Ecology. 2014 Apr;95(4):1096-103. doi: 10.1890/13-1233.1.
Forest die-off caused by mountain pine beetle (MPB; Dendroctonus ponderosa) is rapidly transforming western North American landscapes. The rapid and widespread death of lodgepole pine (Pinus contorta) will likely have cascading effects on biodiversity. One group particularly prone to such declines associated with MPB are ectomycorrhizal fungi, symbiotic organisms that can depend on pine for their survival, and are critical for stand regeneration. We evaluated the indirect effects of MPB on above- (community composition of epigeous sporocarps) and belowground (hyphal abundance) occurrences of ectomycorrhizal fungi across 11 forest stands. Along a gradient of mortality (0-82% pine killed), macromycete community composition changed; this shift was driven by a decrease in the species richness of ectomycorrhizal fungi. Both the proportion of species that were ectomycorrhizal and hyphal length in the soil declined with increased MPB-caused pine mortality; < 10% of sporocarp species were ectomycorrhizal in stands with high pine mortality compared with > 70% in stands without MPB attacks. The rapid range expansion of a native insect results not only in the widespread mortality of an ecologically and economically important pine species, but the effect of MPB may also be exacerbated by the concomitant decline of fungi crucial for recovery of these forests.
山松甲虫（Dendroctonus ponderosa）导致的森林死亡正在迅速改变北美西部的景观。黑云杉（Pinus contorta）的快速广泛死亡可能对生物多样性产生级联效应。一类特别容易受到山松甲虫相关影响的是外生菌根真菌，它们是共生生物，依赖松树生存，对林分再生至关重要。我们评估了山松甲虫对 11 个林分地上（表生孢子果群落组成）和地下（菌丝丰度）外生菌根真菌的间接影响。随着死亡率（0-82%的松树死亡）的梯度变化，大型真菌群落组成发生了变化；这种变化是由外生菌根真菌物种丰富度的减少驱动的。随着山松甲虫引起的松树死亡率的增加，外生菌根真菌的比例和土壤中的菌丝长度都下降了；在高死亡率的林分中，只有<10%的孢子果物种是外生菌根的，而在没有山松甲虫侵袭的林分中，这一比例>70%。一种本地昆虫的快速范围扩张不仅导致一种生态和经济上重要的松树物种广泛死亡，而且山松甲虫的影响可能还会因对这些森林恢复至关重要的真菌的同时减少而加剧。
