifically, the main disasters occurred more frequently in the reproductive period than in the vegetative period. Besides, the spatial changes in the AMD frequency were characterized by region-specific. For example the wheat cultivation areas located on the Loess Plateau and the middle-lower reaches of the Yellow River suffered mainly from drought. All these results were strongly linked to climate change in China. Therefore, sound adaptation options should be taken based on the latest changes of AMD under global warming to reduce agricultural damages.