Characterization of soil properties of Nothofagus spp. forest with and without scarification in the Andean region of Southern Chile

Abstract

Soil scarification has been used as a silvicultural method to eliminate competition in tree regeneration, but it modifies soil characteristics. In order to evaluate soil changes due to silvicultural management, we characterized a volcanic soil subjected to a mechanized scarification in a Nothofagus spp. forest in the Andean region of southern Chile (39° 54' S, 71° 56' W; 970 m asl). Scarification removed between 20 and 40 cm of topsoil in forest gaps. Two scarified areas were selected in different periods and in an undisturbed forest area. Physical properties (bulk density, penetration resistance, porosity, texture) and chemical (pH, soil organic matter, total-N, P-Olsen, K, Mg and Ca extractable, Al saturation) were analyzed in both the scarified soil and undisturbed forest. The morphology of the soil was a result of the formation of a stratified soil. Bulk density was higher in the superficial layer of the scarified soil (0.9 to 1.2 g cm -3 ) when compared to the undisturbed forest (0.3 g cm -3). With regards to the undisturbed forest, soil scarification exposed a superficial soil of coarser texture, lower total porosity (50-60% vs. 80%) and it decreased the soil nutrient supply. There were no large variations in soil properties when comparing the oldest scarified soil with the most recent one. There were important changes in morphology, physical and chemical properties of the scarified soil.

Topsoil removal through scarification improves natural regeneration in high‐graded Nothofagus old‐growth forests

“…Our study showed that topsoil removal was a successful treatment in high‐graded Nothofagus forests in the Andes of south‐central Chile, as it reduced the abundance of C. culeou and at the same time encourages the regeneration of desirable LLES tree species. This supports findings in a number of forest biomes that this ground disturbance can be an effective practice for altering understorey vegetation to encourage tree regeneration (Löf et al., ; Örlander et al., ; Reyes et al., ; Yoshida et al., ). Research has shown that a variety of environmental conditions can be responsible for this effect, including the amount of soil exposure needed to provide safe sites (Cornett, Reich, Puettmann, & Frelich, ), degree of soil compaction (Ampoorter, De Frenne, Hermy, & Verheyen, ; Soto, Donoso & Puettmann, 2014) and soil fertility (Ampoorter et al., ; Reyes et al., ).…”

“…Thus, a close examination of soil conditions, specifically nutrient and soil water conditions, will provide insights into the likelihood of success when applying topsoil removal as a restoration treatments. Earlier work (Reyes et al., ) also pointed out that soil structure, specifically the potential for soil compaction, needs to be considered when such restoration treatments are applied across a broader landscape.…”

“…This treatment has the goals of (1) controlling dense tickets of C. culeou and remove the dense litter layer, (2) exposing mineral soil as safe sites for germination and establishment of Nothofagus spp., and (3) creating open areas for underplanting when seed sources are lacking (Soto et al., ). These operations removed the upper soil layers (20–40 cm), including rhizomes and culms of C. culeou (Reyes et al., ). Topsoil removal created a complex spatial pattern of soil conditions.…”

“…More information about the effects of topsoil removal through scarification on soil chemical and physical properties on our study sites right after treatments can be found in Reyes et al. ().…”

“…(Donoso, 2006). Thus, ground disturbance (e.g., slash, humus, or topsoil removal by scarification) has been used to manage competitive vegetation and encourage more reliable regeneration of desirable tree species (i.e., mostly earlyseral trees) in a number of forest biomes (Löf, Dey, Navarro, & Jacobs, 2012;Örlander, Egnell, & Albrektson, 1996;Reyes, Thiers, & Gerding, 2014;Yoshida et al, 2005).…”