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Linear mixed-effects model of the effects of number of treatment years, site richness, log live biomass, total species cover, and the number of added resources on diversity (ESNpie), with plot nested in block nested in site as random effects, using all 45 sites and data from the maximum treatment year for each site. Δ AIC between model with number of added resources and model without was 33, log-likelihood ratio 35.0, P < 0.0001.