高寒草甸植物磷库和土壤有效磷对短期氮添加的非线性响应

doi:10.1016/j.jia.2024.07.033

摘要/Abstract

摘要：

氮富集会促进土壤磷循环，同时也增加了植物对磷的需求。然而，高寒草甸生态系统中植物磷库、土壤有效磷对氮添加的响应模式及调控机制还不清楚。基于此，以青藏高原高寒草甸为研究对象，设置4个氮添加水平（0, 5, 10和15 g N m^-2 yr^-1），通过测定植物、土壤和微生物中的磷，探究短期氮添加的影响机制。结果表明：（1）氮添加显著增加植物地上生物量，植物磷库对氮添加水平表现为非线性响应；（2）土壤有效磷随着氮添加梯度的增加呈先上升后下降的趋势，氮添加显著降低了稳定无机磷；（3）调控土壤有效磷的关键因子在不同氮添加水平下发生改变。在低氮添加水平下（0和5 g N m^-2 yr^-1），土壤pH下降促进了稳定无机磷的溶解，增加了土壤有效磷。相反，在高氮添加水平下（10和15 g N m^-2 yr^-1），微生物生物量磷增加，加剧了植物和微生物对磷的竞争，导致土壤有效磷下降。研究结果强调了植物磷库和土壤有效磷对氮添加的非线性响应，未来需要关注氮添加速率对磷的不同影响，从而更准确的预测氮富集下生态系统磷循环。

Abstract:

Nitrogen (N) enrichment is expected to induce a greater phosphorus (P) limitation, despite the acceleration of soil P cycling. However, the changing patterns in plant P and soil available P after N enrichment, and their regulatory mechanisms, remain poorly understood in alpine meadows. Here, we conducted a field experiment with four N addition rates (0, 5, 10, and 15 g N m^–2 yr^–1) in an alpine meadow, and investigated the P in plants, microorganisms, and soil to determine their patterns of change after short-term N addition. Our results showed that N addition significantly increased plant biomass, and the plant P pool showed a non-linear response to the N addition gradient. Soil available P initially increased and then declined with increasing N addition, whereas the occluded inorganic P decreased markedly. The critical factors for soil available P varied with different N addition rates. At lower N addition levels (0 and 5 g N m^–2 yr^–1), soil acidification facilitated the mobilization of occluded inorganic P to increase soil available P. Conversely, at higher N addition levels (10 and 15 g N m^–2 yr^–1), the elevated soil microbial biomass P intensified the competition with plants for soil P, leading to a decline in soil available P. This study highlights the non-linear responses of the plant P pool and soil available P concentration to N addition rates. These responses suggest the need for developing ecosystem models to assess different effects of increasing N rates, which would enable more accurate predictions of the plant P supply and soil P cycling under N enrichment.

Key words: nitrogen addition rates , Qinghai-Tibetan Plateau , unimodal response , microbial biomass phosphorus , soil phosphorus fractions

Bing Han, Yicheng He, Jun Zhou, Yufei Wang, Lina Shi, Zhenrong Lin, Lu Yu, Wantong Zhang, Yiyi Geng, Xinqing Shao. 高寒草甸植物磷库和土壤有效磷对短期氮添加的非线性响应[J]. Journal of Integrative Agriculture, 2025, 24(3): 815-826.

Bing Han, Yicheng He, Jun Zhou, Yufei Wang, Lina Shi, Zhenrong Lin, Lu Yu, Wantong Zhang, Yiyi Geng, Xinqing Shao. Non-linear responses of the plant phosphorus pool and soil available phosphorus to short-term nitrogen addition in an alpine meadow[J]. Journal of Integrative Agriculture, 2025, 24(3): 815-826.

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