Nature Conservation and Plant Ecology Group, Wageningen University and Research Centre, Wageningen, The Netherlands.
Oecologia. 2010 Jul;163(3):805-13. doi: 10.1007/s00442-010-1569-5. Epub 2010 Feb 19.
Soil respiration is an important pathway of the C cycle. However, it is still poorly understood how changes in plant community diversity can affect this ecosystem process. Here we used a long-term experiment consisting of a gradient of grassland plant species richness to test for effects of diversity on soil respiration. We hypothesized that plant diversity could affect soil respiration in two ways. On the one hand, more diverse plant communities have been shown to promote plant productivity, which could increase soil respiration. On the other hand, the nutrient concentration in the biomass produced has been shown to decrease with diversity, which could counteract the production-induced increase in soil respiration. Our results clearly show that soil respiration increased with species richness. Detailed analysis revealed that this effect was not due to differences in species composition. In general, soil respiration in mixtures was higher than would be expected from the monocultures. Path analysis revealed that species richness predominantly regulates soil respiration through changes in productivity. No evidence supporting the hypothesized negative effect of lower N concentration on soil respiration was found. We conclude that shifts in productivity are the main mechanism by which changes in plant diversity may affect soil respiration.
土壤呼吸是碳循环的一个重要途径。然而，植物群落多样性如何影响这一生态系统过程仍知之甚少。在这里，我们利用一个由草地植物物种丰富度梯度组成的长期实验来测试多样性对土壤呼吸的影响。我们假设植物多样性可以通过两种方式影响土壤呼吸。一方面，更多样化的植物群落已被证明可以促进植物生产力，从而增加土壤呼吸。另一方面，生物量中养分浓度已被证明随多样性的增加而降低，这可能会抵消因生产力增加而导致的土壤呼吸增加。我们的结果清楚地表明，土壤呼吸随物种丰富度的增加而增加。详细分析表明，这种影响不是由于物种组成的差异造成的。一般来说，混合物中的土壤呼吸高于单培养物的预期值。路径分析表明，物种丰富度主要通过生产力的变化来调节土壤呼吸。没有证据支持假设的低氮浓度对土壤呼吸的负效应。我们得出的结论是，生产力的变化是植物多样性变化可能影响土壤呼吸的主要机制。
