Effects of topsoil treatments on afforestation in a dry Mediterranean climate (southern Spain)

Paloma Hueso-González,Jose Damian Ruiz-Sinoga,Juan Francisco Martínez-Murillo

doi:10.5194/se-7-1479-2016

Abstract

Abstract. Afforestation programs in semiarid areas are associated with a high level of sapling mortality. Therefore, the development of alternative low-cost and low-environmental-impact afforestation methods that ensure the survival of seedlings is crucial for improving the efficiency of Mediterranean forest management. This study assessed the effects of five types of soil amendments on the afforestation success (e.g., plant growth and survival) of a Mediterranean semiarid area. The amendments tested were (i) straw mulch; (ii) mulch containing chipped branches of Aleppo pine (Pinus halepensis L.); (iii) sheep manure compost; (iv) sewage sludge from a wastewater treatment plant; and (v) TerraCottem hydroabsorbent polymer. We hypothesized that in the context of dry Mediterranean climatic conditions, the use of organic amendments would enhance plant establishment and ensure successful afforestation. The results showed that afforestation success varied among the various soil amendment treatments in the experimental plots. The amendments had no effect on soil organic carbon, pH, or salinity, but the results indicated that the addition of mulch or hydroabsorbent polymer can reduce transplant stress by increasing the soil water available for plant growth throughout the hydrological year, and potentially improve the success of afforestation by reducing plant mortality.

Highlights

Introduction1994; Brandt and Thornes, 1996; Puigdefábregas and Mendizábal, 1998; Martínez-Murillo et al, 2016; MuñozRojas et al, 2016a, b; Willaarts et al, 2016)
The combination of climate change, lithology, geomorphology, and human activities has resulted in much of the Mediterranean region being affected by soil and vegetation degradation, which has led to desertification processes (PérezTrejo, 1994; Brandt and Thornes, 1996; Puigdefábregas and Mendizábal, 1998; Martínez-Murillo et al, 2016; MuñozRojas et al, 2016a, b; Willaarts et al, 2016)
In Mediterranean semiarid regions with summer drought or very little rainfalls during this season, this stress could be responsible of the initial increase in plant mortality due to the limited root development of the saplings and their inability to access water contained in the lower layers of the soil profile (Maestre and Cortina, 2002a; Maestre et al, 2002b; Bochet et al, 2007)

Summary

Introduction

1994; Brandt and Thornes, 1996; Puigdefábregas and Mendizábal, 1998; Martínez-Murillo et al, 2016; MuñozRojas et al, 2016a, b; Willaarts et al, 2016) These processes may not be spontaneously reversible, especially in forest environments when certain thresholds are exceeded, as they are necessary to carry out restoration activities (Aronson et al, 1993; Whisenant, 1999). A rapid response of vegetation recolonization could be limited in afforestation proposals due to the climatic conditions of semiarid areas. This can be a consequence of prevailing soil erosion processes and low levels of water and nutrient availability (Breton et al, 2016)

Methods

Results

Conclusion