Land Use Change And Diversity In Neotropical Savannas Juan F. Silva Center for International Development Harvard University

Savannas in South America Cerrado Region Llanos Region Savanna Ecosystems represent a large portion of the flat lands of South America

Total Area: 208 million ha Cultivated Pastures: 49 million ha Native Pastures: 28 million ha Crops (grains): 10 million ha The Brazilian Cerrado

LUC in the Cerrado Region Have some habitats already disappeared? Natural vegetation has being replaced almost totally in some areas… (IBGE, 1998) o < 10% % % % > 40%

The Savannas

Physiognomy Gradients Campo limpo Campo sujo Cerrado ralo Cerrado tipico The changes in tree density and plant species composition have a major impact in the functioning of the ecosystem and the diversity of the animal communities This is a virtual gradient from grassland to closed woodland. In reality, these physiognomies appear forming mosaics

Species?

or Habitats? The real issue is not the protection of a few emblematic species but the preservation of the natural habitats

Biodiversity of the Cerrado Region Dominated by savanna physiognomiesDominated by savanna physiognomies at least 23 different vegetation types, including wooded savannas, deciduous and semideciduos forests and gallery forestsat least 23 different vegetation types, including wooded savannas, deciduous and semideciduos forests and gallery forests considerable variability in physiography and climate considerable variability in physiography and climate high beta diversityhigh beta diversity very rich in endemismvery rich in endemism

A conceptual framework OLSON ET AL., (2001): “…relatively large units of land containing a distinct assemblage of natural communities and species, with boundaries that approximate the original extent of natural communities prior to major land-use change” ECOREGION DINERSTEIN ET AL., (1995): “A geographically distinct assemblage of natural communities that share a large majority of their species, ecological dynamics, and similar environmental conditions, and whose ecological interactions are critical for the long term persistence”

More concepts… NATURE SERVE (2002): groups of plant communities… unified by similar ecological processes (e.g. fire, riverine flooding), substrates, (e.g., shallow soils, serpentine geology), and/or environmental gradients (e.g. local climate, hydrology in coastal zones). They are explicitly defined by spatial and temporal criteria … ECOLOGICAL SYSTEMS LAND SYSTEMS CHRISTIAN & STEWART (1953): “an area or group of areas throughout which there is a recurring pattern of climate, landscape, soils and vegetation ”.

Ecoregions and Savannas One ecoregion The diversity of savanna ecosystems has been largely ignored… Recently, government and NGOs alike are showing great interest in documenting and conserving savanna’s biodiversity (Map from Dinerstein et al., 1995) 18 ecoregions One ecoregion

Patterns and mosaics as habitats MOSAICS IS WHAT MAKES THE CERRADO INTRIGUING AND VALUABLE: DIVERSITY OF PLANTS AND ANIMALS DEPEND ON THESE MOSAICS AND ECOTONES. THE APPROACH OF PATTERNS SEEMS CONVENIENT: TO IDENTIFY MAJOR ECOLOGICAL UNITS OF FUNCTIONING TO STUDY CYCLINGTO IDENTIFY MAJOR ECOLOGICAL UNITS OF FUNCTIONING TO STUDY CYCLING AND BIODIVERSITY,AND BIODIVERSITY, AND THE CONSEQUENCES OF LAND USE CHANGEAND THE CONSEQUENCES OF LAND USE CHANGE

Our approach to the problem Cochrane T.T., Sánchez L.G., Azevedo L.G. De, Porras J.A., & Garver C.L Land in Tropical America. CIAT and EMBRAPA-CPAC. Cochrane et al., identified, mapped and described 25 Physiographic Units and 114 Land Systems for the Cerrado Region Cochrane et al., identified, mapped and described 25 Physiographic Units and 114 Land Systems for the Cerrado Region Land Systems maps at 1:2,000,000

Cochrane’s Land Systems FROM COCHRANE ET AL., WE BUILT A MATRIX WITH 124 LAND SYSTEMS AND 41 VARIABLES… AND WE PROCEEDED TO CLASIFY THE LAND SYSTEMS USING CLUSTER ANALYSIS…

Classifying Land Systems A B We have defined 16 clusters AT THE VERY TOP, TWO MAJOR GROUPS ARE SEPARATED SAVANNA AND FORESTS FLOODING SAVANNAS

Seasonal Savannas and Dry Forests Savanna, high plateaus 6A 5AB 5A 4AB 4A Savanna, plains Dense Savanna (Dense Woodland), plains 3ABA 3A2B 3AB Savanna (Grasslands), plains (rolling) Savanna (Forest), plains 3A predominantly plains 2ABA 2A2BA 2A3B 2AB 2A2B Dense Savanna, hills Dry Forest, hills Savanna (Grasslands), hills AA predominantly hills

Mapping the Clusters 16 CLUSTERS

Methodological Strategy FLORISTIC & FAUNISTIC LISTS MUNICIPAL CENSUS LAND COVER MAPS ECOLOGICAL IMPACTS OF LAND USE CHANGE MAP OF MAJOR ECOLOGICAL UNITS LAND SYSTEM MAP (Cochrane et al. 1985) MAPS OF VEGETATION, SOILS, ETC MULTIVARIATE ANALYSIS

Preview of Results AB3A SemiDeciduos Forest + Dense Savanna On rolling plains and clayey, deep soils South of Goias 2A2BA Dry Forest + Dense Savanna On hilly terrain and superficial soils Northern Tocantins

Conclusions We are developing a methodological framework for the study of ecological diversity and functioning of savanna ecosystemsWe are developing a methodological framework for the study of ecological diversity and functioning of savanna ecosystems The results are allowing us to analyze the consequences of land use change around the questions of what, where and howThe results are allowing us to analyze the consequences of land use change around the questions of what, where and how Since our team is also looking at the economic determinants in spatially explicit ways, these results can be linked to the economic modelingSince our team is also looking at the economic determinants in spatially explicit ways, these results can be linked to the economic modeling The combination of the economic drivers and the ecological consequences, operating at a given spatial scale, will prove useful for the design of conservation strategiesThe combination of the economic drivers and the ecological consequences, operating at a given spatial scale, will prove useful for the design of conservation strategies