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ABSTRACT Changes in species composition and abundance driven by land use change may alter canopy and litter characteristics of forests, and thereby modify rainfall redistribution and hydrological processes. To elucidate the interacting effects between tree species traits, forest structure and annual rainfall patterns on hydrological processes, three types of forest assemblages were selected in a semiarid forest of pine-oak in central northwest Mexico. Forest assemblages included monospecific and mixed patches of Quercus potosina and Pinus cembroides. Total precipitation, throughfall, stemflow and runoff were measured from June 2006 to July 2009. Additionally, tree and litter characteristics were measured. Forest traits played an important role differentiating volumes of each fraction among the three forest patches. Throughfall was 15% greater in Q. potosina than in the other forest patches ( P < 0.01) and only occurred with rainfall events larger than 1.4 mm for all patch types, whereas Q. potosina stemflow was >20% larger compared with the other two forest patch types ( P < 0.01) and occurred following rain events of at least 4.6 mm. Runoff exhibited divergences among forest patches ( P > 0.05) that were related to both the litter decomposition stage and the capacity of litter bed to store water. Thus, Q. potosina litter layer exhibited the largest water holding capacity (62%) and P. cembroides (46%) the least. Hence, surface runoff for Q. potosina was seven times lower than that in P. cembroides patches. This study revealed tree trait effects on water fluxes that might have consequences on the dynamics and productivity of semiarid forests. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Morphological and physiological characteristics of biological soil crusts (BSCs) enhance soil stability and fertility, and influence soil chemistry. However, the effect of BSCs on soil physico-chemical properties may vary depending on taxa (cyanobacteria, lichen, bryophytes) and species, and be susceptible to soil surface disturbance. We examined a wide variety of soil physico-chemical properties associated with five BSC components (cyanobacteria crust, one moss species, three lichen species) naturally occurring in the study area, and bare soil along a disturbance gradient in a semiarid grassland ecosystem in Central Mexico. We addressed the following questions: 1) Do different BSC components create distinct soil microsites characterized by a particular combination of physico-chemical properties? 2) Do distinct soil properties change beneath different BSC components? 3) Does grazing disturbance modify or override species-specific BSC effects? We found that BSC components and bare soil generated distinct soil microsites, however, this effect diminished with increasing grazing pressure. Also, most of the soil variables examined differed between BSC components and bare soil along the gradient. While soil properties associated with cyanobacteria were relatively similar compared to bare soil along the gradient, Diploschistes diacapsis and Lecidella sp. showed decreases in pH and marked differences in mineral nutrient concentration (i.e. variations in Na, Fe and Zn concentration respect to other BSC components and bare soil). Grazing intensity and frequency changed species-specific effects of D. diacapsis, specially modifying its effect on soil texture, diminishing its effect on pH, K and Na concentration, and increasing its effect on Ca and Zn concentration. We conclude that BSC components contribute to natural small-scale soil heterogeneity, and that soil disturbance substantially modifies the nature and magnitude of this effect with potentially important implications on ecosystem processes. Because of the potential influence of other factors (i.e. climate, vascular plants, microbial activity) on BSCs' relation to soil properties, this assertion should be tested including these factors and in multiple ecosystems. [Copyright &y& Elsevier]

Changes in land use across the semiarid grasslands of Northern Mexico have driven a decline of plant cover and alteration of plant species composition. A number of different plant communities have resulted from these changes, however, their implications on the carbon cycle and regional carbon balance are still poorly understood. Here, we examined the effects of plant cover loss and changes in species composition on net ecosystem CO2 exchange (NEE) and their biotic and abiotic controls. Five typical plant community types were examined in the semiarid grassland by encasing the entire above-ground ecosystem using the geodesic dome method. Sites included an oat crop (crop), a moderately grazed grassland (moderate grazing), a 28 yr-old grazing exclosure (exclosure), an overgrazed site with low perennial grass cover (overgrazed), and an overgrazed site presenting shrub encroachment (shrub encroachment). For natural vegetation, rates of daytime NEE for sites with a high plant cover (exclosure and moderate grazing) were similar (P > 0.05) as compared to sites with low plant cover (overgrazed and shrub encroachment). However, night time NEE (carbon loss) was more than double (P < 0.05) for sites with high plant cover compared to sites with low cover, resulting into slight C sinks for the low plant cover sites and neutral or sources for the high plant cover sites on an annual basis. Differences in plant cover and its associated biomass defined the sensitivity to environmental controls. Thus, daytime NEE in low plant cover sites reached light compensation points at lower PPFD values than those from high plant cover sites. Differences in species composition did not influence NEE rates even though there were transient or permanent changes in C3 vs. C4 functional groups. [ABSTRACT FROM AUTHOR]

Abstract: Litterfall is an important ecological process in forest ecosystems, influencing the transfer of organic matter, carbon (C), nitrogen (N), phosphorous (P) and other nutrients from vegetation to the soil. We examined the production of different litterfall fractions as well as nutrient content and nutrient inputs by senesced and green leaf-litter in a semiarid forest from central Mexico. From September 2006 to August 2007, monthly litter sampling was carried out in monospecific and mixed stands of Quercus potosina and Pinus cembroides. Litterfall displayed a marked bimodal pattern with the largest annual amount (5993±655kgha−1 yr−1) recorded in mixed stands, followed by Q. potosina (4869±510kgha−1 yr−1), and P. cembroides (3023±337kgha−1 yr−1). Leaves constituted the largest fraction of total litterfall reaching almost 60%, while small branches contributed with 20–30%. Overall, N content in leaf-litter was higher while lignin content was significantly lower for Q. potosina than for P. cembroides. Thus, greater litter quality together with higher litter production caused the largest C, N and P inputs to forest soils to occur in monospecific Q. potosina stands. Green leaf fall displayed significantly lower lignin:N and C:N ratios in Q. potosina than P. cembroides suggesting faster decomposition and nutrient return rates by the former. Although we recorded only two green leaf fall events, they accounted for 18% and 11% of the total N and P input, respectively, from leaf-litter during the study period. Apart, from the large spatiotemporal heterogeneity introduced by differences in litter quantity and quality of evergreen, deciduous and mixed stands, green litterfall appears to represent a much more important mechanism of nutrient input to semiarid forest ecosystems than previously considered. [Copyright &y& Elsevier]

• Rainfed corn and beans are the main crop system in the semiarid región of Mexico. • High precipitation variability turns corn and beans cultivation into a highly risky cropping system. • Climate trends suggest delaying of first frost and increased hailing in early summer. • Under warming and decreased precipitation we tested late sowing as an adaptation strategy. • Warming contributed to higher yield and impeded frost damage of unripen grain. In the Mexican Altiplano, beans and corn are the main crops. Conditions favoring hail -- high daily minimum temperature and high rainfall intensity -- are expected to increase under climate change scenarios. If soil humidity remains suitable for plant growth until October, an adaptive strategy to reduce hail and frost damage consist in delaying sowing date. This strategy could permit crop maturation while frost events are delayed later in the year with climate warming. To test whether such a future climate scenario would have a negative effect on crop yield, we tested two sowing dates for rainfed beans, representing regular and delayed sowing along with a decreased precipitation regime (-30 %) and increased +2 °C canopy temperature with respect to ambient conditions. The first sowing in 2015 was completely destroyed at the end of July. Results for 2015, 2017 and 2018 revealed that overall warming favored greater grain yield than ambient temperature (P < 0.05) independent of precipitation. One exception were plots receiving ambient temperature and 70 % of rain in the second sowing date. The positive grain yield response appeared to be the result of warming effects speeding up plant development of phenological stages rather than favoring greater growth of plant organs, which showed an erratic response. However, in the second sowing of 2017 the observed reduced grain yield in ambient temperature plots is attributed to the effects of an early frost event occurring during the grain ripening stage. Thus, a sowing date occurring in early August helped to avoid hailstorms but in addition warming accelerated phenology and apparently provided better temperatures for bean maturation and greater bean grain yield [ABSTRACT FROM AUTHOR]

Long-term, inter-annual and seasonal variation in temperature and precipitation influence the distribution and prevalence of intraerythrocytic haemosporidian parasites. We characterized the climatic niche behind the prevalence of the three main haemosporidian genera ( Haemoproteus , Plasmodium and Leucocytozoon ) in central-eastern Mexico, to understand their main climate drivers. Then, we projected the influence of climate change over prevalence distribution in the region. Using the MaxEnt modelling algorithm, we assessed the relative contribution of bioclimatic predictor variables to identify those most influential to haemosporidian prevalence in different avian communities within the region. Two contrasting climate change scenarios for 2070 were used to create distribution models to explain spatial turnover in prevalence caused by climate change. We assigned our study sites into polygonal operational climatic units (OCUs) and used the general haemosporidian prevalence for each OCU to indirectly measure environmental suitability for these parasites. A high statistical association between global prevalence and the bioclimatic variables ‘mean diurnal temperature range’ and ‘annual temperature range’ was found. Climate change projections for 2070 showed a significant modification of the current distribution of suitable climate areas for haemosporidians in the study region.

Mexico is one of the most biodiverse countries in the world, with an important proportion of endemism mainly because of the convergence of the Nearctic and Neotropical biogeographic regions, which generate great diversity and species turnover at different spatial scales. However, most of our knowledge of the Mexican ant biota is limited to a few well-studied taxa, and we lack a comprehensive synthesis of ant biodiversity information. For instance, most of the knowledge available in the literature on Mexican ant fauna refers only to species lists by states, or is focused on only a few regions of the country, which prevents the study of several basic and applied aspects of ants, from diversity and distribution to conservation. Our aims in this data paper are therefore (1) to compile all the information available regarding ants across the Mexican territory, and (2) to identify major patterns in the gathered data set and geographic gaps in order to direct future sampling efforts. All records were obtained from raw data, including both unpublished and published information. After exhaustive filtering and updating information and synonyms, we compiled a total of 21,731 records for 887 ant species distributed throughout Mexico from 1894 to 2018. These records were concentrated mainly in the states of Chiapas (n = 6,902, 32.76%) and Veracruz de Ignacio de la Llave (n = 4,329, 19.92%), which together comprise half the records. The subfamily with the highest number of records was Myrmicinae (n = 10,458 records, 48.12%), followed by Formicinae (n = 3,284, 15.11%) and Ponerinae (n = 1,914, 8.8%). Most ant records were collected in the Neotropical region of the country (n = 12,646, 58.19%), followed by the Mexican transition zone (n = 5,237, 24.09%) and the Nearctic region (n = 3,848, 17.72%). Native species comprised 95.46% of the records (n = 20,745). To the best of our knowledge, this is the most complete data set available to date in the literature for the country. We hope that this compilation will encourage researchers to explore different aspects of the population and community research of ants at different spatial scales, and to aid in the establishment of conservation policies and actions. There are no copyright restrictions. Please cite this data paper when using its data for publications or teaching events., (© 2019 by the Ecological Society of America.)