Forest plantations are a possible way of increasing forest productivity in temperate and tropical forests, and therefore also increasing above- and belowground carbon pools. In the context of climate change, monospecific plantations might become an alternative to mitigate global warming; however, their contribution to the structural complexity, complementarity, and biodiversity of forests has not been addressed. Mixed forest plantations can ensure that objectives of climate change mitigation are met through carbon sequestration, while also delivering anticipated ecosystem services (e.g., nutrient cycling, erosion control, and wildlife habitat). However, mixed forest plantations pose considerable operational challenges and research opportunities. For example, it is essential to know how many species or functional traits are necessary to deliver a set of benefits, or what mixture of species and densities are key to maintaining productive plantations and delivering multiple ecosystem services. At the same time, the establishment of forest plantations in Mexico should not be motivated solely by timber production. Forest plantations should also increase carbon sequestration, maintain biodiversity, and provide other ecosystem services. This article analyzes some matters that affect the development of planted forests in the Mexican national context, and presents alternatives for forest resources management through the recommendation of mixed forest plantations as a means of contributing to climate change mitigation and the delivery of ecosystem services.

Within the Analytic Hierarchy Process (AHP) framework, a hierarchical model was created considering anthropogenic, genetic and ecological criteria and sub-criteria that directly affect Douglas-fir (Pseudotsuga menziesii (Mirb.)) risk of extinction in central Mexico. The sub-criteria values were standardized, weighted, and ordered by importance in a pairwise comparison matrix; the model was mathematically integrated to quantify the degree of extinction risk for each of the 29 populations present in the study area. The results indicate diverse levels of risk for the populations, ranging from very low to very high. Estanzuela, Presa Jaramillo, Peñas Cargadas and Plan del Baile populations have very low risk, with values less than 0.25. On the other hand, Vicente Guerrero, Morán, Minatitlán, La Garita and Tonalapa populations have very high risk (>0.35) because they are heavily influenced by anthropogenic (close to roads and towns), ecological (presence of exotic species and little or no natural regeneration) and genetic (presence of mature to overmature trees and geographic isolation) factors. In situ conservation activities, prioritizing their implementation in populations at most risk is highly recommended; in addition, germplasm collection for use of assisted gene flow and migration approaches, including artificial reforestation, should be considered in these locations.

The design of a sampling unit, whether a simple plot or a subplot within a clustered structure, including shape and size, has received little attention in inferential forestry research. The use of auxiliary variables from remote sensing impacts the precision of estimators from both model-assisted and model-based inference perspectives. In both cases, model parameters are estimated from a sample of field plots and information from pixels corresponding to these units. In studies assisted by remote sensing, the shape of the plot used to fit regression models (typically circular) often differs from the shape of the population elements for prediction, where the area of interest is divided into equal tessellated parts. This raises interest in understanding the effect of the sampling unit shape on the mean of variables in forest stands of interest. Therefore, the objective of this study was to evaluate the effect of circular and square subplots, concentrically overlapped and arranged in an inverted Y cluster structure, over tree density, basal area, and aboveground biomass in a managed temperate forest in central Mexico. We used a Multivariate Generalised Linear Mixed Model, which considers the Gamma distribution of the variables and accounts for spatial correlation between Secondary Sampling Units nested within the Primary Sampling Unit. The main findings of this study indicate that the type of secondary sampling unit of the same area and centroid, whether circular or square, does not significantly affect the mean tree density (trees), basal area (m²), and aerial biomass.

Se presentan los resultados obtenidos al propagar e inocular con hongos micorrizógenos arbusculares a Amelanchier denticulata (tlaxistle) y Eysenhardtia polystachya (palo dulce), plantas nativas de América, que forman micorriza arbuscular y crecen en México sobre suelos someros y con escasez de nutrimentos. La propagación se hizo a partir de semillas, en vermiculita y turba mezcla (2:1). La mitad de las plantas de cada especie se inoculó con una mezcla de tres cepas de hongos micorrizógenos arbusculares aisladas de suelos de Tlaxcala: Glomus claroideum, Acaulospora laevis y A. morrowiae. El tlaxistle y el palo dulce alcanzaron valores por arriba del 40% de germinación y del 80% de supervivencia al trasplante. Aunque, los porcentajes de colonización micorrízica fueron bajos en los dos casos, menores al 10% para palo dulce y al 20% para tlaxistle, los individuos micorrizados mostraron las mejores respuestas en diámetro, altura, biomasa aérea (p<0.001) y contenido de fósforo. También se analizan algunas variables indicadoras de calidad de planta en relación a la micorrización. Se concluye que la propagación a partir de semillas es una buena estrategia para la obtención de plantas de los dos taxa estudiados y que la micorrización favorece significativamente su desarrollo inicial, ya que mejora sus rasgos de crecimiento, lo que es crítico para las plantas que serán destinadas al campo en programas de restauración.

Los modelos dinámicos de crecimiento y rendimiento maderable son importantes para tomar decisiones en el manejo forestal. Estos modelos predicen la dinámica futura en función de atributos del rodal y son herramientas prácticas para aplicar silvicultura en la planeación del manejo de bosques naturales y plantaciones. En México, teca (Tectona grandis L. f.) es de importancia maderable en plantaciones comerciales; sin embargo, las herramientas de este tipo para el manejo técnico y científico son limitadas. Se desarrolló un sistema de crecimiento y rendimiento maderable (Scrm) explícito para plantaciones de teca establecidas en Campeche, México. El Scrm se conformó de ecuaciones dinámicas de diferencia algebraica ajustadas al utilizar información dasométrica de una red de parcelas permanentes con remediciones. La selección de cada componente del Scrm se basó en un análisis de la bondad de ajuste y en una inspección gráfica para comparar la similitud entre el patrón generado y la tendencia observada, se buscó un balance entre consideraciones estadísticas y tendencias biológicas de crecimiento. La mortalidad se determinó a través de la densidad de plantación inicial y fue sensible al índice de sitio. Se seleccionaron sistemas de crecimiento tipo Schumacher para el área basal y el volumen. A la edad del turno planeado a 19 años y con un índice de sitio de 18 m, se estimaron rendimientos de 152.75 m3 ha-1, 136.86 m3 ha-1 y 113.12 m3 ha-1 para toda la plantación en general, para la densidad de 1250 plantas por hectárea (pl ha-1)y para la densidad de 816 pl ha-1, respectivamente. El Scrm generado permite estimar el volumen total con corteza por hectárea bajo las condiciones locales específicas de establecimiento, de manejo silvícola y de calidad de sitio de las plantaciones de teca analizadas.

The amount and structure of the genetic diversity in Mexican populations of Pseudotsuga menziesii (Mirb.) Franco, is almost unknown, since most genetic studies have been carried out on populations from Canada and the United States. Here, we applied a set of 12 microsatellite markers to 12 populations (234 trees) from the central region of Mexico in order to determine values of genetic diversity and differentiation. Seventy-three different alleles were identified: an average number of alleles per locus (Na) of 6.083, effective number of alleles (Ne) of 2.039, observed heterozygosity (Ho) of 0.229, and expected heterozygosity (Ht) of 0.417. Genetic differentiation was high: the coefficient of differentiation (θ) was 0.270, while the coefficient of structure (Φ_st) was 0.278. Bayesian analysis identified two genetic groups in central Mexico. The PCoA and the dendrogram were in concordance with the two genetic groups. The results of the analysis of molecular variance (AMOVA) indicate that genetic variation exists mainly within populations (72.149%). Therefore, conservation efforts should focus on as many individuals within populations as possible, to maintain this variation.