Grasslands are areas where the vegetation is dominated by grasses (Poaceae) and other herbaceous (non-woody) plants (forbs). Plants of the sedge (Cyperacae) and rush (Juncaceae) families can also be frequent in grasslands. Grasslands occur naturally on all continents except Antarctica, and in many other areas they have replaced the natural vegetation due to human influence. In temperate latitudes, such as north-west Europe, grasslands are dominated by perennial species, whereas in warmer climates annual species form a greater component of the vegetation. Grasslands can be found in most terrestrial climates. Grassland vegetation can vary in height from very short, as in chalk downland where the vegetation may be less than 30 cm high, to quite tall, as in the case of North American tallgrass prairie, South American grasslands and African savannah. Woody plants, shrubs or trees, may occur on some grasslands - forming wooded, scrubby or semi-wooded grassland, such as the African savannahs or the Iberian dehesa. Such grasslands are sometimes referred to as wood-pasture or Savannah woodland. Grasslands cover nearly fifty percent of the land surface of the continent of Africa. This book gathers new and important research from around the world in this field.