Cattle grazing within subalpine heathland and grassland communities on the Bogong High Plains: disturbance, regeneration and the shrub-grass balance [Victoria; review]. [Symposium paper]
1990
Williams, R.J. (Melbourne Univ., Parkville (Australia). School of Botany)
The factors affecting the dynamics of heathland and grassland communities are reviewed, with special reference to the effects of cattle on disturbance regimes, and the shrub-grass balance. Establishment of shrubs depends largely upon disturbance, grazing by cattle being the primary agent, causing bare ground patches on which shrubs may establish. In grassland, such grazing-related disturbances may facilitate the invasion of disturbed inter-tussock spaces by shrubs. The expansion of palatable shrubs may be inhibited by cattle activity. Obligate seeders are generally replaced at senescence by grasses, whereas facultative seed reproducers may persist long after establishment. Both the direction and rate of such vegetation changes are affected by the co-incidence of infrequent biotic and climatic events. Discontinuation of grazing is likely to be followed by an expansion of palatable, obligate seeders, but the frequency of disturbances necessary for the regeneration and persistence of these shrubs is likely to diminish substantially. Continuation of grazing may inhibit the growth of palatable shrubs in some sites, but is likely to facilitate the persistence of non-palatable shrubs in other more sheltered sites.
اظهر المزيد [+] اقل [-]الكلمات المفتاحية الخاصة بالمكنز الزراعي (أجروفوك)
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