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Search Results: 1 - 10 of 475919 matches for " A.;Rodríguez-Trejo "
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Incremento en biomasa y supervivencia de una plantación de Pinus hartwegii Lindl. en áreas quemadas
Rodríguez-Trejo, D. A.;
Revista Chapingo. Serie ciencias forestales y del ambiente , 2008,
Abstract: in the year 2002 prescribed fire treatments were applied on open pinus hartwegii lindl., forests in the ajusco volcano, south of mexico city, mexico. the treatments consisted of two fire-intensities: high and low, and two seasons of fire application: march and may, plus an unburned control (one per season). in july of the same year were planted 420 seedlings of two size categories (big and small). in this work were evaluated the survival and biomass increment of such trees three years after plantation establishment. it was recorded the survival in all of the forest plantation and a 30 trees sample was gathered to determine biomass. the mortality probability was estimated with a logistic model. the analysis of variance and the least significant difference test were utilized for the other variables. the probability of mortality of the trees in the control did not show differences with the trees in the may burns, but it was lower than that of the march burns. such response in the march treatments was adduced to the earlier competition, for the competition in the forest plantation was not eliminated, also to a higher understory cover and to a lesser abundance of nurse shrubs. there was no effect of treatments on tree growth. the total biomass increment was equal to 8.5 g·yr-1.
Concentración de carbohidratos y peso fresco durante la germinación de Chamaedorea elegans Mart. y factores que la afectan
Alatorre-Cobos, J.;Rodríguez-Trejo, D. A.;
Revista Chapingo. Serie ciencias forestales y del ambiente , 2009,
Abstract: the information about changes in carbohydrate concentration and fresh weight during seed germination is scarce and the interactions of factors that affect germination of chamaedorea elegans mart. have been scarcely studied. two experiments were conducted in controlled environment chambers, one to determine the best temperature regime and another to analyze the effect of factors: storage (0 and 1 y), shade level (0 %=124 μmol·m-2·s-1, 70%=32 μmol·m-2·s-1 y 100 %=2 μmol·m-2·s-1) and seed size (small <5.25 mm, medium 5.25 a 5.75 mm and large >5.75 mm) on seed germination. a completely randomized blocks experimental design was employed, as well as a mixed procedure for the anova. the temperature regime 25/22 °c yielded 100 % germination; however, there were differences among seed lots to germinate in such regime. in the second experiment (25/22 °c), the three factors and the interaction seed size and storage, and the triple interaction seed size, storage and shade were significant. in the triple interaction, with non storage seed just collected, the three seed sizes showed different responses to light, with the highest germination for medium size seed and 100 % shade (59.3 % germination). the rate of starch use was 12 mg·g-1·month-1.
Plantas nodriza en la reforestación con Pinus hartwegii Lindl.
Ramírez-Contreras, A.;Rodríguez-Trejo, D.A.;
Revista Chapingo. Serie ciencias forestales y del ambiente , 2009,
Abstract: on the ajusco volcano, mexico city, mexico, pinus hartwegii seedlings were planted in five treatments: ne side of lupinus montanus plants, ne side of penstemon gentianoides plants, between festuca tolucensis grasses, in small openings where grasses were cleared away, and in small natural gaps among the grasses. mortality, diameter, height, biomass and foliar nutrient concentration (n, p, k) were evaluated six (dry season) and 12 months (rainy season) after tree-planting. photosintetically active radiation (par) was measured with hemispheric photographs and the program hemiview. mortality was analyzed using logistic regression, while morphological and physiological variables were analyzed with multivariate variance analysis. also was employed analysis of variance. there were no differences in mortality (average of 15 %) among treatments. the anova showed higher trees in the lupinus, penstemon and cleared treatments, in comparison to grass and small natural gaps treatments (p<0.10). the manova exhibited higher tree leaf concentrations of n and k in the seedlings associated to lupinus one year after planting date in the rainy season, in comparison to the grass treatment, and higher n concentrations than the clearing treatment (p<0.10). the par was lower when the seedlings were associated to plants, but did not limit the growth of seedlings. is recommended the use of lupinus as nurse plant associated to pinus hartwegii.
Radiación solar y supervivencia en una plantación de vara de perlilla (Symphoricarpos microphyllus H.B.K.)
Hernández-García, J. D.;Rodríguez-Trejo, D. A.;
Revista Chapingo. Serie ciencias forestales y del ambiente , 2008,
Abstract: a "vara de perlilla" (symphoricarpos microphyllus h.b.k.) plantation was established in the forest nursery of the división de ciencias forestales, universidad autónoma chapingo. the objective was to study survival and growth under different solar radiation condi-tions. the shrubs were planted under a pine forest plantation in different light conditions. with a digital camera with hemispheric lens and the hemiview program?, were measured direct and diffuse solar radiation, and visible sky. from the shrubs was recorded survival, number and length of branches, shoot and root biomass and total biomass. the probability of mortality was obtained with a logistic model, using as explanatory variable direct solar radiation. also was employed linear regression. the logistic model was significant (p= 0.0970), with higher mortality at higher light levels. the lineal regressions were not significant or had a verly low r2.
Efecto del tama?o y color de la semilla en la germinación de Cecropia obtusifolia Bertol (Cecropiaceae)
Tenorio-Galindo, Gabriela;Rodríguez-Trejo, Dante A.;López-Ríos, Georgina;
Agrociencia , 2008,
Abstract: the effect of seed size and color on germination was studied in cecropia obusifolia bertol. tested were two seed sizes: small (1.3 mm long) and large (1.7 mm long); three seed coat colors: black, light brown and dark brown; two day and nighttime temperatures in a controlled environment chamber: 30 °c during the day and 25 °c at night and 25 °c during the day and 20 °c at night. the experimental design was randomized complete blocks, with blocks nested within the factor temperature. color and size had a significant (p<0.05) effect on germinative capacity, as did the interactions temperature x color and size x color, and the triple interaction temperature x size x color. the number of large seeds that germinated was almost double that of small seeds. dark brown seeds germinated well under both temperature regimes. at the higher temperatures, the highest rate of germination was that of large light brown seeds; at the lower temperatures, more large dark brown seeds germinated. thus, the varying seed sizes and colors allow them to germinate in different environmental conditions.
Resistencia a bajas temperaturas en Pinus hartwegii sometido a diferentes tratamientos con potasio
Ramírez-Cuevas, Y.;Rodríguez-Trejo, D. A.;
Revista Chapingo. Serie ciencias forestales y del ambiente , 2010, DOI: 10.5154/r.rchscfa.2009.09.032
Abstract: in order to improve frost resistance in pinus hartwegii lindl, different concentrations of potassium nitrate were tested on 13-month-old seedlings in a forest nursery. an experimental design with randomized complete blocks was used, with four replications. the treatments consisted of five additional applications each of 180 ppm k, 150 ppm k, and 114 ppm k, the last being the regular fertilization dosage applied in the forest nursery during the hardening phase. sixteen seedlings per treatment were placed in a controlled environment chamber, where they were exposed to a -5 °c frost for two hours. afterwards, the damage level (%) in the stems, roots and foliage was visually estimated. using a logistic model, the probability of the seedlings in each treatment suffering frost damage was obtained. both this probability model for frost damage in stems and roots, and the one used for foliage were significant. in the latter, the higher the potassium dosage, the lower the probability of frost damage in the seedlings.
Sinecología del sotobosque de Pinus hartwegii dos y tres a?os después de quemas prescritas
Espinoza-Martínez, Luz A.;Rodríguez-Trejo, Dante A.;Zamudio-Sánchez, Francisco J.;
Agrociencia , 2008,
Abstract: new approaches to fire management involve greater use of prescribed fire, requiring greater understanding of the effects of both prescribed fire and wildfires. low densities of mature trees and lack of regeneration have been observed at the ajusco volcano, federal district, méxico, and have been related to changes in the fire regime. the effects of fire on the understory of pinus hartwegii lindl. two and three years after application of prescribed burning were investigated in this region. fire treatments were applied to plots of between 0.6 ha and 0.75 ha in 2002 under the following conditions: at two times (march and may), two intensities (low and high), two stand canopy conditions (closed and open), with an additional control (unburned) plot. data were collected in the rainy seasons of the second and third years after the fire (2004, 2005) and analyzed using multivariate hypothesis tests. fire treatments favored understory diversity, richness, and cover, especially in the open canopy treatments two years following the burns, with the trend decreasing in the third year. forty-one and 34 species were encountered in the second and third years.
Radiación solar y calidad de planta en una plantación de vara de perlilla (Symphoricarpos microphyllus H. B. K.)
Mendoza-Bautista, Concepción;García-Moreno, Fortino;Rodríguez-Trejo, Dante A.;Castro-Zavala, Salvador;
Agrociencia , 2011,
Abstract: vara de perlilla or rejagar (symphoricarpos microphyllus h.b.k.) is a shrub that prospers among pine, oak and spruce forests; it is used in christmas crafts and brooms, for local use and sale in cities. in this study, an analysis was made of the effect of radiation and seedling quality on the survival and growth of the shrub, for commercial plantation. in la mesa, san josé del rincón, estado de méxico, méxico, a plantation was established with two seedling qualities: small (20 to 35 cm) and large (45 to 60 cm). of each quality, 450 shrubs were planted, of six months of age, under three conditions (pine plantation, oak forest and a control without tree canopy). the experimental design was complete randomized blocks. morphological variables were measured and hemispherical digital images were taken to calculate solar radiation with the hemiview program. average annual survival was 96.4 % in both seedling qualities, and decreased slightly with the highest level of shade. the morphological variables presented higher values with 6000 mj m 2year-1of total solar radiation.
Planeación de un sistema silvopastoril en ladera en Huatusco, Veracruz aplicando el método Nezahualcóyotl
Quinto, L.;Martínez-Hernández, P. A.;Pimentel-Bribiesca, L.;Rodríguez-Trejo, D. A.;
Revista Chapingo. Serie ciencias forestales y del ambiente , 2009,
Abstract: this study describes the design and field implementation of a silvopastoril system on a hillside using the nezahualcóyotl method to establish the tree component made of: swietenia macrophylla king (big leaf mahogany, brazilian mahogany), tabebuia rosea (bertol) dc. (rosy trumpet tree), cedrela odorata l. (spanish cedar, mexican cedar). the field was in the region of huatusco, on this field five leveled mounds-trenches were done and on the top of the mounds tress were planted every 4 m, tress were previously grown for two months in a nursery. after four months on the field survival rate was not different ("=0.05) among species and higher than 80 %. animal component of the system was not field implemented it was described and planned only, this component was made of a brachiaria brizantha pasture and stocker cattle. pasture establishment was design to be done along with growing maize with a share-cropper. main costs for the establishment of a silvopastoril system using the nezahualcóyotrl method were identified and the estimated total was $ 44,347.00 for each 1/3 of a ha. it was concluded that the nezahualcóyotl method is an option in the establishment of the tree component of a silvopastoril system on hillsides.
Alternativas para mejorar la germinación de semillas de tres árboles tropicales
Quinto, L.;Martínez-Hernández, P. A.;Pimentel-Bribiesca, L.;Rodríguez-Trejo, D. A.;
Revista Chapingo. Serie ciencias forestales y del ambiente , 2009,
Abstract: the present study was conducted to determine seed germination in mahogany (swietenia macrophylla king), mexican or spanish cedar (cedrela odorata l.) and rosy trumpet tree (tabebuia rosea (bertol) dc.) with the use coconut (cocos nucifera l) water and when seed is exposed to high temperature. two trials were done, one with five treatments: coconut water from young, mature and dry coconut, distilled water and control; in the other seed germination was compared among trees when environmental temperature was 28/24 °c (day/night) and 12 h light. seed germination in all three species improved (p<0.05) from two to 10 times in relation to control but it was similar (p>0.05) to the one found with distilled water. seed germination was improved only with coconut water from young coconut. at 28/24 °c (day/night) and 12 h light, mahogany, showed seed germination 1.4 and 2 times higher (p<0.05) than cedar and rosy trumpet tree, respectively. seed germination tended to be higher in the trial at higher environmental temperature than at room temperature (coconut water trial). it was concluded that coconut water might improve seed germination in mahogany, cedar and rosy trumpet tree if coconut is young and that mahogany seed shows high germination at high environmental temperature.
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