Soil microbial nutrient constraints along a tropical forest elevation gradient: a belowground test of a biogeochemical paradigm
Soil microbial nutrient constraints along a tropical forest elevation gradient: a belowground test of a biogeochemical paradigm
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DOI：
10.5194/bg-12-6071-2015
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发表时间：
2015-10
期刊：
影响因子：
4.9
通讯作者：
A. Nottingham;Benjamin L Turner;J. Whitaker;N. Ostle;N. McNamara;R. Bardgett;N. Salinas;N. Salinas-N.-Sal
中科院分区：
文献类型：
--
作者：
A. Nottingham;Benjamin L Turner;J. Whitaker;N. Ostle;N. McNamara;R. Bardgett;N. Salinas;N. Salinas-N.-Sal
抽象的。人们普遍认为，在低地热带森林中，林地初级生产力受到磷（P）有效性的限制，而在山地热带森林中，林地初级生产力受到氮（N）有效性的限制。然而，这一模式在多大程度上适用于地下进程仍没有解决。我们测量了在秘鲁安第斯山脉海拔3400米的自然梯度沿着的低地，亚山地和山地热带森林的土壤微生物营养状况的指数。随着海拔的升高，土壤全氮、全磷和易交换性磷含量显著增加，而原位树脂袋法测定的氮矿化量则呈下降趋势。微生物碳（C）和N随着海拔的升高而增加，但微生物C：N：P的比例相对恒定，表明体内平衡。水解酶的活性，这是丰富的N，随着海拔的增加而下降，而参与收购的N和P的酶的比例随着海拔的增加而增加，进一步表明增加的相对需求N相比，P随着海拔的增加。我们的结论是，土壤微生物转移投资养分收购从P到N之间的低地和山地热带森林，这表明不同的营养调节土壤微生物代谢和土壤碳平衡在这些生态系统。
Abstract. Aboveground primary productivity is widely considered to be limited by phosphorus (P) availability in lowland tropical forests and by nitrogen (N) availability in montane tropical forests. However, the extent to which this paradigm applies to belowground processes remains unresolved. We measured indices of soil microbial nutrient status in lowland, sub-montane and montane tropical forests along a natural gradient spanning 3400 m in elevation in the Peruvian Andes. With increasing elevation there were marked increases in soil concentrations of total N, total P, and readily exchangeable P, but a decrease in N mineralization determined by in situ resin bags. Microbial carbon (C) and N increased with increasing elevation, but microbial C : N : P ratios were relatively constant, suggesting homeostasis. The activity of hydrolytic enzymes, which are rich in N, decreased with increasing elevation, while the ratio of enzymes involved in the acquisition of N and P increased with increasing elevation, further indicating an increase in the relative demand for N compared to P with increasing elevation. We conclude that soil microorganisms shift investment in nutrient acquisition from P to N between lowland and montane tropical forests, suggesting that different nutrients regulate soil microbial metabolism and the soil carbon balance in these ecosystems.