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Mycorrhizal type determines the magnitude and direction of root‐induced changes in decomposition in a temperate forest
Author(s) -
Brzostek Edward R.,
Dragoni Danilo,
Brown Zachary A.,
Phillips Richard P.
Publication year - 2015
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.13303
Subject(s) - girdling , soil organic matter , competition (biology) , nutrient , nutrient cycle , agronomy , organic matter , soil water , litter , biology , plant litter , soil carbon , ecosystem , temperate climate , botany , ecology
Summary Although it is increasingly being recognized that roots play a key role in soil carbon (C) dynamics, the magnitude and direction of these effects are unknown. Roots can accelerate soil C losses by provisioning microbes with energy to decompose organic matter or impede soil C losses by enhancing microbial competition for nutrients. We experimentally reduced belowground C supply to soils via tree girdling, and contrasted responses in control and girdled plots for three consecutive growing seasons. We hypothesized that decreases in belowground C supply would have stronger effects in plots dominated by ectomycorrhizal ( ECM ) trees rather than arbuscular mycorrhizal ( AM ) trees. In ECM ‐dominated plots, girdling decreased the activity of enzymes that break down soil organic matter ( SOM ) by c . 40%, indicating that, in control plots, C supply from ECM roots primes microbial decomposition. In AM ‐dominated plots, girdling had little effect on SOM ‐degrading enzymes, but increased the decomposition of AM leaf litter by c . 43%, suggesting that, in control plots, AM roots may intensify microbial competition for nutrients. Our findings indicate that root‐induced changes in soil processes depend on forest composition, and that shifts in the distribution of AM and ECM trees owing to climate change may determine soil C gains and losses.