Includes our current knowledge of the invasion or encroachment and cause of population growth
and spread of some dry land arid zone woody legumes. Community structure population growth
and competition of these woody legumes will also be examined. These species and ecosystems are
both extensive and dynamic. They occur worldwide but mainly in the arid zones of the tropics
and sub-tropics. The cause of the growth and spread of these species and communities has long
been claimed to be caused by distal factors rather than proximal ones. However these species
appear to be influenced and perhaps controlled by anthropogenic factors specifically grazing
and fire or lack of fire. Their overall worldwide distribution has probably changed little in
the recent past but their populations have expanded into grasslands and their density has
increased in many places. Some associated communities have shown dramatic changes in response
to recent large-scale droughts and the loss of most of the dominant overstory species. However
changes in the woody legume communities and their species are generally unknown. ?
