Afforestation With Different Tree Species Causes a Divergent Evolution of Soil Profiles and Properties

German Morazzo,Lucila Álvarez,Elke Noellemeyer,Emmanuel Leizica,Diego Rene Riestra

doi:10.3389/ffgc.2021.685827

Abstract

Land-use change and specifically a change in the type of vegetation cover affects soil morphology, chemistry, biology, and nutrient regimes. Numerous studies have documented that in land-use conversions from agricultural land to forest, or from plantations to restored natural savanna most soil attributes and functions undergo changes. The purpose of the present study was to evaluate the changes brought about by afforestation of degraded croplands and to understand the impact of forest vegetation on soil evolution in a semiarid region where soils originally co-evolved with a savanna biotope. We used long-term experiments (&gt;40 years) of five tree species: Pinus halepensis (PH), Pinus halepensis inoculated with ecto-mycorrhiza at planting (PM), Pinus pinea (PP), Eucalyptus spp. (E), and Gleditsia triacanthos (G) and compared these to an agricultural soil (A) at the same site near Santa Rosa, La Pampa in the semiarid center of Argentina. Soil profiles were described, and samples taken for chemical and physical analyses of soil properties [organic matter (OM), pH, cation exchange capacity (CEC) and exchangeable cations, particle size distribution (texture), aggregate stability (MWD), bulk density (BD), porosity (TP), and water holding capacity (WHC)]. We found a strong effect of tree species on soil profile morphology, even taxonomy, and on all studied variables. PM and G had highest OM, CEC, neutral pH, higher TP, WHC, while PH, PP, and E had acid pH, lower base saturation, OM, TP, and WHC. The effect of tree species on the soil profile was noticeable a depth of about 40 cm, comprising the A and AC, but not the C horizons. The results showed that to obtain reasonable results of OM sequestration under forest systems, tree species should be chosen to include legumes to improve C/N stoichiometry for C fixation, or inoculation with mycorrhiza to promote microbial transformation of forest litter.

Highlights

Land-use change and a change in the type of vegetation cover affects soil morphology, chemistry, biology, and nutrient regimes
The treatments corresponded to four tree species: Aleppo pine, Pinus haleppensis (PH) and Pinus haleppensis inoculated with ecto-mycorrhiza at planting (PM); Stone pine, Pinus pinea (PP); Eucalypt, Eucalyptus spp. (E); and Black locust, Gleditsia triacanthos (G)
Our results confirmed that Eucalypt and Pine plantations without ectomycorrhiza have a deleterious effect on soil biological, chemical, physical conditions, and on the soil profile morphology, resulting in a different taxonomic order for these soils, due to their low base saturation

Summary

Introduction

Land-use change and a change in the type of vegetation cover affects soil morphology, chemistry, biology, and nutrient regimes. Numerous studies have documented that in land use conversions from agricultural to forest systems (Lemenih, 2004), or from plantations to restored natural savanna vegetation (Johnson-Maynard et al, 2002) most soil attributes and functions undergo changes. These changes are driven by environmental factors (climate, parent material) and by the forest species and management. Some studies already pointed out that Corsican pine (Pinus nigra) caused incipient podzolization in soils of Tuscany, while at the same time this process was not observed under silver fir (Certini et al, 1998)

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