Effects of solar radiation on regeneration patterns in a Nothofagus dombeyi (Mirb.) Oerst. old-growth forest in Chile’s central-southern Andes

Abstract

Nothofagus species behave like early successional species that recolonize open sites after of regular and large-scale disturbances. This study analyzed the effects of light regimes on patterns of advanced regeneration dynamics, growth in diameter and height of Nothofagus dombeyi (Mirb.) Oerst. (Density of 240 trees ha-1, basal area of 56.7 m2 ha-1). Systematic sampling every 50 m in three stands (7.5 ha) was used. At each point and with the same center, two concentric circular plots were established, 9.0 m and 1.8 m radius. For estimate solar radiation transmissivity in plots, a solariscope hemispheric photographic camera was used. Diameters at breast height and basal areas (BA), heights (H) were measured and then counted and measured N. dombeyi seedlings and saplings. 13 saplings of advanced regeneration were harvested from all gaps to obtain age (E), total height (TH), absolute radial growth (ARG), and absolute height growth (AHG). As results, solar radiation varied between 3 and 40%. ARG varied between 1.20 and 2.22 mm yr-1 and AHG between 0.15 and 0.43 m yr-1. We found correlation for ARG and AHG with direct and global solar radiation transmissivity, but not with diffuse solar radiation transmissivity. The plant age and transmittance of direct and global solar radiation explains the increases in diameter and height. However, in our study stated that in the Andean region of south-central Chile, N. dombeyi stands is affected by small-scale disturbances. Therefore, transmissivity radiation solar inside the forest, explaining natural regeneration patterns and growth of N. dombeyi.