Threats to the Cerrado remnants of the state of São Paulo, Brazil

Giselda Durigan,Geraldo Antonio Daher Correa Franco,Marinez Ferreira De Siqueira

doi:10.1590/s0103-90162007000400006

Giselda Durigan, Geraldo Antonio Daher Correa Franco + Show 1 more

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https://doi.org/10.1590/s0103-90162007000400006

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Abstract

Patches of natural vegetation remaining in landscapes occupied by man are continuously under threat due to the edge effects and also to land use types around these remnants. The most frequent threats and land use types in the vicinity of 81 Cerrado (tropical savanna type) fragments in the State of São Paulo, Brazil, were analyzed in order to verify if the frequency of every type of disturbance to the natural ecosystem depends on the neighboring land use. The hypothesis of the study assumes that environmental threats are correlated with land use around protected areas. From the 81 areas, the most frequent human-induced land cover types around the Cerrado remnants were: pasture (recorded in 78% of the areas), sugarcane plantations (26%), roads (19%), annual crops and reforestation (14% each). The most frequent sources of threats were invasive grasses (35% of the areas partially or totally invaded) and cattle (observed in 32% of the areas), followed by deforestation (21%), and fire (21%). The chi-square analysis revealed that, with the exception of deforestation, which does not depend on land use, all other threats are influenced by the neighboring land use. The occurrence of invasive grasses and fires are strongly favored by the presence of roads and urban areas. Sugarcane, reforestation, and permanent crops were the less impacting land use types found in the study area, when only considering impact frequency. These land use types have fire and weed control, and also exclude cattle, indirectly protecting natural ecosystems.

Highlights

The Cerrado vegetation occupies more than 2 million km2 in the central part of South America and is the largest, richest and possibly most threatened tropical savanna in the world (Silva & Bates, 2002), and has been highlighted as a global hotspot for biodiversity conservation (Myers et al, 2000)
The causes of destruction and the present situation of the Cerrado biome was analyzed by Alho & Martins (1995), Ratter et al (1997), Cavalcanti & Joly (2002), Klink & Moreira (2002), Machado et al (2004), Alho (2005), Felfili et al (2005), Pivello (2005), Ribeiro et al (2005) and Ratter et al (2006). These studies show that from an almost no impacting low density cattle raising some 40 years ago, the land use of the Cerrado domain has changed to cultivated pastures with African grasses or modern mechanized agriculture, with their techniques for the rapid clearing of extensive landscapes and for the improvement of the soil fertility through liming and fertilization
The Cerrado vegetation, which covered originally 14% of São Paulo State (São Paulo, 1997) has been even more drastically reduced, the remnants corresponding to only 0.81% of the state (Kronka et al, 2005)

Summary

Introduction

The Cerrado vegetation occupies more than 2 million km in the central part of South America and is the largest, richest and possibly most threatened tropical savanna in the world (Silva & Bates, 2002), and has been highlighted as a global hotspot for biodiversity conservation (Myers et al, 2000).Sci. The causes of destruction and the present situation of the Cerrado biome was analyzed by Alho & Martins (1995), Ratter et al (1997), Cavalcanti & Joly (2002), Klink & Moreira (2002), Machado et al (2004), Alho (2005), Felfili et al (2005), Pivello (2005), Ribeiro et al (2005) and Ratter et al (2006). The current Cerrado vegetation in the state (less than 7% of the original cover) has been split into thousands of small areas, and surrounded by pasture, sugarcane, soybean, reforestation, perennial crops, and urban zones

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