Karst rocky desertification restoration increases soil inorganic N supply to reduce plant N limitation

文献类型： 外文期刊

第一作者： Wen, Dongni

作者： Wen, Dongni;Huang, Yuanfei;Ding, Nana;Elrys, Ahmed S.;Meng, Lei;Huang, Yuanyuan;Wen, Dongni;Huang, Yuanyuan;Huang, Yuanfei;Ding, Nana;Wang, Hua;Zhu, Tongbin;Ni, Kang;Gessert, Alena;Zhu, Tongbin;Mueller, Christoph;Mueller, Christoph;Mueller, Christoph;Mueller, Christoph

作者机构：

关键词： Rocky desertification; Nitrogen availability; Plant N limitation; Gross N transformation rates; Soil microbial community

期刊名称：CATENA （ 影响因子：5.4； 五年影响因子：5.9 ）

ISSN： 0341-8162

年卷期： 2024 年 241 卷

页码：

收录情况： SCI

摘要： Nitrogen (N) limitation of plant growth following vegetation restoration is widespread in global terrestrial ecosystems, especially in karst rocky desertification areas. However, neither the temporal changes in plant N limitation during the restoration of those areas nor the mechanisms underlying N availability are well understood. In this study, several indicators reflecting soil N availability, N transformation rates, and plant communities were investigated in four areas in southwest China differing in their grade of rocky desertification. Our results showed that plant growth was severely N limited in the intense rocky desertification areas. The plant community-level foliar N content, N-15 values, and N:P ratio increased significantly as the rocky desertification grade decreased, indicating a decrease in plant N limitation. This was attributed to increased soil N availability, evidenced by the higher soil delta N-15 values as well as total N and inorganic N contents along the rocky desertification grade. With the decreasing rocky desertification grade, the rates of organic N conversion to ammonium (NH4+) and nitrate (NO3-), the adsorption of NH4+ on cation-exchange sites, and the release of adsorbed NH4+ increased significantly, which could enhance soil inorganic N supply capacity and accelerate NH4+ turnover to increase N availability. Noticeably, the sharp decrease in the rate of NH4+ oxidation to NO3- with the decrease in the rocky desertification grade led to a shift in inorganic N from NO3--dominated to NH4+-dominated. The increased contents of soil organic matter, calcium, iron-aluminum oxides, and sand, the proportion of aggregates > 2 mm, as well as the greater abundances of fungi and bacteria were the primary drivers of the N transformation rates along the rocky desertification grade. Overall, our study highlights the importance of N cycling in controlling N availability and thus in determining plant N limitation in karst rocky desertification areas. The results of the study provide a scientific basis for the ecological restoration of rocky desertification in karst ecosystems.

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