Mast (botany)

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Mast is the "fruit of forest trees like acorns and other nuts."[1] It is also defined as "the fruit of trees such as beech, and other forms of Cupuliferae."[2] Alternatively, it can also refer to "a heap of nuts."[1] The term "mast" comes from the Old English word "mæst", meaning the nuts of forest trees that have accumulated on the ground, especially those used as food for fattening domestic pigs.[3]

More generally, mast is considered the edible vegetative or reproductive part produced by woody species of plants, i.e. trees and shrubs, that wildlife species and some domestic animals consume. It comes in two forms.

Hard mast[edit]

Norway spruce (Picea abies) seedlings can establish with greater success during mast years, when seed predator populations are swamped with food.

Tree species such as oak, hickory, and beech produce a hard mast - acorns, hickory nuts, and beechnuts. It has been traditional to turn pigs loose into forests to fatten on this form of mast. Also branch tips of the latest year's growth are eaten by some wildlife, such as deer.

Soft mast[edit]

Other tree and shrub species produce a soft mast - leaf buds, catkins, true berries, drupes, and rose hips.

Mast seeding[edit]

A mast year is a year in which much more mast than usual is produced. The term originally applied solely to trees, like oak trees, that produce fruit useful for feeding farm animals.

Mast seeding or masting[4] is a mass-seeding phenomenon exhibited by some species of plants, which can be defined as "synchronous production of seed at long intervals by a population of plants."[5] Masting, in the strict sense of the term, occurs only in monocarpic (or semelparous) species, whose members reproduce only once during their lifetime, then die.[6]

The prolific seeding provides food for animals like rats and stoats, whose populations can explode during a mast year, having been reduced by a lack of food in previous non-mast years. In turn, this makes it more likely that birds will be targeted by the pests,[7] or that rats will invade nearby fields in what is called a "rat flood."[8]


  1. ^ a b Swartz, Delbert (1971). Collegiate Dictionary of Botany. New York: The Ronald Press Company. p. 284. 
  2. ^ Jackson, Benjamin Daydon (1928). A Glossary of Botanic Terms with their Derivation and Accent (fourth ed.). London: Gerald Duckworth & Co. Ltd. p. 224. 
  3. ^ "mast". Oxford English Dictionary (3rd ed.). Oxford University Press. September 2005. 
  4. ^ Kelly, D. 1994. The evolutionary ecology of mast seeding (PDF). Trends Ecol. Evol.. 9(12): 465-470. Accessed on 24 January 2010
  5. ^ Janzen (1976) in Annul. Rev. Ecol. Syst., 7, 347-391
  6. ^ Strobilanthes callosus; Botany Photo of the Day; Notes posted by Daniel Mosquin; January 13, 2009
  7. ^ Reich, Josh (16 January 2009). "Trappers face pest population explosion". The Nelson Mail. Retrieved 2009-02-11. 
  8. ^ Normile D (February 2010). "Holding back a torrent of rats". Science 327 (5967): 806–7. doi:10.1126/science.327.5967.806. PMID 20150483. 

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