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This paper addresses the study of synoptic-scale meteorological conditions that favor long-range pollen transport in southern South America combining airborne pollen counts, modeled three-dimensional backward trajectories, and synoptic and surface meteorological data. Alnus pollen transport trajectories indicate origins predominantly in montane forests of the Yungas between 1500 and 2800 m altitude. The South American Low-Level Jet is the main meteorological feature that explains 64% of the detected pollen arrival at the target site. Podocarpus and Nothofagus pollen instead are linked primarily to the widespread Subantartic forests in southern Patagonia. Their transport patterns are consistent with previous studies, which show an association with synoptic patterns related to cold front passages carrying pollen in the free atmosphere (27% for Nothofagus and 25% for Podocarpus). These results show the significance of understanding long-distance pollen transport for disciplines such as climate change reconstruction and agriculture, emphasizing the need for further research to refine atmospheric circulation models and refine interpretations of past vegetation and climate dynamics. [ABSTRACT FROM AUTHOR]

Objective: To determine the effect of Alnus acuminata Kunth on the yield and nutritional quality of Cenchrus clandestinus (Hochst. ex Chiov.) Morrone in two pastoral systems in the Colombian Andean mountain range. Materials and Methods: For the evaluation of the yield and quality of the forage biomass of C. clandestinus, an experiment was conducted in a silvopastoral system and a pasture without tree cover. A complete randomized block design was established, defined by the presence or absence of A. acuminata, with pasture cutting frequency every 35 or 45 days. Four treatments and three replicas were defined to determine statistical differences. An analysis of variance and Tukey’s test were performed. The variables green forage production, dry matter, crude protein, neutral detergent fiber, acid detergent fiber, dry matter digestibility and net lactation energy were evaluated. Results: The experimental units of the silvopastoral system were statistically superior to the uncovered pasture treatments. They showed higher yields, in terms of green forage and dry matter, and stood out for their nutritional attributes of crude protein, digestibility and net lactation energy. The treatment with the incidence of the forest species A. acuminata and pasture utilization at 45 days recorded the highest averages in green forage and dry matter (19 360,3 and 123,5 kg) and the best nutritional quality, followed by the silvopastoral system with cutting frequency every 35 days. Conclusions: The silvopastoral system obtained the best results in production and quality of C. clandestinus grass, which indicates the positive impact of the tree species on the evaluated indicators, due to the different interactions that the tree promoted in the agroecosystem.

The preference in the ectomycorrhizal (ECM) - plant association exhibits a wide degree of variation and depends on the identity of the plant but also of the fungal species. Evaluating the degree of specificity of the plant species toward ECM symbionts is an important clue for understanding the functioning of the ECM symbiosis itself. In this work we set out to investigate the patterns of association and specificity of Salix humboldtiana in a wide range of distribution. To do this, we evaluated in a greenhouse experiment if this species establishes symbiosis with ECM fungi belonging to its own rhizosphere (using soil from three provenances of S. humboldtiana distribution in: north, center and south of Argentina) and the rhizosphere of Alnus acuminata and Nothofagaceae species, with which share distribution in the north and the south of Argentina, respectively. Trees of S. humboldtiana associate with ECM fungi belonging to its rhizosphere in the north, center and south of Argentina and from the A. acuminata rhizosphere, but not with those belonging to the Nothofagaceae rhizosphere. Furthermore, PERMANOVA showed that the composition of the associated ECM fungi differed between inoculum provenances. Our results suggest that S. humboldtiana shows low specificity on ECM symbiosis, associating with a small group of fungi that differ in abundance and composition throughout their distribution in Argentina. [ABSTRACT FROM AUTHOR]

El objetivo de la presente investigación fue evaluar los indicadores morfológicos en vivero de cinco especies forestales (Pinus radiata, Alnus acuminata, Escallonia resinosa, Buddleja coriacea y Polylepis incana), en el vivero forestal de la estación experimental agraria “Santa Ana”. Las plántulas fueron producidas durante siete meses en vivero siguiendo los protocolos establecidos en el vivero forestal de la Estación Experimental Agraria “Santa Ana”, las variables morfológicas e índices de calidad de los plantones se analizaron mediante un diseño unifactorial. Los resultados presentaron un efecto significativo (P ≤ 0,05) entre todas las variables evaluados. Además, la Buddleja coriacea presentó un mayor desarrollo en la altura, volumen foliar y peso seco foliar en comparación con las otras especies forestales, mientras el pino presentó un menor desarrollo en altura y diámetro. Los mejores valores de índice de Dickson, índice de contenedor raíz e el índice de robustez, se presentó en el quinual y el pino. Considerando que el índice de calidad predice en mayor exactitud el éxito de la plantación en campo.

Objective: To determine the effect of Alnus acuminata Kunth on the yield and nutritional quality of Cenchrus clandestinus (Hochst. ex Chiov.) Morrone in two pastoral systems in the Colombian Andean mountain range. Materials and Methods: For the evaluation of the yield and quality of the forage biomass of C. clandestinus, an experiment was conducted in a silvopastoral system and a pasture without tree cover. A complete randomized block design was established, defined by the presence or absence of A. acuminata, with pasture cutting frequency every 35 or 45 days. Four treatments and three replicas were defined to determine statistical differences. An analysis of variance and Tukey's test were performed. The variables green forage production, dry matter, crude protein, neutral detergent fiber, acid detergent fiber, dry matter digestibility and net lactation energy were evaluated. Results: The experimental units of the silvopastoral system were statistically superior to the uncovered pasture treatments. They showed higher yields, in terms of green forage and dry matter, and stood out for their nutritional attributes of crude protein, digestibility and net lactation energy. The treatment with the incidence of the forest species A. acuminata and pasture utilization at 45 days recorded the highest averages in green forage and dry matter (19 360,3 and 123,5 kg) and the best nutritional quality, followed by the silvopastoral system with cutting frequency every 35 days. Conclusions: The silvopastoral system obtained the best results in production and quality of C. clandestinus grass, which indicates the positive impact of the tree species on the evaluated indicators, due to the different interactions that the tree promoted in the agroecosystem. [ABSTRACT FROM AUTHOR]

Copyright of Agroindustrial Science is the property of Agroindustrial Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introducción. Es poca la información sobre concentración foliar de nutrimentos en especies forestales en Centro América. Se hace necesario desarrollar conocimiento que permita manejar de manera satisfactoria la nutrición de estos cultivos. Objetivo. Definir los niveles “normales” de concentración foliar al eliminar los valores atípicos fuera del rango de variación con un valor central entre el primer y tercer cuartil en histogramas de distribución de frecuencias de especies forestales. Materiales y métodos. Con material foliar de especies forestales de Costa Rica, Panamá, Guatemala, México y Colombia se confeccionó una base de datos con 3566 entradas con la que se preparó otra más pequeña para los análisis de las especies que se estudian en el presente documento, provenientes de 3 pisos altitudinales. Se calculó la mediana de valores de nutrimento para toda la población como base para determinar las desviaciones estándar y sus valores normales de concentración de N-P-KCa-Mg-S-Fe-Mn-Zn-B-Cu-Al-Na. Resultados. Los resultados fueron una primera aproximación sobre la concentración foliar porcentual total en función del crecimiento de 9 especies forestales en los pisos altitudinales Tropical Húmedo-Muy Húmedo (4,23-6,77%), Tropical Estacionalmente Seco (4,65-6,05%) y Premontano (5,83-9,36%). Son significativamente afectados por el piso altitudinal la concentración de Al en los pisos Tropical Húmedo-Muy Húmedo y el N en el Tropical Estacionalmente Seco. La distribución en porcentaje de las principales especies forestales estudiadas fue C. alliodora (9,36), V. guatemalensis (6,77), C. odorata (6,58), G. arborea (6,05), P. quinata (5,91), A. acuminata (5,83), V. ferruginea (4,81), T. grandis (4,65) y T. amazonia (4,23). Conclusiones. En los pisos Tropical Húmedo-Muy Húmedo la presencia de V. guatemalensis y V. ferruginea mostró elevados valores en mg.L-1 de Al (13 470-22 172)>B(112-130)>Na(401) y porcentuales de P(0,54-0,68). La especie T. amazonia presenta concentraciones porcentuales altas de P(0,59)>B(164)>Cu(46) en mg.L-1. En el bosque Tropical Estacionalmente Seco ninguna de las especies estudiadas (G. arborea, T. grandis y P. quinata) presentó concentraciones elevadas de ningún elemento de los estudiados. En el piso Premontano se encontró valores porcentuales elevados de N(3,57)>K(1,13) en A. acuminata, en C. alliodora de N(3,45)>Ca(3,29)>K(1,24)> Mg(1,02) y en C. odorata de N(3,22).

Summary: Direct belowground nitrogen (N) transfer has often been reported where plants with contrasting nutrients acquisition strategies (N2-fixing and non-fixing) co-occur, and there is still a gap in the knowledge of the extent of this transfer in the top soil under the field conditions. However, assessment under field conditions is challenging. We hypothesized a practical application of the analysis of natural abundance of δ15N supplemented with an isotopic mixing model 'IsoSource' to understand the relative direct contribution of N2-fixing Alnus acuminata to wheat intercrop (non-fixing) N isotopic signatures. A field experiment was conducted in an andic soil of high lands in northern Rwanda to quantitatively determine the proportional contribution of nitrogen by Alnus acuminata to wheat vegetative tissue isotope signatures at different distances from the trees (1 m, 3 m, 5 m, and 7 m). The study involved the measurements and analyses of natural abundance of stable isotopes δ15N and isotopic mixing modeling by IsoSource. Leaf samples were collected from twigs of 10 years old Alnus acuminata grown on the terrace-risers, along with soil samples (0–20 cm) and wheat flag leaf samples across terrace at 1 m, 3 m, 5 m, and 7 m from trees for isotopic measurement. The chlorophyll content index of wheat flag leaf at the four points across terrace was estimated by means of SPAD meter 502. The δ15N proportional contribution by Alnus acuminata to wheat was obtained through IsoSource analysis. We noted a significant (p < 0·01) gradient in depletion of wheat δ15N signatures moving further away from the tree line of Alnus acuminata. The wheat at 1 m from the trees exhibited the δ15N values closer to that of the tree, while at 7 m, the crop δ15N signature was significantly different from that of the tree. An isotopic mixing model 'IsoSource' indicated that the tree N may have provided 33·6 ± 4·3 % of the wheat intercrop N at 1 m distance from the trees. Therefore, this study shows that the understanding of field-based crop N and nutrient transfer in agroforestry may be enhanced by analysis of the physiological basis of stable isotopes signatures. [ABSTRACT FROM AUTHOR]

Sustainable forest management requires tools to guide optimal silvicultural treatments. Timing and intensity of thinnings and timing of final harvest are key decisions. An Optimized Reforestation Management (herein, an ORM) model was developed to reach the optimal combination of thinning times, thinning intensities and rotation periods for Ecuadorian forest plantations of Alnus acuminata, Kunth and Pinus patula Schltdl. & Cham. The ORM model uses non-linear programing to simultaneously optimize the number of trees to harvest in a certain period in order to maximize the plantations' annualized net present values (annuities). Results obtained for optimal silvicultural interventions were compared to current management practices in Ecuador, one with no interventions, and a second with a treatment schedule promoted by the Ecuadorian Ministry of Agriculture. ORM model delivered better financial performance for both species, compared to both alternative scenarios, in terms of annuities and payback periods. Thinnings scheduled by ORM tend to be later than recommended by existing schedules. For Alnus, only one thinning was optimal, independent of the discount rate, while for Pinus two thinnings were optimal for higher levels of the discount rate considered. It is recommended for private and public actors to consider these findings for future management of reforestation areas. [ABSTRACT FROM AUTHOR]

Background: Air pollution is one of the biggest problems in the world, and it is generated by industrial production, vehicular flow and use of fossil fuels, leaving aside other important emission sources such as vegetation. The aim of this research is to quantify the emissions of natural volatile organic compounds produced by the forest species: Eucalyptus globulus L., Pinus radiata and Alnus acuminata in Riobamba, Ecuador. Methods: Identification of plant coverings in the years 2014 and 2017was performed using geographic information systems tools, complemented with the application of the Guenther model for the calculation of monoterpenes and other organic volatile compounds; thus, to analyze the relationship between meteorological variables and concentrations of volatile organic compounds and nitrogen dioxide per species. Results: Mathematical calculation of emissions in Riobamba showed that Eucalyptus globulus L. registered higher emissions in the years 2014-2017, followed by Pinus radiata and Alnus acuminata. These emissions are due to the vegetation cover covering each species. The analysis of volatile organic compounds in forest plantations in air is directly related to the emissions represented in the environment and correlated with the meteorological variables of temperature, global solar radiation and wind velocity. The proposed method manages to estimate concentrations of monoterpenes and volatile organic compounds for the two examined seasons, presenting the influence of the species introduced in this study such as Eucalyptus globulus L. and Pinus radiata, with a reduction in their emissions (less area found in the year 2017, with respect to 2014). However, the emission of Alnus acuminata can be quantified only in 2017, since in 2014 no records of this species were found. Conclusions: Volatile organic compound concentrations in the air are directly related to the emissions represented spatially and correlated with the meteorological variables of temperature, global solar radiation and wind velocity.

Antecedentes: Las plantaciones forestales con especies nativas de crecimiento rápido contribuyen a la captura y almacenamiento de Carbono (C). Sin embargo, se sabe poco sobre la supervivencia, el potencial de captura y almacenamiento de C en plantaciones con especies nativas del bosque mesófilo de montaña (BMM). Preguntas: ¿Es la supervivencia diferente entre Alnus acuminata y Trema micrantha sembrados en plantaciones?, ¿Son diferentes, la tasa anual de captura de carbono y el contenido de C total, entre ambas especies? Especies de estudio: A. acuminata y T. micrantha, de crecimiento rápido y de estados sucesionales tempranos. Sitio de estudio y fechas: Centro estado de Veracruz. 2013. Método: En plantaciones de A. acuminata y T. micrantha de tres años y medio de edad, se registró la supervivencia, el diámetro y la altura. Con estas variables se estimó el volumen, el área basal, el peso de la biomasa aérea, el contenido de C y las tasas anuales de crecimiento en altura, diámetro y contenido de carbono. Resultados: La supervivencia de A. acuminata fue mayor que T. micrantha (P < 0.05). Las plantaciones de A. acuminata almacenaron más C (12.55 ± 0.05 Mg C ha-1) que las plantaciones de T. micrantha (11.62 ± 0.04 Mg C ha-1) (P < 0.001). La tasa anual de captura de carbono en A. acuminata fue mayor (2.6 ± 0.0001 Mg?ha?1?año?1) que T. micrantha (2.02 ± 0.00001 Mg?ha?1?año?1). Conclusiones: Las plantaciones con especies nativas de sucesión temprana representan una estrategia viable en acciones de restauración del BMM y constituyen sumideros de carbono que pueden contribuir a la mitigación del cambio climático.

Los sistemas silvopastoriles, se han convertido en una alternativa sostenible para la producción ganadera, en ese contexto, el presente estudio tuvo por objetivo evaluar la influencia de los sistemas silvopastoriles (SSP) con especies arbóreas nativas como Eritryna edulis (Pajuro), Alnus acuminata (Aliso) y Salix babylonica (Sauce) sobre el rendimiento y valor nutricional de Lolium multiflorum (Rye grass) y Trifolium repens (Trébol). El rendimiento se determinó a través de la cuantificación de forraje verde y materia seca, mientras que el valor nutritivo fue calculado mediante la determinación de proteína, grasa bruta, fibra detergente neutra y fibra detergente ácida. Los resultados alcanzados permiten concluir que, en el rendimiento de biomasa y materia seca para ambas especies de pastos existen diferencias estadísticas (p < 0,05) entre los sistemas evaluados; por otro lado, aunque los niveles de proteína son superiores en los sistemas silvopastoriles, estos no representan diferencias estadísticas entre sistemas. Los resultados de grasa bruta y fibra detergente ácida indican que son estadísticamente iguales, es decir el tipo de sistema productivo no influyo en estas variables.

Copyright of Scientia Agropecuaria is the property of Scientia Agropecuaria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Four signals configurations were studied, two of them built by small increases of potential and two with bigger increments. The highest current values were obtained when pulses with bigger change of potential were used although the best results were shown by the pulse sequence which included an intermediate pulse before the relevant pulse. A mathematical model based on trolox pattern was developed to predict antioxidant capacity of aliso, employing information obtained from all the electrodes, although model validation could be done only employing the information from gold electrode. [ABSTRACT FROM AUTHOR]

In order to quantify the climate change mitigation potential of forest plantations, information on total biomass and its growth rate is required. Depending on the method used, the study of the biomass behavior can be a complex and expensive activity. The main objective of this research was to develop allometric models to estimate biomass for different tree components (leaves, branches, stem and root) and total tree biomass in Alnus acuminata (Kunth) in Costa Rica. Additionally, models were developed to estimate biomass and carbon in trees per hectare and for total plant biomass per hectare (trees + herbaceous vegetation + necromass). To construct the tree models, 41 sampling plots were evaluated in seven sites from which 47 trees with a diametric from 4.5 to 44.5 cm were selected to be harvested. In the selected models for the stem, root and total tree biomass, a r 2 >93.87 % was accomplished, while the r 2aj for leaves and branches was 88 %. For the biomass and carbon models for total trees and total plant biomass per hectare the r2 was >99 %. Average biomass expansion factor was 1.22 for aboveground and 1.43 for total biomass (when the root was included). The carbon fraction in plant biomass varied between 32.9 and 46.7 % and the percentage of soil carbon was 3 %.

Resumen. Se evaluó la respuesta del aliso (Alnus acuminata Kunth) a la inoculación dual con cepas de Frankia spp. y de hongos endomicorrizógenos con dos niveles de boro (B) (0,3 y 0,6 mg kg-1 suelo) y la aplicación de nitrógeno (N) (40 kg ha-1), fósforo (P) (30 mg kg-1 suelo) y un control sin inoculación ni elementos químicos. Se empleó un diseño completamente aleatorizado, con 41 tratamientos y 20 repeticiones. Para el análisis estadístico de componentes principales se empleó el programa Multibiplot. Las variables respuesta correspondieron a la biomasa seca aérea y sus contenidos de N, P, Calcio (Ca) y cenizas (cen). Se encontró que los tratamientos de P y N y las cepas nativas de Frankia spp. (UdeA902, UdeA904 y CUNMS502) combinados con hongos micorrizógenos (UdeA1905 y Glomus fistulosum) respectivamente, favorecieron el rendimiento y contenido de N del aliso. La aplicación de B en algunos casos mejoró el rendimiento y en otros lo afectó negativamente; pero potenció la respuesta de algunas inoculaciones especialmente cuando estuvo presente G. fistulosum aún en el caso de estar acompañado de la cepa de Frankia (CUNMS502). Esta cepa, que presentó bajo rendimiento en otros tratamientos, se vio favorecida notablemente con la adición de B. La inoculación dual es efectiva para favorecer el manejo forestal del aliso siempre y cuando se haga la selección adecuada de las cepas, lo cual puede además condicionar la respuesta a algunos nutrientes como en el caso del B.Abstract. It was evaluated the response of alder (Alnus acuminata Kunth) to the dual inoculation of strains of Frankia spp. and endomycorrhizal fungi with two levels of boron (B) (0.3 and 0.6 mg kg-1 soil) and the application of nitrogen (N) (40 kg ha-1), phosphorus (P) (30 mg kg-1 soil) and a control without inoculation or chemical elements. The experimental design was completely randomized; it was composed kg-1of 41 treatments and 20 replications. The statistical analysis consisted of a Principal Component Analysis using a Multibiplot software. The response variables were: dry-aboveground biomass and the content of N, P, calcium (Ca) and ashes. Results indicated that P and N treatments and the wild strains of Frankia spp. (UdeA902, UdeA904 and CUNMS502) combined with the mycorrhizal fungi (UdeA1905 and Glomus fistulosum) respectively, promoted the yield and the N content of alder. The application of B improved the yield of alder, although in some cases it was affected negatively. Nevertheless, the B promoted the response of some inoculations, especially where G. fistulosum was present, even when it was accompanied by the strain of Frankia (CUMS502). This strain, which showed a low yield in other treatments, was improved significantly with the application of B. Dual inoculation is effective to promote the forest management of alder's trees, as long as the appropriate selections of strains are made. This selection can also influence the response to some nutrients as in the case of B.

Con el propósito de evaluar el impacto de adicionar cal a plantaciones de jaúl (Alnus acuminata (H.B.K.) O. Kuntze) en Andisoles de la cuenca alta del río Virilla, Costa Rica, se realizó el presente trabajo en 2 localidades: 1) Finca Hospicio: Ubicada en la localidad de Vista de Mar, cantón de Goicoechea, a una altitud de 1542 msmn; el suelo se clasificó como Typic Udivitrands y la plantación se estableció en el 2002. 2) Finca Dorval: Ubicada en la localidad de Las Nubes, cantón de Vásquez de Coronado, a una altitud de 1925 msnm; el suelo se clasificó como Thaptic Udivitrands y la plantación se estableció en 1997. Los tratamientos aplicados fueron 0 (testigo), 750, 1500 y 2250 kg.ha-1 de carbonato de calcio y magnesio (Dolomita), 1500 kg.ha-1 de carbonato de calcio (Calcita) y 1500 kg.ha-1 de sulfato de calcio (Yeso). Se midieron el diámetro a la altura del pecho (DAP) a 1,3 m, la altura total de los árboles (m) y se estimó el volumen (V) mediante la formula: V(m3)=2,71828¿10,0557+ln(d)*2,0369+0,9277 18*ln(h) propuesta por Segura et al. (2005), en la cual d es el DAP en cm y h es la altura total en m. Al comparar las mediciones del diámetro a la altura del pecho, incremento medio anual en diámetro (IMA-DAP), altura total, incremento medio anual en altura (IMA-ALT), volumen total e incremento en volumen total, por dosis y fuentes de cal aplicada, se observó que ningún tratamiento causó diferencias estadísticas, en estas variables en ninguna de las 2 fincas comparadas ni entre épocas de medición. La adición de fuentes y niveles de cal no afectó significativamente las variables diámetro, altura y volumen. La falta de respuesta a las diferentes enmiendas comparadas demuestra que el suelo proporcionó suficiente Ca, Mg y S para asegurar el crecimiento óptimo del jaúl. Tampoco se encontró que los suelos mostraran problemas de acidez de magnitud tal que afectaran negativamente el crecimiento del jaúl.

Se estudió el efecto de la adición de B en Andisoles sobre las variables altura, diámetro y volumen de los árboles en 5 plantaciones de Alnus acuminata de edad inicial en años de 0,5 en Hermanas Callejas (HC), 1 en Lechería Experimental (LE), 3 en Rosa Marta Cubero (RMC), 5 en Landelina (L) y 7 en Carter (C); a la última evaluación, las plantaciones tenían 3 años más de edad. El B se suplió como Boronato y se aplicó al voleo en cantidades de 0, 2, 4, 6 y 8 kg.ha-1 para determinar su efecto residual a los 14 meses después de aplicado. El B adicionado incrementó su disponibilidad en el suelo, incremento que puede detectarse mediante extracción con agua caliente presurizada o con Mehlich 3. Los valores de correlación entre el B aplicado y el B extraído por el método de Mehlich 3 son mejores que los obtenidos con el método de agua caliente presurizada. La incorporación de 0 a 8 kg.ha-1 del elemento, no causó ningún incremento en las variables dasométricas del jaúl en los sitios comparados, excepto por un incremento significativo en volumen de madera en la plantación de Landelina (8 años de edad). La poca o ninguna respuesta encontrada, se atribuye a que el contenido inicial de B disponible en el suelo osciló entre 0,19-1,00 mg.kg-1, valores en su mayoría sobre el valor crítico de 0,5 mg.kg-1 mencionado para cultivos en Andisoles y a un bajo requerimiento de B por parte del jaúl. La concentración foliar de B tendió a aumentar ligeramente conforme se elevó la cantidad de B adicionada al suelo, mientras que la concentración de N foliar no mostró ninguna tendencia.

The tropical Andes in Ecuador and Colombia are a biodiversity hotspot that has endured centuries of forest clearance and degradation. Forest restoration has been identified as a regional conservation priority; in recent decades, native species reforestation projects have proliferated, but little information exists on growth performance of commonly planted tree species in relation to site and soil nutrient status. This study analyzed growth of seven common native species ( Alnus acuminata, Baccharis bogotensis, Cedrela montana, Myrica pubesens, Quercus humboltii, Sambucus nigra, Smallanthus pyramidalis) on 12 montane forest sites across the northern region of the tropical Andes. Andean alder ( A. acuminata) was the most commonly planted species, and grows at a mean annual diameter increment (MAI-d) of 1.81 cm y and a mean annual height increment (MAI-h) of 0.95 m y. S. pyramidalis, a short lived pioneer of the Asteraceae family, also exhibited fast growth rates of 1.64 cm MAI-d and 1.21 m MAI-h. Andean oak ( Q. humboltii) was the second-most commonly planted species, growing with an MAI-d of 0.99 cm and MAI-h of 0.56 m. Soil magnesium and potassium were significant predictors of MAI-d and MAI-h for A. acuminata, while soil nitrogen, phosphorous, sodium, and calcium were negatively associated with growth ( p < .001). We speculate that A. acuminata did not grow as well on soils richer in calcium and phosphorus because they were less conducive to nitrogen symbiosis common to this species. Soil magnesium and calcium were significant predictors ( p < .05) of diameter growth for Q. humboltii. For both species, we attribute growth responses to soil nutrients as a result of the variable nature of fertility in the complex and variable soils that make up the volcanic and surficial geological landscape of the northern Andes. Results indicate that native species can grow in a variety of soil conditions, and exhibit growth rates comparable to non-native species. However, our results suggest native species are site restricted for best growth and should be planted on particular soils. We make recommendations for reforestation for the species in this study. [ABSTRACT FROM AUTHOR]

Se encontró que la posición de las muestras en la copa provenientes de árboles de 3 y 5 años de A. acuminata no afecta la concentración foliar para la mayoría de los nutrimentos de manera significativa. La única excepción la constituye el Ca en árboles de 5 años, cuya concentración en la parte alta fue menor que en la parte media de la copa. Aunque no significativa, se observó que la concentración de Fe, Mn y Zn tiende a ser mayor en la sección alta externa de la copa a los 3 años; mientras que, a la edad de 5 años tiende a ser mayor en la parte media externa de la copa. No se observó diferencias significativas en la concentración foliar de los nutrimentos con la edad de la plantación entre 2 y 8 años, en ninguna de las épocas comparadas, excepto para el Mn, elemento que tiende a disminuir con la edad de las plantaciones (86 a 26 mg kg-1). La concentración foliar de Mg, Fe, Zn, Mn, Cu y B fue mayor durante la época seca que durante la época lluviosa, mientras que los contenidos foliares de N y P fueron más elevados durante la época lluviosa y no se observó variación alguna en las concentraciones foliares de Ca, K y S debidas la época de muestreo. Con base a lo encontrado, se define en forma tentativa los niveles críticos foliares para la especie A. acuminata.

Alnus acuminata (Betulaceae) is a pioneer tree that dominates mountain riparian forests throughout the eastern Andes. Early studies associated these forests with particular microclimatic conditions along river beds, but they were later linked to the periodical disturbance regime of mountain rivers. To understand the dynamics of these forests, we analysed tree age and spatial arrangement in two plots along Potrero river and another plot along La Horqueta river, Tucumán Province, north west Argentina. Through intensive tree coring and age reconstruction we identified similar-aged tree cohorts with maximum age ranges of eight years. Tree mapping and Moran's I spatial autocorrelation analysis showed that tree cohorts were spatially clumped, and provided further evidence that coetaneous patches of A. acuminata arise from massive regeneration following catastrophic flooding events. We tested the association between cohort initiation dates and regional maximum river discharge records by means of a randomization procedure and found weak evidence that establishment occurs after devastating floods, which eliminate previous vegetation and create bare sites suitable for A. acuminata regeneration. Dates of tree floodscars sampled along Potrero river precede by one year the most recent cohort initiation date and provide further support of this association. Although previous studies found a positive correlation between El Niño events and mean annual precipitation in northwestern Argentina, we did not detect an association between El Niño and annual maximum stream flow for rivers in Tucumán Province. Therefore, factors driving devastating floods and A. acuminata stand initiation require further studyEl aliso (Alnus acuminata, Betulaceae) es un árbol pionero que domina bosques riparios de montaña en los Andes orientales. Estudios iniciales atribuyeron la presencia de estos bosques a las típicas condiciones microclimáticas de cauces de ríos, pero luego estos fueron vinculados al régimen periódico de disturbios de ríos de montaña. Para comprender la dinámica de estos bosques, analizamos la estructura de edades y el arreglo espacial de árboles en dos parcelas sobre el río Potrero y otra parcela sobre el río La Horqueta, en la provincia de Tucumán, noroeste argentino. Mediante barrenado intensivo y reconstrucción de edades identificamos cohortes de árboles con un rango máximo de edades de ocho años. El mapeo de árboles y el índice de autocorrelación espacial I de Moran indicaron que las cohortes de árboles estaban agrupadas en espacio, proporcionando evidencia adicional de que los parches coetáneos de A. acuminata resultan de eventos de regeneración masiva luego de crecientes catastróficas. Evaluamos la asociación entre años de inicio de cohortes y registros regionales de descarga máxima de ríos por medio de aleatorizaciones y encontramos evidencia débil de que los establecimientos ocurren luego de crecientes devastadoras que eliminan la vegetación preexistente y originan sitios desnudos propicios para la regeneración del aliso. Las fechas de cicatrices de crecientes en árboles del río Potrero preceden por un año al inicio de la cohorte más reciente y dan respaldo adicional a esta conexión. A pesar de que estudios previos encontraron una correlación positiva entre eventos de El Niño y promedios de precipitación en el noroeste argentino, nuestros datos no revelan una asociación significativa entre El Niño y caudales máximos anuales en ríos de la provincia de Tucumán. Se requieren más estudios para identificar los factores que originan crecientes devastadoras y cohortes de A. acuminata

Trees can have important impacts on multiple ecosystem services and biodiversity in agricultural landscapes. The influence of trees can extend beyond forested areas and into adjacent land uses, however, this is rarely accounted for in the ecological literature. To better understand the influence of trees in Andean agroecosystems, we examined alternative landscape scenarios in the community of Quilcas (Junín, Peru), where we explored the potential impact of replacing tree-based land uses (with crops and pasture) on landscape carbon (C) storage and soil biodiversity (soil macrofauna and ground vegetation). Additionally, we estimated the influence of tree-based land uses on soil C storage (0–20 cm depth) and macrofauna diversity in adjacent croplands and pastures. Tree-based land uses were dispersed across the landscape and occupied 26 % of the area, including a mix of forest patches, plantations, and hedgerows. Given that above- and belowground C stocks were generally higher in land uses with trees versus those without, the inclusion of trees in this landscape is estimated to increase the total landscape C storage by 153 %. Macrofauna diversity also varied across different land uses, being highest in alder (Alnus acuminata) forests and hedgerows, such that the inclusion of trees enhances overall macrofauna diversity (Shannon Index) by 25 % but appears to have a slightly negative effect (−6 %) on ground vegetation diversity. When accounting for the influence of trees on adjacent land uses, estimates for overall soil C storage at the landscape scale increased by 1.4 %, while macrofauna diversity increased by approximately 5 %. Our findings indicate that the addition of trees can greatly enhance overall C stocks and soil macrofauna diversity in agricultural landscapes, and that it is important to consider spatial interactions between land uses to fully quantify and optimize these interactions. • Tree-based land uses support C storage and biodiversity in agricultural landscapes. • Trees increased the total landscape C storage by 153 % in a highland Andean community. • Trees enhanced landscape macrofauna diversity (Shannon Index) by 25 %. • Considering tree impacts on adjacent land uses further increases landscape C storage and biodiversity. [ABSTRACT FROM AUTHOR]

Seventeen natural populations in Costa Rica and Panama were used to asses gene flow and geographic patterns of genetic variation in this tree species. Gene flow analysis was based on the methods of rare alleles and FST (Index of genetic similarity M), using the only four polymorphic gene loci among 22 investigated (PGI-B, PGM-A, MNR-A and IDH-A). The geographic variation analysis was based on Pearson`s correlations between four geographic and 14 genetic variables. Some evidence of isolation by distance and a weak gene flow among geographic regions was found. Patterns of clinal variation in relation to altitude (r = -0.62 for genetic diversity) and latitude (r= -0.77 for PGI-B3) were also observed, supporting the hypothesis of isolation by distance. No private alleles were found at the single population level.Diecisiete poblaciones naturales de esta especie forestal en Costa Rica y Panamá, fueron investigadas en relación con sus patrones de flujo genético y de variación geográfica. El análisis de flujo genético fue basado en los métodos de los alelos raros y de FST (Indice de similaridad genética M). Los análisis fueron a su vez basados en los únicos cuatro loci genéticos de un total de 22 investigados que mostraron polimorfismo (PGI-B, PGM-A, MNR-A and IDH-A). Los análisis de variación geográfica fueron basados en el desarrollo de correlaciones de Pearson entre 4 variables geográficas y 14 variables genéticas. Alguna evidencia de aislamiento por distancia así como un débil flujo genético entre regiones geográficas fue encontrado. Fueron también observados patrones de variación clinal en relación con la altitud (r = -0.62 para la diversidad genética) y latitud (r= -0.77 en PGI-B3), que apoyan la hipotesis de aislamiento por distancia para esta especie. No se encontraron alelos privados en ninguna de las poblaciones investigadas.

Para cuantificar el potencial de las plantaciones forestales como mitigadoras del cambio climático se necesita información de la biomasa total y de su ritmo de crecimiento. Estudiar la dinámica de la biomasa es una actividad compleja y costosa según el método utilizado. El objetivo principal de esta investigación fue construir modelos alométricos para estimar la biomasa en los diferentes componentes del árbol (hojas, ramas, fuste y raíz) y en el árbol completo para Alnus acuminata (Kunth) en Costa Rica. Adicionalmente, se desarrollaron modelos para estimar la biomasa y el carbono en árboles por hectárea y para la biomasa y el carbono total (árboles+vegetación herbácea+necromasa). Se evaluaron 41 parcelas distribuidas en siete sitios y se extrajeron 47 árboles con un diámetro entre 4,5 y 44,5 cm. En los modelos seleccionados para el fuste, la raíz y la biomasa total del árbol se logró un r2 >93,87 %, mientras que para las hojas y las ramas un r 2 de 88 %, en los modelos para la biomasa y/o el carbono en árboles y total por hectárea el r2 fue >99 %. El factor de expansión de biomasa promedio fue de 1,22 para biomasa aérea y de 1,43 para la relación biomasa aérea total - biomasa de raíz. La fracción de carbono en la biomasa vegetal varió entre 32,9 y 46,7 % y el porcentaje de carbono en el suelo fue de 3 %.

The gradual increase in reforested areas worldwide, as a strategy for mitigating native forest loss, has stressed the need of assessing their real value as habitat for native species. Forest plantations, particularly those based on native species, could be valuable for conservation purposes, especially in heavily fragmented and disturbed ecosystems. We evaluated the value of a monoculture of a native tree species, the Andean alder ( Alnus acuminata ), for the conservation of avifauna in the Central Andes region, which is considered a bird species diversity hotspot but also suffers from high anthropogenic disturbance levels. Our results suggest that alder plantations are valuable for conservation from three points of view: (1) they have similar or greater bird species richness and abundance than secondary native forests; (2) low community similarities are found between this type of forest compared to secondary forest stands (with 27 species exclusive to alder plantations); and (3) three near threatened species ( Odontophorus hyperythrus , Eriocnemis derbyi , and Cyanolyca viridicyanus ). Further, 27 out of the 85 species found at the alder plantations were of least concern but showing decreasing population trends. While forest plantations do not replace native forests, they offer habitat for many bird species, some of them being of conservation concern (i.e., included in an IUCN threat category) or with decreasing populations. Hence establishing native species plantations among native forest remnants – especially in heavily fragmented landscapes – could have a positive effect in the conservation of threatened avifauna. [ABSTRACT FROM AUTHOR]

Some biological aspects of an isolated fungus of Alnus acuminata roots were studied. It bas been found Tbat between OOC and 4°C tbe fungi grows fast. This condition can result in a important factor in the ecophysiology of 'Aliso' populations, that grows in secondary forests at sub-paramo, After a review of the taxonomic literature, we placed it in the Phytium genus, but not in a particular described species. We assume that it is a new species. We modificated the microculture technique that was simpler and safer and them we made direct observations about tbe fungus growtb and development. As for now it is nominated as Phytiun near Mammillatum Meurs. Palabras Claves: Phytium, bongos, A/nus acuminata HBK., "Aliso".

El motivo del presente trabajo es ampliar el conocimiento sobre la extracción de nutrimentos de A. acuminata en plantaciones entre 2 y 7 años de edad, en suelos Typic Udivitrands (Landelina y Vista de Mar) y Entic Udivitrands (Matinilla). Se encontró que la variación de la concentración de todos los elementos varía en función del tipo de tejido. Los contenidos de N, P, Mg y S de A. acuminata disminuyen en el orden: hojas>ramas secundarias>ramas principales>tallo. La con centración de K, Cu y Mn disminuyó en un orden similar al anterior, excepto para ramas principales y tallo, los cuales tenían una concentración similar. El B y el Ca tienen una mayor concentración en las hojas y ramas secundarias, entre las cuales no hay diferencias, mientras que se encontraron en menor cantidad en las ramas principales y el tallo. La concentración de Zn fue mayor en las ramas secundarias que en las hojas y disminuyó en el orden de ramas secundarias>hojas>ramas principales>tallo. El contenido de Fe en las hojas fue mayor que en las otras secciones comparadas de la biomasa aérea del árbol, entre las cuales no hubo diferencia. Indiferentemente del tejido estudiado y de la edad de la plantación, la concentración porcentual de los macronutrimentos en jaúl descendió en el orden: N>K>Ca>P≈Mg>S y la de los micronutrimentos en el orden: Fe>Zn>Mn>Cu>B. De los tejidos estudiados hasta los 2 años de edad, la copa y el tallo tienen biomasas comparables; a partir del cuarto año el tallo conforma la mayor parte de la biomasa aérea y por ende de los nutrimentos absorbidos, seguido por las ramas principales, las hojas y las ramas secundarias. La extracción total de nutrimentos en las plantaciones de A. acuminata se dio en el orden de N>K>Ca>P>Mg>S y de Fe>Zn>Mn>Cu>B.

En este estudio se evaluó el efecto de fertilizar con 0, 61, 122, 183 y 244 g P2O5 árbol-1 sobre el crecimiento de árboles de jaúl en suelos Typic Udivitrands (Landelina y Vista de Mar) y Entic Udivitrands (Matinilla). Se determinó que los contenidos disponibles de P aumentaron y los contenidos de Al y Fe amorfo y del pH en NaF disminuyeron con la adición de P. La adición de niveles crecientes de P al suelo no produjo variaciones en la concentración foliar de ningún elemento en forma significativa. Sin embargo, con la adición de 61 g P2O5 árbol-1 se observaron aumentos leves en la concentración foliar de K en la plantación de Matinilla y en el contenido de B foliar en la plantación de Landelina. La adición de P no causó diferencia alguna en el diámetro, la altura o el volumen de los árboles en ninguno de los sitios durante el transcurso del ensayo. Al calcular el incremento relativo de las variables de crecimiento, el tratamiento de 61 g de P2O5 árbol-1 es el que mostró la mayor tasa en altura en las 3 plantaciones. La diferencias en diámetro, altura y volumen entre edades fueron evidentes desde el inicio del experimento y se mantuvieron constantes a lo largo del mismo. En la plantación de 3,6 años el ICA para las variables analizadas es mayor que el encontrado en las plantaciones de mayor edad, en las cuales disminuye. El IMA alcanza un punto máximo a la edad de 7,5 años y luego tiende a disminuir.

Abstract: Tropical montane cloud forest has been undergoing a drastic reduction because of its widespread conversion to pastures. Once these forests have been cleared exotic grasses are deliberately introduced for forage production. Exotic grass species commonly form monodominant stands and produce more biomass than native grass species, resulting in the inhibition of secondary succession and tree regeneration. The purpose of this study was to assess the effect of native vs. exotic grass species on the early establishment of two native tree seedlings (Mexican alder, Alnus acuminata and Jalapa oak, Quercus xalapensis) on an abandoned farm in central Veracruz, Mexico. Seedling survival and growth were monitored (over 46 weeks) in relation to grass cover and height, and available photosynthetic active radiation (PAR). More seedlings survived in the presence of the native grass Panicum glutinosum than those growing with the exotic grass Cynodon plectostachyus (92% vs. 48%). The causes of seedling mortality varied between species; Q. xalapensis was affected by herbivory by voles but mainly in the exotic grass-dominated stands, whereas A. acuminata seedlings died due to competition with the exotic grass. A. acuminata seedlings increased more in height in the exotic grass-dominated stands (102±7.8cm) compared to native grass-dominated stands (51±4.7cm). Grass layer height, cover and available PAR were correlated (Pearson; p <0.05). In the exotic grass dominated plots, grass layer height was correlated with the relative height growth rates of Q. xalapensis (Pearson; p <0.05). These results indicate that the exotic grass may be affecting tree regeneration directly (grass competition) and indirectly (higher herbivory). Passive restoration may occur once P. glutinosum dominated pastures are abandoned. However, when C. plectostachyus dominates, introduction of early and mid successional tree seedlings protected against vole damage is needed. [Copyright &y& Elsevier]

We used dendroecological techniques to analyze the effects of rainfall and grazing on fire regime and its implications for tree regeneration in subtropical mountains of northwestern Argentina during the 20th century, a period characterized by increasing rainfall and decreasing land-use intensity. We dated fire scars and establishment of Alnus acuminata (the dominant tree species) in six watersheds along a 600 km latitudinal range. We correlated fire frequency with rainfall records and performed Superposed Epoch Analyses to assess the relationship between rainfall and fire events during the century, and in two sub-periods: 1930-1965 (low rainfall, high grazing) and 1966-2001 (high rainfall, low grazing). We performed permutation analyses to assess the association between fire events and tree establishment, and to describe the spatial distribution of fires and forests in relation to hillslope aspect. Rainfall was associated with regional fires at interannual and decadal scales: fire probability increased after growing seasons with above-average rainfall and through the century, in concurrence with rainfall increase. The climatic control of fire was stronger under lower land-use intensity. Tree establishment was temporally associated with fire events, which occurred mainly in north facing slopes, where grassland cover is more extensive and forest colonization more likely. These results suggest that fire is limited by the availability of fine fuels, which is enhanced by high rainfall and reduced grazing; and tree establishment is limited by the competition with grasses. Consequently, increasing rainfall and decreasing grazing favored higher fire frequency, thus promoting forest encroachment during 20th century. [ABSTRACT FROM AUTHOR]