Too hot to handle? On the cooling capacity of urban green spaces in a Neotropical Mexican city

Urban areas are particularly vulnerable to climate change due to the Urban Heat Island (UHI) effect, which can be mitigated by urban vegetation through shading and evapotranspiration. Nevertheless, there is still a lack of spatially explicit information on the cooling capacity of green infrastructure for most Latin American cities. In this study, we employed Land Surface Temperature (LST) of the Neotropical Mexican city of Xalapa to (1) analyze its Surface UHI (SUHI) compared to its peri and extra-urban areas, (2) to assess the cooling capacity of urban green spaces larger than 1ha, and (3) to evaluate the role of green spaces’ size, shape and their surrounding tree cover percentage (Tc) on green spaces cooling range. We evaluated the cooling range of green spaces and their relationships with green spaces metrics and Tc via a linear mixed-effect model and identify threshold values for the variables at 25, 50, 100, and 200m from the borders of green spaces through Classification and Regression Trees. Xalapa exhibits a SUHI of 1.70 °C compared to its peri-urban area and 4.95 °C to the extra-urban area. Green spaces > 2ha mitigated heat at ~2 °C and the cooling range was influenced by the size of green spaces ≥ 2.8ha and Tc > 21% at 50m and only by Tc surrounding the green spaces at 100m and 200m. This shows that the size threshold of urban green spaces should be complemented with the presence of Tc starting at least 50m to maximize the cooling capacity provided by the green infrastructure. Planning agendas should account for the interaction between the size of green spaces and the cumulative cooling effect of scattered vegetation inside urban areas towards compact green cities to cope with urban warming.Peer reviewe

A Novel Approach for the Assessment of Cities through Ecosystem Integrity

To tackle urban heterogeneity and complexity, several indices have been proposed, commonly aiming to provide information for decision-makers. In this study, we propose a novel and customizable procedure for quantifying urban ecosystem integrity. Based on a citywide approach, we developed an easy-to-use index that contrasts physical and biological variables of urban ecosystems with a given reference system. The Urban Ecosystem Integrity Index (UEII) is the sum of the averages from the variables that make up its intensity of urbanization and biological components. We applied the UEII in a Mexican tropical city using land surface temperature, built cover, and the richness of native plants and birds. The overall ecosystem integrity of the city, having montane cloud, tropical dry, and temperate forests as reference systems, was low (−0.34 ± SD 0.32), showing that, beyond its biodiverse greenspace network, the built-up structure highly differs from the ecosystems of reference. The UEII showed to be a flexible and easy-to-calculate tool to evaluate ecosystem integrity for cities, allowing for comparisons between or among cities, as well as the sectors/regions within cities. If used properly, the index could become a useful tool for decision making and resource allocation at a city level

A Novel Approach for the Assessment of Cities through Ecosystem Integrity

To tackle urban heterogeneity and complexity, several indices have been proposed, commonly aiming to provide information for decision-makers. In this study, we propose a novel and customizable procedure for quantifying urban ecosystem integrity. Based on a citywide approach, we developed an easy-to-use index that contrasts physical and biological variables of urban ecosystems with a given reference system. The Urban Ecosystem Integrity Index (UEII) is the sum of the averages from the variables that make up its intensity of urbanization and biological components. We applied the UEII in a Mexican tropical city using land surface temperature, built cover, and the richness of native plants and birds. The overall ecosystem integrity of the city, having montane cloud, tropical dry, and temperate forests as reference systems, was low (−0.34 ± SD 0.32), showing that, beyond its biodiverse greenspace network, the built-up structure highly differs from the ecosystems of reference. The UEII showed to be a flexible and easy-to-calculate tool to evaluate ecosystem integrity for cities, allowing for comparisons between or among cities, as well as the sectors/regions within cities. If used properly, the index could become a useful tool for decision making and resource allocation at a city level

Gamma-ray and radio properties of six pulsars detected by the fermi large area telescope

We report the detection of pulsed γ-rays for PSRs J0631+1036, J0659+1414, J0742-2822, J1420-6048, J1509-5850, and J1718-3825 using the Large Area Telescope on board the Fermi Gamma-ray Space Telescope (formerly known as GLAST). Although these six pulsars are diverse in terms of their spin parameters, they share an important feature: their γ-ray light curves are (at least given the current count statistics) single peaked. For two pulsars, there are hints for a double-peaked structure in the light curves. The shapes of the observed light curves of this group of pulsars are discussed in the light of models for which the emission originates from high up in the magnetosphere. The observed phases of the γ-ray light curves are, in general, consistent with those predicted by high-altitude models, although we speculate that the γ-ray emission of PSR J0659+1414, possibly featuring the softest spectrum of all Fermi pulsars coupled with a very low efficiency, arises from relatively low down in the magnetosphere. High-quality radio polarization data are available showing that all but one have a high degree of linear polarization. This allows us to place some constraints on the viewing geometry and aids the comparison of the γ-ray light curves with high-energy beam models

Technical note: Toward a near-real time forest monitoring system

In the last decades, Mexico has experienced important forest loss and degradation processes in both temperate and tropical forests (Mas et al., 2004; Velázquez et al., 2010). According to FAO (2010), deforestation rates in Mexico were 0.5% (354 000 ha/year) during the period 1990-2000, and 0.2% (155 000 ha/year) in 2005-2010. Wildfires, urbanization, excessive logging, the extension of areas dedicated to agriculture and livestock raising are the main causes of this phenomenon. The most important consequences of the loss of forest cover include the reduction in the environmental assets and services provided by ecosystems, global warming, alteration of biogeochemical and hydrological cycles, soil degradation and habitat loss (Velázquez et al., 2010)

Are Wildfires in the Wildland-Urban Interface Increasing Temperatures? A Land Surface Temperature Assessment in a Semi-Arid Mexican City

High rates of land conversion due to urbanization are causing fragmented and dispersed spatial patterns in the wildland-urban interface (WUI) worldwide. The occurrence of anthropogenic fires in the WUI represents an important environmental and social issue, threatening not only vegetated areas but also periurban inhabitants, as is the case in many Latin American cities. However, research has not focused on the dynamics of the local climate in the WUI. This study analyzes whether wildfires contribute to the increase in land surface temperature (LST) in the WUI of the metropolitan area of the city of Guanajuato (MACG), a semi-arid Mexican city. We estimated the pre- and post-fire LST for 2018–2021. Spatial clusters of high LST were detected using hot spot analysis and examined using ANOVA and Tukey’s post-hoc statistical tests to assess whether LST is related to the spatial distribution of wildfires during our study period. Our results indicate that the areas where the wildfires occurred, and their surroundings, show higher LST. This has negative implications for the local ecosystem and human population, which lacks adequate infrastructure and services to cope with the effects of rising temperatures. This is the first study assessing the increase in LST caused by wildfires in a WUI zone in Mexico

Are Wildfires in the Wildland-Urban Interface Increasing Temperatures? A Land Surface Temperature Assessment in a Semi-Arid Mexican City

High rates of land conversion due to urbanization are causing fragmented and dispersed spatial patterns in the wildland-urban interface (WUI) worldwide. The occurrence of anthropogenic fires in the WUI represents an important environmental and social issue, threatening not only vegetated areas but also periurban inhabitants, as is the case in many Latin American cities. However, research has not focused on the dynamics of the local climate in the WUI. This study analyzes whether wildfires contribute to the increase in land surface temperature (LST) in the WUI of the metropolitan area of the city of Guanajuato (MACG), a semi-arid Mexican city. We estimated the pre- and post-fire LST for 2018–2021. Spatial clusters of high LST were detected using hot spot analysis and examined using ANOVA and Tukey’s post-hoc statistical tests to assess whether LST is related to the spatial distribution of wildfires during our study period. Our results indicate that the areas where the wildfires occurred, and their surroundings, show higher LST. This has negative implications for the local ecosystem and human population, which lacks adequate infrastructure and services to cope with the effects of rising temperatures. This is the first study assessing the increase in LST caused by wildfires in a WUI zone in Mexico

Urban form datasets of 194 cities delineated based on the contiguous urban fabric for 1990 and 2015

The present research datasets were processed for the article “The global homogenization of urban form. An assessment of 194 cities across time” [1]. They consist of land cover spatial layers, longitude and latitude point data and tabulated data with computed landscape metrics and the characterization of urban form of 194 cities for 1990 and 2015. Contiguous urban fabric at 30 m spatial resolution was derived from the Atlas of Urban Expansion database for 1990 and 2015 [2]. Landscape metrics were computed as quantitative measures of composition and spatial arrangement of each city and dimensions of the database were reduced employing correlation and principal components analysis. Hierarchical clustering was employed to group cities according to the similarity of their urban form and analysis of variance was applied to test for significant differences between them. The spatial layers contained in this article can be complemented with past and future land cover data to model urban form change at broader temporal scales. The landscape metrics are useful for cross-city comparisons at regional, national and global levels in combination with other complementary indicators. The datasets are valuable for urban planners, urban ecologists, NGO's, decision makers and other with interest on local and global landscape change in urban areas, particularly urban expansion and its impacts

Evaluación de las tasas de deforestación en Michoacán a escala detallada mediante un método híbrido de clasificación de imágenes SPOT

In the last decades, the state of Michoacán has suffered high deforestation rates. In this work, we implemented a hybrid classification method that combines automated processing, spatial analysis and visual interpretation, which enabled us to produce land use/cover maps for Michoacán, scale 1:50 000 with a minimum mapping unit of one hectare for 2004, 2007 and 2014. Additionally, we assessed the accuracy of the elaborated cartography. Accuracy assessment of the 2007 map shows an overall accuracy of 83.3%, with a confidence interval of 3.1%. Deforestation rates have decreased in Michoacán (i.e., 2004-2007; 0.17%, 2007-2014; 0.07%). However, there are two main deforestation hotspots in which pine and pine-oak forests have been replaced by avocado orchards (center part of the State) and deciduous forests have been transformed into grasslands (sierra-costa region).En las últimas décadas, se han registrado altas tasas de deforestación en el estado de Michoacán. En el presente trabajo se puso en marcha un método de clasificación híbrido que combina procesos automatizados, análisis espacial e interpretación visual, el cual permitió generar cartografía de cubierta/uso de suelo para el estado de Michoacán, a escala 1:50 000, con un área mínima cartografiable de una hectárea para 2004, 2007 y 2014. Adicionalmente, se evaluó la fiabilidad de la cartografía generada. La evaluación del mapa para 2007 indicó que la fiabilidad global fue de 83.3%, con un intervalo de confianza de 3.1%. Las tasas de deforestación en Michoacán han disminuido (i.e., 2004-2007; 0.17%, 2007-2014; 0.07%). No obstante, existen dos focos principales de deforestación donde bosques de pino y pino-encino han sido sustituidos por huertas de aguacate (centro del estado) y selvas bajas y medianas han sido transformadas en pastizales (región sierra-costa)