Effects of cessation of grazing on vegetation and soil
characteristics
Consistent with our expectations, across all sites, cessation of grazing
had strong effects on plant community composition (Figure S1). In
general, cessation of grazing resulted in plant communities becoming
more dwarf-shrub or fern dominated on acid soils, or dominated by tall
grasses (e.g ., Deschampsia cespitosa) on more alkaline
soils. Sites where grazing was excluded had marginally higher
aboveground biomass (F(1,73)3.28, p=0.07), although this
varied strongly by site (F(11,73)2.77, p = 0.004).
Across sites, cessation of grazing caused the litter layer depth to
increase on average by 28% or 4 cm (F(1,60), P=0.04).
Cessation of grazing also resulted in changes in soil abiotic
properties, including lower mean soil temperature
(F(1,53)22.0, p <0.001) and reduced electrical
conductivity (F(1,53)8.8, p =0.004). Grazing removal
resulted in slightly higher soil inorganic nitrogen concentrations
(F(1,69)4.4, p=0.04), but we detected no changes in
rates of potential N mineralization (p > 0.1) nor in pH (p
> 0.1). Soil bulk densities varied across sites
(F(11,88)8.84, p < 0.001), but were not
affected by cessation of grazing (p > 0.1).