| 杜宁宁,邱莉萍,张兴昌,程积民.半干旱区土地利用方式对土壤碳氮矿化的影响[J].干旱地区农业研究,2017,35(5):73~78 |
| 半干旱区土地利用方式对土壤碳氮矿化的影响 |
| Effect of land use on mineralization of soil carbon and nitrogen in semi-arid grasslands |
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| DOI：10.7606/j.issn.1000-7601.2017.05.11 |
| 中文关键词: 半干旱黄土区 利用方式 有机碳矿化 有机氮矿化 |
| 英文关键词:semiarid loess region land use organic carbon mineralization N mineralization |
| 基金项目:国家自然科学基金项目(41471244)；省自然科学基金项目(2015JQ4103) |
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| 中文摘要: |
| 通过研究云雾山草原自然保护区草地、农地、灌木林土壤有机碳和氮的含量和矿化特征，分析了半干旱黄土区不同土地利用方式对土壤碳氮循环的影响。结果表明，土壤有机碳和全氮平均含量在草地转变为农地后分别降低了53%和64%，在转变为灌木林地后分别降低了54%和44%。不同土地利用方式下土壤有机碳矿化速率均随土层深度的增加逐渐降低，降幅介于29%～46%之间；有机碳矿化比例则逐渐增加，增幅介于45%～67%之间。土壤氮素矿化速率、矿化比例和硝化速率均随土层加深逐渐降低，而且0～20 cm土层氮素矿化体现为硝化过程和铵态氮的固定作用，且硝化过程占主导作用；40～80 cm土层硝化过程和铵化过程的比例接近，表明深层土壤氮素矿化由硝化过程和铵化过程共同主导。草地转化为农地和灌木林地后有机碳矿化速率显著降低，其降低幅度随土层加深逐渐减小；但有机碳矿化比例则有所增加，其增幅随土层加深而增大。草地利用方式发生变化后，土壤氮素矿化速率和矿化比例、硝化速率和铵化速率均显著降低，这些指标在表层土壤以草地转变为农地后降低较多，在深层土壤以草地转变为灌木林地降低较多。综上，半干旱黄土区草地转变为农地和灌木林地后，土壤碳氮循环强度和有效性显著降低，因此应避免草地向其它利用方式的转变。 |
| 英文摘要: |
| To understand the effects of land use on the cycling of OC and N in soils of semiarid grassland, we analyzed the distribution and mineralization of OC and N in soils collected from grassland, cropland and shrub-land in Yunwu mountain natural grasslands. The results showed that averaged concentration of OC and N in soils decreased by 53% and 64% after conversion of grassland to cropland, and by 54% and 44% after conversion to shrub-land, respectively. The mineralization rate of OC declined with increasing of soil depth, with a range of 29%～46% decrease, while the proportion of mineralized OC increased with soil depth, with a range of 45%～67% increase. The conversion of grassland to cropland or shrubland significantly decreased OC mineralization rate but increased the proportion of mineralized OC. The decrease in OC mineralization rate declined, while increase of OC mineralization proportion increased with soil depth. The metrics of N mineralization declined with soil depth. For the 0～20 cm depth, the mineralization was characterized by the nitrification and immobilization of ammonium, and was dominated by nitrification. For the 40～80 cm depth, both nitrification and ammonification contributed to mineralization of N. The conversion of grassland to cropland or shrub-land decreased the metrics of N mineralization. For the top soils, these decreases were greater for the conversion of grassland to cropland, while for the deep soils, the decreases were greater for the conversion to shrub-land, when compared with each other. These results indicated that the cycling and availability of OC and N in grassland were significantly decreased after conversion of grassland to cropland or shrub-land in this semiarid region. Therefore, such land use changes should be avoided from the aspect of soil OC and N sequestration. |
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