Dendroecology Applied to Silvicultural Management in the Southern Patagonian Forests: A Case Study from an Experimental Forest in Tierra del Fuego, Argentina

Abstract

Most of radial growth studies of Nothofagus pumilio (locally known as ‘lenga’) in Tierra del Fuego have focused on mature forests and climate relations, but little is known about growth dynamics after harvesting and even less after applying intermediate treatments. The objective of this chapter is to analyze the effect of thinning and pruning on radial growth of N. pumilio in Tierra del Fuego (Argentina) in the Aguas Blancas experimental long-term forest, which was harvested in 1967 and had different combinations of interventions in 1984–1985 and 1999. Three treatments were analyzed: (i) one thinning (1 T, thinned in 1984–85), (ii) two thinnings (2 T, thinned in 1984 and 1999), and (iii) two thinnings with pruning of 2/3 of the living crown (2 T + P, thinned in 1984 and 1999 with pruning). Using standard dendrochronological methods, ring widths were cross-dated, measured and the mean ring width (RW), basal area increment (BAI) and the corresponding percentages of change in growth (PGC) in 5-year windows were calculated. The three treatments showed significant increments in PGC in both RW (129%) and BAI (419%) after the 1984–1985 thinning. However, from 1999 there were significant differences in periodic growth between the three treatments with the highest RW and BAI in the thinned with pruning treatment. In these forests, dendrochronology emerges as a complementary method to quantify and to reconstruct the individual response of trees affected by silvicultural treatments.