生物多样性减少致植物分解速度放慢

Consequences of biodiversity loss for litter decomposition across biomes

The decomposition of dead organic matter is a major determinant of carbon and nutrient cycling in ecosystems, and of carbon fluxes between the biosphere and the atmosphere1, 2, 3. Decomposition is driven by a vast diversity of organisms that are structured in complex food webs2, 4. Identifying the mechanisms underlying the effects of biodiversity on decomposition is critical4, 5, 6 given the rapid loss of species worldwide and the effects of this loss on human well-being7, 8, 9. Yet despite comprehensive syntheses of studies on how biodiversity affects litter decomposition4, 5, 6, 10, key questions remain, including when, where and how biodiversity has a role and whether general patterns and mechanisms occur across ecosystems and different functional types of organism4, 9,10, 11, 12. Here, in field experiments across five terrestrial and aquatic locations, ranging from the subarctic to the tropics, we show that reducing the functional diversity of decomposer organisms and plant litter types slowed the cycling of litter carbon and nitrogen. Moreover, we found evidence of nitrogen transfer from the litter of nitrogen-fixing plants to that of rapidly decomposing plants, but not between other plant functional types, highlighting that specific interactions in litter mixtures control carbon and nitrogen cycling during decomposition. The emergence of this general mechanism and the coherence of patterns across contrasting terrestrial and aquatic ecosystems suggest that biodiversity loss has consistent consequences for litter decomposition and the cycling of major elements on broad spatial scales.

者：Stephan Hattenschwiler 来源：《自然》发布时间：2014-5-15 11:07:57

生物多样性减少致植物分解速度放慢

近日出版的英国《自然》杂志上发表的一项生态学研究，评估了植物残体的多样性和分解植物残体的生物多样性，这两者对于植物残体分解速度的影响。调查发现，在所有生态系统中，植物残体和腐生生物多样性的减少，都会放慢植物残体中碳循环和氮循环以及分解速度。

未分解的死亡植物组织及其部分分解产物，就是植物残体。由于这些凋落物的分解归还到大气中的量是全球预算中一个重要的组成成分，因此植物残体的分解速率不但对生态系统生产力起作用，更对全球的碳预算产生影响。而理解生物多样性和分解速度之间的关系以及其背后的机制，也成为生态学的一个重要的目标，尤其是考虑到全球范围内物种的迅速丧失。

法国国家科学研究中心的斯蒂芬·海施威勒和他的研究团队，在五个陆地和水生地点进行了植物残体分解实验，地点从亚寒带到热带地区都有。在所有研究的生态系统中，他们都发现植物残体和腐生生物（分解植物残体的无脊椎动物和微生物）的多样性的减少，会带来植物残体中碳循环和氮循环以及分解速度的放慢。而生物多样性减少带来的分解速度放慢，将对给初级生产者的氮供给产生限制。

此研究团队还提出了一个可能推动这一效应的潜在机制。他们报告了从固氮植物的植物残体，向快速分解的植物的氮转移的证据，这突出了在混合的植物残体中的特异性相互作用，能在分解过程中控制碳循环和氮循环。（来源：科技日报张梦然）