Could someone point to me literature that examines how long after a single savanna burn do the effects of fire (especially herbivore preferences) last? What is the longest recorded time?
Duncan-
It really varies among grasslands depending on their productivity and the amount of stem/indigestible material that accumulates in the surrounding unburned areas. We had a paper in J of Applied Ecology in 2014 that looked at this in shortgrass steppe (low productivity, low stem to leaf ratio) ,and found that cattle were only attracted to burns for a short time afterward (weeks to months). Can last much longer in tallgrass, or in areas like the black cottons soils in Laikipia where you work.
Dear Duncan
Your answer on the following links, Please Check out below links.
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http://bepls.com/bepls2014march/35.pdf
http://bepls.com/bepls2014march/34.pdf
Hi Duncan,
I am not clued up on the details of your study, so my answer is probably going to be a bit vague - particularly since it is not clear what kind of a rainfall regime your study area has. There is probably no single best answer anyway ...
The timing of the fire is going to play a role in finding your answer. If you have a flush of grass relatively close to the wet season the sprouting grasses may receive sufficient moisture to grow for a while. The grazed plants are then likely to produce new shoots that are, again, attractive to grazers. You get a kind of "grazing lawn" effect (Coughenour 1991 and McNaughton 1984).
Without rainfall, the duration is likely to depend on the condition of the grass-sward prior to the burn - i.e. the root reserves that the grasses have available. And on the comparative condition of the surrounding vegetation
There is currently a study tracking buffalo after a burn in woodland savanna in Namibia. I am not sure if anything is published yet, but you might get hold of Dr. Dave Joubert through the SASSCAL network (www.sasscal.org), task 148.
Could you provide more details on your study? Sounds like you are working on an interesting topic.
References are below.
Regards,
Patrick
Coughenour, M. B. (1991). Spatial components of plant-herbivore interactions in pastoral, ranching, and native ungulate ecosystems. Journal of Range Management, 44, 530–542.
McNaughton, S. J. (1984). Grazing lawns: animals in herds, plant form and coevolution. The American Naturalist, 124(6), 863–886.
Tainton, N. (1999). Veld management in South Africa. Pietermaritzburg, South Africa: University of Natal Press.
I did a masters project on this in Hluhluwe iMfolozi, SA- it largely depends on the size of the burn. But I found that the immediate nutrient effects only last 3 months. But the feedback by herbivores makes it attractive for up to 9 months following the burn. The attractiveness is lost when the herbivores loose control of their ability to keep the grass shorter. So in high rainfall areas the rainfall means the grass grows faster and the benefit of shorter (I'm not saying its a grazing lawn, just shorter - where the grass is less moribund and stemmy) grass is lost sooner. In the drier areas herbivores sometimes over graze the area and are forced to leave the area as the dry season approaches. Once again this effect is stengthened or diminished depending on the size of the burn