Given the growing demand for harvest residues for energy generation from Pinus radiata forest plantations in south-central Chile, models for estimating site-specific forest residue production are needed. In this study, allometric models were fitted to estimate the potential biomass resulting from the harvest of P. radiata plantations located in volcanic sand, recent volcanic ash and sedimentary soils, taking into consideration management gradients and site productivity, in characteristic sites of south-central Chile. The fitted models allowed estimating conversion factors and developing estimation models at individual tree and stand level. Results suggest that conversion factors for changing from stem biomass to potential residue biomass have a negative exponential relationship with tree size. Models fitted for estimating at individual tree level, starting with diameter and height variables, suggest that the models depend on soil origin, while in the case of stand-level estimates the fitted model is independent of soil origin, gradient management and productivity.Resumen D ada la demanda creciente sobre los residuos de cosecha para la generación de energía en plantaciones forestales de Pinus radiata en la zona centro-sur de Chile, resulta necesario disponer de modelos que permitan la estimación sitio-específico de la producción de residuos. En este estudio se realizó el ajuste de modelos alométricos de estimación de la biomasa potencial de residuos de cosecha para plantaciones de P. radiata, en suelos de arenas volcánicas, cenizas volcánicas recientes y sedimentarios, considerando gradientes de manejo y productividad, en sitios característicos del centro-sur de Chile. Los modelos ajustados permitieron la estimación de factores de conversión, y modelos de estimación a nivel de árbol individual y rodal. Los resultados sugieren que los factores de conversión de biomasa fustal a biomasa potencial de residuos tienen una relación exponencial negativa con el tamaño de los individuos. Los modelos ajustados para la estimación a nivel de árbol individual, a partir de las variables diámetro y altura, sugieren que los modelos dependen del origen del suelo, mientras que para el caso de las estimaciones a nivel de rodal, el modelo ajustado resulta independiente del origen del suelo, gradiente de manejo y su productividad. Palabras clave: Biomasa aérea, biomasa y bioenergía, residuos, modelos de biomasa, factores de conversión de biomasa.

No abstract

Los incendios forestales son una de las mayores causas de degradación de ecosistemas en Chile. La temporada de incendios forestales 2016-2017 destacó por la superficie afectada, incluyendo un bosque y matorral, del tipo forestal Roble-Hualo, de alto valor de conservación. Por lo que este estudio tuvo como objetivo evaluar el efecto del incendio en ambas formaciones, sobre la estructura del dosel mediante la utilización de fotografías hemisféricas. Además, se cuantificó el efecto del incendio en variables químicas del suelo, diversidad y abundancia de la vegetación. Los resultados indicaron una clara degradación de la estructura del dosel del bosque y matorral, aumento en la radiación potencial sobre el piso forestal, reducción del área foliar y cobertura de los doseles sobre el suelo. Asimismo, algunas variables químicas como el pH, materia orgánica(MO%), suma de bases (Sb) y potasio disponible (Kd) aumentaron en el suelo del matorral, no así en el suelo del bosque. La regeneración post-incendio fue escaza en ambas coberturas, además se apreció una considerable pérdida de diversidad arbórea y arbustiva, afectando así la composición de la vegetación, en el bosque y en el matorral.

Sclerophyll forest in Mediterranean central Chile has been subjected to severe degradation due to anthropic disturbances and climate change and is in need of restoration. Since direct seeding is usually unsuccessful, we need to research seed propagation to produce plants for restoration. Our objective was to assess pre-germination treatments for six native woody species (Acacia caven, Lithraea caustica, Quillaja Saponaria, Porlieria chilensis, Kageneckia angustifolia, and Ceratonia chilensis) of the sclerophyll forest, considering its operational applicability and consequences for nursery plant production. Treatments were selected according to previous studies, and operational applicability in nurseries. Germination and level of seeds water imbibition were assessed. Results indicate that time for seed water imbibition is critical for germination in A. caven, P. chilensis and K. angustifolia, with an average germination of 90.2 ± 2.0%, 85.0 ± 4.7%, and 47.4 ± 2.3%, respectively. Gibberellin did not improve germination compared to water soaking in Q. Saponaria, K. angustifolia and P. chilensis. In addition, physical scarification is a suitable treatment for L. caustica and C. chilensis, instead of chemical scarification, avoiding handling toxic and corrosive compounds in nurseries. We recommend assessing seed water imbibition rates as a key factor for proper germination processes.

Nothofagus alessandrii (ruil) is an endangered relict species, endemic to the Mediterranean area of Chile, and one of the most threatened trees in the country. Its natural distribution area has been greatly reduced by the effect of human activities; the remaining fragments are mostly intervened and highly deteriorated as a habitat and refuge for the associated biodiversity. In order to produce healthy and resistant nursery plants for recovery and restoration of N. alessandrii forests, this study evaluates the early effects of mycorrhizal fungal inoculum (MFI) combined with fertilization on the cultivation of seedlings. The experiment was established under a completely randomized design with a factorial arrangement of the mycorrhizal factors (M0 = without mycorrhizal, M1 = Thelephora sp. and M2 = Hebeloma sp.) and fertilization (F1 = standard fertilization and F2 = intensive fertilization), with three replicates of each combination, for each type of plant (P1 = plants from one season and P2 = plants from two seasons). Each experimental unit corresponded to a group of 20 plants, with 720 plants in the test. The results indicate that application of fertilizer and MFI significantly affects some growth and photosynthesis parameters of ruil plants in one and two seasons. The morphological parameters obtained in the study show shoot height values ranging between 67 and 91 cm for P1 and between 96 and 111 cm for P2; while, for shoot diameter, values ranged between 7.91 and 8.24 mm for P1 and between 10.91 and 11.49 mm for P2. Although formation of fully developed mycorrhizal roots was not observed during the assay period, we conclude that inoculation of mycorrhizal fungi combined with fertilization could be an efficient strategy to produce a quality plant, in addition to maintaining a high photosynthetic capacity and, therefore, a higher percentage of survival in the field.