Recovery and germination of Prosopis juliflora (Sw.) DC seeds after ingestion by goats and cattle

ABSTRACT

Prosopis juliflora is a perennial shrub introduced in the 1980s to the Baringo District in central Kenya, and became highly invasive starting around the late 1990s. This period coincides with a shift of the composition of ruminant herds from formerly cattle to goats in this area. To assess the possible role of this shift in herd structure on P. juliflora spread, we conducted feeding trials and germination tests to determine the capacity of seeds to survive the passage through the intestinal tract of goats and cattle, comparing germination with chemically scarified and untreated seeds. Recovery of seeds eight days after ingestion was lower from goats (7%) than from cattle (15%) dung. Germination dynamics were similar for seeds that had been manually extracted from pods with those recovered after intestinal passage. Chemically scarified seeds germinated fastest and reached a germination rate of 100% within five days. While no apparent scarification effect was observed, the main contribution of endozoochorous dispersal of Prosopis seeds is their release from the enclosing pod segments, their dispersal away from the mother plant and possibly the provision of nutrients by the dung for their establishment and initial growth.

KEYWORDS:

• Endozoochory
• invasive plant species
• Kenya
• physical dormancy
• seed dispersal
• seed scarification

Acknowledgments

We thank Timon Moi (Kenya Agricultural Research Institute in Marigat) and his technical staff for their advice and for providing us the platform to conduct the research at their center. Visits to invaded stands and collection of Prosopis pods have been supported by Simon Choge (Kenya Forestry Research Institute in Marigat).