Introduction

Summary

Savannas, barrens, and rock outcrop plant communities are the topic of numerous research and technical articles. Rock outcrop plant communities and serpentine barrens are of interest because they are refugia for endemic species adapted to extreme environmental conditions. Savannas and barrens were major components of the historic landscape before it was extensively altered by agricultural and urban development during the past century. Many of these communities were reduced to less than one percent of their original area and are imperiled ecosystems. There has been relatively little synthesis of information about these ecosystems from papers published in scientific journals, conference proceedings, or technical reports from state and federal governmental agencies and private organizations. Our book synthesizes this technical knowledge and will increase awareness of these vegetation types and communities and aid in their conservation and restoration.

The savannas covered in this volume occur in diverse and geographically distant regions of the continent. They include pine savannas of the southeastern Gulf Coastal Plain; aspen parklands of the Canadian provinces of Alberta, Manitoba, and Saskatchewan; California oak savannas; juniper/piñon savannas; subarctic lichen woodland of northwestern Canada; and others. Some of the savanna types cover broad geographical areas, such as the cross timbers that extended from Kansas into Texas and the southern Gulf Coastal pine savannas that occurred from North Carolina to Texas along the coastal plain. All of these communities have unique ecological features. However, they share a common feature in having an environment that restricts tree growth and prevents development of closed-canopy forests.