The soil seed bank as an indicator of resilience in a nature reserve affected by shrub encroachment

Abstract

Currently, the natural grasslands of the arid and semi-arid central region of Argentina are experiencing an increase in woody and herbaceous species, including exotic species, leading to a loss of ecosystem functions and biodiversity. Their rehabilitation depends on the soil seed bank (BSS) and its dynamics in response to various interventions. The BSS constitutes the main propagule reserve available to a plant community for its maintenance, regeneration, and perpetuation. The objective was to evaluate the response of the BS in different vegetation patches subjected to mechanical thinning and prescribed burning. The study was conducted in the Parque Luro Provincial Reserve, Argentina, in an area with woody cover exceeding 75%, dominated by Neltuma caldenia. Two treatments were established through forest thinning followed by prescribed burning: control (C) and intervened (I). Within each treatment, patches were selected: trees and shrubs (AA), shrubs (A), and grass/herbaceous vegetation (GH). Vegetation surveys and soil samples were taken to study the germinable soil substrate (BSS). Data were analyzed using ANOVA with a split-plot factorial design. In plot I, a greater presence of perennial heliophilous grasses was observed in the GH patches. Perennial shade-loving grasses were most prevalent in patches AA, both in plot C and plot I. Annual dicotyledonous grasses showed no differences between vegetation patches or management practices. Exotic species were most abundant in plot C for AA and A. Species establishment will depend on the presence of the BSS, land use history, the species composition of the current community, and any interventions carried out.