Date of Award:

1987

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Natural Resources

Advisor/Chair:

Thadis W. Box

Abstract

In northeast Brazil grazing is a major use of much of the semiarid woodlands (caatinga). Animal production is limited by lack of dry season forage, primarily deciduous tree leaves. Management is constrained by the persistence of undesirable trees that sprout from the stump (coppice). This study evaluates the possibility of manipulating coppicing trees to improve caatinga management, particularly dry season forage production. The season of cutting can influence coppicing. Trees were cut early and late in the wet and dry seasons. After two years, trees of all species cut in the late wet season produced less biomass than those cut in other seasons. Production of most species was maximized by cutting in the dry season. Desirable species should be cut during the dry season to maximize production and less desirable ones in the late rainy season to reduce coppicing. Seasonal cutting does not cause mortality, nor can it cause any prolonged change in the leaf: stem ratio. Another study quantifies the response to defoliation of coppice growth by goat browsing or manual removal. The palatable browse species sabia and catingueira suffered no mortality while less palatable species experienced significant mortality. One year after defoliation, defoliated trees still produced less biomass than non-defoliated trees. Browsed stumps sprouted again during the dry season. Changes in the abscission phenology of coppice growth were observed. Coppice growth retained leaves from 2 to 12 weeks longer than intact trees of the same species. Regrowth on browsed stumps remained green for the duration of the S month dry season. Delaying abscission regulates the availability of dry season forage, and has implications for animal production that merit further investigation. Coppice growth can be manipulated to change the species composition of the regenerating stand, improve seasonal forage balance, and reduce site disturbance. Changing from even-aged to uneven-aged management might facilitate these changes. Prospects for improving wood production are better than animal production because of the limits imposed by mixed production systems, land tenure, and human population growth.

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