Grazing management
Grazers play an important role in the continuous removal of leaf litter
and generating available space for new recruitment (Lengyel et
al ., 2012; Török et al ., 2018), which can promote species
richness (Towne et al ., 2005; Klaus et al ., 2018).
Germination of the native North American prairie grass, Nassella
pulchra was enhanced by burning and sheep grazing (Dyer, 2002).
Moderate grazing (30-50 within a 303ha enclosure) from Bos bisonsignificantly improved the species richness of a Prairie grassland
within its later stages of development (approximately 10-years after
revegetation) (Wilsey & Martin, 2015), this was also observed within
tallgrass prairies (Towne et al ., 2005). Livestock can transport
seeds of important species over great distances via endo or ectozoochory
if remnant sites are available (Lengyel et al ., 2012; Töröket al ., 2018). Further, the careful management of paddock
rotations for grazing livestock has been identified to be critical in
maintaining genetic diversity for plants threatened by fragmentation
(Plue et al ., 2019). High genetic diversity can allow for a
population to react more responsively to disturbance events through
improved resilience.
Overgrazing by livestock is one of the leading causes of grassland
degradation (Bartolome et al ., 2009; Zha & Gao, 2011; Wortleyet al ., 2013). The effects of different degrees of overgrazing
were observed by Török et al . (2018) within four different
Hungarian steppe grassland communities. They found that the highest
richness was achieved from low grazing (less than one animal per
hectare), but medium was also suitable (1-2.5 animals per hectare), and
grazing densities above this had detrimental effects of species
richness. Further, the different grassland communities responded
differently to the grazing intensities suggesting they are grassland
specific (Török et al ., 2018). Competition dynamics between forb
and grass species were altered by livestock grazing in southern
Argentina (Díaz Barradas et al ., 2001). Under sheep grazing, the
grasses did not produce inflorescences and forbs became taller and more
abundant compared to non-grazing tracts, where grass species dominated
(Díaz Barradas et al ., 2001). Forb cover was also observed to
increase in Prairie grasslands when exposed to grazing from cattle and
bison (Towne et al ., 2005). Therefore, grazing intensities should
be carefully managed, particularly during drought periods to promote
competition from native perennial grasses (Klaus et al ., 2018),
and resting paddocks from grazing when natives are emerging,
particularly if herbage is sparse, could improve their establishment and
survival (Clarke & Davison, 2014).