Spatial patterns of natural regeneration in stands of English yew (Taxus baccata L.); Negative neighbourhood effects

Abstract

Understanding the mechanisms underlying spatial patterns of regeneration of tree species can improve the effectiveness of forest management and restoration activities. English yew (Taxus baccata L.) stands have declined across their native range and yew dominated woodlands have priority status under the EU Habitats Directive. Several conservation and restoration programmes for this species have been established. We investigated population structure and spatial distribution of natural regeneration of yew at six woodlands in the south and west of Ireland. Specifically, the influence of adult conspecific neighbourhood density, canopy cover and distance from seed source on regeneration was explored. Within each site, canopy openness, soil and vegetation characteristics were established. Weiner spatial analysis revealed that the density of conspecific adults was negatively related to the recruitment of yew juveniles. In addition, a significant negative relationship between presence of conspecific canopy cover and regeneration density was evident. Although seedlings and saplings were scarce directly beneath conspecifics, regeneration was highest in nearby areas suggesting that intermediate dispersal distance maximises recruitment probability. Yew regeneration was correlated with a number of habitat characteristics, particularly percentage cover of woody shrubs. Management operations should focus on regeneration around the edges of populations to conserve existing yew stands.