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Vulnerability to climate change was evaluated for three different time periods: 1990, 2000, and 2010. Our objective was to discuss the scope of a multi-temporal assessment of vulnerability. The method used 55 indicators--with emphasis on the agricultural sector in Mexico--of which 27 were updated for the year 2010 and 33 were retrospectively estimated for the year 1990. The results show that in the 20-year study period, the exposure of the municipalities (and inhabitants) has increased, and sensitivity and adaptive capacity have decreased. The number of municipalities vulnerable to climate change declined over the 20- year period. We found that calculating vulnerability by adding exposure and sensitivity and subtracting adaptive capacity (E + S - AC) can lead to unintentional underestimation of total vulnerability. When rating vulnerability, care must be taken in what is reported: the results differ for the number of inhabitants versus the number of municipalities. Our previous published vulnerability evaluation was for the year 2000, so we wanted to evaluate the sensitivity of some variables and the vulnerability formula itself we used in that moment. It is possible to evaluate the vulnerability multi-temporally, which allows to evaluate the sensibility and calibration of the variables and indicators used and the reconsideration of their application. [ABSTRACT FROM AUTHOR]

Abstract: Edifice collapse of the Jocotitlán volcano produced a debris avalanche deposit whose morphology is characterized by conical hummocks and elongated ridges. We consulted aerial photographs, orthophotographs, and conducted field work to define field relationships between mound morphology and stratigraphy. Based on field evidence and geomorphic and geologic interpretation we sub-divide the deposit into three sectors (north, northeastern, and eastern). We determine the emplacement mechanisms of the different sectors based on their distinct morphologic and lithologic features. In this context, we generate a geomorphometric database comprising 17 variables for each mound and apply multivariate statistical methods (principal component analysis and cluster analysis) to define the relationships between them. The principal components incorporated 73% of the total data variance and seven geomorphometric variables (perimeter, major axis, area, height, distance to the source, axis ratio and circularity index) defined two groups: hummocks and ridges. The circularity index and the axis ratio best characterize the elongated form of hummocks composing the deposits. Contrasts in lithological characteristics, such as material strength and mobility, provide evidence for a transition from a sliding mass (debris avalanche deposit) to a debris-flow-like emplacement. Differences in deposit morphology suggest two collapse mechanisms: magmatic intrusion (Bezymianny-type sector collapse) and a tectonic mass-slide, an earthquake could provide the trigger for both collapses. The eastern lower flank of the volcano then collapsed gravitationally due to a movement along a fault (tectonic activity possibly related to the Acambay–Tixmadeje Fault System). This produced the northeastern sector of the debris avalanche deposit dominated by large elongated ridges. The spatial arrangement of both sectors (the N and NE) suggests that the two failure events occurred simultaneously. Finally, the eastern sector of the deposit was emplaced by posterior remobilization of material from the two other sectors through a debris flow. [Copyright &y& Elsevier]

The Sierra Madre Occidental of western Mexico consists of a granitic basement covered by Oligocene ignimbrites that define a reference surface from which to estimate late Cenozoic river incision. A 90-m-grid digital elevation model was used to characterize contemporary topography and interpolate the Late Oligocene surface of the ignimbrite plateau from a surface fit to the highest points in the relatively undissected uplands between major river valleys. Long-term river incision rates calculated from the difference between this reference surface and longitudinal profiles of 11 rivers that flow toward the Tepic-Zacoalco rift zone range from about 0.01 to 0.2 mm year−1. River profiles of this region also show evidence of river capture driven by flexural uplift along the flank of the rift zone. River profile concavity values (θ) in the Sierra Madre Occidental range from 0.22 to 0.63, a range similar to that reported previously for a wide range of environments. In contrast, the empirically constrained ratio of exponents in the stream power model of river incision (m/n) ranges from 0.44 to 0.52, close to the expected theoretical value of 0.5. The wider range of observed θ values may illustrate how θ can differ from the driving values of m/n in non-steady-state bedrock river systems. [Copyright &y& Elsevier]

Presents a method for evaluation of ecological characteristics of shallow ponds in Mexico. Use of video remote sensing and image processing techniques; Correlation between average reflectance values and average values of limnetic variables; Determination of vegetation abundance.

Assesses mangrove vegetation from 1970 to 1993 of the Santiago River Mouth, Nayarit, West of Mexico to describe the plant composition and structure of mangrove and to evaluate the deforestation level and its amplitude by means of a retrospective analysis of mangrove species using LandsatTM imagery. Method used to map cover area and distribution of mangrove; Comparative study of earlier recorded mangrove vegetation area.

This article focuses on ecosystem services of tropical dry forests on the Pacific Coast of Mexico. Very little is known about the ecosystem services provided by tropical dry forests, although they are the basis for the livelihoods of millions of people around the world. In Mexico, 73% of tropical dry forests had been altered, degraded, or converted by the early 1990s; the most common transformation has been to agricultural or cattle grasslands. Land transformation has been driven by agro-pastoral policies that consider tropical forests as "wasted lands," only productive when transformed.