Recovery of understory assemblage along 50 years after shelterwood cut harvesting in Nothofagus pumilio Southern Patagonian forests

M PEREZ FLORES; G MARTÍNEZ PASTUR; JM CELLINI; MV LENCINAS

FOREST ECOLOGY AND MANAGEMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2019 vol. 450 p. 117494 - 117494

0378-1127

Harvesting modifies the understory due to changes in the overstory structure, microclimate and soil properties.The impact is directly related to the harvesting intensity, although studies are usually developed in logged areas(low impact) avoiding stockpiled areas (high impact). Understory resilience is quite variable, and recovery timeremains unknown for different management practices and different temperate forests. The objectives of thiswork were: (i) to evaluate recovery of understory vascular plants and forest structure in Nothofagus pumilioforests of South Patagonia (Argentina) along a chronosequence of years-after-harvesting (YAH) (1?5, 6?10,20?30,>50) in shelterwood cuts compared to unharvested forests (UF), and (ii) to analyze differences in theunderstory recovery in areas with different impact intensity due to the harvesting: low impact harvesting (LIH)in logged areas vs. high impact harvesting (HIH) in stockpiled areas. We selected 12 harvested areas withdifferent YAH, and in each area we sampled three forest treatments (LIH, HIH, UF) with 5 replicas(N=12×3×5=180). In each sampling unit we analyzed the forest structure (primary or remnant overstoryand secondary forests), environmental (soil moisture) and understory variables (richness, cover and speciesassemblage patterns) through univariate and multivariate statistical analyses. Remnant forest structures presentedsignificant decay in the dominant height along the chronosequence, and an increasing in the secondaryforest variables, as well as in the crown cover (remnant+secondary forests). Lower values of forest structurevariables were observed in HIH than LIH, but without significant differences between them. Most of treatmentlevels presented significant differences with UF, and values become similar with time. Understory presentedsignificant differences in richness and cover along the chronosequence, with values become more similar to UFon time. Harvesting impact levels also presented differences, e.g. 104% and 144% more exotic species cover inLIH and HIH compared with 20% in UF. However, greater significant differences were found among treatmentsfor their species assemblage patterns, mainly in the first stages of the chronosequence (e.g., between UF and LIHat 6?10 YAH); meanwhile in the last stage (> 50 YAH), species assemblage patterns become similar with UF,both for LIH and HIH. We conclude that understory vascular plant assemblage of N. pumilio forests recoverspatterns after 50 YAH, being more similar to original ones as the crown cover reaches similar values to unharvestedforests, showing N. pumilio forests as highly resilient to shelterwood cut harvesting, even in highimpacted areas.