How hot? How often? Getting the fire frequency and timing right for optimal management of woody cover and pasture composition in northern Australian grazed tropical savannas. Kidman Springs Fire Experiment 1993-2013

Cowley, Robyn A., Hearnden, Mark N., Joyce, Karen E., Tovar-Valencia, Miguel, Cowley, Trisha M., Pettit, Caroline L., and Dyer, Rodd M. (2014) How hot? How often? Getting the fire frequency and timing right for optimal management of woody cover and pasture composition in northern Australian grazed tropical savannas. Kidman Springs Fire Experiment 1993-2013. Rangeland Journal, 36 (4). pp. 323-345.

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Abstract

A long-term (1993–2013) experiment in grazed semiarid tropical savannas in northern Australia tested the impact of varying the frequency (every 2, 4 and 6 years) and season (June – EDS versus October – LDS) of fire compared with unburnt controls on woody cover and pasture composition, in grassland and open woodland. Over an 18-year period, woody cover increased by 4% (absolute) in the woodland even with the most severe (i.e. frequent, late dry season) fire treatments. With less severe or no fire, woody cover increased by 12–17%. In the grassland, woody cover remained static when subjected to LDS fires every 2 or 4 years, but increased by 3–6% under other fire treatments, and by 8% when unburnt. Major shifts in understorey species composition occurred at both sites regardless of fire regime. The effect of fire on herbage mass and composition was compounded by higher grazing after fires. The herbage mass of perennial grasses declined and that of annual grasses and forbs increased following early or frequent fires. Brachyachne convergens, Gomphrena canescens and Flemingia pauciflora increased in response to fire while Aristida latifolia and Heteropogon contortus decreased. Four-yearly LDS fire provided the most effective management of woody cover and pasture composition. Although EDS fire is recommended for biodiversity management and reducing greenhouse gas emissions in wet tropical savannas, on grazed pastoral land, it can promote woodland thickening and pasture degradation. Optimal fire management, therefore, depends on vegetation type, land use and the prevailing seasonal timing and frequency of fire.

Item ID: 40937
Item Type: Article (Refereed Research - C1)
Keywords: fire management, fire season, rangeland management, time since fire
ISSN: 1834-7541
Funders: Northern Territory Department of Primary Industries and Fisheries, Meat Livestock Australia
Date Deposited: 21 Oct 2015 02:39
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050206 Environmental Monitoring @ 80%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050202 Conservation and Biodiversity @ 10%
09 ENGINEERING > 0909 Geomatic Engineering > 090905 Photogrammetry and Remote Sensing @ 10%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960510 Ecosystem Assessment and Management of Sparseland, Permanent Grassland and Arid Zone Environments @ 50%
96 ENVIRONMENT > 9609 Land and Water Management > 960910 Sparseland, Permanent Grassland and Arid Zone Land and Water Management @ 50%
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