Pinus Oocarpa Schiede Research Articles

Tree Rings Elucidate Differential Drought Responses in Stands of Three Mexican Pines

Knowledge regarding the growth of trees is essential to understanding their response to predicted warmer and drier climate scenarios. We used the annual rings of three Mexican pines (Pinus montezumae Lamb., Pinus oocarpa Schiede ex Schltdl., and Pinus monophylla Torr. & Frém) to explore their drought responses. Correlation analyses showed that hydroclimatic factors differentially impact tree species in terms of the intensity and temporality. The negative influence of the maximum temperature and positive effect of the precipitation on the growth indices were notable, with P. montezumae being the most responsive species, followed by P. oocarpa and P. monophylla. The climate–growth relationships were specific and driven by the differential hydrothermal conditions across the study areas. SPEI analyses indicated that P. monophylla is better able to tolerate drought than P. montezumae or P. oocarpa, especially in recent years. The lower resilience of P. montezumae and P. oocarpa could predispose them to a higher mortality risk if warming and drying rates increase. Our findings strengthen the understanding of the responses of tree growth to seasonal drought, which is critical considering the biogeographic shifts that will potentially be experienced by these forests in the future. This knowledge improves the understanding of young Mexican stands and could contribute to the design of management strategies in the face of predicted climatic variations.

Study of the Spatial Distribution of the Bark Beetle in the Ejido Tixtlancingo

The spatial distribution of Dendroctonus frontalis Zimmermann, 1868, and Dendroctonus mexicanus Hopkins, 1905, was determined from 2020 to 2021 in the Tixtlancingo ejido. The information came from two surveys because, despite the abundant forested areas in this geographical area of the state of Guerrero, Mexico, economic resources for pest biomonitoring are limited. However, it was possible to identify the presence of 76 outbreaks affecting 1117.697 hectares and 95,078 trees, totaling 14,223.8 m3 of standing timber volume. In 2020, 28 outbreaks were reported, with the eastern spatial distribution showing the most damage from bark beetles, particularly in outbreaks 7 and 14 of the surveyed area. The most affected conifers were Pinus maximinoi H. E. Moore (44.71%), Pinus oocarpa Schiede ex Schltdl. (39.93%), and Pinus pseudostrobus Lindl. (15.36%). The affected timber volume was observed in diameter categories of 30 cm for the three pine species, with infestation of 90,549 trees (13,497.6 m3 t.t.v. (total tree volume)) across 1057.64 hectares. In 2021, 48 outbreaks were recorded, with the northeastern and southern parts of the surveyed area showing the most damage from the bark beetle. The trees most affected by the bark beetle were P. oocarpa (59.17%), P. maximinoi (33.94%), and P. pseudostrobus (6.89%). It was observed that the affected volume occurred in trees with diameter categories of 50 cm for the three pine species, affecting 4529 trees (726.214 m3 t.t.v.) distributed over 60.06 hectares. The contribution of this work lies in establishing a baseline for monitoring damage caused by this beetle, which affects forest resources and diminishes the possibility of maintaining carbon capture areas in the medium and long term, thus impacting the Sustainable Development Goals (SDGs) of the 2030 agenda, specifically Goals 11, 13, and 15.

Improving Volume and Biomass Equations for Pinus oocarpa in Nicaragua

We present a new set of equations for tree level volume and aboveground biomass estimation for ocote pine (Pinus oocarpa Schiede ex Schltdl). These equation systems are the first developed for this species in Nicaragua. The first system includes a taper function, a merchantable volume equation, and volume equations for stem, coarse branches, and whole trees. The second system estimates whole tree and individual tree component biomass (stem wood, bark, branches, and needles). Data from 112 sampled trees were used for models’ development. Seemingly Unrelated Iterative Regression and the Generalized Method of Moments were used to simultaneously fit the volume and biomass equations systems, respectively; both methods ensure additivity and compatibility between equations. Weighted regression and a second-order continuous autoregressive error structure were used to correct heteroscedasticity and autocorrelation within the hierarchical dataset. The predictive power of the new proposed equations is higher than the currently used models for P. oocarpa in the country. These equation systems represent a scientific advancement that will enhance forest inventories, optimize timber management of the species, and facilitate accurate monitoring of forest carbon dynamics. Additionally, the new equations will contribute to a more precise accounting of CO2 emissions from the country’s forestry sector.

Different Modelling Approaches to Determine Suitable Areas for Conserving Egg-Cone Pine (Pinus oocarpa Schiede) Plus Trees in the Central Part of Mexico

Various spatial modelling methods and tools have been used in ecology and biogeography. The application of these options serves a dual function: first, they offer information about the potential distribution of species to understand the richness and diversity of unassessed areas. Second, spatial modelling methods employ these predictions to select relevant sites to determine natural conservation areas. In this study, we compared three methods for modelling the spatial distribution of Egg-cone Pine (Pinus oocarpa Schiede), an important non-timber pine in Mexico. The final goal is to estimate suitable areas for the conservation and reproduction of superior individuals (plus trees) of P. oocarpa as a conservation strategy outside the known distribution since this species possesses a high ecological and economic value. The model used were a generalised linear model (GLM) as a parametric regression method, random forest (RF) as a machine-learning method, and the MaxEnt model, a standard procedure, implemented using the Kuenm R package. The results suggest that the models used performed well since the AUROC was between 0.95 and 0.98 in all cases. MaxEnt and random forest approaches provided more conservative predictions for the distribution of suitable areas of plus trees of P. oocarpa than the generalised linear model, but the random forest algorithm achieved the best performance. The results of the study allowed the determination of ex situ conservation areas for P. oocarpa plus trees outside of their known distribution.

Cost Analysis of Seed Conservation of Commercial Pine Species Vulnerable to Climate Change in Mexico

Mexico is home to 40% of the pine species in the world. By the year 2050, 20% of the Mexican forests could be lost because of climate change and other human-related activities. In this paper, we determine the potential areas for seed collecting of four species of the genus Pinus and its ex situ economic value under different future Climate Change Scenarios (CCS). The species analyzed were Pinus oocarpa Schiede ex Schltdl, P. rudis Endl., P. culminícola Andresen et Beaman and P. leiophylla Schiede ex Schltdl. and Cham which together accounts for 19% of the timber production in Mexico. Potential areas of distribution of populations in habitats with Annual Mean Maximum Temperatures (AMMT) for seed collection were modelled through a Geographic Information System and climate database. The seed storage economic value was determined by using the Collection Cost Method. The AMMT of P. oocarpa, P. rudis, P. culminícola and P. leiophylla were 28 °C, 20 °C, 18.3 °C and 27.4 °C, respectively. The economic losses from shortages of these species due to CCS in 2050, were estimated of 88.5 million (USD) and 67.16 million (USD) with severe and conservative future CCS, respectively. The nominal investment rate would be 8.84% or more, for storing seeds of the four species and withstanding climate change. An ex situ seed bank is a medium and long-term investment; among its benefits are establishing a market price for the use and conservation of species in the face of possible adverse scenarios.

How Timber Harvest Affects the Structure and Diversity of a Montane Forest in Southern Mexico

Timber extraction directly affects forest structure by opening the canopy, reducing the density and volume of dominant species, and transforming the composition, diversity, and functioning of the forest. We analyze the richness, diversity, and basal area of tree species in a pine–oak montane forest under two stages of the Silvicultural Development Method (thinning and liberation cut treatments) in comparison with remnants of forest considered to be control treatment in the Ocotones forest. Timber extraction began 14 years previously but its effect on the tree structure has not been studied to date in this area. We quantified and measured all the trees with a diameter at breast height >5 cm in 12 0.1 ha circular plots in each treatment. Diversity (Hill numbers) and the importance value index were calculated in each treatment. Observed species richness did not differ between treatments; Pinus oocarpa Schiede ex Schltdl. and Quercus sapotifolia Liebm. were the dominant species regardless of treatment. The principal differences in density and basal area among the treatments were found between the small oaks and small pines. In general, tree density recovered in managed areas because of newly recruited pines and re-sprouting oaks. Although no significant reduction in species richness was detected between treatments, species composition and vegetation structure were modified by the extraction of pine timber and the permanence of many large oaks. Silvicultural treatments appear to create conditions favorable to the maintenance of species richness. The silvicultural interventions in the site meet the objectives of timber production, regeneration, and biodiversity conservation; however, the question of how long the forest can maintain its species diversity and structure after timber extraction remains to be addressed.

Parámetros genéticos de caracteres de crecimiento en un ensayo de progenies de Pinus oocarpa

Pinus oocarpa Schiede ex Schltdl. es una de las especies forestales en México de mayor importancia ecológica (por su amplia distribución geográfica) y económica (por la extracción de su resina en poblaciones naturales). Una resinación más intensiva requerirá de plantaciones comerciales, que podrían ser multipropósito: resina y madera. El objetivo del presente trabajo fue conocer el control genético (heredabilidad) de caracteres de crecimiento (altura total, ALT), diámetro a la base del tallo (DIAM) y diámetro a la altura del pecho (DAP), de progenies de medios hermanos de árboles originalmente seleccionados para producción de resina. Esto con la finalidad de valorar la factibilidad de un programa de mejoramiento genético multipropósito. Se estableció un ensayo de progenies en el año 2011 en Michoacán, México con 27 familias de medios hermanos en un diseño de 10 bloques completos al azar. A los cinco años después de la plantación, los promedios fueron ALT = 5.5 m, DIAM = 13.4 cm y DAP = 10.4 cm. Hubo diferencias significativas entre familias para todos los caracteres. La heredabilidad a nivel individual (h2i) fue: ALT = 0.15, DIAM = 0.22 y DAP = 0.17; a nivel media de familias (h2f) fue de 0.44, 0.54 y 0.47, respectivamente. A una intensidad de selección de mejores individuos de i=1.4, las ganancias genéticas para ALT, DIAM y DAP fueron de 3.9%, 5.2% y 5.0%, respectivamente. De demostrarse posteriormente asociación entre diámetro y producción de resina, sería factible incrementar ambos, mediante selección de individuos con mayores diámetros.

Ajuste de ecuaciones alométricas para estimar biomasa aérea en Pinus oocarpa y Quercus resinosa en Guerrero, México

Los árboles capturan y almacenan grandes cantidades de carbono en su biomasa e impactan positivamente en la mitigación de los gases de efecto invernadero (GEI). Hasta esta fecha, no existen ecuaciones alométricas que estimen la biomasa de árboles del estado de Guerrero, México. El presente trabajo tuvo como objetivo generar ecuaciones para estimar la biomasa aérea de árboles de Pinus oocarpa Schiede y Quercus resinosa Liebmann. Se realizó un muestreo destructivo de 33 árboles para la primera especie y 19 para la segunda, distribuidos en el bosque templado de la microcuenca del río Hueyapa, Guerrero, México. La biomasa de los componentes del árbol se estimó con base en el peso seco de 6 a 14 muestras por componente arbóreo, según el tamaño del árbol. Se ajustaron modelos potenciales en su forma lineal y con transformación Box-Cox. El modelo que mejor estimó la biomasa aérea en P. oocarpa fue el potencial y para Q. resinosa fue el que se obtuvo con la transformación Box-Cox, usando logaritmo del diámetro normal ( ) y la variable combinada transformada como variable independiente. Las ecuaciones alométricas generadas rellenan el vacío existente para la estimación de la biomasa aérea de estas especies forestales en el estado de Guerrero.

Patrón y magnitud de la variación de la densidad de la madera en rodales semilleros de Pinus oocarpa

En el estado de Chiapas, México, Pinus oocarpa Schiede ex Schlechtendal es una especie predilecta para el establecimiento de plantaciones forestales y de restauración ecológica. Sin embargo, se desconoce la variación de variables importantes como la densidad de la madera. El objetivo fue conocer las fuentes de variación fenotípica de la densidad básica de la madera, los patrones de variación axial y radial, y los modelos predictivos para estimar densidad promedio de la madera (DPM) de Pinus oocarpa en rodales semilleros en Chiapas, México. Se recolectaron especímenes obtenidas a 0.30 m, 1.30 m, a 40% y a 60% de la altura total del fuste. La densidad de la madera (dm) se determinó con el método empírico. La variación fenotípica se determinó mediante análisis de varianza y de componentes de varianza. La variación atribuible a rodales semilleros fue baja (10.70%). La mayor variación se detectó entre y dentro de árboles con 39.30% de la variación total. El patrón de variación axial fue descendente, presentando mayor densidad en la parte baja del fuste. La variación radial indica aumento de la densidad de la madera de la médula hacia corteza. El modelo DPM = 0.107 + (0.714 * den0.30) es el más simple y tiene un valor de R2 ajustada de 0.927 para determinar la DPM del árbol. Los índices de correlación en Corazón del Valle sugieren la posibilidad de seleccionar y producir genotipos de P. oocarpa de rápido crecimiento y obtener al mismo tiempo mayor densidad en la madera producida.

Efectos del fuego en el arbolado de un bosque tropical de pino y en el de una selva baja caducifolia en Villaflores, Chiapas

Debido al aumento global de incendios forestales que se espera con el cambio climático, es necesario entender mejor sus efectos y la ecología del fuego en diferentes ecosistemas. En el municipio de Villaflores, Chiapas, se hacen esfuerzos en manejo integral del fuego. En ese lugar se estudió un bosque de Pinus oocarpa Schiede y una selva baja caducifolia, incendiados 6 y 18 meses antes, respectivamente. Los objetivos fueron: modelar la probabilidad de mortalidad y de rebrotación del primero y estudiar la mortalidad, composición y adaptaciones al fuego en la segunda. En ambos bosques se registraron variables dasométricas, de severidad del fuego y se calcularon valores de importancia. Del pinar se obtuvieron modelos logísticos para estimar probabilidades de mortalidad y de rebrotación, que confirman adaptaciones al fuego y características de los árboles que les permiten sobrevivir. Valores altos en: altura, diámetros, altura a la base de las copas y grosor de corteza, reducen la probabilidad de mortalidad. Mayor altura de cicatriz sobre el tronco, la incrementa. Aunque se trata de una especie adaptada al fuego, con corteza gruesa, recuperación de copa mediante rebrotes epicórmicos, rebrotación en la base del tronco y regeneración, el incendio fue severo, con una mortalidad de 48,8% y altura media de la cicatriz del fuego sobre el tronco de 1,5 m ± 1,3 m. En la selva baja el incendio no fue severo, con mortalidad de 5%, se hallaron 37 especies arbóreas y hubo 28 de ellas con adaptaciones al fuego, como: corteza gruesa, latencia física en semilla o pireno del fruto, regeneración y rebrotación. La abundancia de especies con adaptaciones al fuego, deja ver que históricamente los incendios eliminaron especies sensibles y que esta selva, alterada, tiene más especies adaptadas al fuego que las que se pensaba y la ubica como influenciada por el fuego.

Priorities for Conservation and Sustainable Use of Forest Genetic Resources in Four Mexican Pines

The strategies for the conservation and sustainable use of forest genetic resources, which are essential for the future adaptation of forest species to changing environments, are also a source of valuable genetic resources for breeding and restoration activities. The first step to define and implement cost-effective strategies is to identify specific priority populations. Mexico, in spite of being characterized by high levels of tree species diversity, mostly lacks a combined strategy for the genetic conservation and use of forest genetic resources. The aims of this work are: (i) to identify areas for gene conservation, and (ii) to propose measures for the conservation and sustainable use of forest genetic resources of four pine species: Pinus greggii Engelm. ex Parl., Pinus oocarpa Schiede ex Schltdl., Pinus patula Schiede ex Schltdl. & Cham. and Pinus pseudostrobus Lindl. To do that, we use the existing information on the distribution, genetic variation and conservation and breeding efforts in Mexico. Overall, 51 areas for establishing genetic conservation units were prioritized and 6 genetic zones for the use of forest genetic resources in breeding and selection of forest reproductive material were identified. The current conservation efforts for the four priority Mexican pines should be improved to satisfy the needs of a national breeding and conservation network.

Caracteres ecológicos y dendrométricos que influyen en la producción de resina en Pinus oocarpa de Michoacán, México

El Estado de Michoacán es el primer productor de resina en el país y Pinus oocarpa Schiede ex Schltdl. es una de sus especies más importantes por la alta producción y calidad. El objetivo del presente estudio fue analizar las características dendrométricas y productivas en relación con el clima y el suelo de 30 árboles seleccionados como superiores en producción de resina en condiciones naturales en Michoacán, México. En la zona de estudio se presentan los suelos acrisol ocrico-luvisol y luvisol crómico, dos climas (A)C(w1)(w) y Aw0(w), con temperatura media de 18 °C a 22 °C, precipitación anual entre 800 mm y 1200 mm y humedad relativa predominante de 70% a 90%. El DAP de los árboles varió de entre 31.5 cm y 89.5 cm, la altura total entre 9.0 m y 27.5 m, diámetro de copa entre 5.9 m y 14.35 m, con una producción media de resina en cinco meses de 10.67 kg. Las variables que más aportaron a la producción de resina fueron el tipo de clima, altura de fuste limpio y número de caras vivas. El suelo presentó una correlación positiva con la altura de fuste limpio (r = 0.39). Los resultados sugieren que el clima semicálido subhúmedo, los suelos de tipo luvisol crómico y la temperatura, favorecen la producción de resina en P. oocarpa, por lo que podrían usarse como indicadores en la búsqueda de árboles y zonas con buena producción para esta especie.

Respuesta del crecimiento de Pinus oocarpa Schiede a variables climáticas en el noroeste de Lagunas de Montebello, Chiapas, México

Dendrochronological studies are used to reconstruct some climatic variables; in México these studies have focused on central and northern temperate forests where trees present well defined annual rings. Few studies have been carried out in the southern part of the country where annual ring growth is not easily identified and thus makes cross-dating problematic. We analyzed the dendrochronological potential of Pinus oocarpa Schiede for reconstructing climatic variables in the northwest portion of Lagunas de Montebello, Chiapas. We used a selective sampling approach and collected 65 increment cores from 34 trees. While our samples showed a high frequency of false rings (8 to 60 %), we were able to date 30 samples from 22 trees (46 %) using standard dendrochronological techniques and developed total chronologies for total ring width, earlywood, and latewood for a period of 91 years (1925-2015). We found a significant influence of mean precipitation and mean maximum and minimum temperature over the annual ring growth of P. oocarpa in the period 1961-2004. Our results show that winter-spring precipitation (January-May) was the most important for the species’ annual ring growth. However, we found the highest correlation between spring (March-May) precipitation and the earlywood chronology (r = 0.719, P < 0.05). The earlywood chronology also showed potential for reconstructing minimum temperatures (March to May) (r = 0.732, P < 0.05), while the latewood chronology had the potential for reconstructing the maximum temperature (September to January) (r = 0.714, P < 0.05). These results showed that P. oocarpa can be used to reconstruct climatic variables in the Mexican tropics. We recommend that new areas with older trees should be explored in order to increase the depth of chronologies and reconstruct climate records several centuries into the past.

Growth and yield of nine pine species in Angola

A species introduction experiment including several tropical pines and eucalypts was established in 1966/1967 in the Tchianga research station in Angolan Highlands. Despite 27 years of political conflict (1975–2002) and lack of management, the research experiment has remained relatively well conserved. We measured the best conserved plots that were 41 years old in 2007 to obtain information on the growth of different pine species. We calculated stand characteristics including basal area, dominant height, mean diameter, and stand volume for Pinus patula Schiede ex Schiltdl. Et Cham., Pinus pseudostrobus Lindl., Pinus kesiya Royle ex Gordon, Pinus devoniana Lindl., Pinus chiapensis (Martinez) Andresen, Pinus elliottii Engelm., Pinus greggii Engelm. Ex Parl., Pinus montezumae Lamb. and Pinus oocarpa Schiede ex Schltdl. The growing stock volume at 41 years was the highest in P. pseudostrobus, 1,325 m3·ha−1, followed by P. kesiya with 1,200 m3·ha−1. The widely planted P. patula had a growing stock volume of 892 m3·ha−1. P. oocarpa and P. pseudostrobus had the highest stand basal area, over 80 m2·ha−1. Using increment core analyses we studied the temporal development of stand characteristics. Analysis of the mean annual increment (MAI) showed that rotation lengths of 20–30 years would maximize wood production. With these rotation lengths, the MAI of P. pseudostrobus would be 35 m3·ha−1. Other productive species were P. kesiya, P. oocarpa and P. chiapensis. P. patula had a maximum MAI of 20 m3·ha−1. P. greggii had the lowest mean annual volume production, only about 13 m3·ha−1.

Larva of Atractocerus Brasiliensis (Lepeletier & Audinet-Serville, 1825) (Lymexylidae, Atractocerinae)

The larva of Atractocerus brasiliensis (Lepeletier & Audinet-Serville, 1825), collected for the first time in Pinus oocarpa Schiede ex Schltdl. (Pinaceae) is described and illustrated. Until now, for Lymexylidae, only the larva of Melittomma sp. (Melittomminae) was known from the neotropical region (Brazil). Biological notes, a comparison with the description of A. brevicornis, the type-species of the genus (recorded from Africa and Madagascar), and history of the known lymexylid larvae are also included.

ZONEAMENTO AGROCLIMÁTICO PARA ESPÉCIES DO GÊNERO Pinus NO ESTADO DO ESPÍRITO SANTO

Pinus caribaea var. hondurensis Morelet, Pinus taeda Linnaeus e Pinus oocarpa Schiede ex Schltdl no Espírito Santo (ES), foi realizado o zoneamento agroclimático do estado. Utilizaram-se dados meteorológicos do período de 1977 a 2006, provenientes de 96 postos pluviométricos da Agência Nacional de Águas (ANA), sendo 80 localizados dentro do estado e 16 em estados circunvizinhos, de 11 estações meteorológicas pertencentes ao INCAPER (Instituto Capixaba de Pesquisa e Extensão Rural) e de três do INMET (Instituto Nacional de Meteorologia). Os elementos climáticos para determinar a aptidão foram a temperatura do ar e a deficiência hídrica anual para a capacidade de água disponível de 300 mm. De acordo com os resultados, o estado apresenta áreas com aptidão climática para todas as espécies de Pinus, sendo que a espécie Pinus caribaea var. hondurensis apresenta a maior área de aptidão quando comparada com as demais, devido às suas exigências climáticas serem mais restritas. Palavras-chave: Pinus; balanço hídrico; sistema de informação geográfica; zoneamento agroclimático. Abstract Agroclimatic zoning for cultivation of Pinus in the State of Espirito Santo. A agroclimatological zoning was elaborated to determine the suitable areas for growing Pinus elliottii Engelm var. elliottii, Pinus caribaea var. hondurensis Morelet, Pinus taeda Linnaeus and Pinus oocarpa Schiede ex Schltdl in the state of Espírito Santo, Brazil. It was used meteorological data from 1977 to 2006, from eighty rainfall posts of the Water National Agency (ANA) located within the state and sixteen posts surrounding states, eleven weather stations belonging of the Instituto Capixaba de Pesquisa, Assistência Técnica e Extensão Rural (INCAPER) and three weather stations of the Instituto Nacional de Meteorologia (INMET). The climate elements used were air temperature and annual water deficiency, calculated for a soil water storage capacity of 300 mm. The Espírito Santo State showed areas climatically suitable for all species of Pinus, and the species Pinus caribaea var. hondurensis showed the biggest climatically suitable areas compared with the species Pinus elliottii var. elliottii, Pinus oocarpa, Pinus taeda, which due to its climatic requirements, showed lower climatically suitable area. Keywords: Water balance; climatic zoning, Brazil.

Material properties and nondestructive evaluation of laminated veneer lumber (LVL) made from Pinus oocarpa and P. kesiya

This study aimed at evaluating the mechanical, physical and biological properties of laminated veneer lumber (LVL) made from Pinus oocarpa Schiede ex Schltdl (PO) and Pinus kesiya Royle ex Gordon (PK) and at providing a nondestructive characterization thereof. Four PO and four PK LVL boards from 22 randomly selected 2-mm thickness veneers were produced according to the following characteristics: phenol-formaldehyde (190 g/m2), hot-pressing at 150°C for 45 min and 2.8 N/mm2 of specific pressure. After board production, nondestructive evaluation was conducted, and stress wave velocity (v 0) and dynamic modulus of elasticity (E Md ) were determined. The following mechanical and physical properties were then evaluated: static bending modulus of elasticity (E M ), modulus of rupture (f M ), compression strength parallel to grain (f c,0), shear strength parallel to glue-line (f v,0), shear strength perpendicular to glue-line (f v,90), thickness swelling (TS), water absorption (WA), and permanent thickness swelling (PTS) for 2, 24, and 96-hour of water immersion. Biological property was also evaluated by measuring the weight loss by Trametes versicolor (Linnaeus ex Fries) Pilat (white-rot) and Gloeophyllum trabeum (Persoon ex Fries.) Murrill (brown-rot). After hot-pressing, no bubbles, delamination nor warping were observed for both species. In general, PK boards presented higher mechanical properties: E M , E Md , f M , f c,0 whereas PO boards were dimensionally more stable, with lower values of WA, TS and PTS in the 2, 24, and 96-hour immersion periods. Board density, f v,0, f v,90 and rot weight loss were statistically equal for PO and PK LVL. The prediction of flexural properties of consolidated LVL by the nondestructive method used was not very efficient, and the fitted models presented lower predictability.

Allometric equations for tree species and carbon stocks for forests of northwestern Mexico

Allometric equations were developed and applied to forest inventory data to estimate biomass and carbon stocks for temperate species and forests of Durango and Chihuahua and for tropical dry forests of Sinaloa, Mexico. A total of 872 trees were harvested and dissected into their component parts: leaves and branches, boles, and coarse roots. Coarse roots of 40 temperate trees ranging in diameter at breast height (DBH) from 6.0 to 52.9 cm were excavated in their entirety (i.e., >0.5 cm diameter). The species sampled (number of trees) in tropical dry forests (39) were Lysiloma divaricata (Jacq) Macbr. (10), Haematoxylon brasiletto Karst. (10), Cochlospermum vitifolium (Wild.) (5), Ceiba acuminata (S. Watson) Rose (5), Bursera penicillata ( B. inopinnata) (5), and Jatropha angustifolia Mull. Arg. (4) and in temperate forests (833) were Quercus spp. (118) ( Q. rugosa Neé, 15, Quercus sideroxylla Humb. & Bonpl, 51, Quercus spp., 52), Pinus herrerae Martinez 1940 (19), Pinus oocarpa Schiede ex Schlectendal 1838 (31), Pinus engelmannii Carriere 1854 (7), Psudotsuga menziesii (Mirb.) Franco (19), Pinus leiophylla Schiede ex Schlectendal et Chamisso 1831 (27), Pinus teocote Schiede ex Schlectendal et Chamisso (55), Pinus ayacahuite Ehrenb. ex Schltdl. (58), Pinus cooperi Blanco (48), Pinus durangensis Martinez 1942 (385), and Pinus arizonica Engelmann 1879 (66). Allometric equations having only DBH as an independent variable were developed for each component of each species. Since Pinus herrerae, Pinus engelmannii, Pinus oocarpa and Pseudotsuga menziensii had a small number of trees, an individual allometric equation was developed for these species. We used non-linear regression to fit parameters of the typical allometric power equation. The resulting 31 equations (10 species or groups of species, three biomass components; bole, branch and leaves, and total aerial; and the generalized equation for coarse roots) fit the data well and enable the user to predict biomass by component for each of the 10 different groups of species or each of six temperate species. A single allometric equation that incorporates the basic specific gravity for aboveground biomass of all temperate tree species also fit the data well, and this equation provides both the detail and the accuracy supplied by species-specific, plant-part-specific equations. Biomass equations coupled with forest inventory data for temperate (637 circular, 1/10 ha plots) and tropical dry forests (166 20 m × 20 m-quadrats) of northwestern Mexico predict a mean (confidence intervals) of 130 Mg ha −1 (4.2 Mg ha −1) and 73 Mg ha −1 (7.1 Mg ha −1) for total tree and total aboveground biomass, respectively. Large sample sizes and the economic and ecological importance of the species studied make this data set uniquely useful for biomass estimations and for understanding the inherent heterogeneity of tree structure in dynamic tropical and temperate environments of northwestern Mexico.

Carbon accumulation and fixation in aerial biomass of Pinus oocarpa in natural forests in Honduras

Carbon fixation could be the base of international payment for environmental services mechanisms. The accumulation and growth of aerial biomass as well as the carbon fixation associated to this growth has to be measured In order to establish these schemes. These were studied in 36,139.78 hectares of natural forests of Pinus oocarpa Schiede, the most frequent tree in Honduras, in Cabañas, Santa Ana y Opatoro in the Department of La Paz. A forest survey was done to collect the information on tree distribution in diameter at breast height as well as tree densities. The 71% of the aerial biomass was found in the stems and 21% in branches. The specific gravity of wood and bark was 0.55 grams per cubic centimeter (g/cm3) and 0.53 g/cm3, respectively. The allometric equation with the best fitness for the total aerial biomass estimation was the Combined Logarithmic Equation. The aerial biomass accumulation per hectare and in the total area was estimated as well as the annual biomass growth. The chemical analysis of the aerial biomass samples of Pinus oocarpa showed that the carbon fraction was 51.8% dried weight basis. The carbon accumulation in Pinus oocarpa for the pine forest area of cabañas, Opatoro and Santa Ana was estimated in 913,925.50 metric tons, with an annual CO2 sequestration of 105,989.86 metric to

First Report of Arceuthobium hondurense in Department El Paraiso, Honduras.

The Honduran dwarf mistletoe, Arceuthobium hondurense Hawksw. & Wiens (Viscaceae), has only been reported from three general areas in Honduras (2). During September 2005, we found a fourth location for this rare dwarf mistletoe south of San Lucas in Department El Paraiso (13°52'58″N, 86°58'04″W; elevation 1,350 m). The mistletoe was parasitizing Pinus oocarpa Schiede, and many trees were severely infected in this area. Several dead trees were also observed with evidence of past dwarf mistletoe infection (witches' brooms). Although this report only extends the distribution approximately 40 km to the southeast of populations of this mistletoe in Department Francisco Morazan, to our knowledge, this is the first report of A. hondurense in Department El Paraiso. At one time, A. hondurense was thought to be in danger of extinction (1), but it is now known from four separate locations in Honduras and has been discovered in a few locations in southern Mexico (2). Nevertheless, this dwarf mistletoe remains one of the rarest mistletoes known. Specimens of A. hondurense from El Paraiso have been deposited at the Deaver Herbarium, Northern Arizona University, Flagstaff (Accession No. 80338).