Forest In Mexico Research Articles

Assessment of the classification accuracy of the Globeland30 Forest class for the temperate and tropical forests of Mexico

This paper presents an assessment of the classification accuracy of the 2000 and 2010 GlobeLand30 (GL30) Forest land cover class for the forests in Mexico at the national level. The rich diversity of temperate and tropical forests in Mexico provides an ideal stage for this assessment. As validation data set, we used thousands of field sampling sites with detailed forest cover information from two sampling cycles of the national forests inventory of Mexico. We defined 9 distinct types of forests and assessed the GL30 Forest class classification accuracy for each of them. This accuracy was higher in tropical forests than in temperate forests (around 90% vs. around 77%). The lowest accuracy values (around 73%) were in the tropical and temperate forest with dominance of deciduous tree species. The largest number of wrongly classified sampling sites covered by forests fell in three GL30 classes: Shrublands, Grasslands, and Cultivated. In the temperate forests, almost 100% of the wrongly classified sites fell into the first two land covers. The more specific tropical forest types defined in our study showed distinct patterns of distribution of the misclassified sites between these three GL30 land cover classes.

Fragmentation dynamics in an Abies religiosa forest of central Mexico

Fir (Abies Mill.) forests of Mexico are relicts of the boreal forests that advanced southwards during glaciation periods. Mexico is a center of diversification of the Abies genus, as there are eight species in its territory, six of which are endemic. The forests of Abies religiosa (Kunth) Schltdl. & Cham. near Mexico City are subject to a process of deterioration. We analyzed the fragmentation dynamics of the A. religiosa forest in the northern region of the Sierra Nevada, Mexico. Land cover change detection was done by means of high-resolution images acquired by the SPOT satellite in 2005, 2010, 2015, and 2018. Habitat fragmentation was observed, with a decrease in the size of dense Abies masses. The area covered by Abies decreased by 22.9%. The area occupied by forest openings increased 3% from 2005 to 2010 and then decreased by 1.8% and 1.6% in the following periods. The land patch type Other Forest Cover increased in both frequency and size, with the area increasing by 23.3%, which warns of a change process towards this patch type. The formation of increasingly smaller and isolated remnants of A. religiosa forest in the Sierra Nevada can lead to the loss of this vegetation relict and its replacement by other types of cover in the short term.

Characterizing New Wintering Sites for Monarch Butterfly Colonies in Sierra Nevada, Mexico.

Every year, Danaus plexippus (Linnaeus, 1758) travels to hibernate in oyamel fir forests located between the limits of the states of Michoacán and Mexico in Mexico. Climate change and anthropogenic actions are diminishing oyamel fir forests in Mexico, putting pressure on the habitats of monarch butterflies. In the last decade, new colonies outside their usual range have been predicted through modeling and reported by the National Commission on Protected Areas of Mexico. The objectives of the study were to recover information on the historical and new hibernation sites, reported or modeled, from different literature sources. We also aimed to perform a bioclimatic and forest biometric characterization of new monarch butterfly colonies located in Sierra Nevada in Mexico to provide information to aid in conservation strategies for the monarch butterfly population. We conducted field trips to georeference the colonies at sites located in the Atlautla municipality in Mexico State. Climatic, topographic, and forest biometric variables were used to characterize the sites physically. It was found that the butterfly’s roosts occurred at a higher elevation than those recorded by other sources. The locations where the monarch’s colonies were established, in the east of Mexico State, provide information relevant to defining and developing policies for their conservation.

Assessment of seasonal and spatial variations of biochemical markers in Corydalus sp. (Megaloptera: Corydalidae), a non-conventional biomonitor, in a mountain cloud forest in Mexico

Rivers are critical ecosystems for protecting and harboring high biodiversity. Tropical rivers particularly are unique for facing extreme climatic events under the current accelerated disruption from human activities. The Bobos-Nautla river basin is exposed to climatic events and disturbances from anthropogenic impacts that stress aquatic organisms. We assessed the health condition of this river system using a non-conventional biomonitor, Corydalus sp., with a set of early-warning biomarkers including lipid peroxidation levels (LPO) and antioxidant activity, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and the neurotransmitter acetylcholinesterase (AChE) considering their spatial and temporal variations. Biomarkers and water quality parameters were analyzed, and the integrated biomarker response (IBR) was assessed as a stress index. Biomarkers showed no significant spatial differences; however, a high-stress period during the rainy season was detected, evidenced by the highest LPO levels; this period is related to the leaching of allochthonous materials from agricultural and urban zones. The peak IBR value during the rainy season confirmed the seasonality of biomarkers. A slight increase in IBR was recorded in lowlands, seemingly associated with agricultural land and human settlements. A principal component analysis showed nutrient enrichment during the rainy season and depletion during the cold-dry season, together with a peak activity of antioxidant enzymes. These results highlight the importance of climatic events such as the rainy season on the health condition of Corydalus sp., which is highly sensitive to the complex mixtures of pollutants that enter the waterbody during extreme climatic events, promoting oxidative stress. Our results also showed the ability of Corydalus sp. to recover and return to a basal level.

Functional indicators to explain the anthropic effects on community plant composition changes: The case of a temperate forest in Mexico

Abstract In plant communities, changes in composition driven by the dominance of weed species have been used as ecological indicators to predict the anthropic impacts on these species. Nevertheless, anthropic disturbances do not act directly on species composition, but their effects depend on the species' functional responses. Hence, anthropic effects follow a logical sequence, in which disturbances act at different levels. In order to understand the sequence of the changes in the community there is a need to develop functional and compositional integrated indicators. In order to integrate them we suggest a method based on inference by abduction, to reduce the complexity in predicting the anthropic effects on species functional responses. With this method we develop functional indicators of responses to anthropic disturbances and the effect on composition changes. The method involves building structural equation models (SEMs), through which we evaluate the anthropic and environmental effects on the functional response of species and composition changes in an integral way. From these causal paths, we select the best-fitting model with plausible functional indicators to explain the anthropic effects, according to Akaike’s information criterion (AIC). This research develops a methodological proposal to build up functional indicators with foliar attributes associated to resource acquisition and use strategies of herb and shrub species in the temperate Abies religiosa forest in the Magdalena river basin in Mexico City. The built indicators demonstrate for the first time and in a simultaneous way, that characteristic species (original component) and native weeds (component established under perturbation conditions) have different responses to anthropic perturbations as well as different contributions to community composition changes. This result represents a methodological contribution in the evaluation of anthropic impacts and the use of native weed species as functional indicators.

Drought effects on the plasticity in vessel traits of two endemic Magnolia species in the tropical montane cloud forests of eastern Mexico

AbstractAimsWe aimed to evaluate how climatic fluctuations influence the plasticity of anatomical vessel traits and the width of annual tree-rings of two relict-endemic Mexican Magnolia species. Notwithstanding, few studies have assessed the drought effect on vessel traits in tropical montane cloud trees of eastern Mexico.MethodsThrough digital images of growth rings, we assessed the tree radial growth rate, age of the trees and plasticity in vessel traits regarding climatic fluctuations of the Mexican Magnolia species studied. We compared vessel density, hydraulic diameter and percentage of conductive area in drought years (DY) and non-drought years (NDY) in two Mexican Magnolia species.Important FindingsFor the first time, the plasticity that occurs in porous wood vessel traits to long-term climatic fluctuations was analysed for two endangered Magnolia species (Magnolia vovidesii and M. schiedeana) from two tropical montane cloud forests in Mexico. We found that temperature and precipitation were strongly associated with differences in tree-ring width when DY and NDY were compared. Our analyses revealed that a high plasticity in vessel anatomy of diffuse-porous wood was related to temperature and/or water availability for both Magnolia species studied. We concluded that anatomical adaptations to DY resulted in a substantial reduction in vessel traits when compared with NDY, and that the plastic adaptations played an essential role in water transport and safety for the survival of the studied species during stressful long periods.

A Fourier Spectral Method to Measure the Thermal Diffusivity of Soil

Abstract It is well established that amplitude decays and phase shifts as a function of depth, frequency, and thermal diffusivity when a periodic surface temperature signal conducts into the ground. In historical practice, this principle has often been employed to estimate soil thermal diffusivity using observations of the dominant diurnal and annual temperature signals. We describe and demonstrate a method to infer thermal diffusivity over a broad bandwidth in the frequency domain using high fidelity time-series ground temperature records. We draw information from thermal signals generated by meteorological events over weeks and months, as well as the dominant diurnal signal. Both the decay in amplitude and shift in phase of each frequency band contribute points to plots that define linear functions relative to a parameter that incorporates frequency and depth. Linear regression through the points gives the magnitude and uncertainty of the slope of the function, where the slope is equal to the inverse square root of the average thermal diffusivity over the sampled time-period and depth interval. This allows statistical quantification of the uncertainty in the thermal diffusivity estimate. Furthermore, our method delineates depth intervals where nonconductive processes significantly affect heat transfer. Examples are presented for a dry desert soil in South Australia and the floor of a tropical alpine forest in Mexico.

Thermal ecophysiology of a native and an invasive gecko species in a tropical dry forest of Mexico.

For ectotherms, thermal physiology plays a fundamental role in the establishment and success of invasive species in novel areas and, ultimately, in their ecological interactions with native species. Invasive species are assumed to have a greater ability to exploit the thermal environment, higher acclimation capacities, a wider thermal tolerance range, and better relative performance under a range of thermal conditions. Here we compare the thermal ecophysiology of two species that occur in sympatry in a tropical dry forest of the Pacific coast of Mexico, the microendemic species Benedetti's Leaf-toed Gecko (Phyllodactylus benedettii) and the invasive Common House Gecko (Hemidactylus frenatus). We characterized their patterns of thermoregulation, thermoregulatory efficiency, thermal tolerances, and thermal sensitivity of locomotor performance. In addition, we included morphological variables and an index of body condition to evaluate their effects on the thermal sensitivity of locomotor performance in these species. Although the two species had similar selected temperatures and thermal tolerances, they contrasted in their thermoregulatory strategies and thermal sensitivity of locomotor performance. Hemidactylus frenatus had a higher performance than the native species, P. benedettii, which would represent an ecological advantage for the former species. Nevertheless, we suggest that given the spatial and temporal limitations in habitat use of the two species, the probability of agonistic interactions between them is reduced. We recommend exploring additional biotic attributes, such as competition, behavior and niche overlap in order assess the role of alternative factors favoring the success of invasive species.

Coloración y abundancia de Dendroctonus mexicanus Hopkins, 1905 en cuatro regiones de México

El incremento en la abundancia de escarabajos descortezadores en los bosques de pino y pino-encino en México ocasiona la muerte de grandes masas forestales. Se estima que tal comportamiento responde a un aumento en las temperaturas por efecto del cambio climático; sin embargo, se desconoce la función que desempeñan otras variables climáticas como la humedad y de qué manera influyen en ciertas características morfológicas; por ejemplo, la variación en la intensidad de la coloración del exoesqueleto, entre regiones. En el presente estudio se analizaron la variación de la intensidad de la coloración y la abundancia de las poblaciones de D. mexicanus procedentes de cuatro regiones (Hidalgo, Oaxaca, Jalisco y Nuevo León), y su relación con la humedad, la temperatura y la aridez. Algunos individuos de D. mexicanus exhibieron una coloración más obscura, lo que puede estar asociado a un porcentaje más alto de humedad, y otros con tonalidades más claras (café rojizo) recolectados en zonas con menor humedad (HMA: 82 % = más obscuros; 66 % = más claros). La región del estado de Hidalgo presentó el mayor número de individuos de D. mexicanus, en comparación con las de Nuevo León, Jalisco y Oaxaca. Los índices de aridez promedio máximo e índices de aridez promedio mínimo generaron evidencia de condiciones climáticas idóneas para la presencia de poblaciones de D. mexicanus más abundantes. Las temperaturas extremas y la humedad relativa del ambiente funcionan como factores limitantes en el incremento exponencial de la abundancia de las poblaciones de descortezadores.

Disentangling the influence of ecological and historical factors on seed germination and seedling types in a Neotropical dry forest.

In tropical dry forests, although seed germination and seedling establishment are in general limited by the seasonal availability of water, high interspecific variability, nonetheless, exists in terms of seedling traits and germination dynamics. Differences among species in seed germination and seedling traits may be related to other plant life-history traits, such that assessing these relationships may increase our understanding of factors influencing plant establishment, which would affect the regeneration pathways of tropical dry forest communities. In this study, taking into consideration the effect species' phylogeny, we evaluated the relationships of seed germination metrics (percentage, lag time, and rate of germination) and seedling types (i.e. cotyledons functional morphology), with plant life-history traits (growth form, seed mass, dispersal syndrome and dispersal phenology) for 110 species in a Neotropical dry forest in Mexico. A total of 92% of the species studied disperse their seeds during the dry season, mainly at the beginning of this season (66%), a strategy mostly associated with autochorous herbs. Seed germination was more frequent in species that dispersed seeds at the end of the dry season. Germination percentage was not related to any of the traits studied. However, germination lag time and rate were negatively related to seed mass, a trait that in turn depended on growth form and dispersal syndrome. The dominant seedling type in the community was phanerocotylar epigeal with foliaceous cotyledons (56%), which was mostly associated with small seed mass and herbaceous growth form. Our results provide evidence that several plant life-history traits explain an important part of the variation in seed germination and seedling characteristics observed among species. Therefore, these plant life-history traits may be useful for grouping species in terms of their establishment strategies and roles on the regeneration of tropical dry communities.

Individual Tree Diameter and Height Growth Models for 30 Tree Species in Mixed-Species and Uneven-Aged Forests of Mexico

Lack of knowledge of individual tree growth in species-rich, mixed forest ecosystems impedes their sustainable management. In this study, species-specific models for predicting individual diameter at breast height (dbh) and total tree height (h) growth were developed for 30 tree species growing in mixed and uneven-aged forest stands in Durango, Mexico. Growth models were also developed for all pine, all oaks, and all other species of the genus Arbutus (strawberry trees). A database of 55,158 trees with remeasurements of dbh and h of a 5-year growth period was used to develop the models. The data were collected from 217 stem-mapped plots located in the Sierra Madre Occidental (Mexico). Weighted regression was used to remove heteroscedasticity from the species-specific dbh and h growth models using a power function of the tree size independent variables. The final models developed in the present study to predict dbh and total tree height growth included size variables, site factors, and competition variables in their formulation. The developed models fitted the data well and explained between 98 and 99% and of the observed variation of dbh, and between 77 and 98% of the observed variation of total tree height for the studied species and groups of species. The developed models can be used for estimating the individual dbh and h growth for the analyzed species and can be integrated in decision support tools for management planning in these mixed forest ecosystems.

The new genus Jocatoa (Lecanoromycetes: Graphidaceae) and new insights into subfamily Redonographoideae

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.

Taxonomic revision of the Mesoamerican genus Spathacanthus (Justicieae, Acanthoideae, Acanthaceae).

Spathacanthus is a Mesoamerican genus that occurs in tropical and temperate regions from southern Mexico to Costa Rica; its taxonomy has not been updated for two decades. In view of the fact that a new species has been discovered and that the interspecific affinities in this genus have not been addressed to date, the present study aims to revise the genus Spathacanthus. Specimens of plants of this genus collected from across the distribution range and deposited in herbaria and digital databases were reviewed. In parallel, a cladistic analysis was carried out, based on morphological characters in order to examine relationships between species. Four species of Spathacanthus were recognised: one endemic to Costa Rica, another micro-endemic to Veracruz in Mexico, one more restricted to the forests of Mexico and Guatemala and the last one more widely distributed. Reflecting the previously limited knowledge of the group, many of the specimens that we studied had been misidentified. A key to differentiate these species is provided, supplemented with photographs, drawings and other illustrations, morphological descriptions, synonymy and ecological data. Results, presented here, extend the distribution range of some taxa and a distribution map is presented. The cladistic analysis recovered the genus as monophyletic, showing that S. hoffmannii and S. hahnianus are sister taxa and S. magdalenae was found to be more closely related to S. parviflorus. These plants are vulnerable to degradation and habitat loss.

Arbuscular mycorrhizal fungi diversity and distribution in tropical low flooding forest in Mexico

Arbuscular mycorrhizal fungi (AMF) are obligate symbionts that establish a mycorrhizal interaction with nearly 80% of terrestrial vascular plants. However, their diversity in tropical low flooding forest (TLFF) has not been characterized, and their distribution patterns in natural environments are not fully clear. Our objective was to determine the diversity and distribution of AMF in the TLFF of Yucatan, Mexico. We selected four sites of TLFF where the basal area of trees, herbaceous plant cover and richness and abundance of trees, herbaceous vegetation and AMF were determined. In addition, we determined the quantity of available phosphorus, cation exchange capacity, percentage of organic matter and pH in the soil at these sites. We found significant differences between sites in terms of tree basal area, herbaceous vegetation diversity and in all of the soil variables. We identified 11 species of AMF, and the greatest diversity was found in the site with the least observable anthropogenic disturbance. The abundance of AMF was positively related to the basal area and abundance of the arboreal vegetation and negatively related to the chemical soil properties measured. Our results indicate that the distribution of AMF in TLFF is related to the characteristics of vegetation, chemical parameters of the soil and identity of the AMF. This study sheds additional information to our understanding of the factors involved in AMF distribution in natural flooding environments.

Recent dynamics of pine and oak forests in Mexico

Temperate forests worldwide are dominated by two families, Pinaceae and Fagaceae. In the last decades, temperate forests are experiencing rapid changes and, in some regions, a directional increase in Fagaceae abundance at the expense of Pinaceae has been detected. Here, we analyze the recent forest dynamics of Pinaceae and Fagaceae in Mexican forests to assess whether there is a directional change in the relative abundance of these two families and identify the environmental factors that are determining their recent growth dynamics. We take advantage of repeated surveys data from the Mexican National Forest and Soil Inventory, obtained in 2004–2007 and 2009–2014. Our results show that, at present, there is no overall directional trend in the changes of the relative abundance of Pinaceae and Fagaceae in the temperate forests of Mexico, which likely reflects a complex mixture of forest dynamics, locally dominated by different types of disturbance or successional dynamics. At the same time, however, we find evidence that the growth of Fagaceae species is responding more favorably than that of Pinaceae to currently rising temperatures in Mexico. Although these results need to be confirmed by longer-term studies, the resulting changes in composition could potentially have strong impacts on forest ecosystem function in the midterm.

Especies de aves en riesgo en el bosque mesófilo de montaña en cinco AICA de la Sierra Madre Oriental, México

Para el bosque mesófilo de montaña en México se ha sugerido la presencia de 125 especies de aves que se encuentran en riesgo o son endémicas. Esas aves requieren ser conservadas. En un tiempo de defaunación mundial, y de reducción de estos bosques, es importante determinar qué especies de aves aún habitan en este ecosistema. Del bosque mesófilo localizado en la Sierra Madre Oriental de México no se han publicado datos recientes de campo que indiquen su presencia. En este análisis reportamos los registros de especies de aves en riesgo realizados en 2016 en cinco Áreas Importantes para la Conservación de las Aves con bosque mesófilo de montaña (Sierra Gorda, Tlanchinol, Huayacocotla, Cuetzalan y Río Metlac) ubicadas en cuatro estados de México (Querétaro, Hidalgo, Veracruz y Puebla). En total registramos 60 especies de aves (48%) de las 125, 29 son consideradas amenazadas a nivel nacional y 34 presentan algún tipo de endemismo. Seis de las especies están protegidas globalmente (Dendrortyx barbatus, Ara militaris, Contopus cooperi, Ridgwayia pinicola, Setophaga chrysoparia y Passerina ciris). Esta información puede servir como base para lograr su preservación y establecer monitoreos, estudios y acciones de conservación dirigidos a especies en las zonas de bosque mesófilo.

Does forest restoration assist the recovery of threatened species? A study of cloud forest amphibian communities

Forest restoration may support recovery and conservation of biodiversity. However, the response of biodiversity to forest restoration is likely to vary depending on the restoration strategy used and taxa considered. Our goal was to assess the recovery of amphibians, a highly threatened biological group, in three cloud forests under different restoration strategies. We compared different measures of species diversity in cattle pasture, 13-year-old forest under passive restoration (P13), 23-year-old forest under passive restoration (P23), 23-year-old forest under active restoration (A23) and mature cloud forest in Mexico. We sampled amphibians in 45 plots and measured landscape and habitat variables to assess their influence on amphibian recovery. We found a total of 13 amphibian species, of which 23% are in the Vulnerable (VU) category of the IUCN Red List and 15% are Critically Endangered (CR). All forests under restoration recovered amphibian species richness and composition, including that of the threatened species, but abundance differed among restoration strategies. Abundance of VU and CR species was higher in A23 than in P13 and P23, but that of CR species was highest in cloud forest. Responses to forest restoration differed among taxa; recovery of salamanders was lower than that of anurans. Proximity to water bodies, as well as high canopy and leaf litter cover, had a strong positive influence on amphibian recovery. Our results indicate that recovery of threatened biodiversity could be promoted through forest restoration, particularly active restoration, and highlight the essential role of mature forest in the maintenance and recovery of amphibian communities.

A protocol for online documentation of spider biodiversity inventories applied to a Mexican tropical wet forest (Araneae, Araneomorphae).

Spider community inventories have relatively well-established standardized collecting protocols. Such protocols set rules for the orderly acquisition of samples to estimate community parameters and to establish comparisons between areas. These methods have been tested worldwide, providing useful data for inventory planning and optimal sampling allocation efforts. The taxonomic counterpart of biodiversity inventories has received considerably less attention. Species lists and their relative abundances are the only link between the community parameters resulting from a biotic inventory and the biology of the species that live there. However, this connection is lost or speculative at best for species only partially identified (e. g., to genus but not to species). This link is particularly important for diverse tropical regions were many taxa are undescribed or little known such as spiders. One approach to this problem has been the development of biodiversity inventory websites that document the morphology of the species with digital images organized as standard views. Their main contributions are the dissemination of phenotypic data for species difficult to identify or new with the assignment of species codes, allowing species comparisons between areas regardless of their taxonomic status. The present paper describes a protocol to produce these websites almost automatically. This protocol was successfully applied to 237 species from a tropical primary forest in Mexico. The time and infrastructure required for the documentation of these species are discussed. Taxonomic information in terms of identification challenges, possible new species, and potential nomenclatural issues is described. In addition, the conventional community parameters (e. g., inventory completeness, species richness estimations, sampling intensity) are also calculated and compared through time and between methods. An optimized version for sampling allocation effort per season is presented and compared with protocols optimized for other tropical forests.

Forest Soil Management: A Mexican Experience

Forests improve the livelihoods and resilience of communities in diverse ways. In particular, soils provide important environmental services for communities in addition to performing many essential ecological functions in forest ecosystems, such as nutrient uptake, organic matter decomposition, water storage, and provision of anchorage for plant growth. The sound management of forest soils, although often disregarded, is a key element of sustainable forest management. From 2002 to 2016 the Forest Soil Conservation and Restoration Sub-Program was designed and implemented by the National Forest Commission (CONAFOR) in Mexico. Forests in Mexico have high biological diversity and are often owned, governed, and managed by communities or, in some cases, community forestry is practiced. Despite the importance of periodic monitoring to ensure that policies are both effective and suitable for diverse conditions and decision making, the policies implemented by this program were not evaluated during its years of operation. Therefore, in the present study, we aimed to identify the deficiencies of this policy as well as opportunities based on a review of the official information available on the Forest Soil Conservation and Restoration Sub-Program of CONAFOR during the 2002-2016 period and interviews with key informants. In addition, we aimed to highlight experiences that may be useful for similar soil conservation policies in tropical forest regions. The identified limitations ranged from conceptual problems such as policy weakness and lack of understanding of local drivers of soil degradation to an overly rigid implementation of soil conservation measures across diverse forest ecosystems and socio-ecological contexts. These deficiencies had several unintended outcomes: perhaps the most relevant was the inability of forest communities to build capacities for soil conservation. Another important limitation was the complete lack of monitoring of the program and its outcomes, which could have prevented its poor results. Finally, a lack of transparency in the distribution and determination of funding was noted. In conclusion, the hierarchical approach of this policy appears to have compromised its long-term efficacy.

Anthropogenic and hurricane disturbances had similar negative effects on epiphytic Tillandsia species in a tropical dry forest

The distribution of epiphytes in tropical dry forests has been associated with the availability and traits of their phorophytes. Thus, strong disturbances of the phorophyte community are expected to affect the abundance and composition of epiphytes. Here, we address the effects of anthropogenic and hurricane disturbances on the richness and abundance of Tillandsia species in a tropical dry forest of Mexico. Tillandsia species were sampled at sites corresponding to early, intermediate, and late stages of succession in 2007 and 2016, before and after two successive large hurricanes, Jova (October 2011; Category 2) and Patricia (October 2015; Category 5). Tillandsia species richness and abundance were greater in the late successional stage compared with intermediate and early stages, which did not differ from each other. In addition, both richness and abundance were positively correlated with the abundance of large trees. Tillandsia species richness and abundance were greater before than after hurricanes. We conclude that only old-growth forests or secondary forests in late successional stages can support large populations of Tillandsia species, probably because their recovery time is dependent on the presence of large host trees that provide higher quality substrates. Our results also demonstrated that catastrophic hurricane disturbances are important density-independent factors that decrease the species richness and abundance of Tillandsia epiphytes in tropical dry forests.