Fire and forage quality: post-fire regrowth quality and pyric herbivory in subtropical grasslands of Nepal

Indiscriminate fire is rampant throughout subtropical South and Southeast
Asian grasslands. However, very little is known about the role of fire and
pyric herbivory on the functioning of highly productive subtropical
monsoon grasslands lying within Cwa-climatic region. We collected grass
samples from 60 m x 60 m plots and determined vegetation physical and
chemical properties at regular 30-day intervals from April to July 2020,
starting from 30 days after fire to assess post-fire regrowth forage
quality. We counted pellet groups for the same four months from 2 m x 2 m
quadrats that were permanently marked with pegs along the diagonal of each
60 m x 60 m plot to estimate grazing intensity to the progression of
post-fire regrowth. We observed strong and significant reductions in crude
protein (mean value 9.1 to 4.1 [55% decrease]) and phosphorus (mean value
0.2 to 0.11 [45% decrease]) in forage collected during different time
intervals i.e., from 30 days to 120 days after fire. Mesofaunal deer
utilised the burned areas extensively for a short period, i.e., up to two
months after fire when the burned areas contained short grasses with a
higher level of crude protein and phosphorus. Grazing intensity of chital
(Axis axis) to post-fire regrowth differed significantly over time since
fire, with higher intensity of use at 30 days after fire. Grazing
intensity of swamp deer (Rucervus duvaucelii) did not differ significantly
until 90 days after fire, however, decreased significantly after 90 days
since fire. Large-scale indiscriminate single event fires thus may not
fulfil nutritional requirements of all species in mesofaunal deer
community in these subtropical monsoon grasslands. We recommend for a
spatio-temporal manipulation of fire to reinforce grazing feedback and to
yield for the longest possible period a reasonably good food supply for
the conservation of mesofaunal deer.