Adison Altamirano

Deforestación en ecosistemas templados de la precordillera andina del centro-sur de Chile

SUMMARY A multitemporal analysis to determine the land cover change was conduced in the pre-Andean range of Maule region of Chile. We used satellite imagery from the year 1989 and 2003 to analyze the likely causes of native forest change. In this period, there was a reduction in native forest area of 44% in the study area, which is equivalent to an annual forest loss rate of 4.1%. The native forest area is replaced by shrublands (29%) and exotic forest plantations (27%). A great proportion of current exotic forest plantations are established on lands that were native forest in 1989 (63%). Most forest loss was associated with intermediate elevation and less distance to road network, where native forest area dominated. Native forest replacing by shrublands was associated to selective forest logging and firewood, which leads to degradation of these forests. Native forest replacing by exotic forest plantations was the result of the forestation incentive and an increase in the demand for forest products such as wood and pulp. Because of multiple impacts of the forest loss, we propose to focus the government incentives. Priority areas for incentives must be characterized by high forest loss rate and poverty, presence of threatened species and low availability of water from catchments. Moreover, we propose to prioritize the connectivity of the current network protected areas and to develop an effective forest management monitoring system using advanced technologies.

Influencia de la heterogeneidad del paisaje en la ocurrencia de incendios forestales en Chile Central

Forest fi res are recognized as a serious problem. Despite its importance, research into modelling of forest fi re occurrence is lacking for the southern hemisphere, in particular for Chile. We investigated how landscape heterogeneity affects the probability of the occurrence of forest fi res in Central Chile. We fi tted a logistic regression model which included climatic, topographic, human-related and land-cover variables. Estimated probabilities of forest fi re occurrence increased positively

Incertidumbre de los índices de paisaje en el análisis de la estructura espacial

SUMMARY Landscape indices or metrics have been widely used to relate spatial patterns to ecological processes or ecological functions. Landscape indices have several uses and applications. However, there is evidence that landscape indices are very sensitive to remote sensing imagery analysis. The aim of this study was to assess the effect of accuracy of satellite imagery classification on landscape indices for the analysis of spatial structure. We used the supervised classification method with different classification strategies based on spectral and ancillary information. Eight images classified using different strategies were produced from a single satellite image. Landscape indices at landscape and class level were computed. Overall, results showed that images with higher classification accuracy have lower coefficient of variation of landscape indices. Some landscape indices as Shannon and Simpson diversity, percentage of like adjacencies, and aggregation index showed lower sensitivity to the increase of classification accuracy. However, other indices as patch density and core area were more sensitive. Sources of error in the satellite imagery analysis are very diverse. Hence, caution is advised in the analysis of spatial structure using landscape indices.

Regeneración natural y patrones de distribución espacial de la palma chilena Jubaea chilensis (Molina) Baillon en los bosques mediterráneos de Chile central

Jubaea chilensis es un arbol endemico de la zona central de Chile (31o15’-35o22’ S). Las principales amenazas actuales a su conservacion estarian asociadas a diferentes limitantes a su regeneracion natural, en especial la intensa cosecha de sus semillas. El analisis de patrones espaciales de distribucion puede ser una importante herramienta para entender la dinamica de los bosques y la interaccion entre los individuos. En este trabajo se estudio el patron espacial de reclutamiento de la especie y se identificaron las condiciones favorables para su regeneracion. Se estimo una notoria agrupacion espacial entre los individuos de regeneracion para todos los rangos de distancia analizados, y a su vez una distribucion dependiente de los individuos adultos, agrupandose mayormente cercano a ellos. Por otra parte, la modelacion espacial revelo que la regeneracion natural de J. chilensis se relaciona significativamente con sitios de mayor cobertura vegetacional, y especialmente en sitios con una mayor radiacion solar. Los resultados sugieren que la regeneracion agrupada de J. chilensis se deberia a la asociacion de condiciones ambientales propicias para el establecimiento de nuevos individuos, su mecanismo de dispersion de semillas y escape de la depredacion, herbivoria y cosecha de sus semillas, lo que estaria determinando la estructura espacial de la poblacion. A su vez, los resultados confirman un efecto nodriza, facilitador de la regeneracion natural de la especie.

Disponibilidad y potencial energético de la biomasa del bosque nativo para el desarrollo de la dendroenergía en el centro-sur de Chile

Forest biomass is one of the main alternatives that Chile could promote to supply the long-term demand of energy, which can help to diversify the national en...