Restoration of bee communities in coastal sand ecosystem in Israel

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Karmit Levy and Yael Mandelik, Entomology, The Hebrew University of Jerusalem, Rehovot, Israel

Background/Question/Methods
Bees provide essential pollination services to natural ecosystems and agricultural crops. However, managed and wild (unmanaged) bee populations are in decline worldwide due to a combination of stressors, particularly the fragmentation and loss of natural habitat. Thus, growing efforts are being devoted to restore bee communities through restoration of natural habitats.
Eucalyptus, originated in Australia and New Guinea, is one of the most widely planted genus in planted forests globally. Eucalyptus trees were first brought to Israel in 1884 and since than it was extensively planted in natural habitats. Previous studies show that Eucalyptus forests planted outside Australia support less species than natural forests and shrubland. Though planted Eucalyptus forests are extensive in many parts of the world, little is known about their effect on local wild pollinators, especially on wild bees.
The study is taking place in The Alexander Stream National Park, a rare and threatened coastal sand ecosystem in central Israel. In 2015, the Israel Nature and Parks Authority, in an effort to restore the natural ecosystem, cut-off some of the Eucalyptus trees in the park, using 2 types of restoration approaches-differentiated in the amount of the first investment. This was done in a replicated array creating five blocks of four habitat types: (a) intact Eucalyptus groves (b) Natural shrublands typical of the region (c) Extensive restoration – Eucalyptus clear cutting (d) Intensive restoration – Eucalyptus clear cutting, ploughing and seeding local plants.
Sampling of bee communities as well as surveys of flowering plants and ground cover have been done for five years after the tree clearing (2016-2020).
Results/Conclusions
We found differences in bee abundance and composition between years and habitat types. Among habitat types, bee abundance was the lowest in the intact Eucalyptus groves, Except for the first year. Extensive restoration shows higher bees abundance compare to intact Eucalyptus groves. Starting from the second year, the intensive restoration habitat shows an increase in bee abundance compare to the Natural habitat. The first two years show higher bee diversity in the extensive approach over the intensive one, however this trend has changed in the following years.
These results shed light on the beginning of a succession process which start after the restoration operation, and are part of an ongoing long-term monitoring.