黄土丘陵区刺槐人工林土壤养分特征及演变

为了探明黄土丘陵沟壑区人工林土壤养分状况及其演变规律,应用时空互代的方法,以刺槐林为代表,对该区不同利用年限的人工林土壤养分特征及其时空变化等进行了系统研究。结果表明,黄土丘陵区人工林土壤肥力处于低水平;人工林表层土壤养分中有机质和速效磷的空间变异性较大;坡度、坡向、坡位等环境因子对土壤养分有一定的影响。随利用年限的增加,人工林土壤全氮,有机质、碱解氮、速效钾含量及土壤养分指数均增加,与利用年限有极显著的相关性,其变化趋势符合y=axb模型。全氮,有机质和碱解氮随利用年限的增加量不显著,而速效钾每经过10年就有显著增加,全磷和速效磷含量则保持相对衡定的水平。黄土丘陵区人工林地土壤有机质、全氮、碱解氮、速效钾及养分指数年增长率分别约为0.20g.kg、0.01g.kg、0.69mg.kg、2.27mg.kg和0.04。该区人工林地土壤有机质、全氮、碱解氮及养分指数约需50年、速效钾约需30年可达到中上等养分水平。

The characteristics and evolution of soil nutrient in artificial black locust (Robinia pseudoacacia)forest land in the hilly Loess Plateau

In order to know the soil nutrient condition and its evolution in artificial forest land in the hilly Loess Plateau region, the soil characteristics and its temporal and spatial variation in artificial black locust (Robinia pseudoacacia) forest land with different ages were studied systematically through the approach of substituting the temporal serial with spatial serial. The result showed that the soil nutrient content of artificial forest land in the region was at the low level. The spatial variability of soil organic matter and phosphorous content was larger than that of the other nutrient in topsoil of artificial forestland. The environment factors,such as gradient, aspect and position of the slope, had effect to some extent on soil nutrient. The nutrient content of total nitrogen(TN), organic matter(OM), available nitrogen(AN), available potassium(AK) and soil nutrient index(SNI) increased with the increasing of land use years. A significant correlation was found between the nutrient content in artificial forest land and its land use years except total potassium(TK) and total phosphorus(TP). The SNI was also significantly correlated with land use years. The correlation could be simulated with the following formula: y=ax^b. No significant increase of OM and AN was found with the increase of land use year. However, AK increased significantly every 10years. TP and available phosphorus(AP) kept a relatively stable content in different land use years. The content of OM, TN, AN and AK and SNI increased with land use year at a rate of 0.201g/kg、0.010g/kg、0.69mg/kg、2.27mg/kg and 0.4 per year respectively in artificial forestland. In the hilly Loess Plateau region, OM, TN, AV and SNI could reach to the middling nutrient level of the region after 50years and AK could reach to the middling to up level after 30 years in artificial forestland.