Luis Chauchard

Modelos de crecimiento diamétrico para Nothofagus obliqua

SUMMARY Non-linear, Bertalanffy-Richards-type models of diameter growth were developed for Nothofagus obliqua and fitted for different social tree strata using the diameter annual increment (id) and diameter at breast height (dap). The biological and statistical analyses were conducted from two different sources; an independent data set taken mainly from permanent sample plots and a real growth series obtained from tree cores and stem analyses. Models for different purposes were obtained through both data sets. For the prediction of short-term diameter increments, a model was obtained that related independent data of trees belonging to the same social stratum. Models of higher biological meaning were obtained by relating the growth series and their significance and are discussed here. By means of these biological models, the growth dynamics of N. obliqua were analyzed under different competitive

Curvas preliminares de índice de sitio para bosques puros y mixtos de Nothofagus alpina y Nothofagus obliqua en la Patagonia Argentina

The growth of the dominant height of the stand and the IS is assumed to express the effects of all relevant site factors on the growth. The objective was to ...

Efecto del manejo silvicultural sobre la regeneración de un bosque de Nothofagus dombeyi, N. alpina y N. obliqua en la Reserva Nacional Lanín (Argentina)

Las practicas silviculturales constituyen un importante agente de disturbio y su inadecuada implementacion afecta la sostenibilidad de los bosques naturales. En la Reserva Nacional Lanin, el manejo silvicultural del bosque de Nothofagus dombeyi, N. alpina y N. obliqua se realiza tradicionalmente mediante aclareos sucesivos; y se desconoce su efecto sobre la composicion y estructura de la regeneracion natural. La cobertura del dosel, composicion y area basal de los individuos adultos, y la composicion, edad y distribucion espacial de los renovales fue evaluada en una parcela de 3 ha intervenida en 1993 mediante una corta diseminatoria. La densidad de adultos antes de la corta fue 26 % para N. dombeyi, 38 % para N. alpina y 35 % para N. obliqua, y la remanente fue 20, 44 y 36 %, respectivamente. Previamente al aprovechamiento, el 92 % de la regeneracion estaba constituida por N. alpina, y luego principalmente por N. obliqua (45 %) y N. dombeyi (42 %). Estos valores no se correlacionaron con el area basal de adultos. La edad de los renovales fue mayor en sitios con alta cobertura de dosel y N. alpina fue la especie que se instalo ultima. El aprovechamiento del bosque de Nothofagus no promovio el mantenimiento de la composicion relativa original de la regeneracion. El tiempo de colonizacion de las especies de Nothofagus disminuiria y una mayor cantidad de renovales de N. alpina, especie mas tolerante a la sombra, se estableceria si la cobertura remanente fuera superior a la recomendada en los planes de manejo

DIAMETRIC SITE INDEX: AN ALTERNATIVE METHOD TO ESTIMATE SITE QUALITY IN Nothofagus obliqua AND N. alpina FORESTS

The first step for constructing models of tree growth and yield is site quality assessment. To estimate this attribute, several methodologies are available in which site index (SI) is a standard one. However, this approach, that uses height at a reference age of trees, can be simplified if age is replaced by another reference variable easier to measure. In this case, the diametric site index (DSI) represents the mean height of dominant trees at a reference mean diameter at breast height. The aim of this work was to develop DSI in pure and mixed Nothofagus alpina and N. obliqua forests, and compare these models with the classical proposals based on height-age variables, within the temperate forest of northwestern Patagonia from Argentina, South America. Data originated from temporary plots and stem analyses were used. Tree age and diameter at breast height were obtained from each plot and used for establishing DSI family functions, following the guide-curve methodology. Site classes were proportionally represented among DSI curves of 17.0, 21.5, 26.0, 30.5 and 35.0 m of dominant tree height. Reference diameter instead of reference age can be cautiously used in order to fit site index models.

VOLUME AND TAPER EQUATIONS FOR COMMERCIAL STEMS OF Nothofagus obliqua AND N. alpina

ABSTRACT: Timber volume of standing trees is essential information for management decisions. The increasing need to optimize the potential capacity of forests maintaining their conservation, requires the quantification of the different potential possible timber products. The aim was to adjust taper equations to determine volumes of different timber products for commercial stems of Nothofagus alpina and N. obliqua . Trees of both species were randomly selected in harvesting areas of Lanin National Park (Argentina). Trees were felled and cut into commercial logs, measuring diameter with bark at different heights up to the beginning of the crown, and for each tree the diameter at breast height and total height. Five taper equations were selected and non-linear regression processes were employed for the fittings. We obtained the volume through the integration of the stem profile equation and the rotation in the space thereof through solid of revolution. The Bennet and Swindel (1972) model was selected for both