Deer activity limits tree recruitment in woodland creation sites

Abstract

1. Natural regeneration and tree recruitment are essential for woodland persistence, but deer browsing can disrupt these processes. Browsing impacts are well recognised, yet how local and landscape-scale drivers shape regeneration, recruitment and herbivore pressure over time remains poorly understood. 2. Using a space-for-time approach, we assessed how regeneration, deer activity, browsing damage and tree recruitment vary over time at 82 woodland creation sites across England and Scotland. We used structural equation modelling to test the effects of local and landscape-scale drivers on these processes in England. 3. Regeneration and tree recruitment rates were significantly higher in England than Scotland. Both countries showed similarly low numbers of successive young tree growth stages, with sapling (51–150 cm) and juvenile (151–200 cm) counts being ~5% and 0.7% of seedling (≤50 cm) counts, respectively. 4. Woodland structural attributes influenced deer activity and browsing damage, both being higher in woodlands with lower basal area and greater structural heterogeneity. Browsing damage was also higher in smaller and denser woodlands but was not directly related to deer activity, indicating that woodland structure better predicts deer browsing than deer activity alone. 5. Despite this, deer activity strongly inhibited tree recruitment, with evidence of recruitment failure above an activity threshold of 2 deer plot−1 day−1. Unexpectedly, browsing damage facilitated tree recruitment, possibly by reducing competition. 6. Regeneration declined with woodland age, but age had no consistent effect on deer activity, browsing damage or tree recruitment. Low regeneration and recruitment in 81–170-year-old woodlands suggests suppressed understorey regrowth. 7. Synthesis and applications. Deer activity and browsing damage in woodland creation sites can be reduced through targeted management of structural attributes. Small, dense, structurally heterogeneous woodlands with low basal area are most vulnerable to deer impacts. To ensure continuous tree recruitment, localised deer activity should be minimised, while avoiding complete exclusion to maintain facilitative browsing effects. These actions offer practical means to safeguard ecosystem function and woodland longevity.