Álvaro Promis

Microclima en el interior de un bosque de Nothofagus pumilio y el efecto de una corta de regeneración

Resumen es: El microclima en un rodal virgen de Nothofagus pumilio (BV) y el efecto de una corta de regeneracion (CR) y de un sector desarbolado (SD) fueron estudiad...

Evaluating the usefulness of hemispherical photographs as a means to estimate photosynthetic photon flux density during a growing season in the understorey of Nothofagus pumilio forests

Abstract Old-growth Nothofagus pumilio forests in Chile are managed employing a shelterwood system. A wide range of canopy openings can be found in old-growth and managed forests. Plant survival and growth in the understorey are influenced by the light available. There are limitations (practical and economic) to monitoring the light in the understorey. The aim of this study was to assess the options to estimate the forest understorey photosynthetic photon flux density (PPFD) measured during the growing season (GS) using canopy openness (CO) estimated by means of hemispherical photographs (HP). PPFD was measured using 31 sensors (Li-190SA quantum sensor) over the course of three GSs (October to March). The sensors were installed in an old-growth stand and another subjected to a regeneration felling under a shelterwood system. One HP was taken above each sensor (during the final GS) and the CO estimated. A comparison of the three seasons revealed that the sum of the PPFD during the GSs did not differ significantly. The CO could be used to effectively predict the sum of the PPFD during a GS (R 2 = 0.959). These results demonstrate the usefulness of HPs as a means to estimate the sum of the PPFD during a GS.

Descomposición de hojarasca en rodales de Nothofagus pumilio de la región de Magallanes

SUMMARY Litter decomposition in two Nothofagus pumilio stands located in Magallanes Region (Chile) was studied during two years. One stand was a primary forest (SI), without silvicultural treatment, and the other had a regenerative felling under a shelterwood system (CR). Weight loss and litter decomposition rates were obtained with the litter-bag method. At each stand, 36 litter-bags were systematically placed on the forest floor. A fraction of the litter-bags was then randomly extracted at months 2, 5, 9, 11, 12, 15, 21, 22 and 24. The weight of the collected litter-bags was measured at each sampling period. Litter weight-loss presented differences between the stands only after 12 months since the litter-bag set up. After 24 months, the litter weight-loss was similar between the stands, reaching 60 % of the initial weight. After one year of the experimental set-up, litter decomposition rates (k) were 0.76 and 0.44 for CR and SI stands, respectively. At the end of the trial, these values changed to 0.44 and 0.46 for CR and SI stands, respectively. The model that best fitted the relative litter mass according to the initial litter weight was the quadratic regression model, using the number of months, when the litter was on the forest ground, as the independent variable (R 2 = 0.95 for both stands). These results suggest that the effect of the regeneration felling on the litter decomposition rates decreases with time.

Medición y estimación del ambiente lumínico en el interior del bosque: Una revisión

Forest decline in Desierto de los Leones National Park in Mexico City affects Abies religiosa, a dominant and hard-to-root species in the region. As a result of this decline, the species requires propagation in the region through rooting of cuttings. In this study, a method of vegetative production was developed to determine whether the effect of origin, age of the material, type of hormone used and the presence of decline symptoms affect the rooting capacity of cuttings of this species. Three experiments were conducted, and only the third one produced rooting of cuttings. In this experiment, a substrate composed of peat moss and perlite was used to test rooting of cuttings of two origins, with and without symptoms, generated in two growing seasons and using two auxins (indolbutyric acid and naphthalene acetic acid), keeping the soil moisture between 75-80 %. The combination of these factors produced 16 treatments, which were replicated 50 times. Data were processed by factorial analysis of variance. Results indicate that early December is the best time to collect plant material for rooting of A. religiosa cuttings, as they are the youngest, and that those that received indol-butyric acid rooted the best. Origin and decline symptoms had no effect on rooting. Recibido:14 de junio de 2011 Aceptado: 06 de marzo de 2013 doi: 10.5154/r.rchscfa.2011.06.038 http://www.chapingo.mx/revistas PALABRAS CLAVE: Propagación vegetativa, procedencia, auxinas, edad de estaca, ácido indol-3butírico, ácido naftalenacético.The below-canopy light environment influences the survival, the tree regeneration growth and the development of the understory plant species. Therefore, there has been much interest in measuring the below-canopy light environment. Several instruments, techniques and methods have been developed to measure directly or to estimate indirectly the below-canopy light environment. To date, many comparisons of direct and indirect methods for the measuring and estimation of below-canopy light environment have been conducted in order to determine the best way to measure the light in the understory. In this review a scientific description of the currently instruments, techniques and methods used to measure or to estimate the below-canopy solar radiation is shown. The nature and properties of the different methods, techniques and instruments are commented. Finally, the choice of equipment to meet the needs of the researcher in this topic is supported. Recibido: 29 de febrero de 2012 Aceptado: 12 de febrero de 2013 doi: 10.5154/r.rchscfa.2012.02.014 http://www.chapingo.mx/revistas PALABRAS CLAVE: Radiación solar, luz, medición directa, estimación indirecta, ambiente bajo el dosel arbóreo.The usefulness of forest species in agricultural production systems is an option that helps to reduce the pressure in natural forests; they can also be used in treeless areas. The aim of this study was to evaluate the nutritional quality, germination, development of seedlings grown in nursery and variety of uses of Leucaena lanceolata S. Watson ssp. lanceolata. Edible material and seeds were collected in Tomatlán, Jalisco. Bromatologic analyses, scarification tests and the evaluation of seedlings grown in nursery using three soils with different pH values were performed. The experimental design was completely randomized, with Tukey (P≤0.05) test for media comparison. A survey study, bibliographical revision and review of specimens in the herbariums were used to know the local and potential diversity of uses of this specie. Results show high content of dry matter (97.40 %) and crude protein (29.05 %), greater germination using heat treatments, better seedling development in slightly acid soil (6.57) and the diversity of uses including firewood, forage and timber among others. L. lanceolata represents a viable option to be used in dry tropical silvopastoral systems due to the high nutritional value and the diversity of uses in rural areas. Recibido: 27 de septiembre de 2011 Aceptado: 01 de febrero de 2013 doi: 10.5154/.r.rchscfa.2011.09.070 http://www.chapingo.mx/revistas PALABRAS CLAVE: escarificación, materia seca, proteína cruda, pH,

DESCRIPTION OF THE VASCULAR FLORA IN THE UNDERSTORY OF A SWAMP FOREST AND IN AN ANTHROPOGENIC JUNCUS PROCERUS WET PRAIRIE IN THE VALLE DEL RÍO CISNES, AYSÉN REGION, CHILE

The richness, abundance and density of vascular flora species were evaluated in the understory of a swamp forest (BP) dominated by Luma apiculata and in an anthropogenic Juncus procerus wet praire (PHJ). The most diverse taxonomical groups were fern in BP and dycotiledon in PHJ. Introduced species were only found in PHJ. Epiphytic hemicryptophytes and climbing phanerophytes are indicator species for BP and hemicryptophyes for PHJ.