Editor’s Choice 54:3 – Prescribing burns to increase forage for cattle: are managers ‘biting off more than they can chew’?

Issue 54:3’s Editor’s Choice is written by Associate Editor, Jennifer Firn. The article chosen by the Editors is Fire-induced negative nutritional outcomes for cattle when sharing habitat with native ungulates in an African savanna by Wilfred O. Odadi and colleagues.

Ecological science is increasingly being applied to understand species interactions and to identify thresholds of degradation in more traditional agricultural landscapes (Scherr & McNeely 2008). This increasing focus is partially driven with the recognition, although controversial, that humans and our societal needs have led to the development of the current epoch, the Anthropocene (Steffen et al. 2007).  It is estimated that 75% of Earth’s ice-free land can no longer be considered ‘wild’ (Ellis & Ramankutty, 2008) and many native species including threatened species are dependent not only on small patches of wild habitat but also on the larger production patches in-between (Benton et al. 2003). This reality of modern-day land management necessitates understanding the very basics of interactions between domesticated and wild species, and the land management practices that are so often applied with one of these two broad species groups in mind and rarely with both. Tropical savannahs and rangelands in general are hotspots for both agricultural production and biodiversity conservation and are biomes where domestic and wild herbivores coexist.

Odadi et al. (2016) fully unpack the feeding behaviours of both domestic and wild herbivores in response to prescribed burning in this months Editor’s Choice study. In Laikipia Kenya, it is a commonly held belief by local landholders that domestic and wild herbivores compete for forage in savannahs. Herbaceous plants in tropical savannahs, aided by opportunities for continuous growth, generally have fast growth rates and therefore plant tissue ages quickly reducing its nutritional value and palatability for livestock. Burning is commonly used in the tropics to restart the clock so to speak by burning this old tissue, creating a flush of nutrients and fostering young ‘tastier’ regrowth. In a model example of the effectiveness of thoughtfully designed basic research, Odadi et al. for the first time provide strong evidence that burning in an area open also to wild herbivores provides little net benefit for domestic herbivores in. Odadi et al. found that wild herbivores were also attracted to feed on young nutrient rich tissue and it was then the unburnt patches in the landscape mosaic that ended up being important areas for grazing cattle.

Odadi 9
Odadi et al‘s work looked at the feeding behaviours of both domestic and wild herbivores.  (Image by Wilfred O Odadi)

Odadi et al. went further with this question to separate the responses of both medium-sized herbivores, e.g., zebra, oryx and buffalo, and mega-herbivores, e.g. elephants. It turns out size matters, as their results showed that medium-sized herbivores were attracted to graze the burnt regrowth, at least in the immediate year following a burn; while elephants were found to be more interested in the burnt woody tissue. It is likely that there are further differences in feeding preferences among species that would be interesting to unpack in future research.

What does this all mean for management? As Odadi et al. eloquently suggest—it depends on the objective. If the objective is managing wild herbivores then the fire could be used to protect conservation areas around water bodies by attracting wild populations of herbivores away from these areas to feed on recently burnt vegetation. If the objective is managing domestic herbivores for productivity then maintaining a mosaic of burnt and unburnt patches is important, as is, where  feasible, fencing off areas to reduce competition. Like all novel research, Odadi et al.’s raises a number of additional questions, for example, how long does this ‘dinner plate’ effect remain after burning as this study only presents results after one year; and then how do the dining preferences of domestic versus wild herbivores change over time in response to climatic variability? Another important question is how big should the burnt patches be and how should the size of the patches be adjusted depending on climatic conditions? Larger ‘dinner plates’ may reduce competitive interactions but then when does size hinder recruitment of desirable plant species because of dispersal limitation? More to come in this space, but what is clear is that Odadi et al. present the novel underpinnings to kick-start this interesting new direction for some age-old ecological questions.

The article, Fire-induced negative nutritional outcomes for cattle when sharing habitat with native ungulates in an African savanna is available in the Journal of Applied Ecology.

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