Harpalyce macrocarpa (sangre de doncella) is one of the few tree species occurring in the serpentine thickets of Central Cuba. It relies on the humidity that the running water of nearby streams provides to thrive in the dry serpentine ecosystems. Because of climate change, the seasonal patterns of small watercourses have changed affecting riparian plants like Harpalyce macrocarpa. These changes have led to a decreased number of germinating seeds and an increased mortality of seedlings. They also seem to be inducing the abortion of flowers with a direct impact in the production of fruits and the propagation of the species
In addition, the trees of Harpalyce macrocarpa are locally known by the durability of its wood, a feature that for several years has made the species a target for illegal logging. This threat have resulted in a drastic reduction of the size of the populations..
The natural recovery of this Critically Endangered plant is currently constrained by the reduced number of adults remaining, the low recruitment of seedlings observed, current drier conditions in the riparian forests, and ongoing tree felling. Therefore, specific actions are needed to rapidly increase the size of the population of Harpalyce macrocarpa, restore its habitat, and involve the local community in order to secure its long-term survival.
Planta! started this project in November 2016 with the support of the Whitley Fund for Nature (WFN). During the first two years of the project, several surveys have been carried out looking for remaining individuals and also to assess the population’s dynamics. Previously, only 28 adults were known for the species. However, our results show that the population of Harpalyce macrocarpa includes 328 adults and 131 juveniles. These are very good news for our conservation goals since finding more individuals increases the chances of a successful recovery of the population.
Ex situ collections
Establishing an ex situ collection of Harpalyce macrocarpa to reinforce the wild population is currently one of our main tasks. At each location, ten percent of the seeds available were collected and taken to local nurseries for propagation. So far, the results are encouraging. The ex situ germination rate is very high (90-93% of seeds) and the survival of the seedlings is excellent. By the end of next year, we expect to have at least 150 seedlings of Harpalyce growing at local nurseries.
This is a crucial step to secure the survival of the seedlings. Accompanying species of Harpalyce macrocarpa are also propagated at these local nurseries. Focusing on fast-growing species first, the reintroduction of these trees could restore, in a short term period, the shade and humidity needed for seedlings to thrive; therefore contributing to the restoration of the habitat.
Increasing the natural production of fruits and seeds
Preliminary studies on the species population showed that there is a very low seed supply. The reason, however, for this inefficient production of seeds is still under study. We strongly believe that there are factors limiting pollination. We have conducted field experiments where we hand pollinated the flowers of Harpalyce macrocarpa. Results showed that pollination occurred successfully in 90% of the cases, increasing the production of fruits and seeds. So, the problem seems to be the amount of pollen that is naturally reaching the stigma of the flower.
Our team is still surveying every location to establish factors limiting pollination. These results could help us establishing a plan to manage pollinators populations and the use of pesticides in nearby agricultural areas
Involving the community
We have also been working to involve the local community in this conservation project. It is essential to stop tree felling in private lands and to control illegal logging of Harpalyce macrocarpa in non-protected areas, but in order to succeed we definitely need their help.
During the first year of the project, a workshop was held with locals and stakeholders at the Savana of San Felipe. During the workshop we highlighted the scarcity and imminent extinction of Harpalyce macrocarpa, and introduce them to alternative and accessible timbers like the invasive plant Dichrostachys cinerea. Additionally, we encouraged the ornamental use of Harpalyce. Having multiple clusters of big red flowers we think it will be popular among horticulturists and gardeners. This way, they can get other benefits from the plant while also propagating the species.