Africa has a great diversity of environmental conditions. It is bisected by the equator so that the seasons are six months out of phase north and south of it. There are tropical forests on the west side as well as in the center of the continent. In roughly concentric rings out from the forest, there are progressively drier vegetation types from woodland, savanna, and grassland to desert. There are several major rivers flowing north, west, and east. Africa has also been the center of evolution of many large mammal groups. It has a high diversity of birds and insects. It is also the origin of the human species, and humans have influenced and modified the landscape for hundreds of thousands of years. Humans evolved there over the past four million years. The environment and the biomes that result from it in turn shaped the evolution of humans. Over the Pleistocene (past two million years), the environment swung from warm and wet to cool and dry several times, and consequently the biomes changed in extent from continuous forest (that stretched from the Atlantic to the Indian Ocean) to dry savanna and desert with only small patches of forest in West and Central Africa. These changes that were connected to the ice ages of temperate regions affected human populations. In the past millennium, human numbers have increased and migrations have moved peoples southward through the forests of Central Africa and into eastern and southern Africa. These movements have modified the biomes through grazing pressures on grasslands and agriculture in savanna. In the 20th century, forests were modified through deforestation. Wildlife conservation and ecotourism are prominent in Africa. There are several large protected areas especially in eastern and southern savanna Africa, with some less-known areas of forest reserves. Scientific studies on these protected areas over several decades describe the biology and ecosystem dynamics perhaps better than any other continent. There are scientific syntheses on the Kruger National Park, South Africa, and the Serengeti National Park, Tanzania. Both highlight how the whole ecosystem changes over time with climate change, human population increases, disease outbreaks, and other disturbances. The following sections first cover the vegetation types that are called Biomes; two abiotic environmental factors, climate and fire (Climate Variability and Patterns of Drought and Fire); prominent animal groups characteristic of Africa (Large Mammals, Primates, and Birds); dominant processes such as herbivory, predation, niche partitioning, facilitation, and migration (Herbivory, Predators and Predation, Niche Partitioning, Facilitation, and Migrations); and finally the expansion of human impacts on biomes and the related aspects of traditional livelihoods and conservation (Traditional Human Livelihoods and Conservation). Social and political history also modify human impacts but are not covered in this review.
An Annotated Checklist of Butterflies at Elevated Protected Areas of Pakistan
