Environmental predictors of woody plant encroachment in calcareous fens are modified by biotic and abiotic land-use legacies

Woody plant encroachment in grasslands is a world-wide concern. Assertions that abiotic stress reduction facilitates encroachment are not universally supported. To devise restoration and management strategies, the ability of stress reduction, in the context of co-occurring biotic land-use legacies, needs to be assessed to predict shrub cover. We determined whether legacy-induced reduction in Carex stricta (a potential facilitator of shrub encroachment and attractor of animal dispersers) and an increase in herbaceous invaders (potential competitors) altered the ability of stress reduction to predict woody plant cover in ploughed and never-ploughed plots within 11 Wisconsin (USA) calcareous fens. We hypothesized that drier conditions (low saturation stress) and higher nutrient availability associated with ploughing would be associated with high woody plant cover; that higher cover of herbaceous invaders associated with ploughing would predict low woody plant cover, and C. stricta cover pr...