title: Moth outbreaks alter root-associated fungal communities in subarctic mountain birch forests.
abstract: Climate change has important implications on the abundance and range of insect pests in forest ecosystems. We studied responses of root-associated fungal communities to defoliation of mountain birch hosts by a massive geometrid moth outbreak through 454 pyrosequencing of tagged amplicons of the ITS2 rDNA region. We compared fungal diversity and community composition at three levels of moth defoliation (intact control, full defoliation in one season, full defoliation in two or more seasons), replicated in three localities. Defoliation caused dramatic shifts in functional and taxonomic community composition of root-associated fungi. Differentially defoliated mountain birch roots harbored distinct fungal communities, which correlated with increasing soil nutrients and decreasing amount of host trees with green foliar mass. Ectomycorrhizal fungi (EMF) abundance and richness declined by 70-80 % with increasing defoliation intensity, while saprotrophic and endophytic fungi seemed to benefit from defoliation. Moth herbivory also reduced dominance of Basidiomycota in the roots due to loss of basidiomycete EMF and increases in functionally unknown Ascomycota. Our results demonstrate the top-down control of belowground fungal communities by aboveground herbivory and suggest a marked reduction in the carbon flow from plants to soil fungi following defoliation. These results are among the first to provide evidence on cascading effects of natural herbivory on tree root-associated fungi at an ecosystem scale.
authors: Department of Biology, University of Oulu, POB 3000, 90014, Oulu, Finland, karita.saravesi@oulu.fi.
authors: Karita
authors: K
authors: Saravesi
authors: Sami
authors: S
authors: Aikio
authors: Piippa R
authors: PR
authors: Wäli
authors: Anna Liisa
authors: AL
authors: Ruotsalainen
authors: Maarit
authors: M
authors: Kaukonen
authors: Karoliina
authors: K
authors: Huusko
authors: Marko
authors: M
authors: Suokas
authors: Shawn P
authors: SP
authors: Brown
authors: Ari
authors: A
authors: Jumpponen
authors: Juha
authors: J
authors: Tuomi
authors: Annamari
authors: A
authors: Markkola
mesh_terms: D000818:Animals; D029662:Betula / Q000254:growth & development / Q000382:microbiology*; D005247:Feeding Behavior; D005387:Finland; D065928:Forests; D008969:Molecular Sequence Data; D009036:Moths / Q000502:physiology*; D038821:Mycorrhizae / Q000235:genetics / Q000502:physiology*; D018517:Plant Roots / Q000254:growth & development / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D013559:Symbiosis