Meeting Wild Bees’ Needs on Western US Rangelands

Abstract

Rangelands are areas that are too arid, or with soils too shallow, to support either forests or cultivated agriculture, but that nonetheless produce enough vegetation for livestock grazing. Some arid range land regions, notably those with warm, dry climates in temperate zones (e.g., the warm deserts of the United States and adjacent Mexico, parts of Australia, South Africa, California, and around the Mediterranean) host great diver sities of native bees,1 primarily nonsocial species among which are many floral specialists. Conversely, the world's forested lowland tropics support many more social species of bees, but they have far less bee diversity overall.1 Bees are generally the most important group of pollinators for every continental flora. To better grasp the relevance of human impacts on rangeland bee faunas, and what we can do about it, some generalizations about bees are presented.