Relationships among wood-boring beetles, fungal endophytes and saprotrophs, and the decomposition of forest biomass.

A prevailing paradigm in forest ecology is that wood-boring beetles facilitate wood decay and carbon cycling, but empirical tests have yielded mixed results. We experimentally determined the effects of wood borers on fungal community assembly and wood decay within pine trunks in the southeastern United States. Pine trunks were made either beetle-accessible or inaccessible. Fungal communities were compared using culturing and high-throughput meta-barcode sequencing of DNA and RNA. Prior to beetle infestation, living pines had diverse fungal endophyte communities. Endophytes were displaced by beetle-associated fungi in beetle-accessible trees, whereas some endophytes persisted as saprotrophs in beetle-excluded trees. Beetles increased fungal diversity several fold. Over forty taxa of Ascomycota were significantly associated with beetles, but beetles were not consistently associated with any known wood-decaying fungi. Instead, increasing ambrosia beetle infestations caused reduced decay, c...

森林生态学领域的主流范式认为，蛀木甲虫（wood-boring beetles）可促进木材腐朽与碳循环，但相关实证检验的结果却并不统一。本研究通过实验探明了蛀木甲虫对美国东南部松树树干内真菌群落构建（fungal community assembly）及木材腐朽的影响。实验将松树树干分为甲虫可侵入组与甲虫排除组，通过培养法及DNA、RNA的高通量元条形码测序（high-throughput meta-barcode sequencing）对真菌群落进行对比分析。在甲虫侵染前，健康松树体内已形成多样的真菌内生群落；在甲虫可侵入的树干中，内生真菌被甲虫关联真菌所取代，而在甲虫排除的树干中，部分内生真菌仍以腐生营养型留存。甲虫可使真菌多样性提升数倍。共有超过40个子囊菌门（Ascomycota）类群与甲虫存在显著关联，但甲虫并未与任何已知的木材腐朽真菌形成稳定关联。与之相反，食菌小蠹（ambrosia beetle）侵染程度的加剧反而会降低木材腐朽程度，……