Laboratoire Dynamique de la Biodiversité, UMR 5172 CNRS-UPS, 29, rue Jeanne Marvig, 31055 Toulouse Cedex, France Department of Limnology, Eawag/ETH, 6047 Kastanienbaum, Switzerland.
Ecol Lett. 2005 Nov;8(11):1129-37. doi: 10.1111/j.1461-0248.2005.00815.x.
There is compelling evidence that losses in plant diversity can alter ecosystem functioning, particularly by reducing primary production. However, impacts of biodiversity loss on decomposition, the complementary process in the carbon cycle, are highly uncertain. By manipulating fungal decomposer diversity in stream microcosm experiments we found that rates of litter decomposition and associated fungal spore production are unaffected by changes in decomposer diversity under benign and harsher environmental conditions. This result calls for caution when generalizing outcomes of biodiversity experiments across systems. In contrast to their magnitude, the variability of process rates among communities increased when species numbers were reduced. This was most likely caused by a portfolio effect (i.e. statistical averaging), with the uneven species distribution typical of natural communities tending to weaken that effect. Curbing species extinctions to maintain ecosystem functioning thus can be important even in situations where process rates are unaffected.
有确凿的证据表明，植物多样性的丧失会改变生态系统的功能，特别是通过减少初级生产。然而，生物多样性丧失对分解作用的影响（碳循环中的互补过程）高度不确定。通过在溪流微宇宙实验中操纵真菌分解者的多样性，我们发现，在良性和更恶劣的环境条件下，分解者多样性的变化不会影响凋落物的分解速度和相关真菌孢子的产生。这一结果表明，在将生物多样性实验的结果推广到不同系统时需要谨慎。与它们的幅度相比，当物种数量减少时，群落间过程速率的可变性增加。这很可能是由于投资组合效应（即统计平均）造成的，而自然群落中典型的不均匀物种分布往往会削弱这种效应。因此，即使在过程速率不受影响的情况下，控制物种灭绝以维持生态系统功能也可能很重要。
