Effects on soil nutrients, tree flora, ground flora, decayed wood and tree regeneration away from release pens
This study examined the ecological effects of pheasant (Phasianus colchicus) releasing on ancient semi-natural woodlands (ASNWs) at varying distances from release pens, with relevance to current and future distance-based licensing requirements for gamebird releases near designated conservation sites. Twenty woodland sites across England and Wales, many designated as SACs and/or SSSIs, were surveyed. Each site contained a single pen holding 600–8,000 pheasants. Habitat quality was assessed along transects beginning 5–10 m outside pen edges and extending to a minimum of 1 km, avoiding game management features such as feeders or game crops. Sampling targeted ground flora, soils, invertebrate resources, and tree flora during winter 2023/24 and spring–summer 2024.
Pheasant encounters declined nearly tenfold from pen-edge plots to control areas, confirming a strong gradient of bird activity. However, soil nitrate, phosphate, and potassium levels showed no significant variation with distance, nor were there increases in bare ground, weed abundance, or shifts in plant communities towards higher Ellenberg N values. Ancient Woodland Indicator species also showed no degradation near pens. Nonetheless, ground flora species richness was reduced within 250 m of pens, and tree seedlings were least abundant closest to pens, indicating possible impacts on sensitive or early-growth vegetation. Decaying wood volume was consistent across plots except for higher levels in control sites.
The clearest distance-related patterns occurred in tree epiphytes: nitrogen-tolerant lichens and bryophytes were nearly twice as abundant near pens, while nitrogen-sensitive species were reduced up to ~100 m, suggesting localised nitrogen enrichment. These findings support refinement of release pen placement guidance, particularly in designated woodlands.