London and Johannesburg, as an example, have similar annual average rainfall but they are on opposite ends of the brittleness scale because Jo-Burg has a rainy season and a dry winter and London……well rains constantly!! Land in the non-brittle section of the scale can heal and regenerate after disturbance if left to rest, that is because of the constant humidity allowing biological decay and the recycling of nutrients….the same can’t be said for the other end of the scale.
On the other end of the scale, the brittle side, animal-action is needed to cycle nutrients, break the soil capping that develops after rain and evaporation and provide ground cover for vulnerable soils. Wherever you see large grasslands across the earth brittle zones you find, at least historically anyway, vast herds of herbivores and their accompanying pack-hunting predators! It’s no coincidence that these two components of the ecosystem occur there…..the grasslands have co-evolved with them!
A grass plant grows from its base and largely speaking what you see on top of the soil is mirrored in roots below. Think of the leaves as solar panels and the roots as batteries. The plant produces leaves and they charge the roots. A herbivore comes along and grazes the leaves down and the plant now sums up energy to replace its “solar panels” from its roots. The roots diminish.
If the grazing animal returns before the plant has adequately replaced its lost leaves and charges its root batteries, the plant further depletes its roots to cope and quickly reaches a point where it is overgrazed and can die. Over-rest is as bad as over-grazing because if a grass plant grows all these leaves and nothing eats them they eventually shade out their own growing parts (at the base of the plant) and the plant dies. If it dies and is left standing in dry air, there can be no biological decay!
Actually in really brittle zones it oxidizes and as we know from rusting iron, oxidization take a great deal of time. So, for a healthy grassland to flourish we need a combination of animal action and rest. Naturally it’s the predators that are the engines of that complexity. The presence of predators means herbivores herd together, they are forced to be less picky in their choice of food because of their density and what they don’t eat they crush down and bring to the soil’s surface where, with their dung and urine, allow biological decay to break that material down and cycle its nutrients.
The removal of both the large natural herds of herbivores and their predators are largely the reason that these areas are desertifying and ironically replacing them with livestock as the herbivore and herders as the predators may be the only solution left to us to reverse this loss of our productive lands.
Holistic land and livestock management is the mimicking of nature using livestock and herders to regenerate landscapes. The Soft foot alliance trust has been working with its community for several years to get people to put their livestock together and plan their grazing so as to regenerate their landscapes for people, livestock and wildlife simultaneously
Towards the end of 2021, after a perfectly clean record for 9 years, the first animals were lost to a predator whilst in a Mobile boma. A hyaena in mabale communal lands had learnt to bite the material walls of a mobile boma and tear them to get in a grab a goat. It was a shock to the team but we determined that the hyaena had seen into the boma through several small holes in the walls created by thorns etc. Once it saw what was inside the game was up. We repaired the holes and added solar LED lights that flash at night and the hyaena hasn’t killed again.