Fijación de carbono en sistemas agroforestales gestionados por pequeños productores de los Andes del Ecuador

Los ecosistemas de montaña son extremadamente vulnerables al cambio climático, razón por la cual se encuentran particularmente en riesgo las poblaciones de montaña que dependen de la actividad agrícola y ganadera. Esta investigación se desarrolló en cinco sitios, en las provincias de Imbabura y Carchi con el objetivo de determinar la tasa de fijación de carbono (C) en sistemas agroforestales gestionados por pequeños productores en los Andes del Ecuador. Adicional a esto, se adaptó la metodología al contexto socioeconómico y productivo de los pequeños productores. Las unidades experimentales fueron cinco prácticas agroforestales representativas de la región andina norte. Se cuantificó el contenido de C a partir de la biomasa aérea para cada especie forestal. Para cuantificar la biomasa de las especies agrícolas y pastos, se utilizó el método directo de muestreo des­tructivo. La cantidad de C de cada una de las prácticas agroforestales fue determinada multiplicando el valor de biomasa aérea por la fracción de C 0,5. La mayor tasa de fijación de C fue de 87,13 Mg CO2 ha-1 y se registró en la práctica silvopastoril de Eucalyptus globulus en asocio con Pennisetum clandestinum. Tanto en esta práctica como en las que Alnus nepalensis está asociado con Coffea arabica, e Inga insignis asociado con Phaseolus vulgaris, las especies forestales fijan el 89% del C total y las especies agrícolas el 11%. Los sistemas agroforestales andinos manejados por pequeños productores fijan C con tasas superiores a sistemas similares desarrollados en otros sitios localizados tanto dentro como fuera del país.

Ecological wood anatomy of Alnus nepalensis (Betulaceae) throughout Nepal

Variation in the wood structure of Alnus nepalensis D. Don (Betulaceae) in relation to tree size and habitat altitude was studied in four areas of Nepal: Tamur, Rolwaling, Budi Gandaki, and Bajhang-Khaptad. Alnus nepalensis is a pioneer tree distributed in the Himalayas from northern India to southwestern China and grows throughout Nepal in a wide altitudinal range from 200 m in the tropical zone to 3030 m at the upper limit of the temperate zone. Ecological trends in the wood structure of Alnus nepalensis varied between the studied areas, distinct in the Tamur area, but indistinct in other areas, and tended to be detected in areas with specimens from altitudinal ranges of 2000 m. When all the specimens were separated at 1800 m in elevation and analyzed as two altitudinal groups, features of vessel size and distribution and the ratio of solitary vessels had a significant correlation with tree height in both groups, and tall trees tended to have larger, more solitary vessels. Vessel element and fiber lengths did not have any significant trends in the lower group but had a negative correlation with altitude in the upper group along with the reduction of tree height. Thus, vessel size seems to facilitate the height growth of this pioneer tree, and shorter tracheary elements and more vessel multiples seem to be related to the adaptation of smaller trees at higher elevations.

Comportamiento de Alnus nepalensis D. Don en asocio con tres especies forestales Schizolobium parahyba (Vell.) S.F.Blaque, Swietenia macrophylla King, y Cordia alliodora Ruiz & Pav. bajo sistema agroforestal

La disminución de las fuentes que proveen madera enel Ecuador como son los bosques naturales, se estánreduciendo y con ello se hace necesario encontrar nuevase innovadoras alternativas para el manejo silviculturalde especies forestales. Las tecnologías agroforestalesofrecen una producción sostenible de bienes y serviciosentre estos productos madereros. El objetivo de lapresente investigación fue estudiar el comportamientode las especies forestales Alnus nepalensis, Schizolobiumparahyba, Swietenia macrophylla y Cordia alliodora enasocio con tres especies frutales perennes: Citrus lemon,Citrus aurantifolia y Annona muricata, bajo un arregloagrosilvícola. El estudio se realizó en la comunidadSanta Marianita de Caliche, cantón Mira, provincia delCarchi. El diseño experimental utilizado fue bloquesalzar con tres repeticiones, se estableció el ensayo enhileras intercaladas entre especies forestales y frutales;se realizaron evaluaciones mensuales de las variables:sobrevivencia, altura, diámetro basal y se determinó elincremento corriente anual (ICA). La información seanalizó utilizando estadística descriptiva, prueba de t deStudent, frecuencias, regresión y correlación. Las variablesanalizadas se consideran en su mayoría homogéneas contendencia a distribución normal; los coeficientes r y r2permiten inferir que las especies presentan un crecimientoproporcional. En sobrevivencia, crecimiento en altura,diámetro basal e incremento corriente anual A. nepalensispresenta los mejores resultados. A partir de la prueba det de Student se determinó que el comportamiento delas cuatro especies forestales es estadísticamente muydiferente, sin embargo, existiendo diferencias en lastasas de crecimiento se evidencia que las cuatro especiesforestales presentan una tendencia de crecimiento lineal.

Isolation and Screening of Antibiotics Producing Streptomyces spp from the Soil Collected around the Root of Alnus nepalensis from Godawari

Actinomycetes are considered as the most invaluable prokaryotes whose genome mining show a great number of putative secondary metabolite biosynthesis pathways as well as gene clusters ranging from 20 to 50 per genome. The genus Streptomyces has been explored for its ability to produce 60% antibiotics worldwide. Alnus nepalensis (Alder) has been found to harbor diverse Eubacteria in its rhizosphere. To evaluate the antibiotic production potential from Actinomycetes, we collected soil samples from rhizosphere (5-7 cm deep) of Alder tree. Primary screening was done by cross-streak method against Multidrug Resistant (MDR) such as Methicillin resistant Staphylococcus auereus (MRSA), Vancomycin resistant Enterococcus feacalis (VRE), Imepenem resistant Acinetobacterbaumannii, Vancomycin resistant Klebsiella pneumonia and Imepenem resistant E. coli as well as Non-MDRs (E. coli, Bacillus subtilis, Klebsiella pneumoniae, S. aeureu and Enterococcus feacalis). Extraction of antibiotics was done using rota-vapour from extract obtained by solid-substrate fermentation technique followed by solvent extraction. Secondary screening was done using well diffusion assay against MDRs. Among total of 40 isolates of Actinomycetes recovered, 14 showed remarkable zone of inhibition (ZOI) to various MDRs. NASA 303 showed 26 mm of ZOI against VRE, NASA 101 had ZOI of 34 mm against MRSA, NASA 319 had 33.7 mm ZOI against Imepenem resistant E. coli, NASA 306 had 36 mm of ZOI against Vancomycin resistant Klebsiella pneumoniae, and NASA 108 showed ZOI of 29.6 mm against Imepenem resistant E. faecalis. This investigation revealed that the Actinomycetes found in Rhizosphere of Alder tree had MDR killing potent antibiotics, which needs to be further explored.

Producing Spalted Alder Wood in Yunnan, China

Given the demand for environmentally friendly wood stains, dyeing by fungi has come to light as a suitable process for staining wood, textiles, and other materials. The identification of fungi capable of producing spalted wood merits considerable effort by researchers, and some spalted color or styles found on wood in the wild cannot be cultivated in the laboratory. To find additional fungal candidates and styles for spalting in China, we here collected and identified wood fungi in Yunnan and Guangxi in China. Fungi were purchased or isolated and then inoculated to alder wood blocks (Alnus nepalensis D. Don). Out of seven purchased strains, three formed zone lines, but it was unclear whether Chlorociboria aeruginascens cfcc 87397 could do so. Out of 20 strains, 15 species were isolated from wood forming zone lines with surface black pigments, and only Diaporthe sp. ZXH63-4 formed additional yellow pigments accompanied by zone lines throughout the wood, which is a new means of forming yellow pigments and black zone lines at the same time. Some fungi collected from stained wood samples showed reddish-brown zone lines, but they showed black zone lines when isolated and inoculated on alder.

Carbon stock estimation of Shree Rabutar Forest of Gaurishankar Conservation Area, Dolakha, Nepal

Forests store significant amount of atmospheric carbon in the form of above and below ground biomass and the amount of carbon stored in forests differs along spatial continuum which provides important information regarding forest quality. This study was carried out to estimate the carbon stock of Shree Rabutar Forest of Gaurishankar Conservation Area, Dolakha, Nepal. In total, 20 circular sampling plots with an area 250 m2 were randomly laid in the study area. Ten tree species were observed in the sampling plots laid in the forest. The higher values of density, frequency, abundance and basal area were observed for Rhododendron arboreum, Alnus nepalensis, Pinus roxburghii and Pinus wallichiana. On the basis of Important Value Index, the dominant tree in the forest was Alnus nepalensis followed by Rhododendron arboreum and Pinus roxburghii. Shannon Index of general diversity of trees in the forest was 0.74 with equal value of Evenness Index, whereas the index of dominance was low (0.22) in the forest. Mean biomass of the forest was 464.01±66.71 tonha-1 contributed by above ground tree biomass (384.44 tonha-1), leaf litter, herbs and grasses biomass (2.69±0.196 tonha-1) and below ground tree biomass (76.88±11.13 tonha-1). Mean carbon stock was 262.77±30.79 tonha-1 including soil carbon stock 44.69±2.25 tonha-1. Individuals of trees with 20-30 cm DBH class were observed in maximum number, which shows that the forest has high potential to sequester carbon over time. Carbon stock estimation and forest management can be one of the potential strategies for climate change mitigation especially through carbon dioxide absorption by the forests.