氮磷添加和植物根系对中亚热带常绿阔叶林土壤氮矿化的影响

发布时间：2018-06-09 21:23

本文选题：氮添加 + 磷添加　；参考：《华东师范大学》2016年硕士论文

【摘要】：氮(N)和磷(P)是限制植物生长的重要营养元素,其有效性对于调节森林生态系统结构和功能具有重要的作用。土壤氮矿化是土壤氮循环的重要过程之一。由于化石燃料燃烧和农田施肥量增加等人类活动的加剧,全球向陆地生态系统输入的氮不断增加,进而影响土壤氮循环。在生态系统中,土壤微生物是土壤氮矿化过程的主要参与者,植物根系及其分泌物通过影响微生物活性在土壤氮矿化过程中起到重要作用。本研究以浙江天童亚热带常绿阔叶木荷林(Schima superba)为研究对象,进行了氮磷添加和根系去除对土壤无机氮和氮矿化速率影响的实验。实验设置4种施肥类型(对照CK:0kg N·hm-2·year-1、氮添加N:100kg N·hm-2·year-1、磷添加P:50 kg P·hm-2·year-1和氮磷添加N IP:100 kg N·hm-2·year-1+50 kg P·hm-2·year-1)和根系处理(未去根和根系去除),总共有4×2=8种处理方式,分别为对照(CK)、氮添加(N)、磷添加(P)、氮磷添加(NP)、根系去除、氮添加+根系去除、磷添加+根系去除和氮磷添加+根系去除。通过开展为期3年的季节性动态取样,分析了不同处理下土壤无机氮、pH值、微生物生物量氮(MBN)含量和矿化速率的变化。结果如下：(1)浙江天童常绿阔叶木荷林土壤铵态氮和硝态氮含量有明显的季节动态(P0.001),土壤无机氮的主要存在形式为硝态氮；土壤氮矿化速率也存在明显的季节动态(P0.001)(2)氮添加显著增加土壤铵态氮和硝态氮含量,但显著降低土壤氮矿化速率和土壤pH值;而磷添加作用与之相反；氮磷添加对土壤无机氮和氮矿化速率的影响与氮添加类似；相关性分析表明,土壤无机氮含量和土壤pH值存在极显著的负相关(P0.01)(3)对照样地中,根系去除后,土壤硝态氮含量和土壤年氮矿化速率分别增加了61%和15%；氮、磷单独添加和混合添加处理下,根系去除后,土壤硝态氮含量分别增加了51%、209%和108%,土壤年矿化速率分别降低了27%、32%和27%。我们研究结果表明氮、磷添加对亚热带常绿阔叶木荷林土壤氮循环有不同的影响,根系去除仅改变了磷添加对氮矿化过程作用的方向,有助于预测未来本地区氮、磷沉降增加的情景下土壤氮循环的响应。
[Abstract]:Nitrogen (N) and phosphorus (P) are important nutrient elements limiting plant growth, and their effectiveness plays an important role in regulating the structure and function of forest ecosystem. Soil nitrogen mineralization is one of the important processes of soil nitrogen cycling. As the burning of fossil fuels and the increase of fertilization in farmland, the input of nitrogen to terrestrial ecosystems is increasing, which affects the soil nitrogen cycle. In the ecosystem, soil microorganisms are the main participants in soil nitrogen mineralization. Plant roots and their exudates play an important role in the process of soil nitrogen mineralization by affecting microbial activity. In this study, the effects of nitrogen and phosphorus addition and root removal on inorganic nitrogen and nitrogen mineralization rate were studied in Schima superba, a subtropical evergreen broad-leaved Schima superba forest in Tiantong, Zhejiang Province. Four fertilization types (CK: 0 kg N hm-2 year-1, N: 100 kg N hm-2 year-1, P: 50 kg P hm-2 year-1 and N IP: 100 kg N hm-2 year-1 50 kg P hm-2 year-1) and root treatments (without root removal and root removal) were established. The results were as follows: CK, N, P, N, P, N and P, N, N, N, N, P, N, P, N, P, N, P, N, P, N, P, N, P, N, P, N, P, N, P, The changes of soil inorganic nitrogen pH value, microbial biomass nitrogen (MBN) content and mineralization rate under different treatments were analyzed through seasonal dynamic sampling for 3 years. The results were as follows: (1) in Tiantong evergreen broad-leaved Schima superba forest in Zhejiang Province, the contents of ammonium and nitrate nitrogen in soil were significantly seasonal dynamic (P 0.001), and the main form of inorganic nitrogen in soil was nitrate nitrogen. Soil nitrogen mineralization rate was also significantly seasonal dynamic (P 0.001) N addition significantly increased soil ammonium nitrogen and nitrate nitrogen content, but significantly decreased soil nitrogen mineralization rate and soil pH value, but phosphorus supplementation had the opposite effect on soil nitrogen mineralization rate and soil pH value, while P addition significantly increased soil ammonium and nitrate nitrogen contents, but decreased soil nitrogen mineralization rate and soil pH value significantly. The effect of nitrogen and phosphorus addition on inorganic nitrogen and mineralization rate of soil was similar to that of nitrogen addition, and the correlation analysis showed that there was a significant negative correlation between soil inorganic nitrogen content and soil pH value. Soil nitrate content and soil annual nitrogen mineralization rate increased by 61% and 15%, respectively, and soil nitrate content increased by 51% and 108% after root removal, and the annual mineralization rate of soil decreased by 27% and 27%, respectively. The results showed that nitrogen and phosphorus supplementation had different effects on soil nitrogen cycling in subtropical evergreen broadleaved Schima superba forest, root removal only changed the direction of nitrogen mineralization process, which was helpful to predict nitrogen in the future. The response of soil nitrogen cycle to increasing phosphorus deposition.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S714.2

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