Drought influence over radial growth of Mexican conifers inhabiting mesic and xeric sites

Drought is a major constraint of forest productivity and tree growth across diverse habitat types. In this study, we investigated the drought responses of four conifer species growing within two locations of differing elevation and climatic conditions in northern Mexico. Two species were selected at a mesic site (Cupressus lusitanica Mill., Abies durangensis Martínez) and the other two species were sampled at a xeric site (Pinus engelmannii Carr., Pinus cembroides Zucc.). Using a dendrochronological approach, we correlated the radial-growth series of each species and the climatic variables. All study species positively responded to wet-cool conditions during winter and spring. Despite the close proximity of species at a mesic site, A. durangensis had high responsiveness to hydroclimatic variability, but C. lusitanica was not responsive. At the xeric site, P. engelmannii and P. cembroides were very responsive to drought severity, differentiated only by the longer time scale of the response to accumulated drought of P. engelmannii. The responsiveness to hydroclimate and drought of these tree species seems to be modulated by site conditions, or by the functional features of each species that are still little explored. These findings indicate that differentiating between mesic and xeric habitats is a too coarse approach in diverse forests with a high topographic heterogeneity.Fil: Pompa García, Marín. Universidad Juárez; MéxicoFil: González Cásares, Marcos. Universidad Juárez; MéxicoFil: Acosta Hernández, Andrea C.. Universidad Juárez; MéxicoFil: Camarero, Jesús Julio. Instituto Pirenaico de Ecología; EspañaFil: Rodriguez Catón, Milagros Rocío. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

Monitoring vegetation using remote sensing time series data: a review of the period 1996-2017

Analyzing time series data with remote sensing provides a better understanding of vegetation dynamics, since previous conditions and changes that have occurred over a given period are known. The objective of this paper was to analyze the current status and recent advances in the use of time series data obtained from remote sensors for vegetation monitoring. A systematic search of scientific papers was performed and 167 papers were found, published during the period 1996 to 2017. No significant difference in the amount of years analyzed was found between time series analyzed with a single sensor and those analyzed with a combination of several sensors (i.e. Landsat and SPOT, Landsat and Sentinel, among others). However, the combination of data from different sensors (fusion of images) can improve the quality of the results. Specialattention must also be given to the fusion of optical and radar data, since this offers more unique spectral and structural information for land cover and land use assessments. Highlights Remote sensing provides a better understanding of vegetation dynamics. The number of vegetation monitoring papers published using time series data are becoming more frequent. The fusion of Landsat and Sentinel-2 satellite data shows great potential for timely monitoring of rapid changes. The fusion of optical and radar data points to a new trend in remote sensing, including the use of geospatial open data sources.Analyzing time series data with remote sensing provides a better understanding of vegetation dynamics, since previous conditions and changes that have occurred over a given period are known. The objective of this paper was to analyze the current status and recent advances in the use of time series data obtained from remote sensors for vegetation monitoring. A systematic search of scientific papers was performed and 167 papers were found, published during the period 1996 to 2017. No significant difference in the amount of years analyzed was found between time series analyzed with a single sensor and those analyzed with a combination of several sensors (i.e. Landsat and SPOT, Landsat and Sentinel, among others). However, the combination of data from different sensors (fusion of images) can improve the quality of the results. Specialattention must also be given to the fusion of optical and radar data, since this offers more unique spectral and structural information for land cover and land use assessments. Highlights Remote sensing provides a better understanding of vegetation dynamics. The number of vegetation monitoring papers published using time series data are becoming more frequent. The fusion of Landsat and Sentinel-2 satellite data shows great potential for timely monitoring of rapid changes. The fusion of optical and radar data points to a new trend in remote sensing, including the use of geospatial open data sources

Within-tree carbon concentration variation in three Mexican pine species

SUMMARY Assessing carbon content in forest species is considered essential for programs designed to mitigate global warming. A value of 50 % has been assumed as a generic percentage. However, recent research indicates that there are substantial variations in carbon concentration even within a tree or tissues. The aim of this study was to assess the variations of carbon concentration along the longitudinal profile of Pinus durangensis, P. engelmannii and P. leiophylla in northern Mexico, including its components: root, bark, stem, branches, twigs, leaves and fruits. Using a selective sampling design, dominant and well-shaped trees were selected, whose samples were processed by chemical analyses. Results indicated significant differences in the mean concentration of carbon along the longitudinal profile, with the maximum value always at the base of the tree. Variations at the species level were also recorded. Pinus engelmannii had the lowest percentage with 49.31 %, followed by P. leiophylla (50.18 %) and P. durangensis (50.36 %). In the components of all species, the carbon concentration in the bark was higher than in the rest (52.48 %). A wide range of variation was observed in the carbon coefficients of the components of the species, from 47.39 % in the root of P. engelmannii to 53.49 % in the bark of P. leiophylla. It is therefore appropriate to consider these variations when making more accurate estimates of carbon stocks in forest ecosystems. Key words: Pinus durangensis, Pinus engelmannii, Pinus leiophylla, components, trees. RESUMEN Evaluar el contenido de carbono se considera esencial para programas diseñados a mitigar el calentamiento global. Se ha asumido un valor de 50 % como porcentaje genérico. Sin embargo, investigaciones recientes indican que existen variaciones substanciales en concentraciones de carbono incluso entre árboles y tejidos. El objetivo de este estudio fue evaluar las variaciones de la concentración de carbono a lo largo del perfil longitudinal de Pinus durangensis, P. engelmannii, y P. leiophylla en el norte de México, incluyendo sus componentes: raíz, corteza, tallo, ramas, ramillas, hojas y frutos. Los resultados indican diferencias significativas en la concentración media de carbono a lo largo del perfil longitudinal, con máximos valores siempre en la base del árbol. También se registraron variaciones al nivel de especie. Pinus engelmannii tuvo el más bajo porcentaje con 49,31 %, seguido por P. leiophylla (50,18 %) y P. durangensis (50,36 %). En los componentes de todas las especies, la concentración de carbono en la corteza fue más alta que en el resto (52,48 %). Un amplio rango de variación se observó en los coeficientes de carbono de los componentes de las especies, desde 47,39 % en la raíz de P. engelmannii a 53,49 % en la corteza de P. leiophylla. Es por tanto apropiado considerar estas variaciones cuando se hagan estimaciones más precisas de almacenes de carbono en los ecosistemas forestales. Palabras clave: Pinus durangensis, Pinus engelmannii, Pinus leiophylla, componentes, árboles

¿Hay variaciones en la concentración de carbono entre especies de bosques de alto valor de conservación en el norte de México?

Despite the publication of numerous studies about carbon (C) concentration in various tree components, few have investigated the C variation in spatially restricted tree species. We evaluated differences in C concentrations among four conifer species of High Value Conservation Forests (HVCF) in northern Mexico. Total carbon concentration (TOC) analyses were performed for Cupressus lusitanica Mill, Picea chihuahuana Mtz., Abies durangensis Mtz., and Pseudotsuga menziesii Mirb. Carbon concentration varies within the structural tree component, but no significant difference was found when the aerial samples were classified based on the point of cardinal extraction from where they were taken. The species, P. menziesii, A. durangensis, and P. chihuahuana showed the lowest C concentration in the stems, while C. lusitanica had the highest.A pesar de la publicación de numerosos estudios sobre la concentración de carbono (C) en diversos componentes del árbol, pocos han investigado la variación entre especies de distribución restringida y sus componentes. Se investigaron las diferencias en las concentraciones de C entre las cuatro especies de coníferas de alto valor de conservación (Bosques HVCF) en el norte de México. Se realizó un análisis de la concentración total de carbono (TOC) para Cupressus lusitanica Mill., Picea chihuahuana Mtz., Abies durangensis Mtz., y Pseudotsuga menziesii Mirb. La concentración de C varía dentro del componente estructural de árbol, pero no se encontró ninguna diferencia significativa en la concentración de C según la orientación de la extracción cardinal de muestras de tejidos aéreos. Las especies, P. menziesii Mirb., A. durangensis Mtz. y P. chihuahuana Mtz., resultaron tener la menor concentración de contenido de carbono en los tallos, mientras que C. lusitanica Mill. tuvo la mayor.Fil: Hernández Vera, Diego. Universidad Juárez del Estado de Durango (México). Facultad de Ciencias Forestales.Fil: Pompa García, Marín. Universidad Juárez del Estado de Durango (México). Facultad de Ciencias Forestales.Fil: Wehenkel, Christian. Universidad Juárez del Estado de Durango (México). Instituto de Silvicultura e Industria de la Madera.Fil: Pérez Verdín, Gustavo. Instituto Politécnico Nacional (México). Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional.Fil: Carrillo Parra, Artemio. Universidad Juárez del Estado de Durango (México). Instituto de Silvicultura e Industria de la Madera

Earlywood and Latewood Widths of Picea chihuahuana Show Contrasting Sensitivity to Seasonal Climate

The existence of endangered tree species in Mexico necessitates an understanding of their vulnerability to the predicted climate changes (warming and drying trends). In this study, the sensitivity to climate of earlywood (EW) and latewood (LW) widths of the threatened Picea chihuahuana was determined. The response of EW and LW to climate variables (maximum temperature, minimum temperature, precipitation, evaporation, and a drought index) was analyzed by means of correlation analysis using dendrochronology over the period of 1950–2015. EW and LW production were enhanced by cool and wet conditions during winter prior to the start of growing season. During the growing season, EW and LW production increased in response to cool spring and summer conditions, respectively; temperatures and year-round evaporation, excluding summer and the previous drought in the period prior to the growing season. EW was sensitive to seasonal drought, which is a concern considering the predicted aridification trends for the study area. These results provide further knowledge on the dendroecological potential of Picea chihuahuana.Funding was provided by CONACYT (Consejo Nacional de Ciencia y Tecnología) through the CB-2013/222522 project. Many thanks to the community-based site known as “Ejido el Brillante”, and we also thank the forester responsible for the area (Javier Bretado) for supporting the data gathering. We thank the Dirección General de Vida Silvestre, SEMARNAT (Secretaría de Medio Ambiente y Recursos Naturales), Mexico, for providing technical facilities. Gabriel Sagüesa contributed with sample processing. The authors are grateful to the editors and anonymous reviewers for their useful comments and suggestions.We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)

Estimating dendrometric variables, volume and carbon from stump diameter for Pinus arizonica Engelm. in northern Mexico

It is noteworthy that in the last decade, there has been an increase in the number of studies predicting normal diameter, total height, and stem volume based on stump dimensions. Therefore, the objectives were: a) to determine the mathematical model that best estimates normal diameter, total height, stem volume, and captured carbon as a function of stump diameter for Pinus arizonica Engelm. in northern Mexico; and b) to generate mathematical models through data processing in the Microsoft Excel program. Using a targeted sampling design, we selected 264 Pinus arizonica Engelm. trees to generate the database. The development of prediction models for normal diameter, total height, total tree volume, and captured carbon as a function of stump diameter was carried out using the Microsoft Excel database management package. The fit's adequacy was analyzed based on residuals and statistics such as the root mean square error, the adjusted coefficient of determination, and the coefficient of variation. Model fits indicate a linear trend for the normal diameter variable, while for total height, the model turned out to be logarithmic. As for total tree volume and captured carbon, the relationship is exponential in relation to stump diameter. The R2adj fits were highly reliable for estimating normal diameter, total tree volume, and captured carbon, with values exceeding 95%. The development of prediction models using Microsoft Excel is viable according to the results presented here. The tested techniques can be replicated by forestry technicians, environmental inspectors, and forest landowners who do not have specialized knowledge in the generation prediction models

Calidad del bosque de ribera del río El Tunal, Durango, México; mediante la aplicación del índice QBR

The assessment of the ecological condition of the river banks is an important element in the rivers study around the world.The objective of this work was to evaluate the ecological condition of the riparian forest in a transect of 21 km of ElTunal river in Mexico with the QBR index. In the transect of study six sites were evaluated which were selected by therepresentation, possibilities of access and the heterogeneity of the vegetation. In general, the results have shown a riverwith important signs of deterioration; two sites results in an intermediate quality, two sites results in bad quality and tworesults in poor quality.La evaluación de la condición ecológica de las riberas es un elemento importante en el estudio de los ríos alrededor delmundo. El objetivo del presente trabajo fue evaluar la calidad del bosque de ribera, desde un punto de vista estructural yfuncional, en un tramo de 21 kilómetros del río El Tunal en Durango, México, mediante la aplicación del índice QBR. Enel tramo estudiado se evaluaron seis sitios seleccionados por su representatividad, accesibilidad y heterogeneidad de suvegetación. En general, los resultados muestran un río con indicios importantes de deterioro; se encontraron dos sitios concalidad intermedia, dos sitios presentaron calidad mala y los dos restantes presentaron calidad pésima