Study On The Potential Productivity Of Yaan City In GIS Environment

The main agriculture-resourse databases of Yaan city which include spatial databases and attribute databases was done, based on Geographic Information System. 16032 evaluation units of the potential land productivity were overlaid out.By using the mechamism methodology and relative computing models, Yaan city's land productive potentiality was computed according to synthetic index of land productivity evaluation that was taken as soil effective coefficient.Result of research indicated that:(a)Siol effective coefficient changed from 0.3047 to 0.8550,respectively with medium-low yield farmland of 71.28 percent.(b)The division of climate productivibilty is situated on the third degree and fourth class western area in east of Chian. (c)Land natural productivity increase from 7843 kg/ (hm2-a) to 17335 kg/ (hm2-a) relate to altitude closely,and the mean rate of enhancing yield is 23.53 percent in this region with annual enhancing-rate of 0.64 percent in last 15 years.(d)There are many facters that have been influencing soil effective coefficient that's soil organic matter,total nitrogen,effective phosphine and soil texture in turn.In a word, attenuation cause of land productivity is the result of water and soil.(e)The forestland potential productivity change from 3986 kg/hm2 to 15034 kg/hm2,but it has a high distinction between southern aera and north area in Yaan city.(f)The grassland potential productivity increase from 4085 kg/ (hm2-a) to 16973 kg/ (hm2-a) ,but it has a high classification of potential productivity, (g) Ditribution map was formed of potential land productivity.(h)It could be act as decision support for agriculture development,national land planning and ecotop constructive ,etc.