The conservation management of Imperata cylindrica grassland in Nepal with fire and cutting: an experimental approach

Published source details Peet N.B., Watkinson A.R., Bell D.J. & Sharma U.R. (1999) The conservation management of Imperata cylindrica grassland in Nepal with fire and cutting: an experimental approach. Journal of Applied Ecology, 36, 374-387.
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Summary

Protected areas in the terai of Nepal contain some of the few remaining areas of tall grassland/forest mosaics and associated fauna, previously widely distributed across northern India and southern Nepal. Imperata cylindrica dominated grassland in the Nepal terai supports a number of globally threatened mammals and birds. It is the main source of house thatch material for many local communities. Current widespread cutting and burning is deleterious to cover-dependent vertebrate fauna which would benefit from patches of grassland remaining unmanaged. An experiment was undertaken to examine the effects of four treatments (cutting, burning, cutting and burning, and no management), on plant species abundance, species richness and grassland structure in Royal Bardia National Park (28°15'-28°40'N, 81°15'-81°40'E).

Study site: The experimental site was located in Baghoura Phanta, the second largest I.cylindrica dominated grassland in the park, covering about 80 ha. Other abundant species were Saccharum spontaneum, Vetiveria zizanioides, Desmostachya bipinnata and Schizachyrium brevifolium.

Treatments: A randomized block experiment was set up comprising four blocks, each containing four treatments (in 35 × 35 m plots surrounded by a 3-m wide fire break): cutting, burning, cutting and burning, and no management. Treatments were designed to follow local practice. Plots were cut immediately prior to local people entering the park to harvest grass. Cutting, carried out by local people using sickles, involved removing most above-ground biomass, but leaving a 1-10 cm stubble. The annual harvest began on 2 January 1995, 1996 and 1997. Plots were burned at the end of the 10-day harvest period. Burning was carried out in the direction of the prevailing wind, as park rangers would burn the grassland. The grasses were dry and senescent at the time of burning. Flame heights in the uncut plots reached 2-2.5 m and in cut plots 15-20 cm. The grassland outside the experimental area was burned between 21 January 1995 and 5 February 1996.

Vegetation monitoring: Monitoring was carried out: i) pre-treatment between 10 and 24 December 1994; ii) 11 months after the first treatment, between 28 November and 12 December 1995; and iii) 11 months after the second treatment, between 25 November and 10 December 1996. Within the 25 × 25 m core of each plot, 25, randomly distributed, 1 m² quadrats were surveyed. In each all plant species were identified or collected for later identification. A number of species, especially young growth stages, could not be identified and were recorded as unknown species a, b, c, etc. The percentage cover of each species and bare ground was estimated visually.

Any shrubs, trees or tall grass species occurring in a plot, but not falling within quadrats, were recorded. Estimates of percentage of live above-ground biomass as a proportion of the total above-ground biomass, were made in six randomly located 30 × 30 cm quadrats in the plot core.

Two years after the first treatment, I.cylindrica remained dominant under all treatments. However, it increased in abundance in unmanaged plots and declined in abundance in managed plots. D.bipinnata showed the opposite response. Plant species richness was significantly higher in managed plots, which were also structurally more heterogeneous.

The effects of cutting alone, burning alone, and cutting and burning combined on the structure and composition of the grassland were similar, despite additive effects on total grass cover, total forb cover and forb species richness in cut and burned plots.

Conclusions: There was no difference in the establishment of tall grass species or woody species between managed and unmanaged plots. This suggests that patches of grassland could be left unmanaged on a 2-year rotation without significantly altering the composition of the plant community, thereby providing refugia for cover-dependent fauna.

Note: If using or referring to this published study, please read and quote the original paper, this can be viewed at: http://www.blackwell-synergy.com/doi/full/10.1046/j.1365-2664.1999.00405.x