Browsing (herbivory)

Browsing is a type of herbivory in which an herbivore (or, more narrowly defined, a folivore) feeds on leaves, soft shoots, or fruits of high-growing, generally woody, plants such as shrubs. This is contrasted with grazing, usually associated with animals feeding on grass or other low vegetation. An example of this dichotomy are goats (which are browsers) and sheep (which are grazers); these two closely related ruminants utilize dissimilar food sources.

The plant material eaten is known as browse and is naturally taken straight from the plant, though owners of livestock such as goats and deer may cut twigs or branches for feeding to their stock. In temperate regions, owners take browse before leaf fall, then dry and store it as a winter feed supplement. In time of drought, herdsmen may cut branches from beyond the reach of their stock, as forage at ground level. In the tropical regions, where population pressure leads owners to resort to this more often, there is a danger of permanent depletion of the supply. Animals in captivity may be fed browse as a replacement for their wild food sources; in the case of pandas, the browse may consist of bunches of banana leaves, bamboo shoots, slender pine, spruce, fir and willow branches, straw and native grasses.

If the population of browsers grows too high, all of the browse that they can reach may be devoured. The resulting level below which few or no leaves are found is known as the browse line. If over-browsing continues for too long, the ability of the ecosystem's trees to reproduce may be impaired, as young plants cannot survive long enough to grow too tall for browsers to reach.

Related to browsing is bark peeling. Particularly in forestry this is a problem as the trees may then get diseased and also die. Even if they do not die the trees may suffer fungal infections that affect the wood value. With the rise in deer population in some places, such as Austria, the search for food means that the bark peeling reaches economically serious levels in some forest concerns. There is a difference in mode over the seasons, with winter bark peeling being more gnawing of the trees due to the trees being frozen to some extent. Summer bark peeling, with softer barks manifests more often as long strips pulled off the trees.

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