东北黑土区农田防护林与沟谷侵蚀关系

Relationship between farmland shelterbelt and gully erosion in the black soil region of Northeast China

东北黑土区是中国重要的商品粮基地,但是严重的水土流失给其粮食产量带来了严峻考验。选择东北黑土区黑龙江省的克山县作为研究区,以2007年2.5 m分辨率的模拟真彩色合成的SPOT5影像为基础数据源,获取该区的侵蚀沟分布数据;以2008年分辨率为30 m的标准假彩色合成的TM影像为基础数据源,获取该区的农田防护林分布数据,进而从坡度、距离以及两者密度等方面,分析典型黑土区防护林和沟蚀之间的耦合关系。结果表明:研究区防护林密度在空间分布上沿东北—西南方向逐渐增大,而侵蚀沟密度分布则呈现相反趋势;随着坡度的增加,防护林密度逐渐增大,而侵蚀沟密度与坡度的关系则呈现相反趋势;在距防护林120 m的防护距离内,防护林对沟蚀的防护效应基本一样,120~240 m的防护距离内,随着距离增加,防护林对沟蚀的防护效应线性减弱,而240m以外的距离,防护林对沟蚀的防护效应明显减弱;随着防护林密度的增大,侵蚀沟密度是减少的,从经济和资源角度出发,防护林密度在1 100~1 300 m/km^2时,对沟蚀防护效果达到最优,可以做为防护林参考种植密度。该研究为有针对性的进行沟蚀防治提供科学指导。

[Background] The black soil region in Northeast China is one of the most important marketable grain basis. The serious soil erosion brings crucial challenges to the production of marketable grain. Farmland shelterbelt is a key part of the Three Norths Forest Protection System in Northeast China,which plays a positive role in the prevention and control of soil erosion. The study on the effect of shelterbelt on gully can provide scientific insights into gully erosion control. [Methods] Firstly,the typical black soil region was chosen as the study area in Keshan County,Northeast China,and the distribution of gully and farmland shelterbelt was derived by interpreting the SPOT5 imagery in 2007 and TM imagery in 2008, respectively. Then, the effect of farmland shelterbelt on gully erosion was analyzed,using the spatial analysis and mathematical statistics methods. [Results] Generally,thedensity of farmland shelterbelts increased from northeast to southwest,while the variation law was the opposite for the density of gully. The highest density of farmland shelterbelt occurred in the western and northwestern regions,with the density larger than 1 400 m/km2. And the highest density occurred in northeastern region for gully, 800 m/km2. Furthermore,the defense effect of farmland shelterbelt on gully erosion varied with the defense distance. When the distance was shorter than 120 m,no obvious difference existed for the defense effect. When the distance ranged from 120 to 240 m,the defense effect decreased linearly with the increase of distance. When the distance was longer than 240 m,the defense effect decreased distinctly. Besides,the shelterbelt and gully density showed a highly linear relationship when the shelterbelt density ranged from 500 to 1 300 m/km^2. However,the change of gully density was not obvious when the shelterbelt density was higher than 1 300 m/km^2. [Conclusions] The slope,distance from the gully,and density of farmland shelterbelt were all import factors to the effect of farmland shelterbelt on gully erosion. The effect varied under different conditions of the three above mentioned factors. The farmland shelterbelt should be better planted in regions with the slope less than8°,less than 120 m far away from the gully,and with the density ranging 1 100-1 300 m/km^2 in black soil region of Northeast China. This work may provide a certain scientific suggestion for the erosion prevention and management.