河岸带不同植被类型对土壤有机碳和全氮分布特征的影响-- 以北京地区温榆河为例

河岸带生态系统是河流生态系统和陆地生态系统之间的生态交错带,也是一个敏感和脆弱的生态区域。由于受河道周边人类活动的干扰,河岸带生态系统的植被类型发生了巨大变化。本文以北京市地区的温榆河为研究对象,分析了河岸带7种植被类型对土壤有机碳和全氮含量及其空间分布特征的影响。结果表明:(1)河岸带不同植被类型对土壤有机碳和全氮的影响主要表现在表层土壤,尤其是0~5 cm土层,而对5 cm以下土层的影响相对较小。(2)河岸带不同植被类型土壤全氮和有机碳含量的空间分布特征具有显著差异。随着土层深度增加,土壤全氮和有机碳整体上呈下降趋势,但不同植被类型的垂直变化规律有较大差异,如自然草地、退耕撂荒地和林地的土壤有机碳、全氮含量随土层深度加深而降低的速率明显高于农田生态系统。(3)在0~30 cm土壤剖面上,土壤有机碳平均含量从高到低依次为杨树林(9.54 g.kg 1)、自然荒草地(9.33 g.kg 1)、梨树果园(9.18 g.kg 1)、火炬树林地(8.89 g.kg 1)、退耕撂荒地(7.91 g.kg 1)、玉米地(7.22 g.kg 1)和黄豆地(7.17g.kg 1);土壤全氮的平均含量从高到低依次为自然荒草地(1.30 g.kg 1)、杨树林(0.91 g.kg 1)、梨树果园(0.90g.kg 1)、火炬树林地(0.83 g.kg 1)、退耕撂荒地(0.80 g.kg 1)、玉米地(0.72 g.kg 1)和黄豆地(0.70 g.kg 1)。

Effects of riparian vegetation on soil organic carbon andtotal nitrogen distribution - a case study of Wenyu River, Beijing

Riparian ecosystem is an ecological ecotone that occurs between river and terrestrial ecosystems. Riparian ecosystems are normally sensitive and vulnerable ecological niches. There are vast changes in riparian vegetation systems due to human disturbances of river systems. Thus this study analyzed the effects of 7 riparian vegetation systems on the contents and spatial distributions of soil organic carbon and total nitrogen in Wenyu River in Beijing. The results showed that riparian vegetation mainly affected soil organic carbon and total nitrogen in the surface soil layer, especially in the 0~5 cm soil layer, with relatively minimal effect on below the 5 cm soil layer. The impact of vegetation on the content and distribution of soil total nitrogen and organic carbon was significant. While soil total nitrogen and organic carbon decreased with increasing soil depth, vertical variations among the 7 vegetation systems were different. The rate of decrease in soil organic carbon and total nitrogen with soil depth was significantly higher under natural grasslands, abandoned farmlands and forests than under farmland ecosystems. In the 0~30 cm soil profile, the average content of soil organic carbon was highest under Populus simonii forestland (9.54 g·kg^-1), followed by natural grassland (9.33 g·kg^-1), pear orchard (9.18 g·kg^-1), Rhus typhina forestland (8.89 g·kg^-1), abandoned farmlands (7.91 g·kg^-1), corn field (7.22 g·kg^-1) and then soybean field (7.17 g·kg^-1). Also the average soil total nitrogen was highest under natural grassland (1.30 g·kg^-1), followed by P. simonii for-estland (0.91 g·kg^-1), pear orchard (0.90 g·kg^-1), R. typhina forestland (0.83 g·kg^-1), abandoned farmlands (0.80 g·kg^-1), corn field (0.72 g·kg^-1) and then soybean field (0.70 g·kg^-1).