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The arbuscular mycorrhiza (AM) is among the most ubiquitous symbiosis in the world. A meta-analysis of 759 articles (1978–2012) was conducted to test whether ecologically important host plant traits (N-fixation and C-fixation pathway) affect the response of the plant to mycorrhizal colonization. We found that the effect of N-fixation on mycorrhizal growth response (MGR) depended on whether the plant was woody or a forb. N-fixing forbs had a higher MGR than non-N-fixing forbs, but the reverse was true for woody plants. Moreover, C 4 -grasses had significantly higher MGR than C 3 -grasses, but no significant difference was found between C 3 and C 4 forbs, or between C 3 and C 4 woody species. Overall, woody species had higher MGR than any other functional group. These results demonstrate that MGR does depend on host functional characteristics, but neither N-fixation capacity nor C-fixation pathway are apparently fundamental controllers of MGR. Instead, it would appear possible that these traits influence MGR only insofar as they influence more fundamental functions such as P demand and P supply. [ABSTRACT FROM AUTHOR]

Uncertainties remain as to the potential for tree plantations to affect soil microbial biomass. Our aim was to determine the factors accountable for the maintenance and the increase of soil microbial biomass following tree plantation. Based on mixed effect models, we conducted a meta-analysis with three fixed and two random factors to test the impact of tree plantation on soil microbial biomass. Previous land use was more important than climate or plant species in its effect on soil microbial biomass after tree plantation. There was a positive impact on soil microbial biomass for tree plantations on bare land but a negative impact for which on previously forested land. Climate and plant species were found to be not as important in their effects on soil microbial biomass. Our meta-analysis gives a general pattern that previous land use type is the major controlling factor of soil microbial biomass following tree plantations and promotes our understanding of the effects of rehabilitation of degraded sites on vegetation recruitment. [ABSTRACT FROM AUTHOR]