泾河流域耕地-人口-粮食系统与耕地压力指数时空分布

    Temporal and spatial distribution of cropland-population-grain system and pressure index on cropland in Jinghe watershed

    • 摘要: 根据泾河流域1990-2005年耕地、人口和粮食的数据动态变化情况,计算了流域内31个县(区)的耕地压力指数,在此基础上分析了该指数在时间上的变化和在空间上的区域差异,并进一步探讨了以上变化和差异产生的原因。分析结果表明:耕地面积总体呈持续减少趋势,人均粮食产量呈上升趋势,这与粮食单产的提高有很大关系;最小人均耕地面积逐年减少,耕地压力总体减小,但旱灾期间突变性增大;流域内各县(区) 耕地压力差异较大,西北部的丘陵沟壑区和六盘山地区耕地压力相对较大,中下游的南部丘陵沟壑区和冲积平原地区的耕地压力相对较小;复种指数、人口密度、粮食作物播种面积比例、粮食单产等要素对各县(区)指数的作用强度存在差异。最后提出了解决耕地压力的一些有效措施和方法,并对此领域的研究方向提出展望。

       

      Abstract: Pressure index on cropland is one of the exponents to express the situation of land bearing capacity. The capacity shows different characters within different dimensions. Changes of cropland, population and grain were analyzed in Jinghe watershed. Basing on that, characteristics of the changes of the index in the whole area and that of in 31 counties were analyzed, such as the changes of pressure index on cropland, regional difference and the causes of such that. Results show that: ①On the whole, the area of cropland in Jinghe watershed takes on sustaining decreased trend and the population takes on sustaining increased. But these don't affect the total output greatly. On the contrary, cropland acreage per capita takes on sustaining increased trend because of the increase of grain yield per hectare. What should note is that the change of grain yield per hectare is great due to the disaster of drought. ②Minimum cropland acreage per capita in this watershed shows the trend of sustaining decreased. Hereinto, the values of pressure index on cropland reaches near to 1 in 1990, and larger than 1 in 1995 and 1999 because of drought and cropland repossession program respectively, namely, the pressure on cropland increase. In 2005, the index decreased to 0.973. ③Annual variation and regional distribution of pressure index on cropland is large. For example, in 2005, the number of counties with the values of index exceed of 1 decreased from 21 to 12. The counties bearing larger pressure on cropland distributed mainly in loess hilly region and Liupan Mountain, i.e. the area of west-north of Jinghe watershed area. On the contrary, loess hilly region of middle and lower reaches of Jinghe, alluvial plains regions distribute the units with lower pressure on cropland. ④Multiple cropping index, population density, the proportion of foodstuff, grain yield per unit area act on the pressure index on cropland, but the force is different for different factors in different area. Based on such analysis above, referring to the development of Jinghe watershed area, it is rational to collocating water and land resources within appropriate dimension adopting systematic method, following some policy and measure, such as reinforce the protection of basic farmland, increase the level of agricultural science and technology. At the same time, Jinghe watershed area should develop ecological agriculture, decrease of quantity of pesticide and chemical fertilizer, control the sustaining increase of population and then improve the quality with great efforts.

       

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