Prairie dogs (Cynomys spp.) have been eliminated from over 95% of their historic range in large part from direct eradication campaigns to reduce their purported competition with cattle for forage. Despite the longstanding importance of this issue to grassland management and conservation, the ecological interactions between cattle and prairie dogs have not been well examined. We address this issue through two complementary experiments to determine if cattle and prairie dogs form a mutualistic grazing association similar to that between prairie dogs and American bison. Our experimental results show that cattle preferentially graze along prairie dog colony edges and use their colony centers for resting, resembling the mutualistic relationship prairie dogs have with American bison. Our results also show that prairie dog colonies are not only an important component of the grassland mosaic for maintaining biodiversity, but also provide benefits to cattle, thereby challenging the long-standing view of prairie dogs as an undesirable pest species in grasslands.

RESUMENLa alteración de las condiciones climáticas y el efecto de isla urbana de calor (EIC) son resultado del incremento de la población y de sus actividades en las zonas urbanas. En ciudades medianas como Querétaro es importante determinar la magnitud del EIC y promover la planeación del crecimiento urbano. Conservar y aumentar las áreas con vegetación es una buena opción para mitigar el EIC. En este estudio se analizaron la intensidad del EIC y el efecto de la cobertura vegetal sobre la regularización de la temperatura del aire. Se parcela de medición en la cual se consideraron dos niveles de cobertura vegetal en función del índice de área foliar: bajo y alto (0.5 y 2.0, respectivamente). La temperatura del aire se midió con recolectores de datos a intervalos de 30 min entre junio de 2012 y mayo de 2013. También se analizaron datos climáticos de seis estaciones meteorológicas. La temperatura media diaria aumentó a razón de 0.75 ºC por década (r 2 = 0.38, P < 0.0001); este aumento se relacionó con la dinámica poblacional (r 2 = 0.52, P < 0.0001). Los patrones estacionales de temperatura se describieron como temporada fría de julio a marzo y temporada cálida de abril a junio para la temperatura máxima, y temporada fría de noviembre a marzo y temporada cálida de abril a octubre para la temperatura mínima. La diferencia entre las temporadas cálida y fría fue del orden de 5 ºC ( de la vegetación. Sin embargo, la humedad relativa fue mayor en el nivel alto de la cobertura vegetal. La La intensidad del EIC fue similar para la temporada cálida y fría y varió de 0.1 a 5 ºC. La vegetación con mayor cobertura presentó menor temperatura a las 17:00 horas y mayor de las 9:00 a las 10:00 horas durante la temporada cálida. Al aumentar 50% la cobertura vegetal en la zona urbana se lograría reducir la intensidad del EIC en 2.05 ºC. En conclusión, una mayor cobertura de la vegetación mejora las condiciones ambientales en términos de humedad relativa y regularización de los extremos de temperatura durante la temporada cálida. ABSTRACTAlteration of climatic conditions and the urban heat island effect (UHI) are consequences of increased human population and activities in urban zones. Determining the magnitude of the UHI is important to improve urban planning in medium-size cities like Querétaro. Increase and conservation of vegetated areas is a mitigation option for UHI. Here we characterized both the UHI and the role of vegetation cover over temperature regtemperature and relative humidity were measured with data loggers at a 30 min time step from June 2012 to May 2013. Climatic data from six weather stations was also analyzed. Daily mean temperature increased at a rate of 0.75 ºC per decade (r 2 = 0.38, P < 0.0001), and this was related to population dynamics (r 2 = 0.52, for maximum temperature, and November to March and April to October for minimum temperature. The difference between cold and warm seasons was 5 ºC (P < 0.0001). The minimum temperature was similar doi: 10.20937/ATM.2015.28.03.05 © between canopy cover level...

This paper explores the relation that the inhabitants of an urban space, in this case the city of Querétaro, Mexico, establish with the water supply system. In particular, it seeks to understand the way in which the supply-side policies are configuring the relation that subjects keep with the territory around them. For this purpose, four variables (educational level, land value, housing legal status and development goals) are crossed with the existing knowledge about the water supply system, paying special attention to the differences among different city areas. The final goal is to understand how water modernization policies are affecting the links between subjects and territories. The results express that in the areas where those policies are more deeply consolidated, the links with territory are weaker, generating weakness in the ability to articulate management alternatives. Another weakness lies in the ability to create a much more active role of the subjects in their relation with water and its management as a basic resource.

Increasing the germination percentages from chemical and/or mechanical processes in native species is vital for the conservation of the species. The objective was to evaluate the effect of different treatments on the germination process of species belonging to the tropical deciduous forest (TDF) in a forest nursery. Eight species of trees and shrubs reported to be native to the TDF were selected; the seeds were collected from various sites of the state of Queretaro, Mexico. A randomized design of four replicates with 25 seeds was used, for which three pre-germinative scarification treatments were evaluated for each species: (1) thermal scarification (TS), (2) mechanical scarification (MS), and (3) chemical scarification (CS). Germination was considered as the protrusion of cotyledons onto the substrate and was recorded every 48 h for 60 days. A significant difference was observed between treatments (p ≤ 0.05). The mechanical treatment (MS) obtained the highest germination percentage and the least variation, in contrast to the thermal, chemical, and control treatments, which presented the lowest amount of germinated seeds. The MS treatment was the most effective for all the species studied because it allowed for 100% of the germination to be achieved.

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