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Couturier S.,Research Center En Geografia omatica Ing Jorge mayo Centrogeo | Couturier S.,National Autonomous University of Mexico | Mas J.-F.,National Autonomous University of Mexico | Lopez-Granados E.,National Autonomous University of Mexico | And 3 more authors.
Singapore Journal of Tropical Geography | Year: 2010

The accuracy of the Mexican National Forest Inventory (NFI) map is derived in four distinct ecogeographical areas, using an assessment design tailored for the project. A main achievement of the design was to integrate the high diversity of classes encompassed at the most detailed subcommunity level of the classification scheme within a cost-controlled statistically sound assessment. A hybrid double sampling strategy was applied to the 2.5 million-ha study area. A total of 5955 reference sites were verified against their NFI map label. The availability of detailed quasi-synchronous reference data for the 2000 Landsat-derived NFI and the high diversity of mapped classes allowed a careful thematic analysis on the selected regions, relevant for national extrapolation. Global accuracy estimates of 64-78 per cent were registered among the four ecogeographical areas (two with mainly temperate climate and the other two with mainly tropical climate), with the lower accuracy levels found in areas more densely covered with forests. According to the estimates, the NFI map tends to underestimate the presence of temperate forest (especially oak) and overestimate the presence of tropical forest in the areas investigated. The analysis of confusions reveals difficulties in unambiguously interpreting or labelling forests with secondary vegetation, herbaceous and/or shrub-like vegetation as well as distinguishing between aquatic vegetation types. The design proved useful from the perspective of accuracy assessments of regional maps in biodiverse regions. © 2010 The Authors. Journal compilation © 2010 Department of Geography, National University of Singapore and Blackwell Publishing Asia Pty Ltd.

Sandra C.R.-F.,Research Center En Geografia omatica Ing Jorge mayo Centrogeo | Alejandra L.-C.,Research Center En Geografia omatica Ing Jorge mayo Centrogeo | Jose L.S.-C.,Research Center En Geografia omatica Ing Jorge mayo Centrogeo
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

The tropical coastal landscape of Tulum in Quintana Roo, Mexico has a high ecological, economical, social and cultural value, it provides environmental and tourism services at global, national, regional and local levels. The landscape of the area is heterogeneous and presents random fragmentation patterns. In recent years, tourist services of the region has been increased promoting an accelerate expansion of hotels, transportation and recreation infrastructure altering the complex landscape. It is important to understand the environmental dynamics through temporal changes on the spatial patterns and to propose a better management of this ecological area to the authorities. This paper addresses a multi-temporal analysis of land cover changes from 1993 to 2000 in Tulum using Thematic Mapper data acquired by Landsat-5. Two independent methodologies were applied for the analysis of changes in the landscape and for the definition of fragmentation patterns. First, an Iteratively Multivariate Alteration Detection (IR-MAD) algorithm was used to detect and localize land cover change/no-change areas. Second, the post-classification change detection evaluated using the Support Vector Machine (SVM) algorithm. Landscape metrics were calculated from the results of IR-MAD and SVM. The analysis of the metrics indicated, among other things, a higher fragmentation pattern along roadways. © 2011 SPIE.

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