A MULTIPLE MODEL APPROACH FOR FUTURE POTENTIAL DISTRIBUTION OF HLB: SOUTH AMERICA CASE STUDY

The objective of this work was to estimate the potential geographical distribution of HLB in South America, under historical climate records and future climate change scenarios, based on climatic conditions at the sites where HLB has been established in South America. Different spatial modeling algorithms were used. Climate change estimates of the Fifth IPCC Assessment Report, by the 2050s and 2070s, were considered. Results of assessed models differed significantly in the estimation of areas with greater climatic risk for the establishment of HLB in South America. According to the estimates of the fifth IPCC report, the effects of climate change would determine that in future, high-risk areas for HLB establishment would be displaced towards the southwest of the areas considered riskier nowadays. Even individual models do not present a clear pattern for HLB establishment and distribution, the integration of the results generated by different algorithms in a consensus model, can provide additional information for phytosanitary decision making

Automated mapping of burned areas in semi-arid ecosystems using modis time-series imagery

Understanding spatial and temporal patterns of burned areas at regional scales, provides a long-term perspective of fire processes and its effects on ecosystems and vegetation recovery patterns, and it is a key factor to design prevention and post-fire restoration plans and strategies. Standard satellite burned area and active fire products derived from the 500-m MODIS and SPOT are avail - able to this end. However, prior research caution on the use of these global-scale products for regional and sub-regional applica - tions. Consequently, we propose a novel algorithm for automated identification and mapping of burned areas at regional scale in semi-arid shrublands. The algorithm uses a set of the Normalized Burned Ratio Index products derived from MODIS time series; using a two-phased cycle, it firstly detects potentially burned pixels while keeping a low commission error (false detection of burned areas), and subsequently labels them as seed patches. Region growing image segmentation algorithms are applied to the seed patches in the second-phase, to define the perimeter of fire affected areas while decreasing omission errors (missing real burned areas). Independently-derived Landsat ETM+ burned-area reference data was used for validation purposes. The correlation between the size of burnt areas detected by the global fire products and independently-derived Landsat reference data ranged from R2 = 0.01 - 0.28, while our algorithm performed showed a stronger correlation coefficient (R2 = 0.96). Our findings confirm prior research calling for caution when using the global fire products locally or regionally

Global burned-land estimation in Latin America using MODIS composite data

This paper presents results of the AQL2004 project, which has been developed within the GOFC-GOLD Latin American network of remote sensing and forest fires (RedLatif). The project intended to obtain monthly burned-land maps of the entire region, from Mexico to Patagonia, using MODIS (moderate-resolution imaging spectroradiometer) reflectance data. The project has been organized in three different phases: acquisition and preprocessing of satellite data; discrimination of burned pixels; and validation of results. In the first phase, input data consisting of 32-day composites of MODIS 500-m reflectance data generated by the Global Land Cover Facility (GLCF) of the University of Maryland (College Park, Maryland, USA) were collected and processed. The discrimination of burned areas was addressed in two steps: searching for "burned core" pixels using postfire spectral indices and multitemporal change detection and mapping of burned scars using contextual techniques. The validation phase was based on visual analysis of Landsat and CBERS (China-Brazil Earth Resources Satellite) images. Validation of the burned-land category showed an agreement ranging from 30% to 60%, depending on the ecosystem and vegetation species present. The total burned area for the entire year was estimated to be 153 215 km2. The most affected countries in relation to their territory were Cuba, Colombia, Bolivia, and Venezuela. Burned areas were found in most land covers; herbaceous vegetation (savannas and grasslands) presented the highest proportions of burned area, while perennial forest had the lowest proportions. The importance of croplands in the total burned area should be taken with reserve, since this cover presented the highest commission errors. The importance of generating systematic products of burned land areas for different ecological processes is emphasized. © 2008 by the Ecological Society of America

A new methodology for systematic mapping of land covers in Latin America and Caribbean [Propuesta metodológica para la cartografía periódica de la cobertura del suelo en latinoamérica y el caribe: Estado de situación y avances]

This work was developed in the framework of the Latin American Network of Monitoring and Study of Natural Resources (SERENA) in response to the need for accurate and reliable information on landcover, with a medium spatial resolution in the region of Latin America and the Caribbean (LAC). This article describes the methodology and presents the results obtained for the year 2008