Neglect of mowing and manuring leads to slower nitrogen cycling in subalpine grasslands
Neglect of mowing and manuring leads to slower nitrogen cycling in subalpine grasslands
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DOI：
10.1016/j.soilbio.2006.11.004
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发表时间：
2007-04
影响因子：
9.7
通讯作者：
T. Robson;S. Lavorel;J. Clément;X. Roux
中科院分区：
文献类型：
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作者：
T. Robson;S. Lavorel;J. Clément;X. Roux
草地中氮的有效性随农业土地利用而变化。在亚高山草甸割草和施肥的传统管理制度维持植物群落的开发功能的战略，适合肥沃的土壤，快速周转的养分。我们调查了是否忽视传统的做法，导致减少氮的可用性在两个平行的生态系统（梯田和非梯田）。土壤硝态氮和铵含量进行了评估，使用土芯和离子交换树脂在1年的时间内，和微生物硝化和反硝化酶活性的测定，在生长季节的早期。两个生态系统之间的pH值的差异很大，历史耕作，促进更大的氮比非梯田梯田的可用性。放弃施肥和割草造成的N的可用性和N转化过程，这与植物群落向更保守的功能策略和更大的优势草的转变。我们建议，草地管理制度和优势植物功能策略之间的正反馈保持高的N可用性在这些管理的亚高山草原。当传统的做法，割草和施肥被忽视，直接管理的影响，结合草种的传播与保守的战略，迫使土壤中的氮的可用性，减少微生物活性，改变pH值，并导致长期的损失的特点草本亚高山草甸物种。
Nitrogen (N) availability in grasslands varies with agricultural land use. Traditional management regimes of mowing for hay and manuring in subalpine meadows maintain plant communities with exploitative functional strategies suited to fertile soils with fast turnover of nutrients. We investigated whether the neglect of traditional practices has led to a reduction in N availability in two parallel ecosystems (terraced and unterraced fields). Soil nitrate and ammonium contents were assessed using soil cores and ion exchange resins over a 1-year period, and assays of microbial nitrifying and denitrifying enzyme activities, made early in the growing season. A large difference in pH between the two ecosystems, caused by historical ploughing, facilitated greater N availability in terraced than unterraced fields. Abandonment of manuring and mowing caused a reduction in N availability and N transformation processes, which correlated with a shift in the plant community towards more-conservative functional strategies and greater dominance by grasses. We propose that positive feedback between the grassland management regime and dominant plant functional strategy maintained high N availability in these managed subalpine grasslands. When traditional practices of mowing and manuring are neglected, direct management effects combined with the spread of grass species with conservative strategies force down N availability in the soil, reduce microbial activity, change the pH, and lead to a long-term loss of characteristic herbaceous subalpine-meadow species.