侵蚀条件下生物结皮对坡面土壤碳氮的影响

Effects of biological soil crust on slope soil carbon and nitrogen under erosion conditions

为了探讨侵蚀条件下生物结皮对坡面土壤碳氮的影响,通过野外小区对比试验与室内分析相结合,研究有、无生物结皮坡面土壤有机质、全氮、硝态氮和铵态氮的分布特征。结果表明:生物结皮对坡面土壤碳氮积累具有重要意义,同一坡位下,土壤有机质、全氮和硝态氮含量在0～20 cm剖面上均明显表现为生物结皮大于无结皮。总体来看,生物结皮对土壤碳氮的影响主要集中在0～10 cm土层,与无结皮相比,土壤有机质、全氮、硝态氮和铵态氮平均储量分别增加了44.7%、18.2%、39.2%和4.33%。生物结皮能显著增加0～2和2～5 cm土壤硝态氮含量(P<0.05),这除了生物结皮对土壤养分的保蓄效应外,还可能与生物结皮向土壤释放硝态氮有关。由于铵态氮流失特征不同于硝态氮,加之生物结皮可能会利用或释放铵态氮,使生物结皮对其影响表现出无明显规律性。相关分析表明,土壤有机质与全氮、硝态氮和铵态氮均达到了极显著或显著的正相关关系(P<0.01或P<0.05)。综上所述,侵蚀环境下生物结皮发挥着重要的固土蓄肥功能,这对研究区退化生态系统的恢复和重建具有积极的意义。

In order to reveal the effects of biological soil crust（BSC） on the distribution of soil carbon and nitrogen on slope under erosion conditions,by experimenting on field plots and in laboratory,this study investigated the distribution pattern of soil organic matter,total nitrogen and nitrate nitrogen contents with BSC treatment and without crust group.The results indicated that： biological soil crust played significant role in soil carbon and nitrogen accumulation.In the same position on slope,soil organic matter,total nitrogen and nitrate nitrogen contents of BSC treatment in soil profile of 0-20 cm depth were higher than those without crust group.On the whole,the accumulation effect of BSC on soil carbon and nitrogen was mainly concentrated in the 0-10 cm soil layer.Compared with no crust,the average storages of soil organic matter,total nitrogen,nitrate nitrogen and ammonium nitrogen were increased by 44.7%,18.2%,39.2% and 4.33%,respectively.BSC could significantly increase soil nitrate nitrogen content of 0-2 cm and 2-5 cm soil layers（P〈0.05）,which may be explained by that BSC could control nitrate nitrogen loss by effectively reducing soil erosion and also release some amount of nitrate nitrogen during the studying period.Due to the loss characteristics of soil ammonium nitrogen were different from nitrate nitrogen,the effect of BSC on soil ammonium nitrogen was not obvious.Correlation analysis showed that there were highly significant or significant positive correlations between soil organic matter and total nitrogen,nitrate nitrogen and ammonium nitrogen（respectively P〈0.01,P〈0.05）.Therefore,it can be concluded that the presence of biological soil crust would have favorable effects on soil carbon and nitrogen accumulation under erosion conditions,which indicate BSC could be of great positive significance to restoration and reconstruction of degraded ecosystem in research area.