The Ecology of Browsing and Grazing

Abstract

Globally, many terrestrial ecosystems have been and are being heavily influenced by human activity, both directly and indirectly. Humanity and our domestic animals (1.4 billion cattle, 1.2 billion sheep and 0.5 billion goats, but only some 120 million horses and 13 million camels; Encyclopedia.com) have now so much impact on global ecosystems that we have entered the Anthropocene (Lewis and Maslin 2015). Wild ruminants number at least 75 million (Hackmann and Spain 2010), and are native to all continents except Antarctica. In such ecosystems extensive grazing and browsing by domestic and wild large mammalian herbivores (hereafter called large herbivores) and, in places, burning have shaped vegetation composition, structure and dynamics. Through their grazing, browsing, trampling and defecation large herbivores not only shape the structure and distribution of the vegetation but also affect nutrient flows and the responses of associated fauna. Consequently, it is the interactions between management or population dynamics of large herbivores and the vegetation they consume that shape the biodiversity, structure and dynamics of these ecosystems, covering vast parts of the globe. Therefore, a knowledge of the determinants of the distribution, movements and activities of herbivores, and how these interact with vegetation composition and dynamics, is required in order to predict the broader impact of these animals, now and into the future.