北方农牧交错带以开发能源作物促生态重建的前景

Prospect of ecological restoration through tapping energy crops in Northern interlaced zone of arable lands and grasslands

退耕还林、草已被证明是防止沙化、土壤侵蚀及恢复生态的有效途径。但当前我国执行的退耕补贴政策难以持久,接续产业的开发也很困难。农牧交错带的气候条件对粮、油作物而言相当严酷,但却相对有利于以取得植株营养体———生物量多而非籽粒产出高为目标的多年生作物的生长,实现相对较高的系统生产力。中国耕地面积虽非常有限,但草地和林地的面积却分别是耕地的4和3倍。像北方农牧交错带就拥有大面积的不宜继续农耕的农地和退化草地。近年在发达国家新出现的在边际土地和部分农地种植"专用能源作物",正是能适应我们对土地资源条件扬长避短的要求、可为生物能源提供可靠原料供应的特殊农作方式。初步的试验表明,在北方农牧交错带内的黄土高原地区种植柳枝稷、芒草等能源作物,能实现经济效益与生态效益的"双赢"。在该地区种植能源作物,面积可达2 000万hm2,有望使它年产4亿t(干重)以上的生物质,从而成为我国最重要的生物能源原料基地之一。

To idle arable land and converts it to forest/grassland in western China has been proved as an effective way to ecological restoration and to stop desertification.However the relevant policy of subsidy is unsustainable,and subsequent agro-industries is difficult to establish based on the fallow fields.Although climate conditions do not favor to cropping of grain in the interlaced zone of agriculture area and pasture,it does relatively favor to the planting of vegetation（biomass）-oriented crops,thus gaining relatively higher ＇system productivity＇.China owns very limited arable land,but ample resource of grassland and forest land.Newly emerged energy cropping system in the developed countries could be adopted in China on vast marginal land of Loess Plateau.The so-called dedicated energy crops,such as Miscanthus and switchgrass etc.,have been primarily tested within Loess Plateau,and proved to be the promising crops for ＇win-win solution of ecological benefits and economic benefits.It is estimated that there are about 20 million hectares of marginal land that are suitable to energy grasses and will be produced more than 400 million tons of biomass feedstuff annually,thus making this area one of the most important feedstuff base candidate for bioenergy industry in China.