摘要：Natural disturbances that vary in size, severity, and frequency play a fundamental role in structuring terrestrial, but also aquatic ecosystems by creating heterogeneity at multiple spatial and temporal scales (Pickett and White 1985). As one of the biotic disturbances, large herbivores are an important factor affecting vegetation cover locally and over the landscape (Grant and Edwards 2008). In herbivore-driven ecosystems in boreal and temperate regions, herbivores may inhibit shrub and tree cover expansion by eating shrub and tree seedlings (Kuiters and Slim 2002). Historically, humans have had a continuous and increasing impact, directly or indirectly, on browsing and grazing herbivores’ populations (Danell et al. 1998, Schwarz et al. 2003, Weisberg and Bugmann 2003, Linnell and Zachos 2011, Brown et al. 2012). The character of this impact is related to the goals and intentions humans had for a specific area and the ways to achieve these. Over time, both goals and tools have changed and evolved, altering herbivore populations’ composition and size, and hence consumption pressure on vegetation (Angelstam 2002, Edenius et al. 2002).
