Red de áreas prioritarias para la conservación de la biodiversidad del Eje Volcánico Transmexicano analizando su riqueza florística y variabilidad climática

The Volcanic Belt of Mexico is located in the overlapping area of the Nearctic and Neotropical regions, which makes it the territory with the highest biological richness in Mexico. Based on the diverse flora (4 055 species of seed plants) of this area, as well as its vegetation types and climate variation, network scenarios are delimited to define priority areas for conservation. By means of complementarity metaheuristics analyses and considering three representation percentages (5%, 10% and 25%) of biological and environmental attributes, nine scenarios are described as a basis to define conservation areas in central Mexico. Those defined scenarios are compared with the Protected Areas and Priority Terrestrial Regions already existing in the Volcanic Belt area of Mexico. We found that some areas with a high biological richness are not yet included in any of the conservation areas, a fact that suggests the need to reassess the role that these areas play in protecting biodiversity in a medium and long term.El Eje Volcánico Transversal de México (EVT) es la zona donde se sobreponen las regiones Neártica y Neotropical, lo que ha contribuido para que ésta sea una de las zonas donde se concentra la mayor riqueza biológica del país. Con base en la riqueza florística (4 055 especies de plantas con semillas) de esta zona, los tipos de vegetación y variabilidad climática que la componen, se definen escenarios para definir redes de áreas prioritarias de conservación. Haciendo análisis de complementariedad metaheurísticos y considerando tres porcentajes (5%, 10% y 25%) de representación de atributos biológicos y ambientales, se definen nueve escenarios que sirven como base para delimitar áreas de conservación en el centro de México. Los escenarios definidos se comparan y analizan con las Áreas Naturales Protegidas y las Regiones Terrestres Prioritarias que han sido delimitadas dentro de la zona del Eje Volcánico Transversal de México. Se encontró que algunas zonas con mayor riqueza no se incluyen en ninguna de las áreas de conservación, lo que sugiere que es necesario reevaluar la función que estas áreas desempeñan en la protección de la biodiversidad a mediano y largo plazos

The Potential Distribution of Tree Species in Three Periods of Time under a Climate Change Scenario

Species distribution models have become some of the most important tools for the assessment of the impact of climatic change, and human activity, and for the detection of failure in silvicultural or conservation management plans. In this study, we modeled the potential distribution of 13 tree species of temperate forests distributed in the Mexican state Durango in the Sierra Madre Occidental, for three periods of time. Models were constructed for each period of time using 19 climate variables from the MaxEnt (Maximum Entropy algorithm) modelling algorithm. Those constructed for the future used a severe climate change scenario. When comparing the potential areas of the periods, some species such as Pinus durangensis (Martínez), Pinus teocote (Schiede ex Schltdl. & Cham.) and Quercus crassifolia (Bonpl.) showed no drastic changes. Rather, the models projected a slight reduction, displacement or fragmentation in the potential area of Pinus arizonica (Engelm.), P. cembroides (Zucc), P. engelmanni (Carr), P. leiophylla (Schl), Quercus arizonica (Sarg), Q. magnolifolia (Née) and Q. sideroxila (Humb. & Bonpl.) in the future period. Thus, establishing conservation and reforestation strategies in the medium and long term could guarantee a wide distribution of these species in the future

Sitios prioritarios para la conservación de la riqueza florística y el endemismo de la Sierra Norte de Oaxaca, México

Background and Aims: One of the main strategies for the protection of biological diversity is the es-tablishment of systems of areas for conservation, whose management minimizes the risks of extinction. Currently, in Mexico, protected areas cover approximately 12% of the country’s surface. However, there is a need to increase efforts to conserve plant diversity, especially at the middle altitudes of the mountai-nous areas of the country. Oaxaca is one of the states with greater biological diversity and endemisms; however, the natural areas that are decreed in the state are not sufficient to conserve their biological rich-ness. This study aims to define a network of conservation areas in the Sierra Norte of the state of Oaxaca, a region that is recognized for its great biodiversity. The Sierra Norte is an area of extensive forestry use and to date there are no areas decreed for the conservation of its biodiversity. Methods: Using climatic data and information about presence records of the species of the Asteraceae family, ecological niche models were developed to determine patterns of richness and to identify priority conservation sites. Results: The results identify a network of priority conservation sites within the forestry zones that would assist in the conservation of its great floristic richness. Conclusions: The important areas where conservation strategies could be proposed in the Sierra Norte de Oaxaca are identified. The use of species of Asteraceae as surrogates of biodiversity would work as an axis to concentrate future efforts of inventory and protection of floristic richness in such sites. The Network of Conservation Areas structured in this work will allow in the future to detect and select, with more solid conceptual bases, areas that can be integrated into the National System of Protected Areas.Antecedentes y Objetivos: Una de las principales estrategias para la protección de la diversidad bioló-gica es el establecimiento de sistemas de áreas para su conservación, cuyo manejo minimice los riesgos de extinción. Actualmente, en México las áreas protegidas cubren aproximadamente 12% de la superficie del país. No obstante, es necesario incrementar los esfuerzos de conservación de la diversidad vegetal, especialmente en las altitudes medias de las zonas montañosas del país. Oaxaca es uno de los estados con mayor diversidad biológica y endemismos; sin embargo, las áreas naturales protegidas que se encuentran decretadas en el estado no son suficientes para conservar su riqueza biológica. Este estudio se plantea con el objetivo de definir una red de áreas de conservación en la Sierra Norte del estado de Oaxaca, región que es reconocida por su biodiversidad. Es una zona de amplio aprovechamiento forestal y a la fecha no existen áreas decretadas para la conservación de su biodiversidad. Métodos: Usando datos climáticos y la información sobre registros de presencia de las especies de la familia Asteraceae, se elaboraron modelos de nicho ecológico para determinar patrones de riqueza e identificar sitios prioritarios de conservación. Resultados: Se identifica una red de sitios prioritarios para la conservación, dentro de las zonas con aprovechamiento forestal, que ayudarían en la conservación de la riqueza florística del estado. Conclusiones: Los resultados indican las áreas importantes donde se podrían plantear estrategias de conservación en la Sierra Norte de Oaxaca. El uso de especies de Asteraceae como subrogados de la biodiversidad funcionaría como eje para concentrar futuros esfuerzos de inventario y de protección de la riqueza florística en tales sitios. La Red de Áreas de Conservación estructurada en este trabajo permitirá en un futuro detectar y seleccionar, con bases conceptuales más sólidas, áreas que se integren al Sistema Nacional de Áreas Protegidas.

Análisis cariotípico de Agave marmorata y Agave peacockii (Agavaceae) ubicados en las terrazas aluviales del río Zapotitlán, Puebla, México

The aim of this study was to determine the spatial distribution, chromosome number and karyotype of Agave marmorata Roezl and Agave peacockii Croucher within Zapotitlan Salinas Valley, Puebla. This study reports for the first time the chromosome number of A. marmorata and A. peacockii, which shows that the ploidy levels of both species is 2n = 2x = 60. Moreover, the distribution of A. marmorata in the area is larger that, A. peacockii species only placed at southwestern zone. In conclusion, the spatial distribution of A. peacockii is limited by variation in soil conditions, vegetation types of the area, for being a diploid (2x) and their possible hybrid nature, so their presence in the area depends on the timing the flowering of the parents and their ability to reproduce, by sexual and asexual means.El objetivo de este estudio fue determinar la distribución espacial, el número cromosómico y el cariotipo de Agave marmorata Roezl y Agave peacockii Croucher dentro del Valle de Zapotitlán Salinas, Puebla. Este estudio reporta por primera vez el número cromosómico de A. marmorata y A. peacockii, cuyos niveles de ploidía en ambas especies es de 2n=2x=60. Por otra parte, la distribución de A. marmorata en el área estudiada es más amplia respeto de A. peacockii que únicamente se la encuentra al suroeste. La distribución espacial de A. peacockii está limitada por la variación en las condiciones del suelo, los tipos de vegetación de la zona, por su condición de diploide (2x) y su posible carácter híbrido, por lo tanto, su presencia en la zona depende de la sincronización de la floración de sus progenitores y su capacidad de reproducción sexual y asexual

Simulación del movimiento de partículas contaminantes sobre zonas de vulnerabilidad en el acuífero de los valles centrales de Oxaca

This study is an approach combined with the use of two indices and overlap methodologies: Matus for potential recharge zones and DRASTIC for aquifer vulnerability. In addition, an aquifer model of the Central Valleys made with MODFLOW software, together with a particle simulation method with the MODPATH package. It was found that the most vulnerable zones are: the cultivation area located 1.5 km northwest of San Lucas Quiavini, the body of water at 2.5 km northwest of San Miguel Tlanichico,agricultural land between Guadalupe and San Sebastián Etla and the urban area of San Francisco Telixtlahuaca. These areas are not only a danger for the water quality in the site, but can also affect nearby wells or distant communities, so that require special protection.El presente trabajo integra el uso de dos metodologías de índices y superposición: Matus para definir zonas potenciales de recarga hídrica y DRASTIC para reconocer la vulnerabilidad del acuífero. Además, se hizo una modelación del acuífero de los Valles Centrales de Oaxaca con MODFLOW, aunado a una simulación de partículas con el módulo MODPATH. Se encontró que las zonas más vulnerables a contaminantes son: el área de cultivo localizada a 1.5 km al noroeste de San Lucas Quiavini, el cuerpo de agua localizado a 2.5 km al noroeste de San Miguel Tlanichico, terrenos de cultivo entre Guadalupe y San Sebastián Etla y la zona urbana de San Francisco Telixtlahuaca. Estas áreas no solo son un peligro para la calidad de agua en el sitio, sino que podrían afectar a pozos o comunidades a kilómetros de distancia, por lo que requieren especial protección

Comparative Analysis of Three Forest Management Plans in Southern Mexico

In the middle of the last century, the Mexican government applied a forest administration policy based on state control through concessions to parastatal enterprises. In the 1980s, communities began to regain control of their forests and promote community forestry, with Ixtlán playing a leading role. This study compared three forest management plans (FMPs) that have been implemented in the community of Ixtlán de Juárez, in southern Mexico, and their contributions to the productivity and conservation of forest resources. The information was obtained from three FMPs, considering the silvicultural regimes, the original stand or sub-stand structure, and the species that promoted cutting regeneration. These FMPs represent different management periods; the forest inventory of the first FMP indicates the condition of the forest originated under state control, while the two subsequent ones evaluate the condition of the forest under community forestry. Sub-stand variables of the three FMPs were compared using the nonparametric Kruskal–Wallis test. The results indicated that, in the first FMP, the sub-stands were of old growth, and intensive thinning was applied. In the two subsequent plans, alternate strip clearcutting and single-tree selection were implemented. It was shown that, with increased management intensity in the sub-stands, better characteristics were obtained in terms of increment in basal area and volume variables, promoting regeneration and establishment of Pinus and displacing dominance of Quercus genus, without affecting forest richness and diversity