Sheep grazing differentially affects the canopy attributes and functional diversity of shrubs and perennial grasses in arid rangelands

BAR LAMAS, M; CARRERA, A.L.; BERTILLER, M. B.

PLANT ECOLOGY

SPRINGER

Lugar: Berlin; Año: 2021

1385-0237

We analysed how changes in communityattributes promoted by domestic grazing are reflectedon functional traits in canopies of shrubs and perennialgrasses in rangelands of the Patagonian Monte. Weselected four sites across a gradient of grazing pressureand assessed (i) changes in plant cover, and speciesrichness and diversity and (ii) changes in functionaltraits (community weighted mean: CWM, functionaldiversity and redundancy) related to plant growth (leafN concentration, height of the plant, and specific leafarea-SLA) in shrub and perennial grass canopies.Shrub cover decreased and species and functionaldiversity increased with increasing grazing pressure.Nonsignificant changes were found in shrub speciesrichness and functional redundancy across the grazinggradient. Positive relationships were found betweenshrub species diversity and CWM of SLA, and leaf N,while CWM-height was not related to grazing pressure. Perennial grass cover decreased steadily withgrazing pressure, while species richness decreasedsignificantly at high grazing pressure. Perennial grassdiversity, functional diversity and redundancy offunctional plant traits, and CWM-height increased atintermediate grazing pressure, while the inversepattern was observed for CWM of SLA and leaf N.These results highlighted that species diversity was thecommunity attribute that best reflected functionalchanges induced by grazing pressure in shrub andperennial grass canopies in these rangelands. Weconcluded that shrubs persist under high grazingpressure increasing species and functional diversity ofrelevant plant traits, while perennial grass canopieswere only able to persist under intermediate grazingpressure