Mixed-Species Plantation Effects on Soil Biological and Chemical Quality and Tree Growth of A Former Agricultural Land

Tiziana Danise,Walter S Andriuzzi,Michele Innangi,Georg Guggenberger,Giovanni Mastrolonardo,Francesco Pelleri,Antonietta Fioretto,Francesco Niccoli,Giacomo Certini,Giovanna Battipaglia

doi:10.3390/f12070842

Abstract

Tree planting on abandoned agricultural land could both restore the soil quality and increase the productivity of economically valuable woody species. Here, we assess the impact of mixed-species tree plantations on soil quality at a site in Central Italy where tree intercropping systems were established 20 years ago on a former agricultural land. These intercropping systems include two species of economic interest, Populus alba and Juglans regia, and one of three different nurse trees, i.e., Alnus cordata, Elaeagnus umbellata, both of which are N-fixing species, and Corylus avellana. We measured tree growth and compared how soil organic matter, soil extracellular enzymes, and nematodes of different feeding groups varied among the intercropping systems and relative to a conventional agricultural field. Our results indicate that tree plantation led to an increase in soil carbon and nitrogen, and enhanced enzyme activities, compared with the agricultural land. The proportion of nematode feeding groups was heterogeneous, but predators were absent from the agricultural soil. Multivariate analysis of soil properties, enzymatic activity, nematodes, and tree growth point to the importance of the presence N-fixing species, as the presence of A. cordata was linked to higher soil quality, and E. umbellata to growth of the associated valuable woody species. Our findings indicate that intercropping tree species provide a tool for both restoring fertility and improving soil quality.

Highlights

Cropland abandonment is an important process in many regions of the world and one of the dominant processes of land use change in Europe, where abandoned agricultural lands are estimated to cover between 20,277 and 211,814 km2 by 2040 [1]
The slight but significantly lower pH we measured in the tree plantation plots compared with the agricultural land was plausibly due to higher plant uptake of base cations [45] and higher organic residue deposition and decomposition, which imply a net input of protons to the soil [47]
Our results suggest that the afforestation of arable soils is a valid strategy for improving soil quality

Summary

Introduction

Cropland abandonment is an important process in many regions of the world and one of the dominant processes of land use change in Europe, where abandoned agricultural lands are estimated to cover between 20,277 and 211,814 km by 2040 [1]. Mixed plantations are considered preferable to monocultures to maintain wood production while promoting soil quality. The goal of such management is to combine different species to produce specific interactions that will increase stand-level productivity or individual-tree growth rates relative to monocultures. This enables the harvesting of products from different tree species on different rotations while reducing the risk of market shifts, or pest impacts, or some combination of both [10]

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Conclusion