By Elizabeth A. Gjieli, Ina Vandebroek
Apr 8 2020
Although not related to true cinnamon, Cinnamodendron corticosum is a similar spice tree. It is endemic to Jamaica, meaning it is confined to just two of the fourteen parishes in the east of the island. These parishes comprise the Blue and John Crow Mountains, a National Park and UNESCO World Heritage Site, designated by the World Wildlife Fund (WWF) as a critically endangered eco-region. In 1998, this species was classified by the International Union for Conservation of Nature (IUCN) Red List as having a “vulnerable” conservation status (Bellingham, 1998).
In the field, C. corticosum, or wild cinnamon, can be easily distinguished by botanists and local community members through its appearance and the pungent smell of its bark. Like true cinnamon, the stripped bark of C. corticosum is a sought-after economic commodity that is sold at market by subsistence farmers for extra income. The tree is able to regenerate its bark, but becomes vulnerable after too many harvesting attempts. In order to obtain as much bark as possible to meet increasing demand, harvesters are now resorting to cutting down trees. Considering the species’ restricted geographic range, local reports of overharvesting, and published deforestation rates in Jamaica, an in-depth conservation reassessment of this species was deemed urgent.
Understanding habitat requirements and predicting potential geographical ranges are important for protecting a threatened species. NYBG scientist Dr. Ina Vandebroek and Geographical Information Manager Liz Gjieli are using GIS mapping tools and MaxEnt, specialized modeling software, to assess the distribution of Cinnamodendron corticosum in Jamaica. MaxEnt applies machine learning techniques to predict suitable regions for the tree to grow. The program uses occurence data from herbarium specimens to document where the species is known to occur. Local knowledge of the tree from community members was helpful in selecting a set of environmental and climatic variables for the model. These variables include annual temperature and precipitation data, land use information, soil data, and altitude/slope digital elevation models.
The model showed that precipitation had the highest contribution to the predicted distribution of the species, followed by temperature, and soil type. As was expected, the model showed a severely restricted range for the species, mostly limited to the outskirts of the John Crow Mountains. However, the model was heavily impacted by the lack of known occurrence data for the species. In some cases there was data but it was not specific enough to be included in the model. One of the oldest occurrences of C. corticosum is from a herbarium specimen collected in 1909 by NYBG co-founder Nathanial Lord Britton. It serves as a useful historical reference but the data was too vague to pinpoint the exact location. As a result of this insufficient data, the predictive niche map omitted areas within the protected forest of the John Crow Mountain range. Interviews with local community members contradicted this, insisting that Cinnamodendron corticosum could be found deeper into the forest.
It is not surprising that there have been so few collections documenting wild cinnamon in this region. These montane forests have dense and extremely rugged terrain, containing steep but brittle limestone ridges interspersed with sinkholes. In January 2020, Dr. Vandebroek and her Jamaican field team traversed this terrain in search of the species in order to collect additional data to improve the conservation model. Their search was successful and they were able to record latitude and longitude coordinates for 11 more occurrences of the tree. This information was added to the model and facilitated a more thorough and realistic picture of the species’ distribution. The results of this research will be published and communicated to relevant national government agencies in Jamaica and international conservation organizations, in order to call for increased protection of this rare species. Furthermore, this research demonstrates that the IUCN Red List status for Cinnamodendron corticosum should be revised from Vulnerable to Endangered.
