|M.Sc Student||Bosmat Segal|
|Subject||Ecological Aspects of the Iris bismarckiana Population in|
the Iris Reserve for Development of
|Department||Department of Agricultural Engineering||Supervisor||Professor Carmel Yohay|
|Full Thesis text - in Hebrew|
The Nazareth Iris (Oncocyclus (Siems.) Baker Iris: Iridaceae ) is a rhizomatous geophyte that grows and blooms in the winter and is dormant through summer. It is endemic to a few small and isolated populations in northern Israel and Jordan. The Nazareth Iris Reserve is an area of 13 hectares on the eastern slopes of the Nazareth hills which was dedicated to the species' conservation. A GIS analysis of aerial photographs and visual inspections in the area revealed a large increase in the woody plants' coverage (mostly Prickly Burnet, Sarcopoterium spinosum) in the last four decades. Statistical testing of the spatial distribution of the Iris relative to the Prickly Burnet's aerial coverage showed a significant impact of the Prickly Burnet on the Iris plants. Other possible competitors are herbaceous plants and caterpillars of Ocnogyna Tiger Moth (Ocnogyna loewii). As a response to reports of decline in the Iris population in the reserve a number of active management alternatives were studied. The impact of removal of the Prickly Burnet, depression of the grass cover and extermination of the Ocnogyna Tiger Moth caterpillars was tested during three field seasons in 24 research plots. A GPS-RTK system was used to track and document the experiment's plant population. The natural sexual reproduction was studied in the Nazareth Iris Reserve's population and in the stable population of Mt. Yona, 1.5 km from the reserve. An increase (not statistically significant however) of the number of Iris plants and flowers in the plots from which the Prickly Burnet was removed was noted. A decrease in the number of plants was observed in the plots where the grass cover was depressed, probably due the increase in the activity of moles ) Nannospalax ehrenbergi). Seed setting rates were found to be 15% and 12% in the reserve and Mt. Yona, respectively. Artificial pollination in the reserve by pollen from reserve donor flowers significantly increased both the seed setting rates and the number of seeds per fruit. Artificial pollination of flowers by remote pollen source proved to be more effective than pollination by pollen from flowers within each site, significantly increasing seed setting and seed numbers.