Mycorrhizas in changing ecosystems^,

Abstract

Ecosystems change between arbuscular mycorrhizal and ectomycorrhizal vegetation dominance over anthropological and geological time scales, yet consequences for ecosystem function are unclear. We review four hypotheses for the effect of mycorrhizal status on ecosystem function. Specifically, that differences between ectomycorrhizal and arbuscular mycorrhizal dominated ecosystems are driven by (1) foliar trait differences, (2) positive plant–soil feedback in ectomycorrhizal plants, (3) differences in the ability to dissolve rocks as a source of nutrition, and (4) differences in the ability to use organic nutrients. We find no universal difference in foliar traits with mycorrhizal status. A spatial simulation suggests that positive plant–soil feedback in ectomycorrhizal plants is unlikely to drive ecosystem differences. However, negative feedback appears to be more common in arbuscular mycorrhizal trees than ectomycorrhizal trees and may represent an important ecosystem difference. Rock dissolution occurs under both mycorrhizal types but may differ in rate. Hypothesis 4 was the best supported: a model and some field evidence suggest that decoupling of carbon and nutrients in ectomycorrhizal decomposition leads to inhibition of saprotrophic mineralization, with context-dependent effects. Greater understanding of organic nutrient utilization differences may be key to improving incorporation of mycorrhizas in ecosystem ecology.

Strong effect of climate on ectomycorrhizal fungal composition: evidence from range overlap between two mountains

“…Temperate and boreal forests, which cover B14% of the land surface (FAO, 2012), harbor hundreds of taxonomically and functionally diverse EM fungi (Read and PerezMoreno, 2003;Tedersoo et al, 2010;Koide et al, 2014). Recent environmental change may have altered fungal communities, which would subsequently affect the associated plant communities and ecosystem functioning (Parrent et al, 2006;Johnson et al, 2013;Dickie et al, 2014). Clarifying the drivers of the community structure of EM fungi is critical for predicting the effects of environmental change on forest ecosystems from local to global contexts (Lilleskov and Parrent, 2007).…”

Root morphology and mycorrhizal symbioses together shape nutrient foraging strategies of temperate trees

“…Ectomycorrhizal (EM) symbioses emerged among several of the more advanced lineages of plants (18). In many temperate forests, both AM and EM trees commonly cooccur despite fundamental differences in nutrient acquisition strategies (19,20). EM fungi are, on the whole, better adapted to acquire nutrients from organic substrates than AM fungi (21,22).…”

Palynology and the Ecology of the New Zealand Conifers

“…In broad terms, the Nothofagaceae have higher photosynthetic rates and therefore are well equipped to take advantage of high insolation days and short summers (Richardson et al, 2005a;Whitehead et al, 2011). The Nothofagaceae are also ectomycorrhizal and this brings with it the ability to directly use nutrients locked into organic complexes and also to lower the nutrient content of organic soils to such an extent that they are largely unsuitable for trees with arbuscular mycorrhizal infection (Dickie et al, 2014). However, these advantages over conifers are lessened under cloudy, low insolation summers (growth rate premium reduced) and long, mild winters (breakdown of soil organic matter and release of nutrients enhanced).…”