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close this bookThe Fragile Tropics of Latin America: Sustainable Management of Changing Environments (UNU, 1995)
close this folderPart 4 : The semi-arid north-east
close this folderChanging aspects of drought-deciduous vegetation in the semiarid region of north-east Brazil
View the document(introductory text...)
View the document1 Introduction
View the document2 Study sites and methods
View the document3 Results
View the document4 Discussion and conclusion
View the documentReferences

2 Study sites and methods

The study sites are situated between 7° and 8°S and between 32° and 38°E in the Brazilian North-East (fig. 12.1). Mean annual temperature and total annual precipitation are 20°C and 800-1,000mm, with a severe dry season from October to the following February (Nishizawa, 1976; Rizzini and Pinto, 1964). The soils are classified as solodized solonetz and regosols Ministério da Agricultura e Ministério do Interior, 1971).



Figure 12.1 The study area in North-East Brazil. 1. João Pessoa; 2. Campina Grander 3. Patos.

The vegetation varies from place to place, according to land use, which includes ranching, cultivation, firewood collection, and charcoal Production.

The intensive study sites were located in the vicinity of Campina Grande and Patos, where the vegetation is typical for the region. Nine 10m x 10m quadrats were set out at sites dominated by Mimosa tenuiflora (synonym of Mimosa hostilis) and Caesalpinia pyramidalis. In each quadrat, I measured the diameter of tree stems at 130 cm high (DBH) for each species, and counted the number of shrubs less than 150 cm tall for each species.

For selected specimens of Caesalpinia pyramidalis, Mimosa tenuiflora and Aspidosperma pyrifolium, the weight of stems (Ws:kg), branches (Wb:kg), and leaves (Wl:kg) was taken after first measuring tree height (H:m) and stem diameter (D:cm) at 130 cm high.

The nitrogen and carbon contents of stems and leaves and of the surface soil were determined in the laboratory.