Valdivian Temperate Rainforests in Chile have a global conservation value, but nowadays many correspond to secondary forests following regeneration in agricultural and burned lands, and to high-graded old-growth due to mismanagement, especially at mid to low elevations. Perspectives for increasing old-growth attributes in these productive forests through silviculture are high considering the diverse demands of ecosystem services and the high timber value of tree species. In the Llancahue experimental forest (40°S Lat) we implemented three ecological silviculture approaches: variable-density thinning in a Nothofagus dombeyi secondary forest (NDS), irregular shelterwood in a mature N. dombeyi forest (NDM), and single-tree selection cutting in a partially harvested old-growth forest (OG). Based upon an old-growth index (OGI) that includes density, basal area (BA), BA of the trees >80 cm in diameter, ba of shade-tolerant species, and the Gini coefficient, and aims to estimate how close a given forest is to a typical old-growth forest, these forests had a 22, 22, and 62% OGI before management. The OGI remained similar or declined following management, but 7–10 years after management it increased in NDS and NDM and declined in the OG (significant changes only in NDM and OG). We discuss these results considering that managed forests should target for an OGI ≈70% rather than maximum values. These managed forests contribute to halt degradation, mitigate climate change (carbon stores in the forest and in timber), and may have greater adaptive capacity to disturbances. We discuss perspectives for the potential scale-up of implementing these approaches.
In Chile, Nothofagus spp. is the main native tree genus grown in plantations. Data regarding growth in Nothofagus plantations have been reported for about three decades, and generally illustrate their high productive potential, especially if silvicultural management is carried out on time and established in appropriate places. The aim of this study was to measure the increases in diameter and height of N. obliqua and N. alpina in pure plantations and mixed plantations with both species, plus N. dombeyi and three mid-tolerant native species. These plantations are located close to each other, at 50 -100 m a.s.l., each approximately 1 ha in size, both with southern exposure and the same soil type. They were between 24 -26 years old when they were evaluated. In each plantation, dominant individuals were selected, and their neighboring competition (potentially available area, PAA), total height, and DBH were measured. An increment core was obtained from each individual to evaluate the increase in plantations over the last 6 years (PAI). The PAA of the species in each situation was not significantly different, as there was homogeneity in the competition conditions between individuals in the different plantations, which allowed for comparison of the increase between species according to condition. The total height, the DBH, and the PAI for each species were all significantly higher in the mixed plantation compared to the pure plantation, which is interpreted as a result of the combined effects of reducing competition and facilitation, in which the diversity of species plays a key role.
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