Ongava’s Green Freckles - Remnants from the Past?
Updated: Dec 17, 2021
Ongava Research Centre staff recently came across a distinct and intriguing vegetation patch on the western plains of Ongava. It clearly stands out from the surrounding habitat because it still boasts lush greenery when much of the nearby vegetation is already wilting and bleak by comparison. But what exactly drives this localised productivity? Flying over Ongava, one can see many low-lying pans with similar vegetation. The most obvious explanation therefore seems that these small depressions retain soil moisture longer than the surrounding flats, allowing vegetation to grow when little rain has fallen. But not all circular pans are green right now. Other, seemingly similar, features are dry and barren now. The productive patches come in many different forms. Some have clearly defined boundaries and regular shapes suggesting that they could be nutrient hotspots created by dung accumulation from livestock corralling in the past. After all, Sonop used to be a cattle area and penning may have concentrated nutrients in certain places. Research in Kenya showed that concentrations of dung still fertilise the soil after 3,000 years (see link). Another explanation could be that these productive patches are the remnants of collapsed termite mounds that fertilised soils locally. As so often happens in the wonderful world of science, our first investigations raised more questions than answers about the origin of Ongava’s green freckles.