Foresters counted endangered trees on the island of Socotra

2. 12. 2021 -

Experts from Mendel University in Brno have calculated how many endemic censers and dragonflies are on the island of Socotra in the Indian Ocean. Finally, data is available that scientists have so far lacked. The data will now help assess the degree of threat to these unique trees for the International Union for Conservation of Nature and thus the necessary protection. So far, a total of 8143 individuals of nine different species of incense burners and 80,165 individuals of dragonflies have been inventoried. Scientists also find out the age of trees, the oldest of which reach up to one thousand years.

According to data from Czech scientists, the most endangered are the incense burner Boswellia scopulorum (only 10 individuals), Boswellia nana (193) and Boswellia bullata (260). Populations of other censer species always number more than a thousand individuals. "Nevertheless, all species are endangered because their populations are mostly obsolete without sufficient recovery. The population of dragonflies is more numerous and the trees live longer. Despite the lack of recovery, this species is not threatened with extinction in the near future, but many local populations are endangered," says Petr Maděra from the Faculty of Forestry and Wood Technology at Mendel University in Brno, who coordinates the work of Czech scientists and students at Socotra.

MENDELU experts have been working in Socotra for over 20 years. It took almost two years to find and measure all the endangered trees. "For the inventory of censers and dragonflies, we used a combined method of field surveys and remote sensing of the earth, and in recent years we have been flying inaccessible locations using drones. By repeated measurements, we also determine the thickness growth of trees, which will be the basis for a direct method of estimating their age. So far, we are working with our indirect methods, which show that the oldest dragonflies can reach up to one thousand years, while incense burners live only 150 years," said Maděra.

The island of Socotra is known for a high degree of endemism - in other words, almost every species of the local tree does not grow anywhere else in the world. The absence of natural regeneration of tree species and the aging of their current population is mainly due to growing pastoralism, which causes serious environmental problems. Populations of endemic trees are aging, and due to the increasingly frequent and destructive cyclones, they are dying out and threatening to become extinct.

Therefore, Czech scientists have already built forest nurseries on the island and educated the first workers. They are now also conducting sociological research to find out the relationship of the people of Socotra to the forest as such and their willingness to change grazing habits, as intensive grazing is the main cause of the gradual degradation of local forests. "We also deal with the eating habits of goats in different seasons. Specifically, our students in afforestation activities helped with the measurement of seedlings in experiments, which consist of the observation and comparison of growth and mortality in fenced areas and beyond. The aim is to quantify the effect of goat biting on seedling growth," said Maděra.

The island of Socotra, which is also called the Galapagos of the Indian Ocean, belongs to the Republic of Yemen. It lies on the border of the Gulf of Aden and the Indian Ocean. The degree of endemism and thus uniqueness of the plants here reach up to 38%. To increase the attractiveness of the island in the future, hiking and nature trails are also to be built, which is also one of the tasks of the Brno students, who recorded GPS coordinates and took photo documentation on-site.

Contact for further information: prof. Dr. Ing. Petr Maděra, tel.: 739 341 962,, Faculty of Forestry and Wood Technology

Photo: Tomáš Macháček, night camp in the dracaena forest

Covid-19 information