资源环境科技发展态势分析平台

Wild ungulate numbers are increasing and expanding across most woody systems of the Northern Hemisphere. Simultaneously, wildfire risk has risen considerably over the last decades due to anthropogenic climate change and the increasing continuity of heavier fuel loads. It is therefore imperative to evaluate how human-made structures aimed at wild ungulate management (e.g., supply points) and wildfire prevention and suppression (e.g., firebreaks) affect ungulate use and woody vegetation at increasing distances from the structures to manage forestland accordingly. This study investigates the use of firebreaks and artificial supply points by wild ungulates and the derived effects on woody vegetation (plant damage, fuel load, woody plant diversity and regeneration) along a distance gradient from the human-made structures. Particularly, we examine the effects of a large wild ungulate (Ammotragus lervia) on a highly diverse Mediterranean vegetation following a distance gradient (10-50-100 m) from supply points and firebreaks.

Our results show that ungulate habitat use decreased with distance to structures. Both supply points and firebreaks also showed greater plant damage (browsing, trampling and rubbing) and lower fuel load as distance to structures decreased but effects were rather constant within 50 m (similar to 1 ha) around the structures, indicating a non-linear relationship along the distance gradient. Woody species richness also increased with distance to firebreaks and supply points but changes in plant composition (beta-diversity) were small (0.80-0.87 similarity), mostly due to limited regeneration and heavy use by ungulates along the gradient, which mostly favored the regeneration of ungulate-resistant plants (non-palatable or resprouting).

Importantly, supply points showed significantly greater ungulate effects as compared to firebreaks at any distance for all the study variables. Thus, supply points showed, on average, 1.8 times greater browsing damage than firebreaks at any distance from the boundary. Similarly, fuel load between 100 and 10 m from the structures was reduced by 78% in supply points but only by 20% in firebreaks. Managers should carefully consider the location and distribution of firebreaks and supply points throughout the landscape given their differential capacity to attract ungulates and their associated effects on fuel load reduction and woody plant communities. Fireprone areas within the landscape can benefit from the combined use of firebreaks and supply points to reduce fuel load at a low cost but regeneration of ungulate-sensitive and threatened taxa should be considered.