赣中亚热带森林转换对土壤氮素矿化及有效性的影响

Abstract

PDF HTML阅读 XML下载 导出引用 引用提醒 赣中亚热带森林转换对土壤氮素矿化及有效性的影响 DOI: 10.5846/stxb201208021095 作者: 作者单位: 江西农业大学江西省竹子种质资源与利用重点实验室 南昌,江西农业大学江西省竹子种质资源与利用重点实验室 南昌,江西农业大学江西省竹子种质资源与利用重点实验室 南昌,江西农业大学江西省竹子种质资源与利用重点实验室 南昌,中国林业科学研究院森林生态环境与保护研究所,江西农业大学江西省竹子种质资源与利用重点实验室 南昌;中国林业科学研究院森林生态环境与保护研究所; 作者简介: 通讯作者: 中图分类号: 基金项目: 公益性行业（林业）科研专项经费资助项目（201104009-2）；国家林业科技支撑计划课题资助项目（2006BAD03A0703，2012BAC11B02）；江西省教育厅科学技术研究资助项目（GJJ08192） The effects of forest conversion on soil N mineralization and its availability in central jiangxi subtropical region Author: Affiliation: Jiangxi Provincial Key Laboratory for Bamboo Germplasm Resources and Application,JXAU,Jiangxi Provincial Key Laboratory for Bamboo Germplasm Resources and Application,JXAU,Jiangxi Provincial Key Laboratory for Bamboo Germplasm Resources and Application,JXAU,Jiangxi Provincial Key Laboratory for Bamboo Germplasm Resources and Application,JXAU,Institute of Forest Ecology Environment and Protection,CAF,Jiangxi Provincial Key Laboratory for Bamboo Germplasm Resources and Application,JXAU;Institute of Forest Ecology Environment and Protection,CAF;China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:采用原位培养法和时空替代法，对江西中部亚热带常绿阔叶林、天然马尾松林、人工杉木林、人工马褂木林的土壤氮素矿化速率及其有效性进行了比较研究，以探讨森林转换对土壤氮素矿化作用的影响。结果表明：转换前后各森林土壤无机氮库（NH4+-N、NO3--N）及氮素矿化速率（氨化速率、硝化速率）均呈现明显的季节动态，NH4+-N库冬春较大，NO3--N库夏秋较大，氨化速率与硝化速率均以夏秋强烈。森林转换改变了土壤氮素矿化格局，常绿阔叶林转变成马尾松林、杉木林、马褂木林后，土壤年均氨化速率分别降低了110.67%、100.76%、96.20%，而硝化速率提高了54.92%、24.19%、 24.46%；马尾松林年均总净矿化速率与常绿阔叶林相近，杉木林、马褂木林分别降低了24.68%、26.01%。另外，除常绿阔叶林外，马尾松林、杉木林、马褂木林的土壤氮素矿化量都小于植被吸收量。这些研究结果说明亚热带地区常绿阔叶林转换成其它次生林会增加氮素流失的危险性，氮素缺乏会成为这些森林生长的限制因子。 Abstract:Subtropical region has dramatically experienced land use and coverage change. Historical forest management practice has persistent effects on many ecosystem processes such as soil nitrogen (N) mineralization. Soil N dynamics during forest conversion from zonal forest to secondary forest can provide substantial insight into the impacts of forest management on soil. So far, however, few studies have conducted to investigate the effects of forest conversion on soil N transformation in subtropical region of China. Based on a space-time substitution method, we selected four vegetation types including evergreen broad-leaved forest (EBF, zonal forest), Pinus massoniana forest (PMF, natural regeneration forest), Cunninghamia lanceolata plantation (CLP, artificial forest), Liriodendron chinense plantation (LCP, artificial forest) in Dagangshan National Ecological Station, Jiangxi province. For each forest type, we randomly set two 20 m×20 m plots separated by at least 30 m buffer zones. The concentration of NH4+-N and NO3--N, and the rate of N ammonification and nitrification were measured through in situ incubations using the PVC method. Soil properties (total carbon, total N, C:N ratio, and pH value, 0-15 cm in depth), forest fine root (living root biomass, dead root storage) and the rate of N absorption of vegetation were also quantified. Least significant difference (LSD) in One-way ANOVA was used to determine the effects of forest type on the soil variables. The results showed as follows: (1) Inorganic N pools and N mineralization rates in all forests performed seasonal dynamics, NH4+-N being higher in winter and spring (11.64-15.55 kg/hm2) than in summer and autumn (3.89-8.36 kg/hm2), NO3--N being higher in summer and autumn (0.42-8.60 kg/hm2) than in winter and spring (0.24-6.10 kg/hm2). The pool of NH4+-N was considerably larger than NO3--N pool, and thus NH4+-N was the main component of inorganic N in these forests. The rates of ammonification and nitrification were faster in summer and autumn than in spring and winter. (2) The forest conversion from EBF to PMF, CLP and LCP, soil N mineralization patterns had changed, and annual ammonification rates decreased by 110.67%, 100.76%, 96.20%, however annual nitrification rates increased by 54.92%, 24.19%, 24.46% respectively. (3) Total N mineralization rates were lower 24.68%, 26.01% in CLP and LCP, respectively than in EBF, and insignificant difference between PMF and EBF. Meanwhile, the N supply amount with soil net N mineralization rate in PMF, CLP and LCP (111.85, 89.58, 88.00 kg·hm-2·a-1) were lower than their needs for plant N uptake (137.83, 92.76, 99.28 kg·hm-2·a-1, respectively). (4) The size of inorganic N pool depended on mineralization rate and vegetation N uptake rate. Ammonification rate positively correlated with storage of dead root, N uptake positively correlated with biomass of live root, and nitrification rate positively correlated with NH4+-N concentration and negatively correlated with NH4+-N uptake rate by vegetation. These findings indicated that the forest conversion from EBF to other secondary forests would lead to N leaching, thus N deficiency might become a growth-limiting factor for these forests. 参考文献 相似文献 引证文献