The impact of vegetation succession on soil parameters and its consequences for desertification remediation

The impact of vegetation succession on soil parameters
and its consequences for desertification remediation.

E. Cammeraat (1), J.P. Lesschen (1), B. van Wesemael (2) and G.
Barbera (3)

(1) Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, The
Netherlands, (2) Department of Geography, Catholic University Louvain la Neuve, Belgium,
(3) CEBAS-CSIC, Murcia, Spain, lcammera@science.uva.nl, Fax +31 205257431

Land abandonment is an important factor in Mediterranean landscapes. Abandoned
fields often show increased erosion rates, which decline over time, depending on the
rate of vegetation recovery. This latter factor is depending on climate and vegetation
species but also on topographic position as well as soil type and soil surface properties.
For remediation of desertification it is important to establish the best conditions for
vegetation development. This is not solely dependent on the amount of rainfall, the
effectiveness of natural or artificial water harvesting and the suitability of the vegetation
involved, but of primary importance is also the ability of soils to maintain ideal
available water conditions for successful and sustainable vegetation establishment.
Besides, those landscape spots should be selected that are most effective with regard
to reduction of overland flow and erosion.
In our study a comparison is made of the impact of vegetation succession on essential
soil properties along a soil gradient through the province of Murcia in Spain under
similar semi-arid climate conditions. Vegetation cover and species development over
a time series was compared to the development of soil properties on slates, marls,
limestone and calcrete substratum. Furthermore, exposition (N or S) was incorporated
in the comparison.
It was observed that N exposed slopes on slates showed a natural succession to full Pinus
halepensis forests within 40 years after abandonment, with a strong improvement
of soil aggregation and macro-porosity. However, on S exposed slopes only ‘matoral’
(shrubland) developed in the same period. On the other extreme the marly soils showed
no forest development over the same period on N exposed slopes, and although soil
aggregation and macro-porosity also improved here, the regeneration of soil properties
was much slower.
It can be concluded that vegetation succession strongly depends on exposition and
soil type and that these parameters should be incorporated in remediation schemes
using vegetation. Furthermore, simple indices such as the aridity index, often applied
in revegetation programmes are insufficient alone, and can only be used when other
site dependent environmental parameters are included