Introduction

Abstract

Prosopis and Acacia are two genera of woody legumes that occur worldwide, mostly in dry lands in the arid zone and in the arid and semiarid, temperate, subtropical, and tropical grasslands, savannas, and woodlands (Figs. 1.1 and 1.2) (Simpson 1977a; Heywood 1978; New 1984; Tame 1992). Some Acacia s. l. (sensu lato) species in eastern Africa seem to be riparian species, and a few Australia species seem to be successional species and appear be a part of forest communities which are in wetter areas. In addition, the ecological position of a number of New World tropical Acacia species s. l. is not clear. Many of these New World tropical species seem to be found in disturbed areas (Janzen 1974), but these species and communities will not be described or discussed. In this book, we will mostly deal with a few members of the genus Acacia or more specifically with some members of the former genus Acacia s. l., but there will be some general information about Prosopis and references to Prosopis when comparisons are important and justified. Recently, the genus Acacia s. l. has been divided into five genera including Senegalia and Vachellia (Maslin et al. 2003; CPBD 2004; Seigler and Ebinger 2005; Maslin 2006; Seigler et al. 2007; Crow and Ritter 2012). We will focus on the ecology of a handful of specific members of the genera Senegalia and Vachellia with a few references to Prosopis. Most of the species of the new genus Acacia are found in Australia, and these species and communities will not be discussed here.