Sheep grazing differentially affects the canopy attributes and functional diversity of shrubs and perennial grasses in a
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Sheep grazing differentially affects the canopy attributes and functional diversity of shrubs and perennial grasses in arid rangelands Marlene I. Ba¨r Lamas
. Analı´a L. Carrera . Mo´nica B. Bertiller
Received: 18 December 2019 / Accepted: 21 September 2020 Ó Springer Nature B.V. 2020
Abstract We analysed how changes in community attributes promoted by domestic grazing are reflected on functional traits in canopies of shrubs and perennial grasses in rangelands of the Patagonian Monte. We selected four sites across a gradient of grazing pressure and assessed (i) changes in plant cover, and species richness and diversity and (ii) changes in functional traits (community weighted mean: CWM, functional diversity and redundancy) related to plant growth (leaf N concentration, height of the plant, and specific leaf area-SLA) in shrub and perennial grass canopies. Shrub cover decreased and species and functional diversity increased with increasing grazing pressure. Nonsignificant changes were found in shrub species richness and functional redundancy across the grazing
Communicated by Alessandra Fidelis. M. I. Ba¨r Lamas (&) A. L. Carrera M. B. Bertiller Instituto Patago´nico para el Estudio de los Ecosistemas Continentales (IPEEC)- CONICET, Boulevard Brown 2915, 9120 Puerto Madryn, Chubut, Argentina e-mail: [email protected] A. L. Carrera e-mail: [email protected] M. B. Bertiller e-mail: [email protected] M. I. Ba¨r Lamas A. L. Carrera M. B. Bertiller Universidad Nacional de la Patagonia San Juan Bosco, Boulevard Brown 3700, 9120 Puerto Madryn, Chubut, Argentina
gradient. Positive relationships were found between shrub species diversity and CWM of SLA, and leaf N, while CWM-height was not related to grazing pressure. Perennial grass cover decreased steadily with grazing pressure, while species richness decreased significantly at high grazing pressure. Perennial grass diversity, functional diversity and redundancy of functional plant traits, and CWM-height increased at intermediate grazing pressure, while the inverse pattern was observed for CWM of SLA and leaf N. These results highlighted that species diversity was the community attribute that best reflected functional changes induced by grazing pressure in shrub and perennial grass canopies in these rangelands. We concluded that shrubs persist under high grazing pressure increasing species and functional diversity of relevant plant traits, while perennial grass canopies were only able to persist under intermediate grazing pressure. Keywords Community weighted mean Functional redundancy Patagonian Monte Species diversity Species richness Introduction Plant diversity conservation is crucial for the maintenance of ecosystem processes such as primary productivity and nutrient cycling (Naeem et al. 1999; Dı´az and Cabido 2001). The contribution of individual
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Plant Ecol
plant species to ecosystem processes may vary considerably among and within ecosystems (Grime 1998;
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