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espanolEl arbol de la quina (Cinchona officinalis), especie emblematica de Peru, durante muchos anos ha venido siendo amenazado de desaparecer. El objetivo de este estudio fue evaluar la influencia del tipo de mini-estaca (apical y basal) y el tiempo de absorcion de acido indolbutirico (0, 2, 6 y 10 minutos) sobre la multiplicacion clonal del arbol de la quina. Los brotes fueron colectados de arboles de poblaciones naturales presentes en el bosque montano Conila-Peru, a una altitud de 2800 m. Las mini-estacas, basales y apicales, se trataron con acido indolbutirico a 2000 mg·L -1 y se dejaron inmersas por distintos tiempos. Los datos se sometieron a un analisis de varianza y las medias se compararon con la prueba Tukey. Luego de 60 dias se encontro que las miniestacas basales presentaron un porcentaje de enraizamiento significativamente superior (54,77 %) respecto a las mini-estacas apicales (40,10 %), siendo superior tambien en sobrevivencia (62,75 %) y tamano de raices (17,38 mm). Los tiempos de 6 y 10 minutos de absorcion fueron los mas sobresalientes, mientras que el control (0 minutos) resulto ser el tratamiento mas bajo. En conclusion, el uso de mini-estacas basales y tiempos de absorcion de 6 y 10 minutos son las mejores condiciones para garantizar el enraizamiento de las mini-estacas del arbol de la quina. EnglishThe cinchona tree (Cinchona officinalis), an emblematic species of Peru, has for many years been threatened with extinction. The objective of this study was to evaluate the influence of the type of mini-stake (apical and basal) and the absorption time of indolebutyric acid (0, 2, 6, and 10 minutes) on the clonal multiplication of the cinchona tree. The shoots were collected from trees of natural populations present in the Conila-Peru montane forest, at an altitude of 2800 m. The mini-cuttings, basal and apical, were treated with indole butyric acid at 2000 mg·L -1 and were left to rest for different times. The data were subjected to an analysis of variance and the means were compared with the Tukey test. After 60 days, it was found that the basal mini-cuttings presented a significantly higher rooting percentage (54.77 %) compared to the apical mini-cuttings (40.10 %), being also higher in survival (62.75 %) and size of roots (17.38 mm). The absorption times of 6 and 10 minutes turned out to be the most outstanding, while the control (0 minutes) turned out to be the lowest treatment. In conclusion, the basal mini-cuttings and the absorption times of 6 and 10 minutes turn out to be the most appropriate to guarantee the rooting of mini-cuttings of the cinchona tree.

Tropical trees are particularly vulnerable to forest fragmentation because of their low densities, self-incompatibilty system, and high rates of outbreeding. Forest fragmentation is likely to decrease gene flow, increase endogamy, and eventually produce a high differentiation among remnant populations. Our objectives were to evaluate the effect of forest fragmentation on the reproductive success, progeny vigor, and genetic variation of the tropical dry-forest tree Samanea saman. We conducted our study in the dry forest of Costa Rica and compared two tree conditions to evaluate forest fragmentation: (1) isolated, individual trees more than 500 m from the nearest conspecific and surrounded by agricultural fields, pastures, or small remnant forest patches and (2) trees in continuous populations of 10 or more individuals per hectare and surrounded by undisturbed forest. We compared the probability of natural pollination, seed production, genetic variation, and progeny vigor of trees in isolation and in continuous populations. The probability of flowers receiving more than 23 pollen tubes at the base of styles (the flowers more likely to produce a mature fruit) was significantly greater for trees in continuous populations (2.1%) than for trees in isolation (0.4%). However, flowers from the two tree conditions received similar pollen loads on their stigmas. Fruits of trees from continuous populations produced similar numbers of seeds as isolated trees did and had a similar probability of seed abortion. The probability of seed predation by bruchid beetles was significantly greater in continuous populations (30%) than in isolated trees (20%). The number of undamaged seeds ( potentially viable) was similar for both tree conditions. A genetic analysis of progeny showed that levels of genetic diversity in trees in isolation and in continuous populations were comparable. The effective self-fertilization rate and inbreeding coefficient of the progeny were slightly higher for isolated trees than for trees in continuous populations. In addition, there was more genetic similarity in the progeny of isolated trees, within and between fruits. Seeds produced by different fruits within a tree were more likely to be related in an isolated tree than in a tree from continuous populations. Seeds produced by trees from continuous populations were more likely to germinate and to produce greater leaf area and biomass as seedlings than progeny from isolated trees. We concluded that the fragmentation of tropical dry forests affects the genetic variation and vigor of S. saman progeny. Isolated trees showed high reproductive capacity, however, in spite of their habitat condition. Resumen: Los arboles tropicales son particularmente vulnerables a la fragmentacion de bosques debido a su baja densidad, su sistema de auto-incompatibilidad y altas tasas de exogamia. La fragmentacion del bosque posiblemente decrece el flujo de genes, incrementa la endogamia y eventualmente produce una alta diferenciacion entre las poblaciones remanentes. Nuestros objetivos fueron evaluar el efecto de la fragmentacion del bosque sobre el exito reproductivo, el vigor de la progenie y la variacion genetica del arbol de bosque tropical seco Samanea saman. Realizamos nuestro estudio en el bosque tropical seco de Costa Rica y comparamos dos condiciones de los arboles para evaluar la fragmentacion del bosque: (1) individuos aislados mas de 500 m del individuo conespecifico mas cercano y rodeados por campos agricolas, ganaderos o pequenos fragmentos de bosque y (2) arboles en poblaciones continuas de 10 o mas individuos por hectarea y rodeados de bosque no perturbado. Comparamos la probabilidad de la polinizacion natural, produccion de semillas, variacion genetica y vigor de la progenie en arboles aislados y en poblaciones continuas. La probabilidad de que las flores reciban mas de 23 tubos de polen en la base de los pistilos ( las flores con mayor probabilidad de producir un fruto maduro) fue significativamente mayor para arboles en poblaciones continuas (2.1%) que en arboles aislados (0.4%). Sin embargo, flores en arboles en las dos condiciones recibieron similares cargas de polen en sus estigmas. Los frutos de arboles de poblaciones continuas produjeron similares numeros de semillas y tuvieron similar probabilidad de abortar que los de arboles aislados. La probabilidad de depredacion de semillas por escarabajos bruquidos fue significativamente mayor en las poblaciones continuas (30%) que en arboles aislados (20%). El numero de semillas sin dano ( potencialmente viables) fue similar en arboles en las dos condiciones. El analisis genetico de la progenie mostro que los niveles de diversidad genetica de arboles aislados y en poblaciones continuas fueron comparables. La tasa de autofecundacion efectiva y el coeficiente de endogamia de la progenie fue ligeramente mayor en arboles aislados que en los de poblaciones continuas. Adicionalmente, hubo mayor similitud genetica en la progenie de arboles aislados, dentro y entre frutos. Semillas producidas por distintos frutos del mismo arbol tuvieron mas probabilidad de relacion que los de poblaciones continuas. Semillas producidas por arboles en poblaciones continuas tuvieron mayor posibilidad de germinar y producir mayor area foliar y biomasa que las plantulas de la progenie de arboles aislados. Concluimos que la fragmentacion de bosques tropicales secos afecta la variacion genetica y el vigor de la progenie de S. saman. Sin embargo, los arboles aislados tuvieron una alta capacidad reproductiva a pesar de la condicion de su habitat.

Pimenta dioica L. Merrill, known as pimienta gorda, xocoxochitl (in Nahuatl) or allspice, is native to Mesoamerica. In Mexico, it has been used since pre-Hispanic times due to its medicinal properties and as a condiment for the preparation of “tamales” and “moles”. The dried fruits have a high economic value due to their flavor and aroma: a combination of cinnamon, nutmeg and clove. For this reason, it is known as allspice in English. Xocoxochitl is a dioecious tree. The fruiting, female trees, have a greater economic importance, while non-fruiting trees, or male trees, function to some extent as pollinators. However, leaves and fruits present similar volatile organic compounds (VOCs) responsible for the already mentioned properties. In order to evaluate the VOCs in leaves at different developmental stages, leaves were collected from: 2-years-old sexually undifferentiated trees and 14-years-old female and male differentiated trees. VOCs were collected and evaluated using SPME-GC-MS. Data obtained show a great diversity of VOCs at all leaf developmental stages, regardless of the tree analyzed. The dried fruit essential oil is highly valued by the international industry, but the leaves have minor use. However, leaves showed a great VOCs richness containing most of the dried fruit compounds. The VOCs profile in female and male trees were also evaluated. Individual VOCs displayed a different relative amount in each leaf developmental stage, as well as specific compounds for each type of tree were identified. Resumen. Pimenta dioica L. Merrill, conocida como pimienta gorda, xocoxochitl (en náhuatl) o como allspice, es originaria de Mesoamérica. En México, se ha usado desde la época prehispánica debido a sus propiedades medicinales, así como condimento para la preparación de tamales y moles. Los frutos secos tienen un alto valor económico debido a su sabor y aroma: una combinación de canela, nuez moscada y clavo. Por esta razón, en inglés se le llama allspice. Xocoxochitl es un árbol dioico. Los árboles que fructifican, árboles hembra, presentan una mayor importancia económica mientras que los árboles que no fructifican, árboles macho, funcionan en forma limitada como polinizadores. Sin embargo, las hojas y los frutos presentan compuestos orgánicos volátiles (COVs) similares responsables de las características mencionadas. Con el fin de evaluar los COVs presentes en hojas de diferentes estados de desarrollo, se colectaron hojas de árboles no diferenciados de 2 años de edad, así como de árboles diferenciados, hembra y macho, de 14 años de edad. Los COVs fueron colectados y analizados mediante SPME-GC-MS. Los datos obtenidos muestran una riqueza de COVs en todos los estados de desarrollo de la hoja, independientemente del árbol analizado. El aceite esencial del fruto seco es altamente apreciado en la industria internacional, sin embargo, las hojas presentan un menor uso. Además, también se evaluó el perfil de COVs de árboles hembra y macho. Ciertos COVs mostraron una cantidad relativa diferente en cada estado de desarrollo de la hoja, así mismo, se identificaron compuestos específicos para cada tipo de árbol.

espanolEn condiciones de invernadero se evaluo la calidad de plantulas de progenies selectas de Leucaena esculenta. En este sentido, durante 2017 se estudio el crecimiento de plantas en funcion de progenies de arboles y edad despues de la siembra (DDS) realizando analisis de varianza y pruebas de medias (Duncan, 0.05). Las progenies y los DDS mostraron separadamente diferencias significativas (p ≤ 0.0001) en las variables morfologicas y area foliar. Los indices de calidad fueron diferentes entre arboles (progenies) y DDS, donde el arbol 9 tuvo el valor mayor (4.54 ± 3.03) en el Indice de Dickson. Con los indicadores de calidad de planta se concluye que las progenies del arbol 7 fueron las de mejor calidad con valores mayores de las variables morfologicas. EnglishUnder greenhouse conditions, seedlings quality of Leucaena esculenta selected progenies were evaluated. In this sense, in 2017 the plant growth was analyzing according to tree progenies and age after sowing, AAS, using analysis of variance and mean tests (Duncan, 0.05). The progenies and AAS showed separately significant differences (p ≤ 0.0001) in morphological variables and leaf area. Quality indexes showed significant differences between trees (progenies) and AAS, where tree 9 had the highest Dickson Index (4.54 ± 3.03). According to plant quality indexes, it concludes that seedlings from tree 7 were the best with the highest values of the morphological variables. Keywords: leaf area, plant quality index, orthodox seeds.

La evaluación de los árboles monumentales es una actividad importante para promover su preservación. Según la revisión bibliográfica realizada, se encontró que, actualmente, no existe una legislación clara y suficiente en México para brindar protección a este tipo de individuos arbóreos. El objetivo de esta investigación fue evaluar la monumentalidad de árboles urbanos en México, con la participación de 15 expertos en el tema. Los ejemplares evaluados fueron: "El Tule"; "El Sabino"; "El Ahuehuete"; "La Higuera"; "El Baobab"; "El Ginkgo" y "El Árbol de los Acuerdos"; todos ellos ubicados en diferentes estados del territorio mexicano. Se definieron cinco criterios para la evaluación: tamaño del árbol, estado de conservación, importancia cultural, importancia del paisaje y rareza. El establecimiento de los criterios se basó en metodologías conocidas y utilizadas en la valoración de los árboles. El método PROMETHEE II se utilizó para determinar la monumentalidad. Los resultados del estudio indicaron que el "El Tule" y el "Árbol de los Acuerdos", localizados en el estado de Oaxaca y el Estado de México, respectivamente son los árboles que tienen características particulares que los hacen destacar sobre el resto de los individuos considerados en el estudio. El valor de monumentalidad más destacado fue para "El Tule", debido a que las evaluaciones de los expertos mostraron las preferencias más altas a favor del conjunto de atributos que lo caracterizan.

La minería de datos es una técnica que hoy en día se aplica en muchas áreas de las ciencias, es por ello que con el objetivo de identificar variables meteorológicas predominantes a ocho intervalos de tiempo se aplicó la técnica supervisada árbol de clasificación en data mining. La información se obtuvo de la estación Alao, misma que se encuentra ubicada a 3064 m.s.m en la provincia de Chimborazo, Ecuador. El estudio se realizó mediante código desarrollado en el software estadístico R; los datos corresponden a información por hora del año 2016, las variables analizadas fueron; temperatura del aire, humedad relativa, presión barométrica, radiación solar difusa, radiación solar global, temperatura del suelo a −20cm y velocidad de viento. El árbol mostró que la principal variable en esta zona es la radiación solar global, a horas comprendidas de 06h00 a 08h00, si ésta es mayor o igual a 120w/m2, entonces se puede determinar la presión barométrica de 09h00 a 11h00 de la mañana; y si ésta es mayor o igual que 709w/m2, entonces se predice la temperatura del aire. El árbol de decisión es una técnica que permitió identificar variables meteorológicas relevantes, en determinadas horas donde se encuentra ubicada la estación Alao. Abstract: Data mining is a technique that today is applied in many areas of science, which is why in order to identify predominant meteorological variables at eight time intervals the supervised tree classification technique was applied in data mining. The information was obtained from the Alao station, which is located at 3064 m.s.m in the province of Chimborazo, Ecuador. The study was carried out using a code developed in statistical software R, the data correspond to information by hour of the year 2016, the variables analyzes were air temperature, relative humidity, barometric pressure, diffuse solar radiation, global solar radiation, soil temperature at −20cm and wind speed. The showed that the main variable in this area is the global solar radiation, at hours between 06h00 and 08h00, if it is greater than or equal to 120w/m2, then the barometric pressure can be determined from 09h00 to 11h00 of the morning, if, and it is great than or equal to 709w/m2, then the air temperature is predicted. The decision tree is a technique that allowed us to identify relevant meteorological variables in certain hours where the Alao station is located. Palabras clave: árboles de decisión, datos meteorológicos. Keywords: decision tree, meteorological data.

espanolSe presenta una breve descripcion del arbol “guaba” (Inga marginata Willd.), informacion sobre fenologia como base para la recoleccion de frutos, el manejo de las semillas, la viverizacion y el proceso de germinacion. EnglishThe following issue presents a brief description about the “guaba” tree (Inga marginata Willd.), including information about its phenology which directly relates to fruit recollection, seed treatment, nursery, and germination processes.

Las caracteristicas de los suelos de los bosques humedos tropicales tanto maduros como secundarios son similares en coloracion, textura y densidad aparente. En las zonas tropicales calido-humedas de Ecuador Cecropia es un arbol tipico pionero en bosques secundarios, que se considera importante para la recuperacion de suelos en tierras degradadas. Tiene un bajo requerimiento de nutrientes y produce una gran cantidad de hojarasca que se degrada lentamente. En este estudio se compara el contenido nutrimental del suelo bajo Cecropia en bosques secundarios y maduros en Ecuador y no se duros, las hojas de Cecropia tuvieron un area especifica mas alta y niveles de nitrogeno mas bajos, lo que coincide con la teoria de la economia de la hoja. La variabilidad en las propiedades nutritivas del suelo fue mayor entre las tres estaciones de investigacion que entre las dos edades forestales. ABSTRACT - NUTRIENT CONTENT OF SOIL AND LEAF LITTER OF THE PIONEER TREE Cecropia IN MATURE AND SECONDARY FORESTS OF THE WET TROPICAL ZONE OF ECUADOR The soil characteristics of mature and secondary tropical rainforests are similar in color, texture, and bulk density. Cecropia a pioneer tree in early secondary forest typical of the warm-humid tropics in Ecuador, is considered important to the recovery of soil on degraded lands. It has a low nutrient requirement and produces a large amount of leaf litter that degrades slowly. This study compares soils under Cecropia in abandoned pasture and mature forest in Ecuador. No significant nutritive differences in soils or in Cecropia leaf litter were found between secondary and mature forest. Cecropia leaves have higher specific area and lower nitrogen levels in mature forest, consistent with theory on leaf economics. Variability in soil nutrition among three research stations was higher than between the two forest ages.

Resumen Se estudio la regeneracion natural de Weinmannia lechleriana Engl. (Cunoniaceae) en un bosque montano del sector San Alberto (Parque Nacional Yanachaga-Chemillen) en la selva central de Peru. Se evaluo la regeneracion natural alrededor de diez arboles maduros, mediante el establecimiento de cuatro transectos de 20 metros de longitud. Se encontraron un total de 276 individuos alrededor de los diez arboles; el 57,2 % correspondio a la categoria de brinzal, el 40,9 % a latizal y solo el 1,8 % a la categoria de fustal. El promedio de individuos de regeneracion natural fue de 27 por arbol evaluado y la mayor densidad de regeneracion fue encontrada entre los tres y seis metros alrededor del arbol, para luego ir disminuyendo al incrementar la distancia. Ademas, se hallo una mayor abundancia total de individuos en los transectos oeste y en arboles evaluados en ladera, pero seria necesario evaluar un numero mayor de arboles para llegar a una conclusion al respecto. Finalmente, podemos indicar que Weinmannia lechleriana aparentemente no presentaria problemas de regener­acion en el area de estudio y se recomienda proseguir con los estudios de esta especie. Palabras clave: Cunoniaceae, Pasco, estado de conservacion, regeneracion natural, brinzal. Abstract We studied the natural regeneration of Weinmannia lechleriana Engl. (Cunoniaceae) in a montane forest of the San Alberto Sector (Yanachaga-Chemillen National Park) in the central jungle of Peru. The natural regeneration was evaluated around ten mature trees, through the establishment of four transects of 20 meters in length. A total of 276 individuals were found around the ten trees, 57.2 % corresponded to the category of seedlings, 40.9 % of the saplings and only 1.8% to the category of poles. The average of natural regeneration individuals was 27 per evaluated tree, and the highest regeneration density was found between three and six meters around the tree, and then decreasing with increasing distance. Furthermore, a greater total abundance of individuals was found in the western transects and in trees evaluated in slope, but it would be necessary to evaluate a greater number of trees in order to reach a conclusion. Finally, we can indicate that Weinmannia lechleriana apparently would not present regeneration problems in the study area and it is recommended to continue with the studies of this species. Keywords: Cunoniaceae, Pasco, conservation status, natural regeneration, seedling.

espanolLa disponibilidad de semilla y su viabilidad son procesos clave para la persistencia de los bosques maduros. Existen evidencias de que la senescencia en los arboles no disminuye la fecundidad en edades avanzadas, pero se desconoce si tiene efectos sobre la viabilidad de la progenie. Este trabajo analiza la influencia de la edad del arbol sobre los atributos biometricos de la semilla, la germinacion y la emergencia en los bosques maduros de Quercus suber en los Parques Nacionales de Cabaneros y Monfrague. En cada uno de los PPNN se seleccionaron 45-48 individuos de Quercus suber, entre jovenes y senescentes, cubriendose el rango de diametros encontrados (24 a 100 cm en el PN de Cabaneros y 24 a 176 cm en el PN de Monfrague). Se tomaron sus coordenadas y se midio su tamano (diametro, altura y diametros de copa). Ademas, se estimo la edad a 1,30 m de altura (dbh) mediante la extraccion de testigos de madera. En diciembre de 2018 se recogio toda la semilla presente en los individuos seleccionados, que no fue muy abundante debido a la marcada veceria en 2018. Se determinaron los caracteres biometricos de cada bellota (peso fresco, diametro y longitud), analizandose el efecto de la edad del arbol, a traves del dbh. Los resultados muestran el efecto del sitio, la edad del arbol y el tamano de la bellota, tanto en la produccion de semilla, como en su caracterizacion biometrica, germinacion y emergencia, aunque la baja cosecha registrada en 2018 enmascara las diferencias esperadas. EnglishSeed availability and viability are key processes for the persistence of mature forests. There are evidences that tree senescence does not decrease seed fecundity. However, the effect of senescence on the viability of the progeny in mature forests has not been assessed. This study analyses the influence of tree age on biometric traits of the acorn, germination and emergence in mature forests of Quercus suberin Cabaneros and Monfrague National Parks. We selected 45 to 48 trees in each National Park (NP), covering from young to old trees along the range of diameter at breast height (DBH) found (from 24 to 100 cm in Cabaneros NP, and from 24 to 176 cm in Monfrague NP). Measurements included coordinates, DBH, height and two perpendicular crown diameters. Tree age was estimated at 1.3 m by extracting cores. In December 2018 seeds were collected from the selected trees. The yield was not abundant due to the marked masting year. After numbering the acorns individually, different biometric traits were measured (fresh weight, diameter, volume and length), and the effect of tree age was analysed, considering DBH as a proxy of tree age. Acorns were seeded to monitor germination and emergence. The results show the effect of site, tree age and acorn size on seed production, biometric traits, germination and emergence. Acorn size varied with parental trees and within a tree. The low yield in 2018 could in part mask the results.

espanolEn el presente trabajo se hace referencia a los parametros que normalmente se toman en consideracion para la inclusion de un arbol como monumento vegetal y se comenta la evolucion de la normativa gallega relacionada con la catalogacion de arboles y formaciones singulares. EnglishIn the present work reference is made to the parameters that are normally taken into consideration for the inclusion of a tree as a vegetal monument and comments on the evolution of the Galician regulations related to the cataloging of trees and singular formations.

Ecosystems, 9 (3), ISSN:1432-9840, ISSN:1435-0629

Se describe e ilustra a Bursera zapoteca Rzed. & Medina sp. nov., arbol de la selva mediana subperennifolia de la cuenca del rio Tehuantepec, en el sureste de Oaxaca. El taxon nuevo pertenece al clado de especies relacionadas con B. simaruba (L.) Sarg. y esta estrechamente emparentado con B. permollis Standl. & Steyermark, asi como con B. krusei Rzed., de las que esencialmente se diferencia en sus hojas unifolioladas, no trifolioladas. ABSTRACT : Bursera zapoteca Rzed, & Medina sp.nov., a tree of tropical semi-evergreen forest in the Tehuantepec river basin of the southeastern part of the Mexicane new taxon belongs to the clade ofspecies allied with B. simaruba (L.) Sarg. and is closely related to B. permollis Standl. & Steyerm., as well as to B. krusei Rzed., from which it is essentially differentiated byits unifoliolate and cordiform leaves and by its reddish flowers.

334 p. En esta tesis de investigación se elabora una herramienta, que puede ser empleada en la toma de decisiones respecto a los problemas derivados de la contaminación atmosférica. Para ello, se plantea un objetivo general, ante la necesidad existente, para lograr un modelo aplicable a la resolución de problemas relacionados con la calidad del aire respirable a escala local. A partir del conjunto de datos experimentales de las concentraciones de óxidos de nitrógeno, monóxido de carbono, dióxido de azufre, ozono y materia particulada, recogidos desde 2013 a 2015, se construyen varios modelos de regresión utilizando técnicas basadas en el aprendizaje estadístico, para predecir mediante el modelo resultante la calidad del aire en la ciudad de Oviedo. Una vez obtenidos los modelos planteados, se comparan los resultados con el fin de comprobar que el método híbrido basado en el enfoque PSO-SVM arroja mejores resultados que los métodos alternativos propuestos, red neuronal MLP y árbol de regresión M5, pudiendo modelar con precisión suficiente la calidad del aire a escala local.

Se seleccionaron 50 potreros con 10 años de establecimiento asociados con especies arbóreas, se realizó el inventario de las especies dispersas con diámetros de altura al pecho (DAP) ≥ 5 cm. En cada árbol se midieron las variables dasométricas DAP, altura total, área de copa. Se determinó su frecuencia, riqueza, abundancia, índice de valor de importancia, índice de biodiversidad basada en la abundancia proporcional de especies (Shannon, Simpson) y de riqueza de especies (Margalef). Se registraron 22 familias, el 83,8% corresponden a especies maderables y el 16,2% a especies frutales, la familia con mayor número de individuos fue Boraginaceae con 194 individuos. El DAP explico el 96% de la variación del área basal, a medida que este se incrementó y las estructuras de las especies arbóreas no demostraron influir en la producción de materia seca, cobertura y calidad de las pasturas, debido a la baja cobertura arbórea (3,69 ± 0,67%) y al número de árboles dispersos en los potreros (5 a 7 árboles ha − 1). El impacto de la cobertura arbórea demostró que incide significativamente en el crecimiento de las plantas, demostrando que el cultivar Marandú tiene una mejor tolerancia a la sombra respecto al Dallis y Saboya. Se concluye que los ecosistemas ganaderos Amazónicos del centro norte del Ecuador de acuerdo a los índices de biodiversidad estarían considerados como bajos, pero con una riqueza media de especies dispersas en potreros. Se identificó 4 especies con mayor peso ecológico superior al promedio (3,4%) Cordia alliodora, Cedrela odorata, Schizolobium parahybum y Psidium guajava.// Fifty paddocks of ten years of establishment associated with tree species were randomly selected; an inventory of all dispersed species with breast height diameters (DBH) ≥ 5 cm was made. Dasometric variables as DBH, total height and crown area were measured in each tree. Frecuency, richness, abundance, importance value index, biodiversity index based on proportional abundance of species (Shannon, Simpson) and species richness (Margalef) were determinated. 22 tree families were registered, 83.8% correspond to timber species and 16,2% to fruit species, the family with the highest number of individuals was Boraginaceae with 194,96% of variation of the basal area was explained by BDH. As far as this increased and the structure of tree species do not shown any influence in dry matter production, cover and quality of the three found pasturages, due to low tree cover (3,69 ± 0,67%) and to the number of dispersed trees in the paddocks (5 to 7 trees ha− 1). The impact of tree cover showed that it affects significantly on the growth of the plants, demonstrating that Marandú has the best shadow tolerance respect to Dallis and Saboya. It is concluded that the amazonian livestock system of northem central Ecuador according to the biodiversity indexes could be considerate as low levels, but with a medium richness of dispersed tree species on paddocks. The importance value index allowed identifying 4 species with the highest ecological weight over the average (3,4%) Cordia alliodora, Cedrela odorata, Schizolobium parahybum and Psidium guajava.

A study was performed examining the influence of preference for trees on self-reported levels of physical, psychological and social wellbeing, mediated by optimism, among 323 students in their final years of high school. Findings indicated that the greater the preference for trees, the greater the individual’s optimism, which in turn influenced physical, psychological and social wellbeing. These findings could be important because they pertain to teenagers in school education, residing in a metropolitan area with over four million inhabitants, with a very low ratio of trees to inhabitants. The results could be used in public policy to target this sector of the population in tree planting and environmental education campaigns in ecologically depressed urban areas.

We studied the changes in the number of leaves, roots and height on three cultivars of Capsicum anuumm (Jalapeno, Serrano and De arbol) after inoculation with Glomus intraradices FS18 and Glomus Zac-19. Results indicated that Glomus intraradices FS18 produced greater effects on height (6.12 and 5.63 cm) and number of leaves (10.66 and 5.84) in the cultivars “Jalapeno” and “De arbol”, respectively. On the other hand, Glomus zac-19 stimulated the number of leaves and roots in “Serrano” pepper (6.17 leaves and 15.31 roots) and “Arbol” (6.52 leaves and 26.32 roots). Our results demonstrate the capacity of Glomus intraradices FS18 and Glomus Zac-19 of stimulating seedling growth on the three cultivars of Capsicum annuum L. This demonstrates the potential for using arbuscular mycorrhizal fungi in the production of plants of agronomic interest.

espanolEl objetivo de esta investigacion fue desarrollar modelos de estimacion de la densidad basica de la madera a nivel de arbol completo y a diferentes alturas de arboles de Pinus radiata, a partir de la resistencia de la madera medida con el resistografo, a la altura del pecho a 1,3 m sobre el nivel suelo (DAP). Se utilizo una muestra de 29 arboles de 15 anos de edad, obtenidos al azar, en un ensayo clonal establecido en la Region del Bio-Bio, Chile. Para cada arbol, en seis diferentes alturas relativas del fuste, se determino la resistencia de la madera y la densidad basica, a partir de 174 mediciones realizadas con el resistografo y en muestras de rodelas. Los resultados obtenidos indicaron que tanto la densidad basica como la resistencia de la madera disminuyeron significativamente en funcion de la altura del arbol, en la direccion base y altura comercial, en un 16,8% y 38,5%, respectivamente. Los valores de resistencia media determinados al DAP, presentaron una variacion entre arboles de 11% y 19%. Se genero un modelo que estima la densidad basica a nivel de arbol completo utilizando como unica variable predictora la resistencia media de la madera medida al DAP, con un error de estimacion de 11,9 kg/m3, el cual no disminuye al incorporar variables de estado de arbol (DAP y HT). A partir de este modelo se genero un metodo para estimar la densidad basica en diferentes secciones del arbol. EnglishThe objective of this research was to develop models for estimation of the basic density of wood at full tree level and at different heights of Pinus radiata standing trees, measured from the wood resistance using the resistography at DBH level. A sample of 29 trees of 15 years old was used for the experiment. The trees were selected in a clonal field test established in the Bio-Bio Region, Chile. For each tree, 174 measurements were made with the resistograph and wood disks were obtained to determine the wood resistance and the basic density at six different relative heights of the stem. As a result, a significant decrease of the basic density and resistance of the wood was observed, from the base to the apex of the trees, with values of 16,8% and 38,5% of decrease, respectively for each variable. The average for the resistance values determined at DBH varied between 11% and 19% among the measured trees. A prediction model was generated to estimate the basic density at the tree level using the average resistance of the wood measured to the DBH. The adjustment parameters of the model was a root mean square error value of 11,9 kg/m3, which did not decrease when other variables of tree (DBH or total height) were incorporated. As a main conclusion, a new method to estimate the wood basic density at different sections of the tree was generated using the adjusted model.

Phloeotribus pruni Wood (Coleoptera: Scolytidae) is reported for the first time associated with the collapse of peach ( Prunus persica ) trees in Coatepec de Harinas, State of Mexico, Mexico. One hundred percent incidence of collapsed trees was found in a 2 ha peach orchard. In 10 trees sampled, a mean number of 3.3 adults and 4 larvae per 25 cm2 of bark were found. Trees died 12 to 18 months after the onset of symptoms. The 100% incidence of attacked trees, and the tree death 12 to 18 months after the first detection of the insect, point out the importance of this pest. Sumario Se informa por primera vez la asociacion de Phloeotribus pruni Wood (Coleoptera: Scolytidae) con el colapso de los arboles de Durazno ( Prunus persica : Rosaceae) en Coatepec de Harinas, Estado de Mexico, Mexico. Se encontro una incidencia del cien por ciento de arboles colapsados en un huerto de 2 hectareas de melocotones. En 10 arboles muestreados, se encontro un promedio de 3.3 adultos y 4 larvas por cada 25 cm2 de corteza. Los arboles murieron 12-18 meses despues de la aparicion de los sintomas. El 100% de incidencia de arboles atacados y la muerte del arbol 12 para 18 meses despues de la primera deteccion del insecto senalan la importancia de esta plaga. View this article in BioOne

Heritage trees in a city, echoing factors conducive to outstanding performance, deserve special care and conservation. To understand their structural and health conditions in urban Hong Kong, 30 defect-disorder (DD) symptoms (physical and physiological) subsumed under four tree-position groups (soil-root, trunk, branching, and crown-foliage) and tree hazard rating were evaluated. The surveyed 352 trees included 70 species; 14 species with 233 trees were native. More trees had medium height (10–15 m), medium DBH (1–1.5 m) and large crown (>15 m). In ten habitats, public park and garden (PPG) accommodated the most trees, and roadside traffic island (RTI) and public housing estate (PH) had the least. Tree dimensions and tree habitats were significantly associated. The associations between the 2831 DD and tree-position groups, tree habitats and tree hazard rating were analyzed. Fourteen trees from Ficus microcarpa , Ficus virens and Gleditsia fera had high hazard rating, 179 trees from 22 species moderate rating, and 159 trees from 55 species low rating. RTI, roadside tree strip (RTS), roadside tree pit (RTP), roadside planter (RP) and stone wall (SW) had more moderate hazard rating, and PPG, roadside slope (RS) and government, institutional and community land (GIC) more low rating. Redundancy analysis showed that DD were positively correlated with RTS, RTP, RP and SW, but negatively correlated with PPG, RS and GIC ( p

This study compared the decomposability of leaf, twig and wood litter from 27 co-occurring temperate rainforest tree species in New Zealand. We found that interspecific variation in decomposition was not coordinated across the three litter types. Analysis of the relationships between functional traits and decomposition revealed that traits predictive of wood decomposition varied among the species independently from traits predictive of the decomposition of leaf and twig litter. We conclude that efforts to understand how tree species influence C, N and P dynamics in forested ecosystems through the decomposition pathway need to consider the functional traits of multiple plant structures. Synthesis Plant functional traits are increasingly used to evaluate changes in ecological and ecosystem processes. However our understanding of how functional traits coordinate across different plant structures, and the implications for trait-driven processes such as litter decomposition, remains limited. We compared the functional traits of green leaves and leaf, twig and wood litter among 27 co-occurring tree species from New Zealand, and quantified the loss of mass, N and P from the three litter types during decomposition. We hypothesised that: a) the functional traits of green leaves, and leaf, twig and wood litter are co-ordinated so that species which produce high quality leaves and leaf litter will also produce high quality twig and wood litter, and b) the decomposability of leaf, twig and wood litter is coordinated because breakdown of all three litter types is driven by similar combinations of traits. Trait variation across species was co-ordinated between leaves, twigs and wood when angiosperm and gymnosperm species were considered in combination, or when angiosperms were considered separately, but trait coordination was poor for gymnosperms. There was little coordination among the three litter types in their decomposability, especially when angiosperms and gymnosperms were considered separately; this was caused by the decomposability of each of the three litter types, at least partially, being driven by different functional traits or trait combinations. Our findings indicate that although interspecific variation in the functional traits of trees can be coordinated among leaves, twigs and wood, different or unrelated traits predict the decomposition of these different structures. Furthermore, leaf-level analyses of functional traits are not satisfactory proxies for function of whole trees and related ecological processes. As such, efforts to understand how tree species influence C, N and P dynamics in forested ecosystems through the decomposition pathway need to consider functional traits of other plant structures.

The objective of this study was to characterize hollows found in selected tree species (in Cawston Ranch in Zimbabwe) as a potential habitat for small mammals because cavities are important as resources for wildlife: for foraging, shelter, roosting and nesting purposes. Four vegetation types were chosen for analysis: Baikiaea plurijuga, Colophospermum mopane, Combretum molle and Commiphora mollis according to abundance and dominance in the plots they occurred. Transect sampling was done to collect vegetation data. The total number of living trees and stags were recorded in each plot. Trees in a plot were thoroughly inspected for hollows. The following dimensions were measured on cavity trees: hollow size (diameter), hollow location and diameter at breast height. The results indicate that the rate of hollow formation and utilization is significantly dependent on tree species. There was a significant difference in the provision of hollows in stem and crown of a tree in each of the vegetation classes analysed. B. plurijuga hollows had the highest utilization whilst C. molle had the least utilization. Hollows are utilized irrespective of their location as long as the animal finds a niche, and stags at advanced stages of decay are not important in providing habitats for animals. Resume L'objectif de cette etude etait de qualifier les trous constates dans certaines especes d'arbres (dans le Cawston Ranch, au Zimbabwe) comme habitat potentiel pour de petits mammiferes parce que les cavites sont des ressources importantes pour la faune qui y trouve nourriture, refuge, perchoir ou nid. Quatre types de vegetation furent choisis pour cette analyse: Baikiaea plurijuga, Colophospermum mopane, Combretum molle et Commiphora mollis, en fonction de leur abondance et de leur dominance dans les parcelles ou ils existent. Un echantillonnage par transect fut fait pour collecter des donnees sur la vegetation. Le nombre total d'arbres vivants et de branches fut note pour chaque parcelle. Les arbres de chaque parcelle furent examines attentivement pour y chercher les creux. Les dimensions suivantes furent notees pour les arbres concernes: taille du trou (diametre), emplacement du trou et diametre a hauteur de poitrine (dbh). Les resultats indiquent que le taux de formation de trous et leur utilisation dependent significativement de l'espece de l'arbre. Il y avait une difference significative dans la formation de trous dans le tronc et la couronne d'un arbre pour chaque classe de vegetation analysee. Les trous de B. plurijuga etaient les plus utilises et ceux de C. molle les moins frequentes. Les trous etaient utilises, quel que soit leur emplacement, pour autant que l'animal y trouve une niche, et les branches a un stade de decomposition avance ne sont pas importantes pour ce qui est d'offrir un habitat a des animaux.

This study aims to test the effects of forest age on soil respiration in poplar ecosystems in northern China and to separate the contributions of root respiration (Rr) and soil microbes to the total soil respiration (Rs). Rs in three poplar forests (5, 10, and 15 years old) were measured using an LI-6400-09 soil chamber connected to an LI-6400 portable infrared gas analyzer during the growing seasons in 2007 and 2008. Root respiration was measured using the root excision method. The soil micro-organisms were quantified using the dilution-plate method. The results show that Rs was the highest in the 5-year-old forest and lowest in 15-year-old forest. The contribution of Rr to Rs ranged from 29.4 to 81.0%. Rr/Rs tended to be significantly higher in the 15-year-old forest than that in the younger forests; but Rr was the highest in the 5-year-old forest. Temporal variation in Rs can be largely accounted by fine-root biomass (R = 0.718), while soil N was significantly negatively correlated with Rs (R = -0.646). Rs, Rr and Rr/Rs vary significantly with the forest age. The lower Rs in the older forests increased their carbon use efficiency. Underground factors, dominated by fine-root biomass, affect Rs, Rr and Rr/Rs substantially. Soil microbial community structure is a particularly important underground factor.

Poplar plantations are expanding worldwide but little is known about the hornet clearwing moth, Sesia apiformis, one of their most severe pests. Thirty-two poplar plantations of 1-214 clone were sampled in Spain, according to a factorial design combining stand age, site condition and understorey management to investigate the main drivers of S. apiformis habitat selection at both tree and stand level. In each plantation, one pheromone trap was activated during the flight season to test the correlation between captures and percentage of attacked trees. The proportion of other poplar forests in surrounding landscapes was calculated and used as a covariate in predictive models of trap catches. There were significantly more attacked trees in older stands. In young stands, the percentage of infested trees increased with the percentage cover of understorey vegetation. There was no significant effect of site quality on the rate of infestation and no difference in tree height, diameter or crown condition between attacked and un-attacked trees within each stand, suggesting that S. apiformis could behave as primary pest. We hypothesized that the critical stage in the life cycle of the moth was the first instar larvae, which may benefit from protection of deep bark cracks in older stands and understorey vegetation in younger stands. We observed a positive correlation between trap capture and percentage of attacked trees in a radius of 100 m around the trap. The regression of trap catches against percentage of attacked trees was improved when the area of other poplar plantations within a distance of 600 m was incorporated in the model. This suggests that surrounding poplar stands may act as sources of immigrating moths in monitored stands. Our findings confirm that S. apiformis should be considered as a potential threat to poplar plantations and that pheromone trapping provides a suitable monitoring tool.

The response of the field layer vegetation to co-varying resource availability (soil nutrients, light) and resource loss (herbivory pressure) was investigated along a landscape gradient highly influenced by elephants and smaller ungulates at the Chobe River front in Botswana. TWINSPAN classification was used to identify plant communities. Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA) were used to explore the vegetationeenvironment relationships. Four plant communities were described: Panicum maximum woodland, Tribulus terrestris woodland/shrubland, Chloris virgata shrubland and Cynodon dactylon floodplain. Plant height, species richness and diversity decreased with increasing resource availability and resource loss. The species composition was mainly explained by differences in soil resources, followed by variables related to light availability (woody cover) and herbivory, and by interactions between these variables. The vegetation structure and species richness, on the other hand, followed the general theories of vegetation responses to herbivory more closely than resource related theories. The results suggest a strong interaction between resource availability and herbivory in their influence on the composition, species richness and structure of the plant communities.

We prove a finitary version of the Halpern–Läuchli Theorem. We also prove partition results about strong subtrees. Both results give estimates on the height of trees.

We investigated the tree growth and physiological response of five pine forest stands in relation to changes in atmospheric CO 2 concentration (c a ) and climate in the Iberian Peninsula using annually resolved width and δ 13 C tree-ring chronologies since AD 1600. 13 C discrimination (Δ ≈ c i /c a ), leaf intercellular CO 2 concentration (c i ) and intrinsic water-use efficiency (iWUE) were inferred from δ 13 C values. The most pronounced changes were observed during the second half of the 20th century, and differed between stands. Three sites kept a constant c i /c a ratio, leading to significant c i and iWUE increases (active response to c a ); whereas a significant increase in c i /c a resulted in the lowest iWUE increase of all stands at a relict Pinus uncinata forest site (passive response to c a ). A significant decrease in c i /c a led to the greatest iWUE improvement at the northwestern site. We tested the climatic signal strength registered in the δ 13 C series after removing the low-frequency trends due to the physiological responses to increasing c a . We found stronger correlations with temperature during the growing season, demonstrating that the physiological response to c a changes modulated δ 13 C and masked the climate signal. Since 1970 higher δ 13 C values revealed iWUE improvements at all the sites exceeding values expected by an active response to the c a increase alone. These patterns were related to upward trends in temperatures, indicating that other factors are reinforcing stomatal closure in these forests. Narrower rings during the second half of the 20th century than in previous centuries were observed at four sites and after 1970 at all sites, providing no evidence for a possible CO 2 'fertilization' effect on growth. The iWUE improvements found for all the forests, reflecting both a c a rise and warmer conditions, seem to be insufficient to compensate for the negative effects of the increasing water limitation on growth.

Modeling the environmental benefits of urban trees requires data which relate crown height, crown diameter, and leaf area to tree age or stem diameter (DBH). Growth prediction curves, that can be derived from the same data, can also be very useful for a better planning, design and development of the urban forest. However, very little information is available on the growth behavior of urban trees, and limited to few species and regional contexts. The aim of this study was to determine the relationships between tree age and various parameters of tree size in order to develop models to predict the growth of the most important species of an urban forest in northeastern Italy. The logarithmic regression model, proposed by Peper et al., 2001a , Peper et al., 2001b and applied by Stoffberg et al., 2008 , Stoffberg et al., 2009 , and other equations were tested in order to obtain the best fit for each species and parameter. All the models provided a better fit for the larger species (Tilia x vulgaris Hayne, Fraxinus angustifolia Vahl., Acer platanoides L.) than for the smaller ones (Prunus cerasifera “pissardi” (Carriere) L.H. Bailey and Lagerstroemia indica L.). The equations for predicting tree sizes and leaf area are presented and applied to compare size and growth 15 and 25 years after planting. According to the models A. platanoides attained the largest average annual DBH growth with values ranging from an average of 1.25 cm years−1 between 0 and 15 years after planting and 1.52 cm years−1 between 15 and 25 years after planting. L. indica showed the smaller DBH growth, ranging from 0.34 cm years−1 in the first period to 0.48 cm years−1 in the second period. 25 years after planting. A. platanoides L. is the tallest species and reaches the largest crown diameter, whith the largest average annual growth, followed by F. angustifolia and Tilia x vulgaris that show similar growth patterns. A comparison with predicted sizes in other studies confirms the need to extend the knowledge to the behavior of more species and more site specific conditions.

We examined radial growth responses of ponderosa pine (Pinus ponderosa var. ponderosa) between 1905-1954 and 1955-2004 to determine if the effects of increased intrinsic water-use efficiencies (iWUE) caused by elevated atmospheric CO 2 concentrations were age-specific. We collected 209 cores from five sites in the Northern Rockies and calculated iWUE using carbon isotope data from 1850 to 2004. Standardized radial growth responses were age dependent, with older trees exhibiting significantly higher values than younger trees during the later period at four sites and all sites combined. No significant differences in radial growth existed either for the individual sites or combined site during the earlier period. Increases in iWUE during 1955-2004 were 11 % greater than during 1905-1954, and pentadal fluctuations in iWUE were significantly correlated with the radial growth of older trees from 1850 to 2004. Radial growth of younger trees and iWUE were not significantly correlated. Our results suggest that: (1) responses to elevated atmospheric CO 2 in old-growth ponderosa forests are age-specific; (2) radial growth increases in older trees coincided with increased iWUE; (3) ponderosa had increased growth rates in their third, fourth, and fifth centuries of life; and (4) age-specific growth responses during 1955-2004 are unique since at least the mid-16th century.

Most theories of forest biodiversity focus on the role of seed dispersal and seedling establishment in forest regeneration. In many ecosystems, however, sprouting by damaged stems determines which species occupies a site. Damaged trees can quickly recover from disturbance and out-compete seedlings. Links among species' traits, environmental conditions and sprouting could offer insight into species' resilience to changes in climate, land use, and disturbance. Using data for 25 Neotropical tree species at two sites with contrasting rainfall and soil, we tested hypotheses on how four functional traits (seed mass, leaf mass per area, wood density and nitrogen fixation) influence species' sprouting responses to disturbance and how these relationships are mediated by a tree's environmental context. Most species sprouted in response to cutting, and many species' sprouting rates differed significantly between sites. Individual traits showed no direct correlation with sprouting. However, interactions among traits and site variables did affect sprouting rates. Many species showed increased sprouting in the higher-quality site. Most nitrogen-fixing species showed the opposite trend, sprouting more frequently where resources are scarce. This study highlights the use of functional traits as a proxy for life histories, and demonstrates the importance of environmental effects on demography.

Although the overlap in fruit diet between birds and bats is low, they sometimes consume and compete for fruits of the same plant species. What is poorly known is how birds and bats compare with each other in relation to the effectiveness of seed dispersal. In this paper we contrasted birds and bats in relation to quantitative (the amount of fruits removed from plants) and qualitative (germination performance of seeds) components of the seed dispersal of Solanum granuloso-leprosum, a pioneer, small-seeded tree of open areas and forest edges in south Brazil. We tagged fruits on the plants and monitored their removal by day and night. We compared the final percent of germination and speed of germination of seeds ingested by birds and bats with non-ingested, control seeds. While bats removed more fruits than birds, performing better in the quantitative component, birds improved the germination performance of seeds, an aspect of the qualitative component of seed dispersal effectiveness. Although bats are more likely to deposit seeds in highly disturbed sites that favor the recruitment of pioneer plant species, birds frequent forest edges, which is also suitable habitat for S. granuloso-leprosum, We concluded that birds and bats are not ‘redundant’ seed dispersers for S. granuloso-leprosum because in conjunction they may enhance its recruitment by diversifying the microsites where seeds are deposited, performing in addition different ecological functions in terms of quantity and quality of dispersal.

In most wind-dispersed species, young seedlings usually grow in clusters. Dense stands of seedlings are however not often recommended for most restoration sites due to poor stand growths. We evaluate the effect of varying neighbor distances on biomass (above ground) and survival of Cottonwood (Populus deltoides) seedlings. We used four different neighbor distances (5, 15, 25, and 35 cm) as treatments and planted seedlings in the field in hexagonal arrays. Each array had 31 equidistant seedlings. Bases on the position, seedlings were categorized as growing in the ‘core’ or the ‘edge’ in the array. Morphometric measurements of seedling, seedling biomass and survival were recorded. Seedling biomass was lower in treatments where neighbor distances were large, 35 cm or small, 5 cm. There was an optimum neighbor distance (15 cm) where seedlings had the greatest biomass accumulation. Morphometric comparisons of plants growing in different treatments showed that, seedlings had greater stem diameter and more leaves at the neighbor distance of 15 cm than at other distances. Seedling survival did not differ among the four treatment types but was significantly different based on the position of the seedling within an array, with greater survival in the core region than the edge.

Secondary habitats are increasing in importance in tropical countries due to ongoing destruction of pristine vegetation. In spite of the magnitude of current changes, our understanding of their effects on nontrees (e.g., nonvascular or vascular epiphytes) is still very patchy, particularly in lowland habitats. Here, we report a study with isolated pasture trees in southwest Panama. The >800 studied trees, which belonged to >100 different species, harbored almost 27,000 epiphytes of 83 species. Orchidaceae was the most species-rich family, with almost 60 percent of all species, while Bromeliaceae were most abundant. A rainfall gradient in the study region from ca 1000 to >3000 mm explained more of the variation in species abundance and richness than host characteristics (e.g., species identity, tree size). The unexpectedly large number of epiphytes in these pastures still represents a substantial change relative to a natural setting, which is suggested by a comparison with a forest inventory under similar climatic conditions. In pastures, species richness was lower as deduced from individual-based rarefaction curves, a larger proportion of species and individuals showed crassulacean acid metabolism, and the relationship of epiphyte abundance/species richness and tree diameter was much less steep. Even the already reduced diversity, however, may be only transient in secondary habitats—the long-term persistence of epiphyte populations in pastures is an open question and has to be addressed by repeated monitoring to fully evaluate the significance of pasture trees for the conservation of vascular epiphytes in tropical lowlands. RESUMEN Debido a la destruccion en curso de vegetacion pristina, los habitats en regeneracion estan acrecentando en importancia en paises tropicales. A pesar de la magnitud de los cambios en curso, nuestro entendimiento de sus efectos en plantas no arboreas (ej. Epifitas vasculares y no vasculares) es aun bastante fragmentario, particularmente en habitats de tierras bajas. Aqui, reportamos un estudio con arboles aislados en pastizales en el suroeste de Panama. Los mas de 800 arboles estudiados, que pertenecen a mas de 100 especies diferentes, albergaron casi 27 000 epifitas pertenecientes a 83 especies. Orchidaceae fue la familia mas especiosa, conteniendo casi el 60% de todas las especies, mientras que Bromeliaceae fue la mas abundante. Un gradiente de precipitacion en el area de estudio desde ca. 1000 mm a 3000 mm explico mayor parte de la variacion en la abundancia y riqueza de especie que las caracteristicas de los arboles hospederos (ej. identidad de las especies, tamano de los arboles hospederos). El inesperado alto numero de epifitas en estas pasturas aun representa un cambio substancial en relacion con el escenario natural, sugerido por la comparacion con un inventario realizado en un bosque con condiciones climaticas similares. En los pastizales, la riqueza de especies fue mas baja, segun las curvas de rarefaccion basada en individuos, una proporcion mayor de especies e individuos mostro CAM, y la relacion riqueza de especies/abundancia de epifitas con el diametro del arbol fue mucho menos marcada. Sin embargo, incluso la ya reducida diversidad sea quiza solo transitoria en habitats secundarios. La persistencia de poblaciones de epifitas a largo plazo en pastizales es una pregunta sin responder y tiene que ser aclarada a traves de monitoreo repetido para evaluar enteramente el significado de los arboles en pastizales para la conservacion de las epifitas vasculares en los bosques de tierras bajas.

The complex structure of tree bark reflects its many functions, which include structural support as well as defence against fire, pests and pathogens. Thick bark, however, might limit respiration by the living tissues of the trunk. Nevertheless, little research has addressed community-level variation in bark thickness, and to the best of our knowledge, no one has tested multiple hypotheses to explain variation in bark thickness. We conducted an extensive survey of bark thickness within and among species of trees in the tropical rain forests of French Guiana. Trunk bark thickness increased by 1.2 mm per 10 cm increase in stem diameter, and varied widely at all taxonomic levels. Mean trunk bark thickness was 4.5 mm (range: 0.5-29 mm), which was less that found in two Amazonian rain forests in previous studies. This survey of bark thickness should be of use for forest management since tree survival through fire is strongly predicted by bark thickness. We combined the survey data with multiple datasets to test several functional hypotheses proposed to explain variation in bark thickness. We found bark to provide an average of 10% of the flexural rigidity of tree stems, which was substantially less than that found in the only other study of bark stiffness. Bark thickness was uncorrelated with species' association with fire-prone habitats, suggesting that the influence of fire on bark thickness does not extend into moist Forests. There was also little evidence that bark thickness is affected by its function as a defence against herbivory. Nor was there evidence that thick bark limits trunk respiration. A re-analysis of previously collected anatomical data indicated that variation in rhytidome (non-conducting outer bark) thickness explains much of the variation in overall bark thickness. As rhytidome is primarily involved in protecting the living tissues of the trunk, we suggest that bark thickness is driven mostly by its defensive function. Functional explanations for the variation in bark thickness were not clear-cut. Nevertheless, this study provides a foundation for further investigation of the functional bases of bark in tropical trees.

One of the five most important global biodiversity hotspots, the Neotropical Atlantic forest supports a diverse community of birds that nest in tree cavities. Cavitynesting birds may be particularly sensitive to forestry and agricultural practices that remove potential nest trees; however, there have been few efforts to determine what constitutes a potential nest tree in Neotropical forests. We aimed to determine the characteristics of trees and cavities used in nesting by excavators (species that excavate their own nest cavity) and secondary cavity-nesters (species that rely on existing cavities), and to identify the characteristics of trees most likely to contain suitable cavities in the Atlantic forest of Argentina. We used univariate analyses and conditional logistic regression models to compare characteristics of nest trees paired with unused trees found over three breeding seasons (2006‐2008). Excavators selected dead or unhealthy trees. Secondary cavity-nesters primarily selected cavities that were deep and high on the tree, using live and dead cavity-bearing trees in proportion to their availability. Nonexcavated cavities suitable for birds occurred primarily in live trees. They were most likely to develop in large-diameter trees, especially grapiaApuleia leiocarpaand trees in co-dominant or suppressed crown classes. To conserve cavity-nesting birds of the Atlantic forest, we recommend a combination of policies, economic assistance, environmental education, and technical support for forest managers and small-scale farmers, to maintain large healthy and unhealthy trees in commercial logging operations and on farms.

1. Modelling growth strategies among tropical trees is an important objective in predicting the response of tree dynamics to selective logging and in gaining insights into the ecological processes that structure tree communities in managed tropical forests. 2. We developed a disturbance index to model the effects of distance to and area of logging gaps on stem radial growth rates. This index was tested using census data of 43 neotropical tree species, representing a variety of life-history strategies and developmental stages, from a selectively logged forest at Paracou, French Guiana. Growth strategies were analyzed in light of two indicators: the inherent species growth rate (when disturbance index is null) and the species reaction (change in growth rate) to logging gaps. 3. Across species, the predicted inherent growth rates in unlogged forest ranged from 0AE25 to 6AE47 mm year)1, with an average growth of 2AE29 mm year)1. Ontogenetic shifts in inherent growth rate were found in 26 of the 43 species. 4. Species growth response to logging gaps varied widely among species but was significantly positive for 27 species. The effect of ontogeny on growth response to logging was retained for 14 species, and species with inherent fast growth rate (5 mm year)1) responded less to logging gap disturbances than did species with slow inherent growth (1 mm year)1). 5. Functional traits explained 19-42% of the variation in the inherent growth rate and in species' response across all developmental stages. Whereas maximum diameters and seed mass were strong predictors of inherent growth rate, maximum height, wood density, mode of germination and stem architecture were additionally involved in tree growth response. 6. Synthesis and applications: This study provides a necessary framework for developing predictive post-logging growth models for the thousands of species comprising tropical forests and is sufficiently general to apply to a broad range of managed tropical forests. (Resume d'auteur)

Indigenous broadleaf plantations are increasingly developing as a prospective silvicultural management approach for substituting in place of large pure conifer plantations in subtropical China. However, little information is known about the effects of tree species conversion on soil-atmosphere greenhouse gas (GHG) exchanges. Four adjacent monospecific plantations were selected in subtropical China to examine the effects of tree species on soil-atmosphere exchanges of N2O, CH4 and CO2. One coniferous plantation was composed of Pinus massoniana (PM), and the three broadleaf plantations were Castanopsis hystrix (CH), Michelia macclurei (MM) and Mytilaria laosensis (ML). We found that mean soil N2O and CO2 emissions in the PM plantation were 4.34 μg N m−2 h−1 and 43.25 mg C m−2 h−1, respectively, lower than those in the broadleaf plantations (>5.25 μg N m−2 h−1 and >56.38 mg C m−2 h−1). The PM plantation soil had higher mean CH4 uptake (39.03 μg C m−2 h−1) than the broadleaf plantation soils (

Summary 1. Lianas compete intensely with trees, but few studies have examined long-term effects of liana infestation on tree growth and mortality. We quantified the effects of lianas in tree crowns (n = 2907) and rooted within 2 m of trees (n = 1086) on growth and mortality of 30 tree species from 1995 to 2005 on Barro Colorado Island (BCI), Panama, documented liana infestation in tree crowns in 1996 and 2007 to determine the dynamics of liana infestation, and quantified liana infestation in the crowns of 3231 additional canopy trees (d.b.h. ‡20 cm) in 2007 to compare with the same metric determined by previous studies in 1967 and 1980. 2. Severe liana infestation increased tree mortality: 21% of liana-free trees in 1996 had died by 2007, whereas 42% of trees with more than 75% of the crown infested by lianas in 1996 had died by 2007. 3. Liana infestation of tree crowns significantly reduced tree growth, particularly on sun-exposed trees. The proximity of rooted lianas significantly reduced the growth of shaded trees. 4. Liana infestation was dynamic: 10.9% of trees with severe liana infestation in their crowns in 1996 had shed all of their lianas by 2007 and 5.3% of trees with no lianas in their crown in 1996 had severe liana infestation in 2007. 5. Liana infestation was common: lianas were present in 53% of trees of the 30 focal species. Including lianas rooted within 2 m of the tree increased this percentage to 78%. Using both aboveand below-ground measures may provide a better estimate of liana competition than either measure alone. 6. Liana infestation is increasing on BCI. Lianas were present in the crowns of 73.6% of canopy trees (d.b.h. ‡20 cm). Liana canopy infestation was 57% higher than in 1980 and 65% higher than in 1967, which is consistent with reported increases in liana abundance, biomass, and leaf and flower production. 7. Synthesis. We used one of the largest studies ever conducted on lianas to confirm the negative effects of lianas on tree growth and survival over 10 years. Liana infestation of trees was widespread, dynamic and increasing on BCI.

Tropospheric ozone causes severe oxidative stress in plants. To investigate the transcriptional responsiveness of adult trees to ozone, fully-expanded sun and shade leaves of mature beech trees were harvested at four time points over the entire vegetation period in 2005 and 2006. Microarray analyses were conducted on leaves from trees grown in the field under ambient and twice-ambient ozone concentrations at Kranzberger Forst (Bavaria). Beech trees changed their transcript levels in response to ozone. In the years 2005 and 2006 different transcription patterns were observed; this may have been a result of different weather conditions and ozone uptake. Furthermore, we obtained differences in mRNA expression patterns between shade and sun leaves. In the ozone-treated sun leaves of 2005, slightly up- and down-regulated transcript levels were detected, particularly in the spring and autumn, whereas shade leaves clearly exhibited reduced mRNA levels, particularly at the end of the vegetation period. In 2006, this pattern could not be confirmed, and in the autumn, four other transcripts were slightly up-regulated in ozone-treated shade leaves. In addition, two other transcripts were found to be influenced in sun leaves in the spring/summer. While we detected changes in the levels of only a few transcripts, the observed effects were not identical in both years. In conclusion, elevated ozone exhibited very small influence on the transcription levels of genes of mature beech trees.

Whole-stand models normally require data on initial stand basal area and dominant height. Dominant height measurements are time-consuming and often imprecise, compromising subsequent predictions. Poplar plantations provide a special case where basal area correlates with site index; a whole-stand model could thus be based on stand basal area. We report a static model constructed by the generalized algebraic difference approach (GADA) for poplar plantations for three different hybrid poplars (Populus × euramericana (Dode) Guinier “I-214”, “MC”, and “Luisa Avanzo”) in northeast Spain. The transition function was based on current stand basal area and was fitted with data from 158 permanent plots ranging from 1- to 17-year-old plantations. Merchantable stand volume was estimated by a volume equation where height was predicted by a height–basal area relationship based on 458 temporary plots. The model differences between clones were compared using the nonlinear extra sum of squares method. Significant differences were detected, while Luisa Avanzo presented the highest merchantable volume at the end of the rotation. Errors in basal area predictions were below 20% within 6 years in the case of Luisa Avanzo and MC clones, and within 3 years in the case of I-214. Our research showed that satisfactory predictions can be obtained using GADA with a single transition function based on an easily measurable variable such as stand basal area.

In a 50- to 70-year-old mixed stand of Norway spruce (Picea abies (L.) Karst.) and European beech (Fagus sylvatica L.) in Germany, tree cohorts have been exposed to double ambient ozone (2xO(3)) from 2000 through 2007 and can be compared with trees in the same stand under the ambient ozone regime (1xO(3)). Annual diameter growth, allocation pattern, stem form, and stem volume were quantified at the individual tree and stand level. Ozone fumigation induced a shift in the resource allocation into height growth at the expense of diameter growth. This change in allometry leads to rather cone-shaped stem forms and reduced stem stability in the case of spruce, and even neiloidal stem shapes in the case of beech. Neglect of such ozone-induced changes in stem shape may lead to a flawed estimation of volume growth. On the stand level, 2xO(3) caused, on average, a decrease of 10.2 m(3) ha(-1) yr(-1) in European beech.

Spaced poplar (Populus spp.) trees are used widely in New Zealand for soil conservation on erodible pastoral hill country. Their root distribution in this environment, and factors that affect it, are poorly understood. Robust recommendations on effective tree spacing depend on knowledge of root systems. This study determined the effect of tree density, position between trees, and soil depth (0–90 cm) on root number, root diameter distribution, root area ratio (RAR), and cross sectional area per root for young trees on slopes. Data were collected for lateral roots using trenches. Greater than 80% of roots were < 5 mm diameter and root attributes were highest in shallow soil. Trees at 770 stems per hectare (sph) had 3–12 times more roots and 3–9 times greater RAR than those at densities of ≤ 237 sph, representative of most tree-pasture systems. Mean cross sectional area per root was similar across densities. Positions close to trees had twice as many roots (46 vs. 23/m2) and RAR (109 vs. 52 mm2/m2) as positions midway between trees. The study provided quantitative understanding of variation in root distribution with tree density and information useful for supporting and strengthening recommendations on densities for effective erosion control.

Summary 1. The Janzen–Connell (J–C) Model proposes that host-specific enemies maintain high tree species diversity by reducing seedling performance near conspecific adults and promoting replacement by heterospecific seedlings. Support for this model often comes from decreased performance for a species at near versus far distances from conspecific adults. However, the relative success of conspecific versus heterospecific seedlings recruiting under a given tree species is a critical, but untested, component of the J–C Model. 2. In a shade-house experiment, we tested plant–soil feedbacks as a J–C mechanism in six tropical tree species. We assessed effects of conspecific versus heterospecific cultured soil extracts on seedling performance for each species, and we compared performance of conspecific versus heterospecific seedlings grown with soil extract cultured by a particular tree species. Additionally, we tested whether soil microbes were creating these plant–soil feedbacks and whether low light increased species vulnerability to pathogens. 3. Among 30 potential comparisons of survival and mass for seedlings grown in conspecific versus heterospecific soil extracts, survival decreased in seven and increased in two, whereas mass decreased in 13 and increased in 1. To integrate survival and growth, we also examined seedling performance [(mean total mass × mean survival time)/(days of experiment)], which was lower in 16 and higher in 2 of 30 comparisons between seedlings grown with soil extract cultured by conspecific versus heterospecific individuals. Based on performance within a soil extract, conspecific seedlings were disadvantaged in 15 and favoured in 7 of 30 cases relative to heterospecific seedlings. 4. Species pairwise interactions of soil modification and seedling performance occurred regardless of sterilization, suggesting chemical mediation. Microbes lacked host-specificity and reduced performance regardless of extract source and irradiance. 5. Synthesis. These results, along with parallel research in temperate forests, suggest that plant–soil feedbacks are an important component of seedling dynamics in both ecosystems. However, negative conspecific feedbacks were more prevalent in tropical than temperate species. Thus, negative plant–soil feedbacks appear to facilitate species coexistence via negative distance-dependent processes in tropical but not temperate forests, but the feedbacks were mediated through chemical effects rather than through natural enemies as expected under the J–C Model.