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Roa-Fuentes L.L.,Centro del Cambio Global y la Sustentabilidad en el Sureste | Templer P.H.,Boston University | Campo J.,National Autonomous University of Mexico
Oecologia | Year: 2015

Leaf traits are closely associated with nutrient use by plants and can be utilized as a proxy for nutrient cycling processes. However, open questions remain, in particular regarding the variability of leaf traits within and across seasonally dry tropical forests. To address this, we considered six leaf traits (specific area, thickness, dry matter content, N content, P content and natural abundance 15N) of four co-occurring tree species (two that are not associated with N2-fixing bacteria and two that are associated with N2-fixing bacteria) and net N mineralization rates and inorganic N concentrations along a precipitation gradient (537–1036 mm per year) in the Yucatan Peninsula, Mexico. Specifically we sought to test the hypothesis that leaf traits of dominant plant species shift along a precipitation gradient, but are affected by soil N cycling. Although variation among different species within each site explains some leaf trait variation, there is also a high level of variability across sites, suggesting that factors other than precipitation regime more strongly influence leaf traits. Principal component analyses indicated that across sites and tree species, covariation in leaf traits is an indicator of soil N availability. Patterns of natural abundance 15N in foliage and foliage minus soil suggest that variation in precipitation regime drives a shift in plant N acquisition and the openness of the N cycle. Overall, our study shows that both plant species and site are important determinants of leaf traits, and that the leaf trait spectrum is correlated with soil N cycling. © 2015, Springer-Verlag Berlin Heidelberg. Source

Hernandez Galvez G.,Centro del Cambio Global y la Sustentabilidad en el Sureste | Dorrego Portela J.R.,Istmo University of Mexico | Nunez Rodriguez A.,Istmo University of Mexico | Lastres Danguillecourt O.,Istmo University of Mexico | And 4 more authors.
International Journal of Energy Research | Year: 2014

This study presents a selection of optimal energy alternatives for electrical self-sufficiency in a rural university (Universidad del Istmo, UNISTMO), located in the state of Oaxaca, Mexico and for the electricity supply for a rural community (Gran Piedra) in Santiago, Cuba. The analysis follows a multicriteria approach. It uses a method called compromise programming and takes into account the technical, economical, environmental and social criteria. The hybrid optimization model for electric renewables (HOMER) software was used to generate alternative energy sets through enumerative search, with which decisional matrices were built for each case study. The influence of weighting for each criterion was assessed. In the case of self-sufficiency in UNISTMO, when the decision-making center has a preference for the minimization of equivalent emissions in the life cycle (ESLC), a wind system is suitable. On the other hand, when there is a preference for the minimization of levelized cost of energy, a photovoltaic (PV) system is suitable; both systems connected to the national electrical grid. Obviously, a preference for the minimization of capital cost led to keeping the power supply from the grid. In the case of Gran Piedra, a diesel generator-based system is suitable when the criterion 'capital cost' absorbs 70% or more of the preferences of the decision-making centers. When the preference is less than 70% regardless of the weighting given to other criteria, the best alternatives are those involving renewable technologies, reaching renewable fractions of 75% and 94% in two potential configurations of energetic systems. © 2013 John Wiley & Sons, Ltd. Source

Bejarano-Castillo M.,Pronatura sur | Campo J.,National Autonomous University of Mexico | Roa-Fuentes L.L.,Centro del Cambio Global y la Sustentabilidad en el Sureste
PLoS ONE | Year: 2015

Atmospheric N deposition is predicted to increase four times over its current status in tropical forests by 2030. Our ability to understand the effects of N enrichment on C and N cycles is being challenged by the large heterogeneity of the tropical forest biome. The specific response will depend on the forest's nutrient status; however, few studies of N addition appear to incorporate the nutrient status in tropical forests, possibly due to difficulties in explaining how this status is maintained. We used a meta-analysis to explore the consequences of the N enrichment on C and N cycles in tropical montane and lowland forests. We tracked changes in aboveground and belowground plant C and N and in mineral soil in response to N addition. We found an increasing trend of plant biomass in montane forests, but not in lowland forests, as well as a greater increase in NO emission in montane forest compared with lowland forest. The N2O and NO emission increase in both forest; however, the N2O increase in lowland forest was significantly even at first time N addition. The NO emission increase showed be greater at first term compared with long term N addition. Moreover, the increase in total soil N, ammonium, microbial N, and dissolved N concentration under N enrichment indicates a rich N status of lowland forests. The available evidence of N addition experiments shows that the lowland forest is richer in N than montane forests. Finally, the greater increase in N leaching and N gas emission highlights the importance of study the N deposition effect on the global climate change. © 2015 Bejarano-Castilloet al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

Dechnik-Vazquez Y.A.,National Autonomous University of Mexico | Meave J.A.,National Autonomous University of Mexico | Perez-Garcia E.A.,National Autonomous University of Mexico | Gallardo-Cruz J.A.,National Autonomous University of Mexico | And 2 more authors.
Journal of Tropical Ecology | Year: 2016

The role of canopy gaps in tropical dry forest (TDF) dynamics remains unclear. Here, 75 canopy gaps, mostly formed by the fall of Bursera spp. and Pachycereus pecten-aboriginum individuals, are described, and their potential consequences for forest regeneration are analysed in a Mexican TDF. In 50 randomly selected gaps, understorey vegetation was sampled with a paired design (inside and outside gaps) and by distinguishing two plant height categories. In total, 1940 plants were recorded (63% in gaps and 37% in non-gap plots). Community attributes (density, community cover, taxonomic richness and Shannon diversity) were significantly higher for both height categories in gap plots. Conversely, neither an NMDS ordination nor a multinomial classification of 187 species by habitat affinities revealed floristic segregation between gaps and non-gaps; almost all species were classified as habitat generalists, with only a few opportunistic forbs (but no single tree species) being classified as gap specialists. The most important effects of gap formation are significant increases in plant abundance and species richness, but not a different species composition. Against earlier views that gap-phase dynamics is inconsequential for TDF dynamics, these results suggest a more active, albeit modest, role of treefall gaps in TDF, through promoting an abundant establishment. © Cambridge University Press 2016. Source

Charruau P.,Centro del Cambio Global y la Sustentabilidad en el Sureste | Nino-Torres C.A.,University of Quintana Roo
Diseases of Aquatic Organisms | Year: 2014

Congenital defects in crocodilians have received little interest. In the context of global change and increasing threats to biodiversity, data on birth defects occurring in wildlife could be of importance for estimating the health of species populations and their ecosystems. Herein, we report the first case of amelia (i.e. absence of limbs) in Morelet's crocodiles Crocodylus moreletii from Mexico and the third on the southern Yucatan Peninsula. The crocodile in question was a juvenile (41 cm total length) captured in July 2012 in the Río Hondo, the river that forms the border between Mexico and Belize south of the state of Quintana Roo. The prevalence of this malformation in the C. moreletii population of Río Hondo (0.35%) is similar to that reported in 2 previous cases in Belize. Several causes of birth defects in crocodilians have previously been cited in the literature. Although we do not have relevant information to elucidate this case, we discuss some plausible explanations for this birth defect. © Inter-Research 2014. Source

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