Since 2015 an extension of the Project Zelkova has been elaborated in order to explore and protect other genera and families of relict trees. The main focus is put on the genus Pterocarya and on the family Juglandaceae. The genus Pterocarya has six extant species with similar disjunctions as in Zelkova. Many highly isolated populations, especially for Pterocarya fraxinifolia, are very threatened and have been never collected and/or investigated.
Leading researchers: Sébastien Bétrisey and Yi-Gang Song
The project Pterocarya comprises four main objectives: (1) Ex situ conservation of Pterocarya fraxinifolia and other relict trees of the Transcaucasia. (2) In situ conservation of Pterocarya fraxinifolia with pilot restoration sites in Georgia. The coordinator of this part will be Ilia State University, Tbilisi. (3) Phylogeographic analyses of the genus Pterocarya covering the whole distribution area of Pterocarya fraxinifolia and of the whole genus Pterocarya. This part of the field work as well as the molecular analyses will be done by Ilia State University, Tbilisi, Georgia in collaboration with the Zelkova team of the University of Fribourg, Switzerland. (4) Production of a richly illustrated and detailed booklet on the conservation status and actions needed for the whole genus Pterocarya as well as on the diversity and importance of the whole Juglandaceae family. This part, including exchange and field work in Europe, Asia and America, will be carried out by the Zelkova team of the University of Fribourg in Switzerland.
A high diversity of Carya species across the East Coast
The genus Carya is quite common in temperate forests of the northeastern United States and also in the vicinity of swamp forests throughout the southeastern states. Our journey began in South Carolina, with the exploration of the Congaree National Park, one of the most important old growth bottomland hardwood forests still existing in the country. These complex ecosystems are seasonally flooded and represent a unique habitat for singular trees such as the bald cypress (Taxodium distichum) and the water tupelo (Nyssa aquatica). Our goal was to take pictures and gain knowledge and information on natural stands of water hickory (Carya aquatica) and nutmeg hickory (Carya myristiciformis), which are often present in less flooded parts of this type of forest.
For the second part of our expedition, we benefited from close partnerships with the Arnold Arboretum of the Harvard University, which holds probably the most comprehensive ex-situ collection of the genus Carya in the world. Thanks to the help of Michael S. Dosmann, curator of the living collections, we were able to visit and document a part of this extraordinary collection. We then visited some natural stands of Carya (C. ovata, C. glabra and C. cordiformis) in the Blue Hills Reservation with the help of Irina Kadis and Kathryn Richardson from the Arnold Arboretum, who organized our expedition.
Understanding the ecology of a species requires expeditions to its country of origin and visiting its wild populations. However, field explorations are often cost- and time-consuming, especially when lacking a solid background on the species that we want to study. The Royal Botanic Garden in Edinburgh offers a unique alternative and allows studying different species of the genus Pterocarya found in its ex-situ collections. In 2016 we have visited the garden twice and been able to observe the most important criteria of differentiation between the species (especially terminal buds, leaflet and nuts) and bring back numerous pictures and knowledge, which will be very helpful for future expeditions in wild populations of Pterocarya in Asia. We would like to thank warmly Peter Brownless of the Royal Botanic Garden of Edinburgh for his precious help and advice.
In April 2016 our Zelkova-team organized a scientific expedition to Costa Rica in order to explore and collect iconographic material of poorly documented Juglandaceae of Neotropis. Costa Rica is a center of species diversity for two genera of this family: Alfaroa (minimum 4 species) and Oreomunnea (2 species). They are typical elements of mountain forests and are growing often together with some other trees belonging to temperate families and genera (e.g., Quercus, Alnus, etc.).
We would like to thank all field guides and research assistance for their help in finding populations in topographically very difficult terrain. Special thanks go to Bryan Finegan, Leonel Coto and Diego Delgado (CATIE, Turrialba) for finding Alfaroa manningii and Oreomunnea mexicana as well as to Erick Viquez for A. williamsii and A. costaricensis.
Between the 4th and 7th of July 2016 a workshop entitled “Relict trees in peril: conservation challenges and research projects across Eurasia” organized by our Zelkova-team took place in Tbilisi, Georgia (in collaboration with the Ilia State University, National Botanic Garden of Georgia and Batumi Shota Rustaveli State University). Invited speakers from Switzerland, Italy, Poland, Iran, Azerbaijan, China, Vietnam and Japan as well as Georgian scientists presented their research projects and conservation actions carried out in different countries and regions from the Mediterranean to Eastern Asia. The symposium was followed by a scientific expedition to Western Georgia in order to visit natural populations of Zelkova carpinifolia and Pterocarya fraxinifolia and to discuss with local stakeholders the long term conservation of the relict forests of the Colchis region. The participants visited the Ajameti Nature Reserve, one of the best preserved forest fragments dominated by Zelkova carpinifolia in the Colchis region as well as as the Kolkheti National Park with its riparian Pterocarya-forests, rivers, wetlands and mires.
The road that joins Eastern adn Western Georgia crosses rich historical cities and unique Monastery and links the Great Caucasus to the very touristic shore of the Black Sea. The Balck Sea coastal region hosts thousands of tourists and only few natural habitats have been preserved in this area. The establishment of the Kolkheti National Park in 1999 was a very strong and positive sign for the conservation of the last lowland forests and wetlands of the whole region. Izolda Matchutadze (Batumi Shota Rustaveli University) gave us the opportunity to explore the most remote areas of the Kolkheti National Park. The use of a small boat is necessary to follow the course of the rivers and reach pristine vegetation established in riparian corridors. Nowadays, Kolkheti National Park is facing many challenges, such as impact of intensive tourism, poor socio-economic conditions of local communities and invasive species. The variety of habitats included in the National Park (wetlands, forests, mires, sand dunes, etc.) and various economic interests make the long term conservation of the park very complex. A global management plan is currently under preparation. The conservation team of the University of Fribourg will participate in this great effort and is drawing up an ambitious conservation project of reforestation and restauration of degraded riparian habitats with Pterocarya fraxinifolia.
One of the most remarkable stands of P. fraxinifolia in Eastern Georgia can be found in a vast and preserved floodplain near the small village of Lapankuri. The great dynamic of the Lopota river coming from the Great Caucasus allows the development of a singular riparian forest. In that particular area, P. fraxinifolia does not only grow along the main rivers and adjacent channels, but forms an original and vast forest spread deep into the land. This particular forest requires special protection status, in order to prevent further damages, especially plantation of maize and logging. We have also visited the magnificent Batsara-Babaneuri Protected Areas, home of the most important and preserved Zelkova carpinifolia forest for the Western Caucasus. The strict limitation of human activities within the perimeter of the Reserve is the only way to save relict flora vegetation and endemic fauna.
Pterocarya tonkinensis has the most southern distribution among the species of the genus - it occurs in riparian forests of Southern China, Laos and Vietnam. An expedition was held in 2015 to find and investigate this fascinating tree and collect some samples for genetic analyses (in collaboration with Prof. Hoang Van Sam, Director of Biodiversity Center, Vietnam National University of Forestry in Hanoi).
Cuc Phuong National Park, located only 120 km from Hanoi, was an excellent location to start our research on Juglandaceae and relict trees of Vietnam. We have found well preserved riparian forests adjacent to the National Park with important P. tonkinensis populations. Further research and expeditions are still needed to assess the current status of this species throughout its natural range.
Pterocarya rhoifolia in Japan
Riparian forests with P. rhoifolia are extremely rich in other interesting tree species, for example Cercidiphyllum japonicum, Fraxinus platypoda and several Acer species: A. shirasawanum, A. capillipes, A. distylum and A. carpinifolium. In July 2015 the Zelkova team from Fribourg and Prof. Hitoshi Sakio (Sado Station, Field Center fro Sustainable Agriculture and Forestry) carried out a joined excursion in Chichibu Mountains in order to explore these unique forests.
Quand les arbres nous parlent / Wenn Bäume sprechen könnten
The conference took place at the Botanic Garden of the University of Fribourg, Switzerland. The main focus was put on relict forests and trees of Crete and Japan. Examples of species - Crete: Zelkova abelicea, Phoenix theophrasti, Platanus orientalis; Japan: Pterocarya rhoifolia, Cercidiphyllum japonicum, Acer shirasawanum, Zelkova serrata, etc.