Impacts of horse grazing on botanical composition and diversity in different types of heathland

摘要: Plant dynamics under horse grazing was studied in a three-year field experiment heather-gorse shrublands NW Spain. The experimental design consisted of three vegetation types with four replicates (paddocks): (1) heather (Ericaceae)-dominated (H), (2) gorse (Ulex gallii Planch.)-dominated (G), and (3) co-dominated by heath-grasses (GG). Each paddock (1.2 ha) grazed from May to October two crossbred mature mares (310 ± 52 kg bodyweight), one dry lactating (plus foal). Two other paddocks (one H GG) were excluded grazing. cover height sampled times year (spring, summer, autumn) point-quadrat method. Floristic composition diversity annually at 10 25-m2 quadrats per paddock. Data subjected mixed models for repeated-measures redundancy analyses. Horse resulted overall increases (P < 0.001) herbaceous (from 13% 27%, 16% 23%, respectively), decreases 35% 17%; 30 25 cm), scarce differences among types. (species richness Shannon index) increased more over time than ungrazed paddocks. Redundancy analyses revealed that effects on plant species assemblages depended type, communities evolved differently between treatments both abundance frequency data. Some characteristic heathlands favoured reduced dominance G GG vegetation, controlling excessive accumulation combustible material reducing fire risk, promoted the presence conservation interest, so it offers promising management tool restoration their biodiversity.