African Wildlife Environment Issue 75 FINAL

FAUNA, FLORA & WILDLIFE

in gamebirds I followed the studies of red grouse on the Scottish heather moors, where nutrition, and especially P, are limiting on grouse densities. I came to understand that because there is lots of ‘untamed’ water or vegetation out there, it does not necessarily follow that wildlife abounds. I recall, for example, a skin-and-bones Blue Wildebeest standing belly deep in grass. Superficially it is paradoxical that an animal should be dying of starvation in an apparent sea of plenty. But Blue Wildebeest graze like sheep. They need short nutritious grass, and while they might fill their bellies with thatch or mtshiki grass, they cannot digest it fast enough and can die of starvation with a belly-full. When the then Department of Water Affairs & Forestry commendably undertook actively to manage the mountain catchments of the KZN Drakensberg in the 1970s, there was the intention to burn veld every two years but, alas, the actual fire return period was more like three to five years. I was still engaged in francolin research in the mountains and acutely aware of the depressive effect of infrequent burning on wildlife populations. In one of my Honorary Forest Officer annual reports I wrote that Forestry was creating ‘straw deserts’. Up until this time, while I was convinced that frequent burning was necessary for the maintenance of the extensive grasslands of highland KZN, my understanding of exactly why was fuzzy. But roll on a few decades… A mining client took me to a rehabilitation site that I had not seen for ten years. When I first saw it, it was poor rehabilitation with insufficient soil fertility. In the intervening decade all the miner had done was lease the land to a nearby farmer who put cattle on the land. I was astounded. On my second visit the place was bustling with birds, butterflies, beetles and grasshoppers. How come this sudden burst of life without boosting soil fertility? I put it down to the cows grazing the grass and cycling the scarce nutrients that otherwise were locked up in the grass. The cow’s digestion system is not efficient; 80-90% of ingested nutrients are returned to the pasture in dung and urine. Coincidentally, that night when I got back home there was a message from my friend Dr Jeremy Anderson. He had been out in the game reserve with Allan Savory, talking jumbo. Reportedly Allan had commented to effect: “take elephants out of here and the system will collapse. Elephants are the only animals who can eat this coarse grass and woody stuff, and they are cycling the nutrients, making life possible for other animals”. I have consulted to the coal mining industry on opencast mining rehabilitation for more than 30 years. My assessments consider land capability, landscape form, soil erosion, soil fertility, species

composition, plant cover and plant vigour. Below a certain threshold soil fertility, especially soil P, plants are sparse and small, soil organic carbon does not increase, and succession does not advance beyond krulblaar, kweek and steekgras. However, develop soil fertility, maintain it for a few years, and either cut and bale, or preferably graze with cattle, and superb restoration can be achieved, to the extent that few people would recognize that it has been dug up and put back again. Grazing opencast mining rehabilitation with cattle, provided the rehabilitation is done right in the first place, confers upon the system a vibrancy that does not happen with cut and bale. While by no means extensively researched, the reason seems to be nutrient cycling and stimulation of vegetative reproduction in the grasses. The cow biting off the growing grass stems stimulates the grass to sprout from its base, and the nutrients coming out the cow’s rear fuel the grass regrowth on which live all manner of insects that in turn support birds. Along with the cows come dung beetles, who too further aid the nutrient cycling. As I trudge home from Pillar Cave, I query why burning is now only occasional. Because the natural veld fire ignition frequency is low, and infrequent fire increases biodiversity, we are told. Yet man and his predecessors have been lighting fires in southern Africa for over a million years. Anthropogenic fire is natural. The biota is adapted to it. Precluding fire from most of the Berg landscape benefits the scrub and forest initially, and that might be interpreted to increase biodiversity, but in the meantime grassland ecosystem function comes to a stop for want of nutrients that are locked up in dead plant material. If and when a fire does occur after years of absence there is a huge fuel load which burns with extreme heat and mineralizes the soil. In sandy soils, for example in the sandstone and mudrock country below the basalt, most of the soil nutrients are held by soil organic carbon. Burn off that carbon and the already nutrient-poor soils become even poorer. I reflect again. ‘It’s better to burn too often.’ ‘P can be limiting on ecosystem function.’ ‘If you take elephants out of here the system will collapse.’ ‘… straw deserts’… cows, elephants, fire…one or other of these make the nutrients go around. This is the very stuff of ecosystem function that parks management should ensure.

Dr Mike Mentis mmentis@saol.com

33 | African Wildlife & Environment | Issue 75 (2020)