Are there any trade-offs between forage provision and the ecosystem service of C and N storage in arid rangelands?

OÑATIBIA G.; AGUIAR MR; SEMMARTIN M

ECOLOGICAL ENGINEERING

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 vol. 77 p. 26 - 32

0925-8574

Changes in land use often increase the provisioning ecosystem services at the cost of decreasing theregulating services. Thus, the appropriation of primary production to optimize the supply of forage forlivestock production may undermine C and N storage, essential to maintain the integrity of ecologicalsystems and the biosphere. The aim of this work was to study this trade-off by estimating the effect ofgrazing intensity on two provisioning and regulating ecosystem services (forage supply and C and Nstorage, respectively) in a 300 km2 Patagonian steppe. In areas with different historical sheep grazingregime (intensive, moderate and ungrazed), we estimated forage supply through the abovegroundbiomass of preferentially consumed species as well as total C and N storage in plants, through forage andnon-forage aboveground biomass, litter and root biomass in the top 20 cm of soil. We found that foragesupply and C and N storage were highest in moderately grazed areas and were positively correlated,indicating the absence of trade-offs between them. Grazing exclusion had no effect on total plant C and N,but decreased these stocks in green grass biomass in relation to moderate grazing. Intensive grazingdecreased both provisioning and regulating services, markedly diminishing grass C and N stocks andgrass forage compared to other conditions. Conversely, shrubs and roots were not influenced by grazingregime. This study provides evidence that in arid rangelands, an adequate grazing management could bea key control to complementarily maximize both provisioning and regulating ecosystem services