Does grazing induce intraspecific trait variation in plants from a sub-humid mountain ecosystem?
WHITWORTH-HULSE, JUAN I.; CINGOLANI, ANA MARÍA; ZEBALLOS, SEBASTIÁN ; POCA, MARÍA; GURVICH, DIEGO E.
WILEY-BLACKWELL PUBLISHING, INC
Lugar: Londres; Año: 2016
Livestock grazing represents an important human disturbance for vegetation worldwide. We analysed theintraspecific differences in mean trait values between different grazing regimes (ungrazed and grazed) and exploredwhether these differences are consistent across species in a sub-humid mountain ecosystem in Central Argentina.We selected 14 species of eight different families, co-occurring in both regimes and comprising herbaceous (grassesand forbs) and woody (shrubs and trees) plants. For each species and grazing regime we measured 12 traits relatedto plant size, carbon fixation and water use. We found that plants in the grazed regime had consistently smaller leavesand shorter stature and internodal length than plants of the same species under the ungrazed regime. For the remainingtraits the responses were species-specific. Dry matter content, leaf tensile strength and minimum leaf water potential(Ψleaf) showed contrasting responses to grazing. Specific leaf area, wood density and potential water content of woodshowed almost no significant responses except for very few species. Neither leaf area per shoot mass nor leaf area persapwood area differed significantly between grazing regimes. Our study suggested that the intraspecific variation foundfor the size-related traits would allow species to respond to grazing without modifyingmarkedly other structural traits, aplastic response that might increase the probability of species success.