BackgroundCuatrociénegas is a region of unique biological, geological, geographical and evolutionary importance. It is part of the Chihuahua Desert, its current population is mestizo; however, it has a high historical, cultural and tourist relevance. It has been cataloged as a Flora and Fauna by Mexican law, as well as a High Protection site by the World Wildlife Fund and UNESCO. Because of its complex biological and sociocultural characteristics, we consider it important to know, determine, identify and analyze the traditional ethnobotanical knowledge and practices in this region.MethodsBetween 2016 and 2019, seven field trips were made to document the knowledge and use of flora. Cuatrociénegas is a protected area, collecting botanical material is regulated, so specimens were photographed and collected in neighboring communities, and in public and private gardens. Later permission was obtained to complete the collection of specimens (2019-2020). The plants were identified and entered into the flora database of the state of Coahuila, and deposited in the Herbarium of the Faculty of Forest Sciences, Autonomous University of Nuevo León, Mexico. One hundred and ten local residents (50 men and 60 women) aged between 27 and 91 years were interviewed (semi-structured interviews). The cultural importance of ethnobotanical resources (cultural significance index) and its significance with respect to ethnobotanical richness in other Biosphere Reserves in Mexico (Mann-Whitney test) ware evaluated.Results and DiscussionThe ethnobotanical information registers 158 species and 132 genera in 57 vascular and non-vascular families, documenting a greater knowledge and use of cultivated species (84) with respect to wild species (74). The diversity of plants reported, compared to other ethnobotanical studies carried out in Biosphere Reserves, is similar. The people local pay special attention to medicinal and ornamental plants. The species that presented the highest use values are Larrea tridentata, Jatropha dioica and Machaeranthera pinnatifida, three characteristic species of the desert region.ConclusionsThe particular diversity of wild flora in Cuatrociénegas Valley, combined with the varied introduced flora, is an important multifunctional resource. Special attention to introduced species is associated with use restrictions; as well as the high value of ornamental species, difficult to maintain in desert areas. The extensive knowledge and use of ethnobotany are an example that biocultural diversity (at the conceptual level) is also, strongly associated with socio-ecological system with mestizo groups and semi-urban rural landscapes, ceasing to be exclusive to indigenous regions.

The sierra de Zapalinamé lies at the southeastern portian of the State of Coahuila, in a transitional area between the Chihuahuan Desert Region and the Sierra Madre Oriental. lt has the status of a protected natural area by the state government. The Chihuahuan desert scrub is the most common vegetation type; however, spruce forest grows where the climate conditions are cold and temperate. Ten circular plots of 1,000 m2 were established to determine the floristic composition, structure of the forest and other ecological variables. Diameter and height were measured for every tree and shrubs and herbs were recorded. Seedlings were evaluated in five plots of 2 m2 per site. Attributes of the vegetation like density, basal area and the importance value of the tree species were estimated. The spruce forest of the sierra de Zapalinamé is found between 2,668 to 3,025 m of elevation where the annual average precipitation rain varies from 560 to 600 mm and with a temperature of 12.5ºC, over litosol soils with a slope of 34% to 70%. The forest is dominated by Abies vejarii, species which grows at elevated places and another important species is Pseudotsuga menziesii. Regeneration is of a few seedlings; nevertheless, due to microclime and soil sorne regeneration is successful. A total 73 species were recorded in these forests, being the most diverse Asteraceae (15 species), Pinaceae (4) and Poaceae (4). Conservation of the spruce forest is important due to its ecological value; in addition Abies vejarii is listed under status of conservation in the Mexican red list, and also because a number endemic species of plants are in this protected area.

Background Cuatrociénegas, part of the Chihuahuan Desert, is a region of unique biological, geological, geographical, and evolutionary importance. Its current population is mestizo; nevertheless, it has high national historical, cultural, and touristic relevance in Mexico. It has been cataloged as nationally significant for its flora and fauna by Mexican law, as well as being designated a High Protection site by the World Wildlife Fund and UNESCO. Because of its diverse and complex biological and sociocultural characteristics, we considered it important to determine, identify, and analyze various aspects of the traditional ethnobotanical knowledge and practices in this region. Methods Between 2016 and 2019, seven field trips were made to document the knowledge and use of flora. Cuatrociénegas is a protected area, collecting botanical material is regulated, so specimens were photographed and collected in neighboring communities, and in public and private gardens. Later permission was obtained to complete the collection of specimens (2019–2020). The plants were identified and entered into the flora database of the state of Coahuila, and deposited in the Herbarium of the Faculty of Forest Sciences, Autonomous University of Nuevo León, Mexico. One hundred ten local residents (50 men and 60 women), aged between 27 and 91 years, were interviewed (semi-structured interviews). The cultural importance of ethnobotanical resources (cultural significance index) and its significance with respect to ethnobotanical richness in other Biosphere Reserves in Mexico (Mann-Whitney test), and similarities in the diversity of exotic species (Sørensen index) were studied. Results and discussion The ethnobotanical information registers 158 species and 132 genera in 57 vascular and non-vascular families, documenting a greater knowledge and use of cultivated species (84) with respect to wild species (74). The diversity of plants reported is compared to other ethnobotanical studies carried out in Mexican Biosphere Reserves. These results are highly relevant, in spite of unique exotic species. The people local pay special attention to medicinal and ornamental plants. The species that presented the highest use values are Larrea tridentata, Jatropha dioica, and Machaeranthera pinnatifida, three species characteristic of the desert region. Conclusions The particular diversity of wild flora in Cuatrociénegas Valley, combined with the varied introduced flora, is an important multifunctional resource. Special attention to introduced species is associated with harvesting use restrictions in the protected area as well as the high value of ornamental species that are difficult to maintain in desert areas. The extensive use of ethnobotanical knowledge is an example that biocultural diversity (at the conceptual level) is also strongly associated with socio-ecological systems incorporating mestizo groups and semi-urban rural landscapes, thus ceasing to be an exclusive focus of indigenous communities and regions.

Quantitative data on the ecology of the main plant communities along an altitudinal gradient in northeastern Mexico were obtained with the aim of identifying the most important environmental variables that affect plant distribution and composition. The main threats to these communities were also investigated. Importance value index (IVi) of the 39 most important species and 16 environmental variables were recorded at 35 altitudinal gradients each spaced at intervals of at least 100-m altitude. Classification and ordination of vegetation showed six well-differentiated but overlapping plant communities: alpine meadow, cold conifer forest, mesic mixed forest, xeric scrub, Tamaulipan piedmont scrub, and halophytic grassland. Altitude, minimum and average temperatures, and organic matter content are the main variables affecting the plant distribution in northeastern Mexico. Urban growth, mechanized agriculture, and changes in land use are the main threats in the short and medium term to plant communities in this area. Climate change also seems to be having an impact at present or in the near future as shown by the presence of exotic shrubs from warmer areas in mesic and temperate areas inhabited by oak and oak-pine forest.

RESUMENSe revisa la distribución de especies de plantas endémicas tomando como base el concepto de Megacoahuila, que amplía la superficie del estado en más de 100%. La región ofrece variación climática y fisiográfica que da lugar a la presencia de al menos 13 tipos de vegetación de los que el matorral desértico es el dominante. Se presenta un listado de 350 especies y taxa infraespecíficos. Esta cifra representa 11.2% del total de la flora. Los tipos de vegetación con mayor incidencia de elementos con distribución restringida son los matorrales micrófilo y rosetófilo y la localidad con el mayor número es Cuatro Ciénegas. Se sugiere la creación de reservas bióticas en las áreas particularmente ricas en endemismos.Palabras clave: Coahuila, endemismo, Megacoahuila, México, plantas vasculares. ABSTRACTA review is made of the endemic plants following the Megacoahuila concept, that increases the state area for more than 100%. The region has climatic and physiographic variation that leads to the development of at least 13 main vegetation types, the desert shrubland being the dominant one. A total of 350 species and infraspecific taxa are listed, representing 11.2% of the total flora. The desert shrubland (matorrales micrófilo y rosetófilo) is the vegetation with the highest endemism and the Cuatro Cienegas basin the richest locality. The areas with highest endemism are suggested to be considered biotic reserves.

The objective of this study was to investigate the influence of environmental and soil factors on the structure and floristic woody composition of oak forests. Oak forests of the Sierra de Zapalinamé in northeastern Mexico (25°N) are distributed in canyons and northwest slopes with higher humidity, surrounded by montane chaparral. We carried out a vegetation inventory across an altitudinal gradient. All trees with diameter at breast height of ≥3 cm were identified and measured. In addition, the cover of understory species was measured in each plot. Using multivariate techniques, we detected two oak forest associations: Quercus greggii -Q. mexicana forest and Q. saltillensis -Q. laeta forest. The forests studied are rich in woody species, including 19 tree and 50 shrub species. The number of tree species decreased at lower elevations, but the shrub species increased. Environmental variables evaluated included elevation, precipitation, temperature, soil pH and electrical conductivity, and soil percentage of sand, clay, and silt. All these variables revealed significant differences for the two oak forest associations. With respect to biotic parameters, significant differences (P < 0.05) in basal area were observed. Multivariate analysis revealed the species distribution along a moisture gradient across elevation. The ecological study of oak forests provides the basis for future research on forest dynamics and can guide conservation efforts to maintain species diversity and endemism in the mountain studied.

In order to describe community structure and richness in oak and walnut forests occurring along the San Rodrigo, San Diego, Escondido and Arroyo de las Vacas rivers on the Northeastern Coastal Plain (NE Coahuila, Mexico), we established 30 1 000-m 2 circular plots, where we measured diameter at breast height (DBH) and tree heights. Tree regeneration and herb and shrub stratum were assessed in 5 2-m 2 quadrats per site. A total of 48 species distributed in 29 families were recorded. Families with the largest richness were Poaceae, Asteraceae, and Malvaceae. For the oak forest, tree stratum density and basal area values were 386 stems/ha and 24.36 m 2 /ha, respectively, whereas for the walnut forest the corresponding values were 302 stems/ha and 21.26 m 2 /ha. The species with the highest relative importance values were Quercus fusiformis (59.48%) and Carya illinoinensis (57.58%). Total tree richness was 14 species, the most common ones being Celtis reticulata and Diospyros texana, followed closely by C. illinoinensis and Q. fusiformis. Anthropogenic impact appears to result in a poor regeneration reflected as a low sapling density, as well as in the reduction and fragmentation of these communities; in turn, this process has led to intrusions of species typical of the xerophytic Tamaulipan Thorn Scrub. Further studies are needed on the regeneration of the dominant species of these forests in order to describe their dynamics and to promote their preservation.

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