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Hurricanes are extreme climatic events frequently affecting tropical regions such as the tropical dry forests (TDFs) in Mexico, where its frequency/intensity is expected to increase toward the year 2100. To answer how resistant is a Mexican tropical dry forest to a high-intensity hurricane, and if its degree of resistance was mediated by its conservation degree, we evaluated the effect of a category 4 hurricane over the tree community, soil nutrients, and soil enzymatic activity in two contrasting TDF ecosystems: Old-Growth Forest (OGF) and Secondary Forest (SF). In general, vegetation richness and diversity showed very high resistance one year after the hurricane, but several structural attributes did not, especially in the OGF where the tree mortality related to vegetation structure and spatial distribution of individuals was higher. Then, in the short term, SF vegetation appeared to be more resistant, whereas the OGF, with more biomass to lose, appeared to be more vulnerable. Conversely, most soil attributes showed low resistance in both stages, but especially in SF which could face more severe nutrient limitations. The response of TDF to high-intensity hurricanes, in terms of above- and belowground processes, was in part dependent on its disturbance level. Moreover, an increase in the intensity/frequency of hurricanes could lead this TDF toward a high nutrient limitation (especially by phosphorus) for the plants and consequently toward a loss of soil functioning, especially in the SF. This eventually could produce a severe degradation in fundamental attributes and functions of the ecosystem. [ABSTRACT FROM AUTHOR]

The fruits of some Anacardiaceae tree species are important sources of food and water for vertebrate species in seasonal tropical forest. During a monitoring study using camera-traps in a tropical dry forest of the Tehuacán-Cuicatlán Biosphere Reserve, Mexico, we documented tree visitation and fruit consumption in the 'Chupandillo' Cyrtocarpa procera by medium to large-sized terrestrial mammals species. From 2012 to 2017, we established cameras-traps in front of six adult chupandillo trees during 385–499 days. A total of 4,831 photographs were obtained during a total of 2,706 days. The camera-traps recorded 12 mammals species visiting, passing in front the tree, or consuming its fruits. The white-tailed deer, cotton rabbit, collared peccary and gray fox were the species that presented the highest number of visit events, with the two ungulate species recorded visiting all of the sampled trees. These species, as well as coati, consumed fruits of this tree species from September to October. The white-tailed deer visited during the day, while the collared peccary mainly visited during the twilight-night time period. We propose that fruits of C. procera are an important resource for mammals in this region, in particular for white-tailed deer and collared peccary. [ABSTRACT FROM AUTHOR]

Genetic diversity is a key component of evolution, and unraveling factors that promote genetic differentiation in space and time is a central question in evolutionary biology. One of the most diverse and ecologically important tree genera in tropical forests worldwide is Ficus (Moraceae). It has been suggested that, given the great dispersal capacity of pollinating fig wasps (Chalcidoidea; Agaonidae), the spatial genetic structure, particularly in monoecious fig species, should be weak. However, no studies have addressed the factors that determine the genetic structure of Ficus species in regions of high geological, geographic, and climatic complexity, such as the Mexican Transition Zone. Using nuclear single nucleotide polymorphisms (5311 SNPs) derived from low‐coverage whole genomes and 17 populations, we analyzed the population genomics of Ficus pringlei to characterize neutral and adaptive genetic variation and structure and its association with geographic barriers such as the Trans‐Mexican Volcanic Belt, environmental heterogeneity, and wind connectivity. From genomic data of 71 individuals, high genetic diversity, and the identification of three genomic lineages were recorded (North, South, and Churumuco). The results suggest that genetic variation is primarily determined by climatic heterogeneity. Ficus pringlei populations from the north and south of the Trans‐Mexican Volcanic Belt also exhibited minimal genetic differentiation (FST = 0.021), indicating that this mountain range may not act as an insurmountable barrier to gene flow. Wind connectivity is also highlighted in structuring putative adaptive genetic variation, underscoring the intricate complexity of the various factors influencing genetic variation in the species. This study provides information on the possible mechanisms underlying the genetic variation of endemic species of the tropical dry forest of Western Mexico, such as F. pringlei. [ABSTRACT FROM AUTHOR]

Understanding why animals avoid some locations is needed to improve the theory of habitat selection. This is key in semi‐sedentary organisms, such as antlion larvae, because once established they rarely move, and their performance largely depends on local environmental conditions.Antlion larvae are sit‐and‐wait predators that build conical pitfall traps in sandy soils to capture passing prey. They clean constantly their traps, expelling soil, prey carcasses and debris out of the pit to maintain their trapping success. Therefore, we propose that they avoid soils with leaf litter because leaves hinder the maintenance of their pits; a hypothesis that has not yet been tested.We first demonstrated that antlion larvae (Myrmeleon inmaculatus) are rare from soils with leaf litter in a tropical semi‐deciduous forest in Mexico. We then experimentally tested the effect of leaf litter on pit maintenance by adding debris in 90 antlion traps, 45 of which were covered with a leaf, and 45 remained uncovered. Two hours after adding the debris, we recorded its location and quantified the variation in depth and diameter of the pits.Larvae in uncovered traps were twice as effective at cleaning up the debris than larvae in covered traps. Furthermore, in just 2 h, covered traps were on average 21% shallower than control traps, probably because unsuccessful attempts to clean debris caused sand slides to fill the pit partially.Leaf litter seems to hinder the proper maintenance of antlion traps, explaining at least partially, why these animals are rare under leaf litter. [ABSTRACT FROM AUTHOR]

Background: The patterns of richness, diversity, and abundance of an odonate assemblage from San Buenaventura, Jalisco are presented here. A total of 1087 specimens from seven families, 35 genera and 66 species were obtained through monthly samplings of five days each during a period of one year. Libellulidae was the most diverse family (28 species), followed by Coenagrionidae (21), Gomphidae (7), Aeshnidae (6), Calopterygidae (2), Lestidae (1) and Platystictidae (1). Argia was the most speciose genus. The highest species richness and Shannon diversity were found during August and September, whereas the highest abundance was observed in June and the highest Simpson diversity was recorded in September -- all of which were associated with the rainy season. The highest values of phylogenetic diversity were found from June to October. The different diversity facets of this assemblage were positively correlated with precipitation and minimum temperature, whereas maximum temperature showed no influence. In addition, we found that this odonate diversity was higher than most Mexican localities with tropical dry forest (TDF) studied. New information: We continue our efforts to describe the patterns of richness, diversity and abundance of some insect groups associated with the tropical dry forest ecosystem in Mexico, following a latitudinal gradient of the distribution of this ecosystem in the country. Our emphasis here was to evaluate the spatial and temporal patterns of richness and diversity of an Odonata assemblage from Jalisco, Mexico. [ABSTRACT FROM AUTHOR]

Based on 40 years of meteorological data, we characterized and analysed long‐term climatic trends in the Chamela‐Cuixmala Biosphere Reserve on the Pacific coast of central Mexico. The region is still covered by a large proportion of well‐preserved tropical dry forest, characterized by a short period of rain and a dry season of around 8 months. We found a sustained temperature increase which is likely driven by global climate change. An increasing trend in rainfall was also found, but the trend was detected only during the wet season. Correspondingly, an increase in runoff during the rainfall season was also detected; this seems to be linked with an increasing number of intense rainfall events, rather than an increase in the total number of rainy days. El Niño years are likely to present below average precipitation during the wet season and above average precipitation during the dry season. The opposite is expected during La Niña years, when tropical cyclones are likely to come closer to the coast and cause intense rainfall events during the hurricane season. As many of the studied variables are likely to change under climate change scenarios, our results highlight the need to understand the expected impacts of global climate change on tropical dry forests. In particular, it is necessary to monitor changes in water availability to anticipate its consequences for the forest and the human communities that depend on it. [ABSTRACT FROM AUTHOR]

Little is known of intra- and inter-specific territoriality in Neotropical raptors that may defend territories throughout the year, and face greater inter-specific competition for resources. We evaluated intraand inter-specific territorial responses of four species of Neotropical raptors in the tropical dry forest of the Chamela-Cuixmala Biosphere Reserve, Mexico. We conducted broadcast calls in territories of the Collared Forest-Falcon (Micrastur semitorquatus), Crane Hawk (Geranospiza caerulescens), Gray Hawk (Buteo plagiatus), and Roadside Hawk (Rupornis magnirostris), and measured the latency, duration, and type of territorial response to broadcast calls of conspecifics and sympatric raptor species. We applied repeated measures analysis to determine differences in intra- and inter-specific territorial responses of raptors, and GLMMs to evaluate whether traits of body size, nest type, and hunting technique were associated with territorial response by focal raptors. Large-bodied focal raptor species showed high intra-specific territoriality, giving faster, prolonged responses of various types, including duets and combined responses, to broadcast calls of conspecifics compared to sympatric species. All focal raptors showed some inter-specific territorial response, but this was mainly as vocalizations or displacements towards sympatric species broadcast calls. Species traits of body size, nest type, and hunting technique were associated with latency and duration of territorial response by the larger raptor species that nest in the forest canopy. These traits may be more strongly associated with territorial response of forest raptors that defend limited resources in a structurally complex environment. [ABSTRACT FROM AUTHOR]

Coleopterans are the most diverse animal group on Earth and constitute good indicators of environmental change. However, little information is available about Coleopteran communities' responses to disturbance and land-use change. Tropical dry forests have undergone especially extensive anthropogenic impacts in the past decades. This has led to mosaic landscapes consisting of areas of primary forest surrounded by pastures, agricultural fields and secondary forests, which negatively impacts many taxonomic groups. However, such impacts have not been assessed for most arthropod groups. In this work, we compared the abundance, richness and diversity of Coleopteran morphospecies in four different successional stages in a tropical dry forest in western Mexico, to answer the question: How do Coleopteran assemblages associate with vegetation change over the course of forest succession? In addition, we assessed the family composition and trophic guilds for the four successional stages. We found 971 Coleopterans belonging to 107 morphospecies distributed in 28 families. Coleopteran abundance and richness were greatest for pastures than for latter successional stages, and the most abundant family was Chrysomelidae, with 29% of the individuals. Herbivores were the most abundant guild, accounting for 57% of the individuals, followed by predators (22%) and saprophages (21%) beetles. Given the high diversity and richness found throughout the successional chronosequence of the studied tropical dry forest, in order to have the maximum number of species associated with tropical dry forests, large tracts of forest should be preserved so that successional dynamics are able to occur naturally. [ABSTRACT FROM AUTHOR]

The biodiversity within tropical dry forests (TDFs) is astounding and yet poorly catalogued due to inadequate sampling and the presence of cryptic species. In the Mexican TDF, endemic species are common, and the landscape has been continually altered by geological and anthropogenic changes. To understand how landscape and environmental variables have shaped the population structure of endemic species, we studied the recently described species of leaf-toed gecko, Phyllodactylus benedettii , in coastal western Mexico. Using double-digest restriction site-associated DNA sequencing data, we first explore population structure and estimate the number of ancestral populations. The results indicate a high degree of genetic structure with little admixture, and patterns corresponding to both latitudinal and altitudinal gradients. We find that genetic structure cannot be explained purely by geographical distance, and that ecological corridors may facilitate dispersal and gene flow. We then model the spatial distribution of P. benedettii in the TDF through time and find that the coastline has been climatically suitable for the species since the Last Glacial Maximum. Landscape genetic analyses suggest that the combination of isolation by distance (IBD) and isolation by resistance (IBR; forest cover) has influenced the spatial genetic structure of the species. Overall, our genomic data demonstrate fine-scale population structure in TDF habitat, a complex colonization history, and spatial patterns consistent with both IBD and other ecological factors. These results further highlight the Mexican TDF as a diversity hotspot and suggest that continued anthropogenic changes are likely to affect native fauna. [ABSTRACT FROM AUTHOR]

The surface runoff was estimated using the curve number (CN) method for different storm events, and it was associated with the morphometric parameters of an ungauged watershed in Jalisco, Mexico. We derived the land use and land cover map for the year 2019 from the unsupervised classification of a Sentinel-2 image at 10 m resolution. The morphometric analysis revealed that the study area is dominated by areas of gentle slope and moderate to high permeability with dense vegetation and low relief. It is a well-drained watershed with low flood potentiality besides a groundwater potential zone. About 69% of the study area corresponds to natural cover with tropical dry forest and evergreen forest as the most representative classes. The number of storm events identified from 2013 to 2019 was 77, with runoffs ranging from 0.05 to 227.2 Mm³. September and October were the months with the most intense rainfall and, therefore, the months with the highest runoff volume. The average runoff was 14.52 Mm³, corresponding to an average runoff coefficient of 12.86%. Together, the methods used here provide useful results for delineating conservation strategies at the watershed level. [ABSTRACT FROM AUTHOR]

Bursera comprises ~100 tropical shrub and tree species, with the center of the species diversification in Mexico. The genomic resources developed for the genus are scarce, and this has limited the study of the gene flow, local adaptation, and hybridization dynamics. In this study, based on ~155 million Illumina paired-end reads per species, we performed a de novo genome assembly and annotation of three Bursera species of the Bullockia section: Bursera bipinnata, Bursera cuneata, and Bursera palmeri. The total lengths of the genome assemblies were 253, 237, and 229 Mb for B. cuneata, B. palmeri, and B. bipinnata, respectively. The assembly of B. palmeri retrieved the most complete and single-copy BUSCOs (87.3%) relative to B. cuneata (86.5%) and B. bipinnata (76.6%). The ab initio gene prediction recognized between 21,000 and 32,000 protein-coding genes. Other genomic features, such as simple sequence repeats (SSRs), were also detected. Using the de novo genome assemblies as a reference, we identified single-nucleotide polymorphisms (SNPs) for a set of 43 Bursera individuals. Moreover, we mapped the filtered reads of each Bursera species against the chloroplast genomes of five Burseraceae species, obtaining consensus sequences ranging from 156 to 160 kb in length. Our work contributes to the generation of genomic resources for an important but understudied genus of tropical-dry-forest species. [ABSTRACT FROM AUTHOR]

Mexico is one of the richest countries in amphibian species (420 spp.), with a high level of endemism (69%). The order Anura represents the most diverse and widespread of the three extant amphibian orders (257 spp.). The anurofauna of Mexico's tropical dry forest ecosystem host a high proportion of the species and endemism registered in the country. In terms of conservation, both dry forests and amphibians are at risk due to climate change because it is expected that as the temperature becomes higher and precipitation decreases, this vegetation type may experience water stress. We applied the MaxEnt algorithm to estimate the potential current and future (year 2070) geographic distribution patterns of 95 endemic Mexican anuran species inhabiting the country's tropical dry forests by considering two representative concentration pathway scenarios (RCP4.5/RCP8.5) and analyzed the potential distributional pattern changes. The results indicated that overall, species would experience enough of a significant warming effect to cause a reduction in the original distribution area, with 44% of species losing an average of 50% of their original range (9 spp. in threatened category); additionally, 22% of the species in the dry forest ecosystem will experience an average increase of almost 50% in their original area, two species will lose more than 80% of their range, and one will disappear. [ABSTRACT FROM AUTHOR]

Distremocephalus gonzalezi. sp. nov., from Ixtlahuacán, Colima is described and illustrated; it is compared with D. wittmeri Zaragoza-Caballero, 1986for being a close species. New statal record is presented for D. leonilae Zaragoza-Caballero, 1986. Aspects about the distribution of the genus Distremocephalus in Mexico are commented. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the structure of the community and seasonality of the Cerambycidae family in the tropical deciduous forest (TDF) of San Andrés de la Cal, Tepoztlán in Morelos, Mexico. Following a year of systematic collections, and with the addition of data obtained from breeding chambers and sporadic collections, 155 species, 91 genera, 35 tribes, and 4 subfamilies were recorded. Thirty-three of these species, >21% are new records for the state of Morelos. Sample coverage was 97% and, according to the Chao 1 richness estimator, we found 80% of the species present in the study area. Greater species richness, abundance, and diversity were found during the rainy season, which generates a significant difference between seasons. The ordering of faunal similarities between months indicated a marked seasonality in the composition. The data suggest that the diversity of TDF insects is not completely known (i.e., new records were found), but comprises a diverse community, composed of a high proportion (78%) of rare species. Our findings reinforce the need to continue documenting insect diversity in TDF, especially considering that this is among the least protected of the ecosystems, and one that is negatively affected to a greater degree by anthropogenic activities and climate change. Resumen: El propósito de este estudio fue conocer la estructura de la comunidad de la familia Cerambycidae del bosque tropical caducifolio (BTC) de San Andrés de la Cal,Tepoztlán, Morelos, México. Después de un año de recolectas sistemáticas, además de datos adicionales de cámaras de cría y recolectas esporádicas, se registraron 155 especies, 91 géneros, 35 tribus y 4 subfamilias. Treinta y tres especies (>21%) son nuevos registros para el estado de Morelos. La cobertura de muestra fue del 97% y según el estimador de riqueza Chao 1, el 80% de las especies del área de estudio están representadas. La mayor riqueza, abundancia y diversidad de especies ocurrió durante la temporada de lluvias y el ordenamiento entre meses indicó una marcada estacionalidad. La estructura de la comunidad refleja una gran diversidad, compuesta por una alta proporción (78%) de especies raras. Los datos muestran que la diversidad de insectos en el BTC es alta y que los datos de distribución están incompletos (e. g. nuevos registros) lo que refuerza la necesidad de seguir documentándolo, especialmente considerando que este ecosistema se encuentra entre los menos protegidos y con mayor riesgo de desaparecer por la presión de las actividades antropogénicas y el cambio climático. [ABSTRACT FROM AUTHOR]

Copyright of Biotropica is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Therya is the property of Asociacion Mexicana de Mastozoologia, A. C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Seasonal dry tropical forest (STDF) is a widespread vegetation type in western Mexico. Generally, this type of forest develops in semihumid habitats where lacustrine basins are scarce, preventing documentation of the vegetation history and forest dynamics using a paleoecological approach. Here, we present a palynological record from the Santa Maria del Oro crater lake, located within the distribution area of the STDF and the adjacent dry oak forest which gives insight into the changes in diversity and human impact at this tropical site. Pollen data, in combination with geochemical analysis and microcharcoal data from a lacustrine sequence, are used to discuss vegetation change and diversity in the plant assemblages related to drought or anthropogenic activity over the last 5000 years. Our results show three distinct periods of drought in the basin, from 4200 to 3850, 3100 to 2300, 1570 to 1100 and 300 cal year BP, with changes in vegetation composition mainly related to a decrease in taxa diversity during these periods. Based on the presence of maize pollen, two periods of human activity (3790–2160 and 280 cal year BP to present) were detected with an increase in herbaceous pollen used as a surrogate for deforestation. These two disturbance periods, pre-Columbian and postcolonial, occurred during wet conditions in the basin. Our results highlight the correlation between El Niño events, drought and fire with changes in the composition and diversity of STDF. [ABSTRACT FROM AUTHOR]

Geographic variation in acoustic signals may arise in vocal learning species due to processes of cultural evolution and population dynamics, but few studies have evaluated geographic vocal variation for large-bodied non-oscine species such as parrots. We evaluated similarity in a contact call of the Military Macaw (Ara militaris) among three populations along the coast of Jalisco, Mexico. We compared contact calls among sites using two approaches i) analysis of specific acoustic parameter measures using GLMM on Principal Components; and ii) evaluation of spectrogram similarity using cross-correlation with a Mantel test to evaluate site and distance effects. Acoustic parameter analysis found that incorporating the site where recordings were obtained significantly explained variation in call features, for both the complete and reduced, balanced dataset. The spectrogram cross-correlations similarity analysis indicated an association with site in spectral similarity of calls, and that call similarity decreased with distance. Our results demonstrated the accumulation of small, fine-scale changes in Military Macaw calls with distance, suggesting that large-bodied non-oscines such as macaws may be able to maintain connectivity among sites by dispersal, facilitating call diffusion, while limited movements among some populations may account for the differentiation among sites in call features. [ABSTRACT FROM AUTHOR]

The Big Crested Mastiff Bat, Promops centralis (Thomas, 1915), is widely distributed from Mexico to South America but has yet to be reported in the state of Sinaloa, Mexico. We collected 122 acoustic recordings of P. centralis from tropical dry forest and agroecosystems in Sinaloa and Sonora for two years (2015 and 2016). We documented a new record for P. centralis outside the known distribution area in northwestern Mexico. Our results reveal that the current P. centralis distribution needs to be reevaluated. [ABSTRACT FROM AUTHOR]

The green plumage of parrots confers a degree of camouflage amidst the canopy foliage the birds frequent. In parrots, green feather colors result from the juxtaposition of endogenously produced yellow pigments, termed psittacofulvins, and spongy structures in the feather barbs that produce a blue color. In rare individuals, the yellow pigments are missing, resulting in a blue phenotype, a variant plumage coloration. The Mexican Parrotlet (Forpus cyanopygius) is endemic to Mexico and the male sports a largely green body with turquoise-blue color on the underwing coverts, lower back, and rump. While inventorying the avifauna of the tropical dry forest at Sierra de Quila, Jalisco, in west-central Mexico, we captured a blue individual with no hint of green. Typically, in parrots, a blue phenotype results from a recessive mutation that prevents the production of yellow pigments thus revealing the underlying blue structural color. As far as we know, this is the first documented record of a blue (or cyanistic) Mexican Parrotlet. Declining numbers of parrotlets in Mexico could potentially increase the probability of birds becoming homozygous for the recessive mutation. [ABSTRACT FROM AUTHOR]

Functional diversity is a tool for understanding biological communities and the influence of environmental filters on assembly rules. However, few studies explore the relationships of diversity metrics across contrasting ecosystems. We evaluated the effect of ecosystems (tropical dry forest and pine-oak forest) and seasons (wet and dry) on the functional diversity and community composition of amphibians in western Mexico. Our study showed that associations among metrics of diversity were not constant across contrasting ecosystems. The amphibian communities were related to changes in the environmental variables of elevation, temperature and relative humidity. We analyzed the functional diversity of the amphibian community based on 11 traits related to reproduction, trophic flow and habitat use. Seven functional groups with distinct ecological characteristics were detected, of which, four presented functional redundancy and two were represented by a single species. While the tropical dry forest during the wet season showed the highest species richness, the richness and diversity of functional groups were significantly lower than in the pine-oak forest in both seasons. These results suggest that the seasonal drought in the tropical dry forest could act as an environmental filter, promoting dominance of similar functional traits among species, while limiting similarity could be acting in the pine-oak forest, in the face of relatively stable hydric conditions, allowing a greater functional diversity. Analysis of the relationship between biological communities and ecosystem functioning is necessary to undertake conservation strategies. [ABSTRACT FROM AUTHOR]

Copyright of Biotropica is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

One new genus and two new species of Graphidaceae are described from tropical dry forests of Mexico, based on morphological and molecular data of the mtSSU, nuLSU and ITS markers. The new genus Jocatoa in subfamily Graphidoideae is described to accommodate the species Graphis agminalis (syn.: Medusulina texana), previously known from Colombia and North America. The new genus resembles Diorygma but differs by having simple paraphyses tips that do not form an epithecium. Jocatoa agminalis is similar to Diorygma monophorum but differs by having larger ascospores, hypostictic and stictic acids and by the type of paraphysis tips. In subfamily Redonographoideae, the two new species Gymnographopsis corticicola and Redonographa parvispora are described, representing the first corticolous species in the subfamily. Gymnographopsis corticicola is characterized by the smallest spores in the genus, the presence of norstictic acid, and a rectangular perispore that appears to be a newly recognized character state in fungi. Redonographa parvispora is characterized by warty periphysoids, small ascospores with 3 transverse septa, and norstictic acid. It also frequently develops a rectangular perispore. We present a phylogenetic analysis, based on the markers mtSSU, nuLSU and RPB2, that includes all the genera in the family Graphidaceae, with available sequences, to accommodate the new genus and to validate for the first time the position of Gymnographopsis. Diagnostic anatomical and ecological characters are discussed for Redonographoideae. Gymnographopsis is newly reported to the Northern Hemisphere. [ABSTRACT FROM AUTHOR]

We report two new records of rare fern species for the state of Morelos, Mexico: Hemionitis pinnatifida and Myriopteris longipila subsp. brevipila. For both species, we describe their main characteristics, cite studied material and present photographs and distribution maps, followed by comments on their habitat characteristics, historical record, rarity, and differential characteristics to closely related species or varieties. [ABSTRACT FROM AUTHOR]

Extreme climatic and weather events are increasing in frequency and intensity across the world causing episodes of widespread tree mortality in many forested ecosystems. However, we have a limited understanding about which local factors influence tree mortality patterns, restricting our ability to predict tree mortality, especially within topographically complex tropical landscapes with a matrix of mature and secondary forests. We investigated the effects of two major local factors, topography and forest successional type, on climate‐induced tropical tree mortality patterns using an observational and modeling approach. The northernmost Neotropical dry forest endured an unprecedented episode of frost‐induced tree mortality after the historic February 2011 cold wave hit northwestern Mexico. In a moderately hilly landscape covering mature and secondary tropical dry forests, we surveyed 454 sites for the presence or absence of frost‐induced tree mortality. In addition, across forty‐eight 1 ha plots equally split into the two forest types, we examined 6,981 woody plants to estimate a frost‐disturbance severity metric using the density of frost‐killed trees. Elevation is the main factor modulating frost effects regardless of forest type. Higher occurrence probabilities of frost‐induced tree mortality at lowland forests can be explained by the strong influence of elevation on temperature distribution since heavier cold air masses move downhill during advective frosts. Holding elevation constant, the probability of frost‐induced tree mortality in mature forests was twice that of secondary forests but severity showed the opposite pattern, suggesting a cautious use of occurrence probabilities of tree mortality to infer severity of climate‐driven disturbances. Extreme frost events, in addition to altering forest successional pathways and ecosystem services, likely maintain and could ultimately shift latitudinal and altitudinal range margins of Neotropical dry forests. [ABSTRACT FROM AUTHOR]

Copyright of Biotropica is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Termites play a key role as ecosystem engineers in numerous ecological processes though their role in the dynamics of wood degradation in tropical dry forests, particularly at the level of the crown canopy, has been little studied. In this study, we analysed the occurrence of termites in the forest canopy by evaluating the density and proportion of living and standing dead trees associated with termites in deciduous and riparian habitats of the tropical dry forest in Chamela, Mexico. The results indicated that 60–98% of standing dead trees and 23–59% of living trees in Chamela were associated with termites. In particular, we found that the density of standing dead trees was higher in deciduous forests (0.057–0.066 trees/m²) than in riparian forests (0.022 and 0.027 trees/m²), even though the proportion of trees was not significantly different among habitats. Additionally, we found a higher density of trees associated with termites in trees of smaller size classes (0.01–0.09 trees/m²) than in larger class sizes (0–0.02 trees/m²). Interestingly, 72% of variation in the density of trees associated with termites is explained by the density of standing dead trees. Overall, these results indicate that standing dead tree availability might be the main factor regulating termite populations in Chamela forest and suggest that termites could play a key role in the decomposition of above-ground dead wood, mediating the incorporation of suspended and standing dead wood into the soil. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • 31P NMR analysis was applied on SDTF plants, litter and mineral soils across a rainfall gradient. • Labile and stable P forms in vegetation and soils were characterized. • Quality and abundance of P forms would be sensitive to expected increase in drought intensity. Abstract We analyzed the influence of mean annual rainfall and duration of seasonal drought on soil P cycling along a rainfall regime gradient including mature tropical dry forests growing under similar temperature, rainfall seasonality and geological (limestone) conditions. We investigated the distribution of different P forms in fine roots, litterfall, forest floor and mineral soils, and we examined how the distribution was related to rainfall regime. The total concentration of extractable P differed across sites. Thus, the P concentration in roots and litterfall was higher in the wettest stands than in the driest stands. The P concentration fluctuated in the forest floor, and in mineral soils it increased as the rainfall decreased. Solution 31P NMR revealed that orthophosphates and monoester-P dominated the P content of roots, litterfall, forest floor and mineral soils. Although the concentration of orthophosphate in roots decreased as the rainfall decreased, this P form accumulated in the forest floor and mineral soils under conditions of drought. Low rainfall also affected the concentration of monoester-P in roots, litterfall and mineral soils, which decreased as rainfall decreased. Diester-P and pyrophosphate were detected in small amounts in all materials analyzed, and although the concentrations of these compounds in roots fluctuated across the rainfall gradient, they generally decreased in the litterfall and mineral soils with decrease in rainfall. We conclude that the long-term consequences of an increase in drought in these forest ecosystems will include a decrease in the cycling of organic P forms and an increase in inorganic P content in soils, mainly due to restricted uptake of P by plants and less soil leaching. If primary productivity is maintained, these tropical dry forests may therefore become significant soil P hotspots under the predicted increased duration of drought. [ABSTRACT FROM AUTHOR]

Crescentia alata is a natural resource with cultural and economic value from Mexico to Costa Rica. Nevertheless, protection of natural populations and establishment of plantations are limited by lack of information on seed germination and plant growth. This study aims to characterize size, weight and number of fruits and seeds, to evaluate the seed germination process at different temperatures and light conditions, and to determine the optimal conditions of temperature, humidity, and storage periods for viable seeds. We measured germination at five different temperatures (15, 20, 30, 20-30, and 25-30 °C), in light-dark conditions, with seed storage at three temperatures (5 °C, 15 °C, and ambient temperature: 22-24 °C) during 36 months. Mean values: fruit roundness index -1.86 (i.e. they are flattened-rounded). Fruit height 7.90 ± 2.58 cm, diameter 9.62 ± 1.21 cm; seeds were 0.75 ± 0.07 cm long and 0.67 ± 0.05 cm wide. Fruit mass 414.57 g; each fruit contained on average ca. 691 seeds. Seeds did not germinate at 15 °C or 20 °C; germination decreased in darkness; germination and viability decreased when seeds were stored at ambient temperature (22-24 °C), and when they were preserved inside fruits. The seeds of C. alata germinate better at 30 °C, exposed to light, and separated from the pulp before storage. When seeds are stored at low temperatures (5 °C and 15 °C), high germination and viability percentages (ca. 90 %) can be maintained for three years, allowing conservation programs for the species. [ABSTRACT FROM AUTHOR]

Evidence is presented about the presence of Phaseolus microcarpus in Costa Rica, while it was previously reported northwards in other Central American countries and Mexico. Fourteen populations are currently known, four from the Peninsula of Nicoya, and ten are in the tropical dry forest of the mainland of this country. [ABSTRACT FROM AUTHOR]

Rainfall, runoff and sediment yield have been measured over three decades (1983–2015) in five contiguous small watersheds (12–28 ha) covered by mature tropical dry forest (TDF) at the Chamela Biological Field Station, UNAM, in the southern Pacific Coast of Jalisco, Mexico. Hydrological dynamics strongly drive the seasonal and inter-annual variability of TDF primary productivity, litter decomposition and nutrient cycling. Although the study region is constantly influenced by storms related to hurricane activity, they rarely make landfall. However, hurricanes have landed twice over a four-year period in the reserve: category 2 Hurricane Jova, in October 2011, and category 4 Hurricane Patricia, in October 2015. The long-term data has allowed to evaluate ecosystem’s response to these two major hydrometeorological events, in the context of the historic rainfall/runoff pattern. The results showed that antecedent precipitation and rainfall intensity were the major factors controlling rainfall-runoff and soil erosion processes. The analysis also showed the timing of the onset of the rainy season was very regular but the length of the rainy season was quite variable. The highly variable rainfall pattern and high probability of intense storms at the onset of the wet season were linked with the vulnerability of TDF to soil erosion. Also, two types of recurrent and intense drought periods have been identified: the high inter-annual droughts; and the frequent within-wet season droughts (“canículas”). There is a clear influence of the “El Niño”- Southern Oscillation phenomenon (ENSO) on the study area, with lower annual rainfall during its hot phase, and higher annual rainfall during its cold phase (“La Niña”). The relevance of these findings is discussed in terms of forest ecosystem management practices in the region and its implications concerning the current climate-change forecast for the study area. [ABSTRACT FROM AUTHOR]

Given the current evidence of global change, extreme events are projected to be more frequent and intense. At a river basin scale, the immediate effects of hurricanes include changes in soil properties, vegetation structure and composition, and water volume and quality, which lead to changes in species distribution and community structure. The goal of this study was to identify key abiotic and biotic elements for monitoring hurricane events at the river basin scale by linking databases of vegetation cover, small mammal diversity and water quality between 2010 and 2016. Abiotic parameters and biotic communities were monitored in a tropical dry forest (TDF) landscape on the coast of Jalisco, Mexico after two major events: Hurricanes Jova (2011) and Patricia (2015). Three zones (1-upper, 2-middle and 3-lower basin) adjacent to the TDF were analyzed along the Cuitzmala River catchment areas before and after the events. We used the Enhanced Vegetation Index (EVI) as a proxy for vegetation greenness and the diversity index of a small mammal community of rodents and bats as indicators of terrestrial habitat quality, and Fecal Coliform (FC), Fecal Enterococci (FE), and Electrical Conductivity (EC) as indicators of the river-water condition. During the years of hurricanes (2011 and 2015) there was a decrease in the EVI and small mammal diversity, as well as changes in the concentration of FC, FE and EC. The main effects associated with the two hurricanes were observed in the lower basin where hurricanes made landfall and the forest had been converted to other land uses. The EVI, communities of small mammals, and abiotic and biotic water conditions were responsive to the effects of hurricanes and can thus be useful for a long-term ecological monitoring program at the basin scale. This program would allow a faster evaluation and response to future extreme meteorological events. Our results could be implemented through the Urban and Environmental Plans at the state level ( Ordenamiento Territorial del Estado de Jalisco ), through the regulation of sustainable agricultural and livestock techniques, and by educating local populations of the effects of extreme meteorological events. [ABSTRACT FROM AUTHOR]

Hurricanes are meteorological events with intense effects on coastal ecosystems where the change in wind kinetic energy is first concentrated. The quantification of forest change and the understanding of forest recovery trajectories after hurricane impact require a series of observations from before and after the event. Our objective was to quantify the immediate and delayed impacts of two successive large hurricanes, Jova (October 2011) and Patricia (October 2015) on the canopy structure and some ecosystem functions of the Chamela tropical dry forest on the Pacific coast of Mexico. This forest is not typically affected by large disturbance events, but has a background of extreme rainfall seasonality and corresponding phenological responses. We used a series of detailed historic and recent measurements of canopy structure and Photosynthetic Photon Flux Density (PPFD) coupled with a continuous series of remote sensing indices (NDVI) to help assemble a comprehensive view of the effects from hurricanes Jova and Patricia, category 2 and 4 in the Saffir-Simpson Hurricane Wind Scale, respectively. From ground-based LiDAR observations of canopy structure we estimated aboveground forest biomass at various times before and after the hurricanes. The net aboveground biomass loss from the two hurricanes combined (26.4 Mg ha −1 ) was about 33.7% of the pre-hurricane value of 78.4 Mg ha −1 . Biomass loss from the first hurricane was about 8.6 Mg ha −1 (11.0% of the original). Damage from the second storm alone might have been as much as 22.7%, depending on the course of recovery between hurricanes. We also found a temporary decline in the fraction of Absorbed Photosynthetically Active Radiation (fAPAR). NDVI, well correlated to fAPAR, also showed this pattern after both hurricanes. Canopy structure was considerably altered by both hurricanes, including leaf area and persistent vertical and horizontal woody components. The effects of wind and precipitation differed in several ways: whereas biomass loss appears related to hurricane wind energy, the duration of extended greenness may be due to the extra aseasonal precipitation. Our data suggest that different aspects of ecosystem structure and function will recover at different time scales. The recovery of greenness occurs rapidly, on the order of weeks to months but canopy cover and production will recover more slowly. The re-establishment of persistent canopy structure and total biomass will likely take decades in the absence of other major disturbances or active forest management. [ABSTRACT FROM AUTHOR]

Bee communities were studied with three different conditions of land-use: 1) urban area; 2) crops and livestock; and, 3) preserved vegetation. All three conditions have elements of tropical dry forest and are in the "Sierra de Quila" Flora and Fauna Protection Area and its influence zone. Sampling was carried out throughout the year (three days per month) for each land-use condition. Bee species and their abundance were registered with the intention of knowing how changes in the vegetation are related to bee community structure (richness, abundance, and a and ß diversity). A total of 14,054 individuals from 160 species were registered. A rarefaction analysis, showed that the preserved areas had significantly greater richness and diversity. Beta diversity analysis revealed a species turnover of nearly 32% among each pair of conditions. It is concluded that the changes in land-use negatively affect richness and diversity and causes major changes in species composition of the bee community. For this reason, it is recommended that the protection of the tropical dry forest, both for this study area but also in general for Mexico, is essential to guarantee the conservation of this group of insects, which are required for the reproduction of a great number wild and cultivated plant specie. [ABSTRACT FROM AUTHOR]

Tropical dry forest (TDF) is important due to its biodiversity. In the Isthmus-Coastal region of the state of Oaxaca, in Southeast Mexico, there are many areas of TDF with varying categories of legal protection (1) Protected Natural Areas (PNA), (2) Voluntarily Designated Conservation Areas (VDCA) and (3) Areas of Common Use (ACU). In each of these, tree vegetation structure was analysed, recording plants with a DBH = 2.5 cm and sampling 15 plots of 100 m². Observed richness was 90 species, belonging to 36 families and corresponding to 80% (Jackknife) and 85% (ICE) of expected richness. A cluster analysis identified two groups with 90% dissimilitude: the first (G1) included all the sampled plots in the PNA; and the second (G2), grouped together those from the VDCA and the ACU. The Shannon, Simpson dominance and Jost true diversity indices for G1 were H'= 2.43, D= 0.21 and qD= 11 and for G2, H'= 2.76, D= 0.28 and qD= 15 respectively, with no differences between groups (P < 0.05). The species that presented the highest relative importance value (RIV) in both groups, corresponded to secondary vegetation. Species density of G1 was 1 829 ind/ha and 2 370 ind/ha for G2. Mean height (6.8 m) and basal area (19.7 m²/ha) of G1 did not vary significantly (P < 0.05) when compared to G2 (7.9 m y 22.1 m2/ha). The VDCA and ACU presented similar composition and structure, differing from the PNA. Continual monitoring of the TDF is suggested. [ABSTRACT FROM AUTHOR]

Termites play a key role as ecosystem engineers in numerous ecological processes though their role in the dynamics of wood degradation in tropical dry forests, particularly at the level of the crown canopy, has been little studied. In this study, we analysed the occurrence of termites in the forest canopy by evaluating the density and proportion of living and standing dead trees associated with termites in deciduous and riparian habitats of the tropical dry forest in Chamela, Mexico. The results indicated that 60–98% of standing dead trees and 23–59% of living trees in Chamela were associated with termites. In particular, we found that the density of standing dead trees was higher in deciduous forests (0.057–0.066 trees/m² ) than in riparian forests (0.022 and 0.027 trees/m² ), even though the proportion of trees was not significantly different among habitats. Additionally, we found a higher density of trees associated with termites in trees of smaller size classes (0.01–0.09 trees/m² ) than in larger class sizes (0–0.02 trees/m² ). Interestingly, 72% of variation in the density of trees associated with termites is explained by the density of standing dead trees. Overall, these results indicate that standing dead tree availability might be the main factor regulating termite populations in Chamela forest and suggest that termites could play a key role in the decomposition of above-ground dead wood, mediating the incorporation of suspended and standing dead wood into the soil. [ABSTRACT FROM AUTHOR]

Understanding how aboveground biomass (AGB) is spatially distributed in the landscape and what factors are involved is critical to identify the ecological constraints limiting the magnitude and the allocation of carbon (C) stocks. Yet these factors remain poorly quantified for much of the world. The aim of this study is to identify the factors that influence the reconstruction of potential AGB and its spatial heterogeneity under current climate. A range of statistical approaches is used here to reconstruct the spatial distribution of AGB found in a tropical dry forest in Mexico. This is one of the first studies to directly quantify the predictive performance of various techniques within a common framework applied to AGB estimates from field observations and biophysical variables. The results suggest that general linear model (GLM) and the general additive model (GAM) performed similarly and outperformed other more complex approaches, such as automated neural networks, generalized linear mixed models via penalized quasi-likelihood, MaxEnt and random forest. GLM and GAM approaches also showed good performance in comparison to independent field observations over different spatial resolutions. MaxEnt performed poorly against independent validation data. The GLM, GAM, neural networks and regression tree models returned comparable mean AGB, suggesting that the potential AGB in the studied area is ∼132 Mg ha −1 . The biomass spatial distribution is represented differently by the different models. Neural networks and regression tree approaches tend to cluster similar AGB estimates with a large range of the spatial autocorrelation, while the GLM is capable of reproducing the spatial distribution of the biomass. [ABSTRACT FROM AUTHOR]

Biotic homogenization--the erosion of biological differences between ecosystems owing to human perturbation--is a trait of the global biodiversity crisis that can affect tropical dry forest biodiversity. We tested whether biotic homogenization was occurring in resident forest bird communities in west-central Mexico. We conducted point-count surveys to assess biotic dissimilarity between resident bird communities in tropical deciduous and oak forests in the upper Balsas River basin across 3 levels of anthropogenic perturbation: primary forest, second-growth forest, and human settlements. We detected a reduction in species richness and taxonomic dissimilarity with increasing anthropogenic effects, due to a directional pattern in which lowland species expanded their elevational distributions up into oak forests. These results point to a need to change agricultural strategies to mitigate impacts on natural vegetation cover and biodiversity. [ABSTRACT FROM AUTHOR]

• Tree communities influence diversity, interactions and turnover of orchids. • Drought-adapted and terrestrial orchids were more frequent in the dry forest. • The orchid-host tree network was more specialized than other epiphyte networks. • Conservation of different habitats is a priority to conserve orchid communities. At the regional scale, abiotic environmental heterogeneity related to elevation and climatic profiles influences patterns of diversity and species composition. At the local scale, little is known about the influence of biotic environmental heterogeneity (habitat diversity) on the diversity, composition, and networks of interspecific interactions (epiphyte-host tree) of plant families with species of epiphytic and terrestrial habit. As a study model, we selected the orchids of a tropical landscape in central Veracruz, Mexico, which comprises natural habitats of tropical oak forest (TOF), semi-humid deciduous forest (SDF), and tropical dry forest (TDF), as well as shaded coffee plantation (SCP). In this landscape, we recorded a total of 635 individual orchids, belonging to 51 species (80% of epiphytic habit). The TOF and SDF, with 36 and 30 orchid species, respectively, were at least twice as diverse than TDF and SCP, and also presented greater similarity in terms of species composition. The TDF presented a particular composition of orchids comprising species that are morphologically adapted to conditions of drought, and also presented more species of terrestrial habit than the other habitats. The SCP hosted a subset of the species of TOF. The structure and specialization of the network of orchid-host tree interactions (at the landscape level) was less nested, and more modular and specialized than has been reported previously for commensalist networks of vascular epiphytes. The most abundant and tallest tree species favored the orchid-host tree interactions. For this reason, at the landscape scale, the particular tree community of different habitats promotes the great diversity and acts to structure the composition and interactions of one of the most representative plant families of the Neotropics. [ABSTRACT FROM AUTHOR]

• The loss of forest cover modifies the structure and composition of the assemblages of sand flies, but does not influence the co-occurrence patterns of the species. • Sites with high proportion of forest cover area/low heterogeneity exhibit similar sand fly structure and composition. While anthropophilic species persist along the gradient, strictly zoophilic species are lost. • The sex ratio follows the gradient of land use change, with females being more abundant than males, with the latter declining further with loss of forest cover. • Despite sand flies abundance decreases in disturbed areas, opportunistic and vectors species tend to be dominant. • The apparent plastic or colonialist profile of Lutzomyia cruciata in disturbed areas deserves attention because could represent a potential risk of "domiciliation" and lead to changes in the transmission patterns of leishmaniasis. As land use intensifies in tropical forests, it is expected that species assemblages will be modified and that key functions of these ecosystems will be affected. The latter scenario is important from a public health perspective, because the land use change has been linked the outbreaks of vector-borne diseases. In this study, we evaluated the response of Phlebotominae (Diptera: Psychodidae) assemblages and their pattern of co-occurrence in four sites with different land use in an emerging cutaneous leishmaniasis focus in Yucatan, Mexico. Our hypothesis is that the conservation status (as forest cover) will positively influence the structure and composition of sand flies' assemblages. Using three different traps over a period of five months, a sampling effort of 1, 440 night-traps was performed. A total of 7, 897 sand fly specimens belonging to six genera and 10 species were collected. Our hypothesis was partially achieved since sand fly diversity increased as forest cover increased and vice versa, however random patterns of co-occurrence in assemblages were detected among sites. Even though the high abundance of sand flies in the forest fragment suggests an amplification effect, our results show that different vector species directly dominate in each site. We discuss the potential implications of the nestedness of species dominance. We suggest that in this emerging focus and under the land use gradient, Lutzomyia cruciata and Psathyromyia cratifer could play a pivotal role in maintaining the transmission cycles of Leishmania. The apparent generalist or colonialist profile of Lu. cruciata in disturbed areas deserves attention, due to the potential risk of leishmaniasis "domiciliation". This information is essential to understand the eco-epidemiology of leishmaniasis and the factors associated with its emergence in Yucatan, Mexico. [ABSTRACT FROM AUTHOR]

Summary Runoff in forested tropical catchments has been frequently described in the literature as dominated by the rapid translation of rainfall to runoff through surface and shallow subsurface pathways. However, studies examining runoff generation in tropical catchments with highly permeable soils have received little attention, particularly in tropical dry forests. We present a study focused on identifying the dominant flowpaths, water sources and stream water residence times in a tropical dry forest catchment near the Pacific coast of central Mexico. During the wet season, pre-event water contributions to stormflow ranged from 72% to 97%, with the concentrations of calcium, magnesium, sodium and potassium closely coupling the geochemistry of baseflow and groundwater from the narrow riparian/near-stream zone. Baseflow from the intermittent stream showed a strongly damped isotopic signature and a mean baseflow residence time of 52–110 days was estimated. These findings all suggest that instead of the surface and near-surface subsurface lateral pathways observed over many tropical catchments, runoff is generated through vertical flow processes and the displacement and discharge of stored water from the saturated zone. As the wet season progressed, contributions from the saturated zone persisted; however, the stormflow and baseflow geochemistry suggests that the contributing area of the catchment increased. Our results show that during the early part of the wet season, runoff originated primarily from the headwater portion of the catchment. As the wet season progressed and catchment wetness increased, connectivity among sub-basin was improved, resulting in runoff contributions from across the entire catchment. [ABSTRACT FROM AUTHOR]

This paper presents the first detailed faunistic study in Mexico for the family Cleridae, an important group of predatory beetles. The study was carried out in El Limon de Cuauchichinola, Tepalcingo, in the state of Morelos, Mexico, over a year of systematic collections (June 2006 to May 2007). The family Cleridae was found to be represented in the study area by seven subfamilies, 18 genera, and 44 species. The dominant genera were Phyllobaenus Dejean with nine species, followed by Cymatodera Gray with eight, and Enoclerus Gahan with seven. The nonparametric estimators Incidence Coverage Estimate, Chao2, and second-order Jacknife estimated that between 65 and 78% of the true richness was recorded. The family showed a marked seasonality, with greater richness and abundance found during the rainy season. Sweeping and beating vegetation were the most efficient collection methods, producing 71.7% of the recorded species richness. Of the species determined, 18 represent new records for Morelos and five of these are new records for the country. The results provide evidence that the tropical dry forest of the Sierra de Huautla Biosphere Reserve is an ecosystem rich in species. The new records also serve to contribute to our general knowledge of the distribution of Cleridae in Mexico. [ABSTRACT FROM AUTHOR]

Jacaratia mexicana is not only an endemic and typical tropical dry forest tree of Mexico, it is considered as a direct ancestor of the papayo (Carica papaya). Locally it is mainly used in traditional medicine, for human food or for feeding backyard animals (forage plant), but its use value is very restricted or even unknown. Nevertheless, various abiotic and anthropogenic pressures in its Mexican habitat are causing populations of this tree to decline alarmingly. Arbuscular mycorrhizal fungi (AMF) are microorganisms that have an important role for the regeneration of tree species by increasing their ability to absorb water and nutrients. The aim of this study was to determine the effect of AMF on growth and survival of seedlings of J. mexicana transplanted within a fragmented area of the remaining dry forest located in the central portion of the state of Veracruz. We measured height, stem diameter, number of leaves, percent seedling survival and mycorrhizal colonization. Results showed increases in all growth-related variables when seedlings were inoculated with AMF. The results suggest that micosymbionts can play a critical role for the regeneration of J. mexicana and possibly other species of tree within the dry forest, especially helping this endemic species that is currently surviving in a fragmented environment under unfavorable conditions of low availability of water and nutrients. [ABSTRACT FROM AUTHOR]

In forested catchments, the exceedance of rainfall and antecedent water storage thresholds is often required for runoff generation, yet to our knowledge these threshold relationships remain undescribed in tropical dry forest catchments. We, therefore, identified the controls of streamflow activation and the timing and magnitude of runoff in a tropical dry forest catchment near the Pacific coast of central Mexico. During a 52 day transition phase from the dry to wet season, soil water movement was dominated by vertical flow which continued until a threshold soil moisture content of 26% was reached at 100 cm below the surface. This satisfied a 162 mm storage deficit and activated streamflow, likely through lateral subsurface flow pathways. High antecedent soil water conditions were maintained during the wet phase but had a weak influence on stormflow. We identified a threshold value of 289 mm of summed rainfall and antecedent soil water needed to generate >4 mm of stormflow per event. Above this threshold, stormflow response and magnitude was almost entirely governed by rainfall event characteristics and not antecedent soil moisture conditions. Our results show that over the course of the wet season in tropical dry forests the dominant controls on runoff generation changed from antecedent soil water and storage to the depth of rainfall. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sexual dimorphism and reproductive cycle were studied in a population of Sceloporus horridus horridus from a tropical dry forest in central Mexico. Males with 90.66 mm (71.5-111.0 mm ± 12.79 mm) snouth vent-length were larger than 86.32 mm (71.0-101.0 ± 7.94) females. Reproductive activity is seasonal in both sexes and occurs in the period spring-summer as it has been observed in several oviparous species of tropical dry forest. The vitellogenesis occurs between March and April and the spermatogenesis from February to March. The ovulation occurs on late April and the eggs are in the oviducts between May-July. Mean eggs mass was 0.46 g (0.3-0.6) and meanclutch size was 15.3 eggs (10-20). Clutch size was related significantly to mass (r = 0.669) and physical condition of females (r = 0.676). The relative clutch mass value was 0.31 conforming to the strategies predicted for sit and wait species of lizards. The on set of reproductive activity in males was related with temperature (r = 0.508) and in females with precipitation (r = 0.775). Liver and fat body mass in males and females, showed an inverse relationship with the peaks of breeding activity. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Dilemmas of natural resources governance have been a central concern for scholars, policy makers, and users. Major debates occur over the implications of property rights for common resources management. After the Mexican Revolution (1910-1917), land was distributed mainly as ejidos conceived as a hereditary but unalienable collective form of property. In 1992, a new Agrarian Law was decreed that allows individual ownership by removing various restrictions over the transfer of land. Scholars have examined the reform mainly focusing on land-tenure changes and environmental fragmentation. This study examines how the new ownership regime is affecting collective decision-making in ejidos located in a tropical dry forest (TDF) ecosystem. Information on decision-making processes before and after the 1992 reform was gathered through 52 interviews conducted in four ejidos selected along a gradient including agricultural, cattle-raising, and TDF use. The new individualized land property system reduced collective action in ejidos but did not trigger it. Collective action responses to the 1992 reform were buffered by self-organization each ejido already had. Heterogeneous users who shared a short history and showed little understanding of TDF and low dependence on its resources seemed to explain why ejidos have not been able to share a sense of community that would shape the construction of institutions for the collective management of forest resources. However, when a resource is scarce and highly valuable such as water the same users showed capacities for undertaking costly co-operative activities. [ABSTRACT FROM AUTHOR]

Among the many explanations for the large biological diversity of Mexico is that it is the result of the contact between the Nearctic and Neotropical biotas; however, this contact-related explanation is not fully satisfactory and needs further examination in the light of historical biogeography. We offer newer insights into this issue by examining the history of the flora and the vegetation heterogeneity of the seasonally dry tropics of this country. Several environmental criteria can be used to define the seasonally dry tropical regions, but setting their precise geographical boundaries is not always straightforward. This is largely due to the large vegetation heterogeneity of this region, within which the tropical dry forest (TDF) is prominent. The origin of the TDF flora can be traced back at least as far as 20 million years before present and seems to be associated with the Tertiary North American flora. Available evidence does not support a South American origin of the TDF flora. Similarly, the separation of the TDF and the hot North American desert floras into two different bio-geographical realms is not warranted. The history of the seasonally dry tropical flora of Mexico strongly suggests that this bio-geographical dichotomy should be replaced by the recognition of the existence of a Pan-American Realm. [ABSTRACT FROM AUTHOR]

We investigated the influence of rainfall attributes on litter decomposition over an 8-year period in a well-preserved tropical dry forest ecosystem in western Mexico. We examined the relationship between the size and number of rainfall events and rainy-season litter decomposition rates and determined if this relationship varied along a landscape gradient. A mass balance approach was used to estimate decomposition rate in four permanent 2,400 m plots located in two small watersheds. Watershed I included three plots in different landscape positions (upper, middle, and lower) in the elevation gradient, whereas Watershed IV included one plot in the middle position. Surface litter C mass was lower in the rainy than in the dry season in all plots in response to seasonal fluctuations in rainfall. The frequency of small (≤5 mm) and medium (5.1-9.9 mm) size rainfall events largely did not correlate with litter decomposition, but the frequency of large events (≥10 mm) had a positive correlation with decomposition rates ( P < 0.05), except in plot IV ( P < 0.1). Decomposition rates were similar among plots at the different landscape positions within Watershed I ( P > 0.05). The relevance of large rainfall events (≥10 mm) in rainy-season litter decomposition suggests that changes in the precipitation regime which alter the frequency of these rainfall pulses or increase their variability would affect the vulnerability of the litter C and nutrient pools to extreme events. [ABSTRACT FROM AUTHOR]