Amphipterygium adstringens (Schltdl.) Schiede ex Standl (Anacardiaceae): An Endemic Plant with Relevant Pharmacological Properties.

Diseases, such as cancer, peptic ulcers, and diabetes, as well as those caused by drug-resistant infectious agents are examples of some of the world's major public health problems. Amphipterygium adstringens (Schltdl.) Schiede ex Standl is an endemic tree to Mexico. Its stem bark has been used medicinally since pre-Hispanic times, but in recent decades it has been scientifically proven that it has properties that help counteract some diseases; extracts with organic solvents of the plant are outstanding for their anticancer, gastroprotective, and antimicrobial properties; terpenes and long-chain phenols have been identified as the main active compounds. Currently, overharvesting is causing a sharp reduction in natural populations due to an increase in demand for the stem bark by people seeking to improve their health and by national and transnational companies seeking to market it. Because of the growing interest of the world population and the scientific community, we reviewed recent studies on the bioactive properties of A. adstringens. Through the orderly and critical compendium of the current knowledge of A. adstringens, we provide a reference for future studies aimed at the rational use and protection of this valuable endemic natural resource.

Tree structure and diversity of a Humid Mountain Forest in the protected natural area La Martinica, Veracruz, Mexico / Estructura y diversidad arbórea de un bosque húmedo de montaña en el Área Natural Protegida La Martinica, Veracruz, México

Abstract Introduction: The Humid Mountain Forest (HMF) has the highest number of plants per unit of surface, whose vegetation grows under heterogeneous environmental conditions and possess a high floristic variation. HMF conservation is important due to the biodiversity it harbors and the environmental services it provides. Objective: This work evaluated the effect of the terrain aspect and density of the forest canopy on the structure and tree diversity in La Martinica Protected Natural Area, Mexico. Methods: Stratified sampling was performed in four terrain aspects and two canopy density conditions. Twenty five sampling units of 20 x 25 m were considered, in which the normal diameter (ND), total height and the largest and smallest diameters of the crown of the individuals with a ND ≥ 10 cm were registered. The diversity was estimated by rarefaction curves and the structure was analyzed through the importance value index (IVI) and the forest value index (FVI). Results: 37 species belonging to 30 genera and 24 families were recorded. Greater diversity was observed in the north terrain aspect and in the closed canopy. Tree species with the highest structural values were different between terrain aspect and canopy types; Carpinus tropicalis presented the highest values in the zenithal terrain aspect, Lippia myriocephala in the east and south terrain aspect, and Liquidambar styraciflua in the north. In both canopy types Lippia myriocephala obtained the highest IVI values and FVI in the open canopy; Carpinus tropicalis reached a higher FVI in the closed canopy. Conclusions: Tree structure was different in the four terrain aspects and two canopy conditions studied. The greatest difference in species composition and diversity was observed between the north and east terrain aspects; the north presented the highest richness values, frequent and dominant species.

Resumen Introducción: El Bosque Húmedo de Montaña (BHM) posee el mayor número de especies vegetales por unidad de superficie, cuya vegetación se desarrolla en condiciones ambientales muy heterogéneas y presenta una alta variación florística. La conservación del BHM es importante debido a la biodiversidad que alberga y los servicios ambientales que proporciona. Objetivo: Este trabajo evaluó el efecto de la orientación del terreno y la densidad del dosel del bosque sobre la estructura y diversidad arbórea en el Área Natural Protegida La Martinica, México. Métodos: Se efectuó un muestreo estratificado en cuatro orientaciones del terreno y dos condiciones de densidad del dosel; se consideraron 25 unidades de muestreo de 20 x 25 m, en las que se registró: el diámetro normal (DN), la altura total y los diámetros mayor y menor de la copa de los individuos con un DN ≥10 cm. La diversidad se estimó por medio de curvas de rarefacción y la estructura se analizó con el índice de valor de importancia (IVI) y el índice de valor forestal (IVF). Resultados: Se registraron 37 especies pertenecientes a 30 géneros y 24 familias. Se observó una mayor diversidad en la orientación norte y en el dosel cerrado. Las especies arbóreas con valores estructurales más altos fueron diferentes entre orientaciones y tipos de dosel; Carpinus tropicalis presentó los valores más elevados en la orientación cenital, Lippia myriocephala en las orientaciones este y sur, y Liquidambar styraciflua en la norte. En ambos tipos de dosel Lippia myriocephala obtuvo los valores más altos del IVI e IVF en el dosel abierto; Carpinus tropicalis alcanzó un IVF más elevado en el dosel cerrado. Conclusiones: La estructura arbórea fue diferente en las cuatro orientaciones estudiadas y en las dos condiciones del dosel. La mayor diferencia en composición de especies y diversidad se observó entre las orientaciones norte y este, de ellas, la norte presentó los valores más altos de riqueza, especies frecuentes y dominantes.

Climate and categories: Two key elements for understanding the Mesoamerican hot-cold classification of illnesses and medicinal plants.

ETHNOPHARMACOLOGICAL RELEVANCE: The concepts of health and illness, and their causes, are fundamental for understanding medicinal plant choice and use by traditional people. The hot-cold system is widespread in Mesoamerican traditional medicine and guides many therapeutic decisions. AIM OF THE STUDY: This study explores a hypothesis that climate influences the hot-cold classification of illnesses and medicinal plants, and the perception of hazard of illnesses. In addition, we examine the classification categories within the system used in different regions of Mexico. MATERIALS AND METHODS: Studies from Mexico with quantitative and qualitative data on the hot-cold properties of medicinal plants and ailments were reviewed. The information was organized and then related to the climate type of the study areas. RESULTS: In temperate climates, most diseases were considered cold, and hot medicinal plants were dominant. Conversely, in warm-tropical climates, hot diseases dominated, and the majority of medicinal plants were cold; however, this evidence was weaker. The perception of hazard was congruent with the number of illnesses for temperate climates. There were additional classification categories within the hot-cold system for diseases and medicinal plants, and they were expressed in different terms in Spanish, English, and indigenous languages. Although similar terms and categories were used in the classification of diseases and medicinal plants, they can differ conceptually and vary between places and cultures. Publications are sometimes unclear if the terms used are emic or etic. The basic principle of using plants with the opposite property of the disease does not always apply strictly. CONCLUSIONS: Climate appears to influence the hot-cold classification of diseases and medicinal plants in Mexico, and the system is not strictly dual. Improved knowledge of the hot-cold system is necessary to understand Mesoamerican medicinal plant use and culture.

Domestication of aromatic medicinal plants in Mexico: Agastache (Lamiaceae)-an ethnobotanical, morpho-physiological, and phytochemical analysis.

BACKGROUND: Most reports of domesticated plants that involve a domestication gradient or inter-specific hybridization in Mexico have focused on those used as food. This study provides knowledge about these processes in two aromatic medicinal plants, Agastache mexicana (Lamiaceae) and A. m. subsp. xolocotziana, widely used in Mexican traditional medicine for the treatment of gastrointestinal ailments and for their sedative effect. Different populations of A. mexicana along a gradient of domestication are found in the foothills of the Popocatepetl volcano of central Mexico, while in this same area the subsp. xolocotziana grows only in the cultivation, possibly a product of hybridization between A. mexicana and Agastache palmeri. This study links ethnobotanical, morpho-physiological, and phytochemical evidence to document the domestication of both taxa as well as elucidates the possible hybrid origin of the subsp. xolocotziana. METHOD: We analyze three groups of data derived from (1) 80 semi-structured interviews aimed at documenting the selection criteria related to the use and management of A. mexicana; (2) a cultivation experiment under homogeneous conditions, evaluating 21 floral, vegetative, and seed characters (that were important according to ethnobotanical information) in 97 plants corresponding to 13 populations of the taxa under study; and (3) the chemical profiles of the essential oils of these plants by means of a thin-layer chromatography. RESULTS: By linking the three types of evidence, two evolutionary processes are distinguished: (1) A. mexicana occurs in the encouraged-cultivated phases of the domestication gradient and (2) A. m. subsp. xolocotziana may have originated through inbreeding depression or hybridization. These two cultivated plants show a domestication syndrome based upon organoleptic differentiation due to their dissimilar phytochemical composition and gigantism in flowers, seeds, and rhizomes (the last enhancing their asexual reproductive capacity). In addition to this, A. mexicana exhibits more intense floral pigmentation and foliar gigantism while subsp. xolocotziana presents floral albinism and partial seed sterility. CONCLUSION: Two divergent evolutionary processes are reported for the domestication of A. mexicana as a result of the intensification of its use and management. The selection processes of these plants have resulted in alternation of the organoleptic properties based upon the divergence of the phytochemical composition. Also, gigantism has been selected in culturally preferred plant parts and in correlated structures. The preceding characteristics reinforce the joint use of these plants in infusion in Mexican traditionalmedicine for the treatment of gastrointestinal diseases and for their sedative effects.

Plantas medicinales utilizadas para enfermedades del sistema digestivo en Tetela del Volcán, Estado de Morelos, México / Medicinal plants used for diseases of the digestive system in Tetela del Volcan, State of Morelos, Mexico

The medicinal plants has been used since Prehispanic times by Mexican people to treat digestive diseases. Nowadays their use is a common practice in the poor communities. This work describes the traditional use of medicinal plants to cure these type of ailment in the community of Tetela del Volcán. Guided collect of botanical material and a total of 92 semi-structured interviews to 58 people were carried out. A total of 78 species, 70 genus and 36 families were registered. The families Asteracea and Lamiaceae predominanted culturally. Most of the species were cultivated and branches were preferably utilized. Of the total of 24 diseases, stomach pain and diarrhea were the most important. The species Matricaria chamomilla L., Mentha x piperita L., Artemisia absinthium L. y Psidium guajava L had the highest modified Friedman Fidelity Indexes. This biocultural heritage contributes to health, thus to the well-bearing of inhabitants of Tetela del Volcán.

Los mexicanos han utilizado las plantas medicinales para las enfermedades del sistema digestivo desde la época prehispánica, actualmente son particularmente empleadas en las comunidades pobres. Se describe el uso de las plantas medicinales para curar dicho tipo de padecimientos en la comunidad de Tetela del Volcán. Se realizaron colectas guiadas de material botánico y 92 entrevistas semi- estructuradas a 59 informantes. Se registraron 78 especies pertenecientes a 70 géneros y 36 familias. Las familias Asteracea y Lamiaceae dominan culturalmente. La mayoría de las especies son cultivadas y se usan preferentemente las ramas. De 24 enfermedades, el dolor de estómago y la diarrea fueron las más importantes. Las especies Matricaria chamomilla L., Mentha x piperita L., Artemisia absinthium L. y Psidium guajava L. tuvieron los mayores Índices de Fidelidad de Friedman modificados. Este patrimonio biocultural contribuye en la salud y, por lo tanto, al bienestar de los habitantes de Tetela del Volcán.

Traditional and formal ecological knowledge to assess harvesting and conservation of a Mexican Tropical Dry Forest.

This research integrates Traditional and Formal Ecological Knowledge (TEK / FEK) of a Tropical Dry Forest in central Mexico, in order to assess harvesting and conservation of the non-timber forest species. We were interested in: knowing the structure and diversity of the forest community; identifying which are the tree resources of common interest to the users through participatory workshops. A further interest was to identify those resources which are important to local people in terms of preservation; explaining the relationship of the species with some environmental factors; and visualizing which management practices endanger or facilitate the conservation of species. Studied areas were defined and labelled on a map drawn by local informants, where they indicated those plant species of common interest for preservation. Ethnobotanical techniques were used to reveal the TEK and assess harvesting and conservation of the species. With the FEK through community and population ecology, we detected the importance of five environmental factors, obtained various ecological indicators of the vegetation, and studied the population structure of the relevant species. The FEK was analyzed using descriptive and multivariate statistics. As a result, low density and small basal area of trees were registered. Species richness and diversity index were similar to other natural protected areas in Mexico. Tree species harvested shown an asymmetric distribution of diameters. Harvesting, elevation, and accessibility were the most influential factors on tree density. FEK demonstrated that TEK is helpful for the assessment of forest harvesting. Ecological analysis complemented the local knowledge detecting that Lysiloma tergemina is a species non-identified for the people as interesting, although we discover that it is a threatened species by over-harvesting. Haematoxylum brasiletto was identified as important for conservation due to its scarcity and medicinal use. Our results advanced on how the traditional harvesting of tree community has contributed to preserve diversity, when comparing with protected areas. Discrepancies between both kinds of knowledge should be reconciled for contributing to the preservation of priority resources by the local society.

Traditional uses and seed chemical composition of Jatropha spp. (Euphorbiaceae) in Tehuacán-Cuicatlán, México / Usos tradicionales y composición química de la semilla de Jatropha spp. (Euphorbiaceae) en Tehuacán-Cuicatlán, México

Abstract The Tehuacán-Cuicatlán Biosphere Reserve in México holds genetic richness and endemism for the genus Jatropha, but the specific use of the plants and the seed chemical profiles are still unknown. We recorded the traditional forms of use of Jatropha species, and analyzed the chemical composition of Jatropha spp. seeds. For this, a semi-structured survey was conducted in 15 towns, and 20 interviews were applied in each one between May and August 2012 to estimate the Significant Use Level and Relative Use Value per species. Besides, seeds from J. neopauciflora, J. rufescens, and J. rzedowskii were collected between August and October 2013, and to seed flour samples we determined total lipids by the Soxhlet method, crude protein by the Kjendahl method, and ashes according to AOAC methods; fatty acid profile and phorbol esters were determined by gas chromatography and by HPLC, respectively. The species J. neopauciflora, J. oaxacana, J. rufescens, J. ciliata, and J. rzedowskii, are used as traditional medicine, food, and ornaments, except for J. ciliata, for which none use was recorded. The Significant Use Level as food was found not significant, but for medicinal purposes, J. neopauciflora obtained the highest Relative Use Value (9.0 %). The latex is used to treat 13 disorders, including dental problems and oral diseases with a Significant Use Level of 32.9 %; it is also used as a hemostatic. The protein content among species varied from 23.37 to 26.06 %, and total lipids from 34.79 to 36.60 %. The principal unsaturated fatty acids were oleic (25.08 to 30.09 %) and linoleic (44.55 to 48.46 %), and the saturated fatty acids were palmitic (10.11 to 16.50 %) and stearic (9.47 to 11.15 %). Phorbol esters, the main cause of seed's toxicity, were absent in J. neopauciflora, J. rufescens, and J. rzedowskii. In conclusion, the Significant Use Level of Jatropha species studied was low, with little cultural acceptance and sporadic utilization. The Relative Use Value was important for medicinal purposes, especially for J. neopauciflora. The dehulled seeds of J. neopauciflora, J. rufescens, and J. rzedowskii are potentially useful as food, having high protein contents, and unsaturated oleic and linoleic fatty acids. With this study we report three non-toxic Jatropha species and recommend to scientifically validate the antimycotic use of J. neopauciflora latex. Rev. Biol. Trop. 66(1): 266-279. Epub 2018 March 01.

Resumen La Reserva de la Biosfera Tehuacán-Cuicatlán, México contiene riqueza genética y endemismo para el género Jatropha, pero se desconoce el uso específico de las plantas y la composición química de la semilla. Documentamos las formas tradicionales de uso de las especies de Jatropha y, analizamos la composición química de las semillas de las especies de Jatropha. En 15 comunidades se aplicaron 20 entrevistas semiestructuradas entre mayo y agosto de 2012 para estimar el Nivel de Uso Significativo y el Valor de Uso Relativo por especie. Se colectó semilla solo de J. neopauciflora, J. rufescens, y J. rzedowskii entre agosto y octubre de 2013 para determinar mediante los métodos de la AOAC, el contenido total de lípidos en una muestra de 3 g de harina mediante el método de Soxhlet, proteína cruda en una muestra de harina de 0.4 g por el método Kjendahl y ceniza en una muestra de 5 g de harina. El perfil de ácidos grasos se determinó por cromatografía de gases y el contenido de ésteres de forbol mediante HPLC. Las especies registradas fueron J. neopauciflora, J. oaxacana, J. rufescens, J. rzedowskii y J. ciliata, que se usan en medicina tradicional, alimento y como ornamental, excepto J. ciliata, para la cual no se reportó ningún uso. El Nivel de Uso Significativo como alimento no fue importante, pero para propósitos medicinales J. neopauciflora tuvo el mayor Valor de Uso Relativo (9.0 %). El látex es usado para tratar 13 trastornos, incluyendo problemas dentales y enfermedades bucales con un Nivel Significativo de Uso de 32.9 %; y también es usada como hemostático. El contenido de proteína entre especies varió de 23.37 a 26.06 % y los lípidos totales variaron de 34.79 a 36.60 %. Los principales ácidos grasos insaturados fueron oleico (25.08 a 30.09 %) y linoleico (44.55 a 48.46 %); los ácidos grasos saturados fueron palmítico (10.11 a 16.50 %) y esteárico (9.47 a 11.15 %). No se detectó la presencia de ésteres de forbol (la causa principal de la toxicidad de la semilla) en J. neopauciflora, J. rufescens, y J. rzedowskii. En conclusión, el Nivel de Uso Significativo de las especies de Jatropha fue bajo, con poca aceptación cultural y utilización esporádica. El Valor de Uso Relativo fue importante para propósitos medicinales, especialmente para J. neopauciflora. Las semillas sin testa de J. neopauciflora, J. rufescens, y J. rzedowskii son potencialmente útiles como alimento por su alto contenido de proteínas, ácidos grasos insaturados oleico y linoleico. Se identificaron tres especies no toxicas de Jatropha. Se recomienda validar científicamente el uso antimicótico del látex de J. neopauciflora.

Variación arquitectónica y morfológica de Hintonia latiflora (Rubiaceae) en relación a la cosecha de corteza y factores ambientales / Architectural and morphological variation of Hintonia latiflora (Rubiaceae) in relation to bark harvest and environmental factors

ResumenHintonia latiflora es una especie ecológicamente rara y económicamente importante del bosque tropical caducifolio de la Cuenca del Balsas, México, cuya corteza se comercializa como medicinal. Las prácticas de descortezado han modificado la forma de las plantas, su arquitectura y morfometría. Se desconoce, si además, existe influencia de factores topogáficos y edáficos sobre estos atributos. Se propone que las condiciones ecológicas en las áreas de distribución y cosecha determinarán las características morfométricas y la variación de la arquitectura de los individuos. Para probar esta hipótesis, evaluamos la relación de factores topográficos y edáficos en diferentes características morfológicas de juveniles (n = 143) y adultos (n = 117) de ocho zonas de cosecha de H. latiflora. Las zonas de cosecha, con una superficie de 0.6 ha, fueron seleccionadas al azar con el apoyo de mapas participativos elaborados por los recolectores del área de estudio. Los datos fueron analizados mediante componentes principales (ACP), y correspondencia canónica (ACC). Los primeros tres CP explicaron el 92.1 % de la variación morfológica; la altura, diámetro basal y cobertura fueron las variables que explicaron las diferencias morfométricas entre juveniles y adultos en las ocho zonas de cosecha. La pendiente del terreno, orientación de la pendiente, profundidad del suelo y pedregosidad, fueron los factores ecológicos estadísticamente relacionados con las diferencias morfométricas. Una menor pendiente, poca pedregosidad, profundidad de suelo, orientación E-O en juveniles (azimut 90˚-270˚) y N-S en adultos (azimuth 0˚-180˚), fueron los factores asociados a mayor altura, número de ramas basales, diámetro basal y cobertura en H. latiflora. Las zonas con mayor intensidad de cosecha estuvieron integradas por árboles monopódicos y algunos individuos basítonos reiterados. Los adultos de estas zonas tuvieron mayor número de frutos. En estos sitios, las plantas de H. latiflora fueron más abundantes y productivas para corteza, pero la alta intensidad de cosecha influyó en la arquitectura vegetal, formando individuos arbustivos multirramificados que originalmente fueron mesótonos. Las áreas con menor intensidad de cosecha estuvieron caracterizadas por pendientes abruptas, suelos superficiales y pedregosos, dominadas por árboles basítonos de menor talla, delgados y escasos en el área. Estos sitios son los menos recomendados para cosecha, debido a que producen menos corteza por árbol, pero sirven para mantener a la especie en el lugar. Con base en estos resultados, podemos desarrollar programas de rehabilitación en áreas afectadas por la explotación comercial, establecer plantaciones forestales en sitios clave para asegurar el desarrollo de individuos con características deseables para cosecha de corteza y contribuir a la conservación in situ de H. latiflora en la Cuenca del Alto Balsas.

AbstractHintonia latiflora is a rare ecologically and economically important species from the Tropical Deciduous Forest of the Balsas Basin, Mexico, whose bark is traded as medicinal. Debarking practices have modified the shape of plants, their architecture and morphometry; but it is unknown if some topographic and edaphic factors may also influence in these attributes. Here we propose that the ecological conditions of this species distribution and harvesting areas, may determine the morphometric characteristics and the individuals variation in their architecture. To test this hypothesis we assessed the relationship of topographic and edaphic factors on the morphological characteristics of saplings (n = 143) and adults (n = 117), in eight harvesting areas of H. latiflora. The harvesting areas, with a surface of 0.6 ha, were selected randomly with the support of participatory mapping elaborated by gatherers of the study site. Data were analyzed using principal components (PCA) and canonical correspondence (CCA) analyses. The first three PC explained 92.1 % of the morphological variation; height, basal diameter, and coverage, explained morphometric differences in both, saplings and adults, in all eight harvesting zones. The terrain slope, slope orientation, soil depth and stoniness, were ecological factors statistically related with morphometric differences. A lower terrain slope, little stoniness, soil depth, slope orientation E-W in saplings (azimuth 90˚-270˚) and N-S in adults (azimuth 0˚-180˚) were the factors associated to height, number of basal branches, basal diameter and coverage of H. latiflora. Areas with higher harvesting intensity were composed by monopodic trees and some reiterated basitone individuals; the adults of these areas also had more fruits. At these sites, plants of H.latiflora were more abundant and produced more bark, but the high-intensity of harvesting, changes plant architecture, forming shrubby, multi-stemmed individuals, that originally were mesotone trees. Areas with lower harvesting intensity were characterized by steep slopes, shallow and rocky soils, and were dominated by basitone trees of smaller size, thin and scarce in the area. These sites are the least recommended for harvesting, because they produce less bark per tree, and serve to preserve the species at the site. Based on these results, we can develop restoration programs in areas affected by commercial harvesting, establish forestry plantations in key sites to ensure the establishment and development of individuals with desirable characteristics for bark harvesting and contribute to in situ conservation of H. latiflora in the Alto Balsas Basin. Rev. Biol. Trop. 65 (3): 900-916. Epub 2017 September 01.

Prosopis laevigata and Mimosa biuncifera (Leguminosae), jointly influence plant diversity and soil fertility of a Mexican semiarid ecosystem.

Prosopis laevigata and Mimosa biuncifera are frequently found in arid and semiarid shrublands, but scarce information is available about their influence on plant community structure and soil fertility. We compared plant community structure, diversity and soil nutrients of three semiarid shrubland sites located in Mezquital Valley, Mexico. These sites differ in their dominant species: Site 1 (Bingu) P. laevigata, Site 2 (González) M. biuncifera, and Site 3 (Rincón) with the presence of both legumes. The results showed that the plant community with P. laevigata and M. biuncifera (Site 3) had more cover, taller plants and higher plant diversity than sites with only one legume (Site 1 and Site 2). Soil organic matter (SOM), soil organic carbon (SOC), total nitrogen (TN), phosphorus-Olsen (P) and C mineralization were higher in the soil under the canopy of both legumes than in bare soil. In contrast, soil cation concentrations were lower under the canopy of P. laevigata, but not for M. biuncifera. In addition, the density of arbuscular mycorrhizal fungi spores was higher within the soil under the canopy of M. biuncifera than in the soil under the canopy of P. laevigata. Thus, resource islands (RI) created by P. laevigata increased the amounts of SOC, TN and P when compared with the RI of M. biuncifera. This study provided evidences about the importance of species identity in order to expand the niche availability for the establishment of other plants, and highlights that P. laevigata and M. biuncifera jointly influencing plant colonization within semiarid ecosystems.

Prosopis laevigata and Mimosa biuncifera (Leguminosae), jointly influence plant diversity and soil fertility of a Mexican semiarid ecosystem

Prosopis laevigata and Mimosa biuncifera are frequently found in arid and semiarid shrublands, but scarce information is available about their influence on plant community structure and soil fertility. We compared plant community structure, diversity and soil nutrients of three semiarid shrubland sites located in Mezquital Valley, Mexico. These sites differ in their dominant species: Site 1 (Bingu) P. laevigata, Site 2 (González) M. biuncifera, and Site 3 (Rincón) with the presence of both legumes. The results showed that the plant community with P. laevigata and M. biuncifera (Site 3) had more cover, taller plants and higher plant diversity than sites with only one legume (Site 1 and Site 2). Soil organic matter (SOM), soil organic carbon (SOC), total nitrogen (TN), phosphorus-Olsen (P) and C mineralization were higher in the soil under the canopy of both legumes than in bare soil. In contrast, soil cation concentrations were lower under the canopy of P. laevigata, but not for M. biuncifera. In addition, the density of arbuscular mycorrhizal fungi spores was higher within the soil under the canopy of M. biuncifera than in the soil under the canopy of P. laevigata. Thus, resource islands (RI) created by P. laevigata increased the amounts of SOC, TN and P when compared with the RI of M. biuncifera. This study provided evidences about the importance of species identity in order to expand the niche availability for the establishment of other plants, and highlights that P. laevigata and M. biuncifera jointly influencing plant colonization within semiarid ecosystems.

Prosopis laevigata y Mimosa biuncifera coexisten en los matorrales semiáridos; sin embargo, se desconoce su influencia sobre la diversidad de la comunidad vegetal y el suelo. Este estudio evaluó el efecto de P. laevigata y M. biuncifera sobre la estructura, diversidad vegetal y nutrimentos del suelo, en tres matorrales del Valle del Mezquital, México. Los sitios difieren en la especie dominante: Sitio 1, P. laevigata; Sitio 2, M. biuncifera y Sitio 3, ambas leguminosas. En cada sitio se recolectó suelo, tanto abajo y fuera del dosel de las leguminosas, además, se realizaron transectos para medir e identificar las plantas arbóreas y arbustivas, se calculó el índice de valor de importancia y la diversidad del matorral. Asimismo, se registró mayor riqueza y diversidad en el Sitio 3 (ICE 29 spp. y H’ 2.7), en comparación con el Sitio 1 (24 spp. y 2.4) y Sitio 2 (26 spp. y 2.1). La materia orgánica y el carbono orgánico del suelo, así como el N total, el P-Olsen y la mineralización de C fueron mayores en el suelo bajo dosel de ambas leguminosas. La abundancia de esporas de hongos micorrizógenos arbusculares fue favorecida por M. biunficera. La influencia de P. laevigata para crear islas más ricas en recursos fue mayor que en M. biunficera, lo anterior sugiere que cada leguminosa modifica de una forma diferente el microambiente, sin embargo, juntas aumentan la disponibilidad de nichos para el establecimiento de otras especies, lo queayuda a comprender el papel de P. laevigata y M. biuncifera sobre la colonización vegetal en ecosistemas semiáridos.