DISTRIBUCIÓN Y ABUNDANCIA DE LAS ESPECIES ARBÓREAS Y ARBUSTIVAS EN LA SIERRA FRÍA, AGUASCALIENTES, MÉXICO

Our objectives were to recognize the composition of forest species, characterize theirdistribution and abundance, and identifythe factors that determine their presence orabsence in the area of Sierra Fria, Aguascalientes, Mexico. A sampling plan was elaborated using three criteria: altitude, relief andforest cover. Sixty samplings were realizedin sites of 600 m2 and randomized in different solar expositions. The arboreal andbrush species, the frequency, and ecologicalconditions that determine their presence or100Núm. 34: 99-126 Agosto 2012absence in site were identified. A CanonicalCorrespondence Analysis and Montecarlo’stest (α≤0.05) was conducted. We identified50 species; three are new reports in the area.Quercus potosina was found and Juniperusdeppeana is more widely distributed; themost abundant are J. deppeana, Q. potosina,and Pinus leiophylla. The greater ß diversityis in convex sites (ßw= 5.80) and sites withaltitudes of 2400 and 2600 m (ßw = 7.22).The altitude, relief, the slope and solar exposition are variables more implicated in thedistribution and abundance of the species(Montecarlo’s test, p = 0.0020). For thisreason, the interventions of handling mustconsider the relation species-environmentEl presente trabajo tuvo tres objetivos:1) identificar la composición de especiesleñosas forestales, 2) caracterizar su distribución y abundancia y 3) relacionarlascon variables del medio ambiente en laSierra Fría, Aguascalientes. Para ello seelaboró un plan de muestreos usando trescriterios: altitud, relieve y exposición. Serealizaron 60 muestreos en parcelas de600 m2 donde se identificaron las especiesarbóreo-arbustivas, así como su frecuenciay se anotaron las condiciones ambientalesprevalecientes en cada sitio. Posteriormentese realizó un análisis de correspondenciascanónicas, corroboradas mediante la pruebade Montecarlo (α ≤ 0.05). Los resultadosnos muestran un total de 50 especies registradas en la zona de estudio, de las cualestres son nuevos reportes. Las especies másampliamente distribuidas son Quercuspotosina y Juniperus deppeana,; las másabundantes son J. deppeana, Q. potosinay Pinus leiophylla. La diversidad ß esmayor en los sitios convexos (ßw = 5.80)y en sitios con altitudes mayores a 2 400y 2 600 m (ßw = 7.22). La altitud, relieve,pendiente y exposición a la radiación solarson los descriptores que mejor explican ladistribución y abundancia de las especies(prueba de Montecarlo, p = 0.0020). Losresultados de este trabajo contribuyen amejorar las intervenciones de manejo en elANP Sierra Fría. En particular en lo referente a la conservación de la biodiversidad y ala restauración de zonas degradadas

Análisis preliminar de la diversidad y estructura arbórea-arbustiva del bosque mesófilo en el Sistema Volcánico Transversal de Michoacán, México

ResumenEl objetivo del presente análisis es determinar la biodiversidad y estructura del bosque mesófilo de montaña (BMM) ubicado en el Sistema Volcánico Transversal de Michoacán (SVTM), actualmente amenazado por los intensos cambios de uso de suelo. A través de muestreos en transectos de 50×2m en un número variable de acuerdo con la superficie de los 11 fragmentos muestreados. Se encontraron 2 083 individuos que representaron a 57 especies arbóreas y arbustivas. Los resultados obtenidos con el índice de Shannon, los de similitud (Jaccard con 45% y Sorensen con 31% máximos), el diámetro normalizado, la estructura vertical y de copa demuestran una importante heterogeneidad en los fragmentos, pero con elementos florísticos de BMM. El 50% de las especies reportadas presentan un diámetro normalizado promedio entre 2.5–9.49cm y el 13% tienen <38cm. El área basal estimada va de 7.59 (fragmento 3) a 114.4m2 ha−1 (fragmento 6). Considerando el valor de importancia relativa sobresalen Styrax argenteus, Pinus pseudostrobus y Ternstroemia lineata como las especies dominantes en todo el BMM. En cada fragmento se observó que el BMM en el SVTM se encuentra confinado a barrancas y que la superficie de los fragmentos reportados por el Inegi están sobrestimados en su área. La comparación de las especies que se presentaron en los BMM analizados contra sitios cercanos y regionales del mismo ecosistema, resultó en una baja similitud, encontrándose que a mayor distancia mayor es la disimilitud de especies.AbstractThe objective of this study was to analyze the biodiversity and structure of Cloud Mountain Forest (CMF) located in the Trans Volcanic System in Michoacán (TVSM), Mexico, which is threatened by current land use changes. We sampled a variable number of 50×2m transects depending on the total area in each of 11 CMF fragments. We found a total of 2 083 individuals representing 57 tree and shrub species. Results obtained with species abundance, Shannon Index, Similitude (Jaccard with 45% and Sorensen with 31%, as maxim values for both), normalized diameter, vertical structure and cover showed an important heterogeneity in the fragments but with floristic elements from CMF. Fifty percent of reported species had normalized diameters between 2.5–9.49cm, and 13% had normalized diameters <38cm. Estimated Basal area ranged from 7.59 (fragment 3) to 114.4m2 ha−1 (fragment 6). Styrax argenteus, Pinus pseudostrobus and Ternstroemia lineata were dominant in terms of the relative importance value in all CMF fragments sampled. We observed that CMF in the TVSM is confined to ravines, and that area of fragments reported by Inegi was overestimated. Comparisons between the occurrence of species in the CMF analyzed and in nearby and regional sites with the same ecosystem, showed a low similitude, with a higher dissimilitude the distance to the CMF we studied was larger

Ecology of Plant Communities in Central Mexico

In Central Mexico converge three biogeographic provinces: Altiplano sur, Sierra Madre Occidental and Costa del Pacífico. Each one of them is composed by different plant communities: Thorn Forest, Temperate Mountain Forest and Dry Tropical Forest respectively. Our objective is to show, through phytoecological analysis, the species richness, diversity and the structure of the plant communities from the Temperate Mountain Forest and from the Tropical Dry Forest. In the Temperate Mountain Forest, 50 forest species were recorded, with a Shannon Wiener diversity index H´ = 1.63 on altitudes from 2400 to 2600 m. The Whittaker β index is Bw = 7.22. In the tropical dry forest, we identified 79 plants species with a mean diversity index H´ = 3.49 on altitudes from 1951 to 2100 m. In this ecosystem the Bw index is 8.12. This study offers important information for the establishment of management practices, considering the protection status from the areas in which this vegetation type is distributed

A Standard Protocol for Liana Censuses 1

A recent increase in published studies of lianas has been paralleled by a proliferation of protocols for censusing lianas. This article seeks to increase uniformity in liana inventories by providing specific recommendations for the determination of which taxa to include, the location of diameter measurement points on individual stems, the setting of minimum stem diameter cutoffs, the treatment of multiple-stemmed and rooted clonal groups, and the measurement of noncylindrical stems. Use of more uniform liana censusing protocols may facilitate comparison of independently collected data sets and further our understanding of global patterns in liana abundance, diversity, biomass, and dynamics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75009/1/j.1744-7429.2006.00134.x.pd

Temporal patterns of active fire density and its relationship with a satellite fuel greenness index by vegetation type and region in Mexico during 2003-2014

Background: Understanding the temporal patterns of fire occurrence and their relationships with fuel dryness is key to sound fire management, especially under increasing global warming. At present, no system for prediction of fire occurrence risk based on fuel dryness conditions is available in Mexico. As part of an ongoing national-scale project, we developed an operational fire risk mapping tool based on satellite and weather information. Results: We demonstrated how differing monthly temporal trends in a fuel greenness index, dead ratio (DR), and fire density (FDI) can be clearly differentiated by vegetation type and region for the whole country, using MODIS satellite observations for the period 2003 to 2014. We tested linear and non-linear models, including temporal autocorrelation terms, for prediction of FDI from DR for a total of 28 combinations of vegetation types and regions. In addition, we developed seasonal autoregressive integrated moving average (ARIMA) models for forecasting DR values based on the last observed values. Most ARIMA models showed values of the adjusted coefficient of determination (R2 adj) above 0.7 to 0.8, suggesting potential to forecast fuel dryness and fire occurrence risk conditions. The best fitted models explained more than 70% of the observed FDI variation in the relation between monthly DR and fire density. Conclusion: These results suggest that there is potential for the DR index to be incorporated in future fire risk operational tools. However, some vegetation types and regions show lower correlations between DR and observed fire density, suggesting that other variables, such as distance and timing of agricultural burn, deserve attention in future studiesAntecedentes: Una adecuada planificación del manejo del fuego requiere de la comprensión de los patrones temporales de humedad del combustible y su influencia en el riesgo de incendio, particularmente bajo un escenario de calentamiento global. En la actualidad en México no existe ningún sistema operacional para la predicción del riesgo de incendio en base al grado de estrés hídrico de los combustibles. Un proyecto de investigación nacional actualmente en funcionamiento, tiene como objetivo el desarrollo de un sistema operacional de riesgo y peligro de incendio en base a información meteorológica y de satélite para México. Este estudio pertenece al citado proyecto Resultados: Se observaron en el país distintas tendencias temporales en un índice de estrés hídrico de los combustibles basado en imágenes MODIS, el índice “dead ratio” (DR), y en las tendencias temporales de un ìndice de densidad de incendios (FDI), en distintos tipos de vegetación y regiones del país. Se evaluaron varios modelos lineales y potenciales, incluyendo términos para la consideración de la autocorrelación temporal, para la predicción de la densidad de incendios a partir del índice DR para un total de 28 tipos de vegetación y regiones. Se desarrollaron además modelos estacionales autoregresivos de media móvil (ARIMA en inglés) para el pronóstico del índice DR a partir de los últimos valores observados. La mayoría de los modelos ARIMA desarrollados mostraron valores del coeficiente de determinación ajustado (R2 adj) por encima de 0.7 to 0.8, sugiriendo potencial para ser empleados para un pronóstico del estrés hídrico de los combustibles y las condiciones de riesgo de ocurrencia de incendio. Con respecto a los modelos que relacionan los valores mensuales de DR con FDI, la mayoría de ellos explicaron más del 70% de la variabilidad observada en FDI. Conclusiones: Los resultados sugirieron potencial del índice DR para ser incluido en futuras herramientas operacionales para determinar el riesgo de incendio. En algunos tipos de vegetación y regiones se obtuvieron correlaciones más reducidas entre el índice DR y los valores observados de densidad de incendios, sugiriendo que el papel de otras variables tales como la distancia y el patrón temporal de quemas agrícolas debería ser explorado en futuros estudiosFunding for this work was provided by CONAFOR-CONACYT Project 252620 “Development of a Fire Danger System for Mexico.” This work was also cofinanced by the Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria and European Social Fund (Dr. E. Jiménez grant)S

Modification of Fire Regimes Inferred from the Age Structure of Two Conifer Species in a Tropical Montane Forest, Mexico

Research Highlights: Age structure was used to infer fire regimes in the Monarch Butterfly Biosphere Reserve. Uneven-aged structures in stands dominated and co-dominated by pine and fir species, which are distributed according to an altitudinal gradient, indicated a regime of frequent, low-severity, and low-intensity fires. Background and Objectives: Age structure analyses have been used to infer natural and disrupted fire regimes when field-based descriptions of fires are scarce or unavailable. In montane conifer forests, fire regimes typically vary according to an altitudinal gradient, shaping contrasting tree establishment patterns. In the Monarch Butterfly Biosphere Reserve, Mexico, the altitudinal distribution and fire regimes of sacred fir forests (Abies religiosa), smooth-bark Mexican pine forests (Pinus pseudostrobus), and mixed-conifer forests are poorly documented. The objectives of this study were to determine the altitudinal ranges occupied by mono-dominant and co-dominant stands and to reconstruct tree establishment history to infer historical fire regimes. Materials and Methods: Six altitudinal transects were established along the reserve, each one at elevations from 2400 to 3300 m, with sampling sites at every 150 m of elevation. In each site, increment cores were collected from the base of 25 mature trees. A total of 800 increment cores were collected and cross-dated. Results: P. pseudostrobus is dominant in stands between 2400 and 2850 m, A. religiosa between 3150 and 3300 m, and both species co-dominate between 2850 and 3150 m. The establishment pattern for both species has been continuous, represented by uneven-aged structures, suggesting that tree establishment in smooth-bark Mexican pine forests, mixed-conifer forests, and sacred fir forests, is likely to be associated with frequent, low-severity, and low-intensity fires. Conclusions: These fire regimes suggest, by the one hand, the disruption of natural fire regimes by human activities, limiting the occurrence of high-severity fires; on the other hand, a distinctive feature of these tropical montane forests

Avocado Cover Expansion in the Monarch Butterfly Biosphere Reserve, Central Mexico

Avocado cultivation has reduced the extent of forest ecosystems in central Mexico, even in natural protected areas such as the Monarch Butterfly Biosphere Reserve (MBBR) where information on the extent and expansion dynamics of avocado cover is scant. This study aimed to identify avocado plantations within the MBBR through photo interpretation for the 2006–2018 period. Change rates of the avocado cover extent were calculated for the northern, central, and southern zones of the MBBR, and topographic attributes such as elevation, soil type, slope, and slope aspect were identified. A total extent of 958 ha is covered by avocado plantations within the MBBR. The southern zone hosted the largest area under avocado cultivation (570 ha), but the northern zone had the highest change rate between 2006 and 2018 (422%). Most avocado orchards have been established mainly in Acrisol soils, south-facing slopes, on steep hillsides, and in elevations between 2050 and 2800 m. The conversion from traditional agricultural lands has been the main mechanism for the establishment of avocado orchards. However, 40 ha under avocado cultivation derived from deforestation, mainly in the central zone. The expansion of avocado plantations could trigger environmental impacts, even threatening the overwintering habitat and the migratory phenomenon of the monarch butterflies

Distribución y abundancia de las especies arbóreas y arbustivas en la Sierra Fría, Aguascalientes, México

Our objectives were to recognize the composition of forest species, characterize their distribution and abundance, and identify the factors that determine their presence or absence in the area of Sierra Fria, Aguascalientes, Mexico. A sampling plan was elaborated using three criteria: altitude, relief and forest cover. Sixty samplings were realized in sites of 600 m² and randomized in different solar expositions. The arboreal and brush species, the frequency, and ecological conditions that determine their presence or absence in site were identified. A Canonical Correspondence Analysis and Montecarlo's test (α ≤0.05) was conducted. We identified 50 species; three are new reports in the area. Quercus potosina was found and Juniperus deppeana is more widely distributed; the most abundant are J. deppeana, Q. potosina, and Pinus leiophylla. The greater ß diversity is in convex sites (ßw= 5.80) and sites with altitudes of 2400 and 2600 m (ßw = 7.22). The altitude, relief, the slope and solar exposition are variables more implicated in the distribution and abundance of the species (Montecarlo's test, p = 0.0020). For this reason, the interventions of handling must consider the relation species-environment.El presente trabajo tuvo tres objetivos: 1) identificar la composición de especies leñosas forestales, 2) caracterizar su distribución y abundancia y 3) relacionarlas con variables del medio ambiente en la Sierra Fría, Aguascalientes. Para ello se elaboró un plan de muestreos usando tres criterios: altitud, relieve y exposición. Se realizaron 60 muestreos en parcelas de 600 m² donde se identificaron las especies arbóreo-arbustivas, así como su frecuencia y se anotaron las condiciones ambientales prevalecientes en cada sitio. Posteriormente se realizó un análisis de correspondencias canónicas, corroboradas mediante la prueba de Montecarlo (α ≤ 0.05). Los resultados nos muestran un total de 50 especies registradas en la zona de estudio, de las cuales tres son nuevos reportes. Las especies más ampliamente distribuidas son Quercus potosina y Juniperus deppeana,; las más abundantes son J. deppeana, Q. potosina y Pinus leiophylla. La diversidad ß es mayor en los sitios convexos (ßw = 5.80) y en sitios con altitudes mayores a 2 400 y 2 600 m (ßw = 7.22). La altitud, relieve, pendiente y exposición a la radiación solar son los descriptores que mejor explican la distribución y abundancia de las especies (prueba de Montecarlo, p = 0.0020). Los resultados de este trabajo contribuyen a mejorar las intervenciones de manejo en el ANP Sierra Fría. En particular en lo referente a la conservación de la biodiversidad y a la restauración de zonas degradadas

Análisis espacial del paisaje como base para muestreos dendrocronológicos: El caso de la Reserva de la Biosfera Mariposa Monarca, México

Landscape spatial analyses using Remote Sensing (RS) and Geographic Information Systems (GIS) has been scarcely used to indentify sites with dendrochronological potential. For this study, we designed a protocol to identify areas with climatically sensitive trees, based on the spatial analysis of landscape biophysical features. The protocol included the analyses of slope angles, slope aspect, and the distribution of Land Cover and Land Use (LCLU) using RS and GIS tools. The protocol was validated through dendrochronological sampling in two adjacent sites. Analyses of tree ring widths were done using COFECHA and dplR. Results suggest that sensitive trees grow in 18% of the Monarch Butterfly Biosphere Reserve. Trees from the two sites differed in age, diameter, and mean ring width. Our protocol allowed us to identify sites with long-lived and sensitive trees as represented by the high inter-annual variation found in tree ring widths. The spatial analysis of biophysical variables prior to sampling enables the identification of sites with sensitive trees implying the elimination of less samples. Our proposed protocol is efficient and can be used in other areas.El análisis espacial del paisaje, con técnicas de Percepción Remota (PR) y herramientas de Sistemas de Información Geográfica (SIG), es un procedimiento poco usado en la identificación de sitios potencialmente idóneos para el muestreo dendrocronológico. En el presente trabajo se diseñó un protocolo para identificar áreas con árboles climáticamente sensibles, empleando un análisis espacial de variables biofísicas. El diseño consistió en el análisis de la pendiente del terreno, la orientación de laderas y la distribución de Cobertura Vegetal y Uso de Suelo (CVUS), mediante el uso de técnicas de PR y herramientas de SIG. El protocolo se validó mediante un muestreo dendrocronológico en dos sitios adyacentes. Los análisis estadísticos del ancho de anillos de crecimiento se realizaron mediante los programas COFECHA y dplR. Los resultados indicaron que 18% de la Reserva de la Biosfera Mariposa Monarca presenta características aptas para colectar muestras dendrocronológicas sensibles a variación climática. Los análisis estadísticos indican que existen diferencias entre los dos sitios en edad de árboles, diámetro y ancho de los anillos. La propuesta del diseño de muestreo permitió ubicar sitios con árboles longevos y sensibles, lo que se traduce en alta variación interanual en el ancho de anillos. El análisis espacial de variables biofísicas previas al muestreo dendrocronológico, contribuye a la identificación de sitios con árboles sensibles y a eliminar menos muestras. El protocolo propuesto es eficiente y puede ser replicable en otras áreas