This material is published by Conservation Biology (2015, 29: 1695-1703).
A meta-analysis of functional group responses to forest recovery outside of the tropics
Rebecca Spake, Thomas H. G. Ezard, Philip A. Martin, Adrian C. Newton and C. Patrick Doncaster
Both active and passive forest restoration schemes are used in degraded landscapes across theworld
to enhance biodiversity and ecosystem service provision. Restoration is increasingly also being implemented
in biodiversity offset schemes as compensation for loss of natural habitat to anthropogenic development. This
has raised concerns about the value of replacing old-growth forest with plantations, motivating research on
biodiversity recovery as forest stands age. Functional diversity is now advocated as a keymetric for restoration
success, yet it has received little analytical attention to date. We conducted a meta-analysis of 90 studies that
measured differences in species richness for functional groups of fungi, lichens, and beetles between oldgrowth
control and planted or secondary treatment forests in temperate, boreal, and Mediterranean regions.
We identified functional-group-specific relationships in the response of species richness to stand age after
forest disturbance. Ectomycorrhizal fungi averaged 90 years for recovery to old-growth values (between
45 years and unrecoverable at 95% prediction limits), and epiphytic lichens took 180 years to reach 90% of
old-growth values (between 140 years and never for recovery to old-growth values at 95% prediction limits).
Non-saproxylic beetle richness, in contrast, decreased as stand age of broadleaved forests increased. The slow
recovery by some functional groups essential to ecosystem functioning makes old-growth forest an effectively
irreplaceable biodiversity resource that should be exempt from biodiversity offsetting initiatives.
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