Aboveground vegetation and perennial grass seed bank in arid rangelands disturbed by grazing

BERTILLER, MB; CARRERA, AL

Rangeland Ecology and Management (ex JRM)

SOC RANGE MANAGEMENT

Lugar: Boulder, Colorado; Año: 2015 vol. 68 p. 71 - 78

1550-7424

    Recruitment by seeds can be an important mechanism for recovery of plant communities following disturbance. Our objective was to assess the density and spatial patterning of perennial grass (highly preferred by herbivores) seeds in litter patches at locationswith different aboveground vegetation structure in sites with different grazing history characteristic of the Patagonian Monte (Argentina).We asked whether structural  differences in aboveground vegetation are reflected in the density and spatial patterning of perennial grass seeds in litter patches. We selected two study sites characteristic of the PatagonianMonte and within themthree locations representing different vegetation states, resulting fromdifferent combinations of grazing and/or release fromgrazing history. At each location,we assessed the density of perennial grass seeds in litter patches at microsites beneath plant patches (canopy) and in interpatch areaswithout orwith scattered vegetation (bare soil) at three dates during the reproductive and seed dispersal periods. The density of perennial grass seeds in litter patches was greater at canopy than at bare soil microsites, and the number of litter patches without seeds increased with decreasing total plant cover at both microsites. The density of perennial grass seeds in litter patches did not vary with differences in total plant cover or litter patch attributes at canopymicrosites, while it was reduced with decreasing total plant cover at bare soilmicrosites.We concluded that differences in aboveground plant cover differentially affected the density of perennial grass seeds in litter patches at contrasting soil microsites. Thus potential microsites for perennial grass recruitment by seedswould increase fromlitter patches at bare soil microsites to litter patches at canopymicrosites at locationswith high and lowaboveground plant cover, respectively. These issues should be considered for the sustainable management of these rangelands.