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Accueil du site → Doctorat → Australie → 1990 → Environmental regulation of processes controlling yield in peanut (Arachis hypogaea L.)

Australian National University (1990)

Environmental regulation of processes controlling yield in peanut (Arachis hypogaea L.)

Bagnall, David James

Titre : Environmental regulation of processes controlling yield in peanut (Arachis hypogaea L.)

Auteur : Bagnall, David James

Université de soutenance : Australian National University

Grade : Doctor of Philosophy (PhD) 1990

Description
The effects of fire, buffalo and vegetation on the distribution, abundance and activities of termites occupying epigeal structures in the savannas of Kakadu National Park were investigated. Distribution and abundance were studied by surveying 2600 structures built by termites over two years, within 36 sites of 0.25 ha spread over three vegetation types and subject to three different frequencies of early dry season fires. An additional 200 structures on six sites subject to buffalo grazing were also studied. Subterranean termites were sampled at three sites and the production of alates and respiration rates of Tumulitermes pastinator were studied under two of the fire regimes at six sites. Most of the termite species feeding on standing grass (harvesters) or fine litter (foragers) known from the region were found in the structures studied, but only hatf of the species feeding on woody litter (wood foragers) or wood (xylophages). Size of structures occupied by harvesters and foragers was greater in grassland and woodland than in open forest, and was directly related to percentage cover or biomass of perennial, herbaceous monocotyledons. Number of structures containing wood foragers and xylophages was greater in open forest than in woodland or grassland. There were more foragers and fewer harvesters where buffalo were present. Number of structures occupied by harvesters increased in the absence of fire ; number of structures occupied by xylophages decreased. Changes in foragers were related to the vegetation types. The abundances of food sources seem responsible for the patterns of termite distribution ; perennial monocotyledons for harvesters, litter for foragers and wood for xylophages.

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