 One of the most interesting questions in ecology is what explains the distribution of grasses and trees. In some parts of the world forests are the norm and others, grasslands, cover broad landscapes. In yet others, savannas are grassland woodland ecosystems dominating in which there is a mix of grasses and trees. Savannas are defined as having a continuous grass understory and an open canopy of trees, often widely spaced. There are many potential explanations for the coexistence of grasses and trees in savannas, why one life form does not dominate. And these include such things as frost, herbivory, which is grazing of animals, fire, or even for soil conditions. Each of these factors may limit the competitive ability of trees in particular, allowing grasses to outcompete them. One hypothesis is that trees survive in savannas only when they have grown tall enough to withstand a fire event, meaning that there is enough time without fire for them to grow. If fires are too frequent, the trees won't survive. Fire has a long and complex socio-ecological history in the South African landscape. Humans inhabited South Africa for millennia and fire has been a common tool for managing the landscape. In fact, in other parts of Africa, for example the Messiah in Kenya, are known to use fire as a tool for reducing tick populations in grasslands, thus protecting their livestock. Other uses of fire include hunting or maintaining grassland conditions for grazing. In fact, animals prefer new grasses that grow back after a fire because they tend to be higher in nutrients and are tastier to them. Cows can often be seen grazing in newly burned fields, even when green fields are close by. These new grass tufts hold more nutrients because they are re-growing, using stored nutrients from the roots. Those roots are unharmed by the fire and so are ready to re-sprout after the fire. Humans are not the only cause of fires in the landscape though, because lightning is also a source of ignition at certain times of the year. Moreover, the environment controls fire by creating the dry conditions and ample fuel loads to sustain fire. For example, grasses can grow quickly during the wet season, but dry up dramatically during a prolonged dry season, creating the perfect conditions for fire and subtropical ecosystems. Interestingly, one phenomenon occurring in many systems is called woody encroachment. This is when trees are growing in areas that were formerly dominated by grasslands. Ideas for why this is happening are mixed. Some say it's due to the effect of elevated carbon dioxide in the atmosphere that essentially acts as a fertilizer for trees, enhancing photosynthesis, growth rates, and thus the competitive ability against grasses. Another idea is that the exclusion of fire from these systems has allowed trees to survive past their sapling stage. Once established, they're able to outcompete grasses. Both factors are likely. Understanding the consequences of these changes in woody systems is important for understanding ecosystem carbon storage and the flow of nutrients and water. In addition, these changes are likely to have large impacts on local communities, but often in complex ways. For example, people depend on woody trees for many livelihood activities, including making fences or using the wood as fuel wood for cooking. At the same time, people depend on open grazing areas for their livestock. So shifts in the dominance of grassland and woodland ecosystems is likely to affect people's use of the landscape as well. Fire management is a priority for many conservation areas, including those in South Africa. Once human fires are excluded from the landscape, managers must then decide how to bring fire back into the landscape often through specific burning prescriptions. The goal of these prescribed burns is to maintain grassland ecosystems that have evolved from millennia with fire in the absence of fire where the woodlands would encroach. Because grasslands in South Africa are extremely biodiverse, some of the most diverse in the world, they hold many hundreds of different species of grasses, forbs, and associated wildlife. Shifts away from grassland systems could negatively hurt biodiversity. Interestingly, in the eastern Cape of South Africa, fire exclusion could cause a decrease in species richness because they were once very biodiverse. But the invasion of critically endangered species of finbos vegetation can come in in the absence of fire. This vegetation type is common to other parts of South Africa. Thus fire management is complex. Managers need to understand how much to burn and how frequently in order to maximize multiple objectives in the context of many ecosystem trade-offs, such as trading species richness, rarity, as in that example. This work is even more complex when considering that fire is a tool used by poachers to attract animals. Because grass is more nutrient rich and tastier following fire, grazing animals such as zebra or blessed buck are attracted to burned patches of land. Poachers can burn from outside the park into the reserve, thus attracting animals to the boundary of the reserve where they can easily be shot.