Shrub clearing and extensive livestock as a strategy for enhancing ecosystem services in degraded Mediterranean mid-mountain areas

Abstract

Land abandonment in the Mediterranean mountains since the 20th century has led to a reduction of ecosystem services, due to revegetation and homogenization of the landscape. To counteract these effects, the regional administration of La Rioja in Spain initiated a Plan for Shrub Clearing (PSC) combined with extensive livestock grazing in 1986, which is still in action today. This study analyses the effects of pairing clearing with grazing in an experimental area of the Leza valley (Iberian System) on: (i) the landscape structure and structural diversity; (ii) the production of pasture; (iii) fire control; (iv) soil organic carbon sequestration (also considering soil environmental types); (v) surface water resources. The results show that: (i) a more fragmented landscape with greater diversity is created; (ii) grazing land is almost doubled in alkaline soils and four-fold in siliceous soils; (iii) fires are considerably reduced, with the mean surface fire spread falling from 34.1 ha/year from 1968 to 1985, to 1.2 ha/year between 1986 and 2022; (iv) regenerated post-clearance grazing soils sequester more organic carbon than that of shrublands, especially older clearings on alkaline soils (55.3 % more); (v) clearing increases hydrological connectivity and water resources. The conclusion is that managing the Mediterranean mid-mountains could be a very effective strategy to improve the supply of certain ecosystem services and improve the current socio-economic perspective of these marginal areas in a context of Global Change. The PSC also contributes to local development by increasing livestock numbers.