PARENT SESSION
Poster Session # 16: Invasive Species.

Wednesday, August 6 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Introduced (Prosopis juliflora and Azadirachta indica) and native (Acacia nilotica var. adansonia) trees spreading in Senegal, West Africa.

Salo, Lucinda^*,1, ¹ USGS Snake River Field Station, Boise, ID

ABSTRACT- Plant invasions from the Old World to the New World are more frequent than the reverse. Many of the New World plants that have become invasive in the Old World are woody species and many of these were intentionally introduced. Determining the age structure of a population is a first step in understanding whether or not it is regenerating and in predicting whether or not it may spread and become invasive. This study determined the size structure, and mapped all individuals, of three woody species at a site at Foundiougne, Fatick Region, Senegal. These included mesquite (Prosopis juliflora), introduced from Central America, and neem (Azadirachta indica), introduced from India. I also examined the only native tree regenerating at this site, Acacia nilotica var. adansonia. These three species were all represented by large numbers of seedlings and progressively fewer individuals of successively larger size classes. This indicates that these species are regenerating successfully and that introduced species are spreading from where they were planted. All other native tree species at this site were represented only by a few mature, heavily used individuals. The Prosopis and the Acacia species both appear able to regenerate, and to spread, due to 1) spines that reduce browsing and rooting by livestock, 2) the ability to resprout after browsing, 2) pods that are eaten and spread by livestock, and 3) low frequency of fire, due to heavy grazing by livestock.

Key words: mesquite, invasive species, neem