ranking methodology for assessing relative erosion risk and its application to dehesas and montados in Spain and Portugal

• Published in: Land degradation & development 2002-03, Vol.13 (2), p.129-140
• Main Authors: Shakesby, R.A, Coelho, C.O.A, Schnabel, S, Keizer., J.J, Clarke, M.A, Lavado Contador, J.F, Walsh, R.P.D, Ferreira, A.J.D, Doerr, S.H
• Format: Article
• Language: English
• Subjects: agroforestry; biodiversity; cork; dehesa; Eucalyptus; field experimentation; land management; land use; Mediterranean; montado; plantation forestry; plowing; Portugal; Quercus suber; rainfall simulation; recreation; risk; soil conservation; soil erosion; soil properties; Spain; stocking rate; tourism; trees
• ISSN: 1085-3278; 1099-145X
• DOI: 10.1002/ldr.488

The dehesas and montados of Spain and Portugal cover about 6 million ha and form open savannah-type woodland comprising cork (Quercus suber) and holm (Q. rotundifolia and Q. ilex) oaks. Following their decline until the 1960s, these land management practices have become valued at national and international policy-making levels for their biodiversity, aesthetic qualities and potential for tourism and recreation, but comparatively little attention has been given to consequences for soil conservation. In this paper, the soil erosion risks associated with these land uses are compared with those of selected alternative forestry and agroforestry land uses. Selected soil properties, results of rainfall simulation experiments and field observations of erosion features for (a) two montado and three dehesa sites differing in terms of grazing pressure and tree type, (b) six alternative forestry plantations of various ages and (c) an olive grove are ranked according to relative erosion risk. None of the dehesa or montado sites has an overall mean rank indicating an erosion risk as low as that in established forestry plantations (at least four–five years old). One (heavily grazed) dehesa has a relatively high overall mean rank indicating a relative erosion risk only slightly lower than that obtained for an erosion-prone, newly ploughed and planted eucalyptus plantation. It is concluded that present day dehesa and montado variants can be prone to severe erosion if stocking rates and/or tillage frequency become excessive. The advantages and limitations of the ranking methodology used are discussed.