Urgent call for action to save Sri Lanka’s floral diversity from extinction

By Ifham Nizam

Plant extinctions signify a loss of biodiversity with profound ecological consequences. Deforestation, urbanization, and changes in land use significantly contribute to habitat loss, while altered climatic conditions impact plant species adapted to specific environments, says a top Scientist.

Speaking to The Island, Research Professor S. Wijesundara of the National Institute of Fundamental Studies (NIFS) expressed concern that the introduction of non-native invasive species, overexploitation for various purposes, and the disappearance of pollinators are among the anthropogenic factors driving plant extinctions.

Stemonoporus moonii (in the family Dipterocarpaceae) known as ‘hora wel’ in Sinhala. This endemic plant is only found in a marshy area in Walawwatte, Wathurana. The population is limited to only a few individuals. “We are working on a project to recover this population,” he stressed.

 “The interconnectedness of species in the ecosystems means that the loss of specific plants can trigger cascading drastic effects as plants play vital roles in ecosystems, contributing to their stability’ said Professor Wijesundara, the Former Director Royal Botanic Gardens, Peradeniya.

Sri Lanka stands out for its exceptional flowering plant diversity, with 863 endemic flowering plant species primarily found in the central and southwest regions. However, the 2020 national Red List reveals a concerning reality — 48.6% of the country’s flowering plants is under threat, classified as critically endangered, endangered, or vulnerable.

He said that of the 185 families evaluated for the Red List, 64 have 50% or more threatened species, predominantly concentrated in wet zone districts like Kandy, Ratnapura, Nuwara Eliya, Badulla, Galle, and Kalutara. He added: “It should be noted that the 2020 National Red List of Sri Lanka listed two species Strobilanthes caudataand Blumea angustifolia,as extinct. Additionally, 128 species are listed as critically endangered or possibly extinct, emphasizing the urgent need for conservation measures.”

According to him, the threats to flowering plants are diverse, ranging from direct causes like habitat loss to indirect factors such as pollinator unavailability. Given the high proportion of threatened plants, urgent attention and action from all concerned parties are imperative.

Human dependence on plants for food, medicine, and materials directly impacts plant extinctions on livelihoods and cultural practices. The current biodiversity crisis, largely attributed to human activities, necessitates urgent conservation measures.

Efforts to mitigate plant extinctions include habitat protection, restoration, and sustainable land-use practices. Botanical gardens, acting as custodians of plant diversity, play a crucial role in seed preservation. International agreements, like the Convention on Biological Diversity or Biodiversity, aim to address root causes and promote sustainable practices.

Despite ongoing conservation efforts, challenges persist, including habitat destruction, climate change, and invasive species. Continued research, public awareness, and global collaboration are crucial for developing effective strategies to prevent further plant extinctions and promote overall biodiversity conservation.

Dr. Maarten Christenhusz, a scientist attached to the Royal Botanic Gardens, Kew, UK, has recently authored a comprehensive book on plant extinctions in Dutch. He actively participated in a symposium earlier this week (5th- 8thFeb 2024) focused on new insights in plant systematics and biodiversity conservation at the Royal Botanic Gardens Sri Lanka.

Coincidentally, the Hemas Group company is contributing financial support, facilitated by the Wildlife and Nature Protection Society of Sri Lanka, for recovery programs targeting several critically endangered plants and animal species.

Sanjaya Weerakkody, the coordinator of the WNPS projects, several scientists engaged in recovery initiatives and botanists from the botanic gardens met with Dr. Christenhusz, who played a significant role in the symposium, and shared invaluable ideas to enhance local conservation activities.

“This collaborative effort reflects a holistic approach toward addressing the challenges of plant extinctions and biodiversity conservation in Sri Lanka,” Professor Wijesundera added.

He believes that substantial contributions can arise through the concerted efforts of private sector organizations and citizen scientists, focusing their attention on this pressing matter. It is earnestly anticipated that our priceless floral richness will be safeguarded before facing the threat of extinction.

Conserving hora weland suwanda
Flowering plant diversity in Sri Lanka is remarkably higher due to a multitudeof factors. One of the striking features of our flowering plant flora is the high percentage of endemicspecies. These species are distributed mainly in the Central and South West region of the island.

However, like many other groups of organisms, flowering plants are also threatened by many factors. Out of 863 endemic species listed in the 2020 Red List, 625 arethreatened. This is about 72.5% of the total endemic flowering plant species in Sri Lanka. Besides, 13 out of 18 endemic subspecies and 50 out of 69 endemic varieties are threatened. If all endemictaxa (species, subspecies and varieties) are considered 688 (72.4%) are threatened.

Threats to these endemic flowering plants may range from direct causes such as habitat loss and environmentalpollution to indirect factors such as unavailability of pollinators or dispersal agents. Whatever, thecausal factors there may be, the proportion of threatened endemic angiosperm plant species isexceedingly high. Therefore, a serious attention needs to be paid without delay by all concerned.

Some endemic flowering plant species are seriously affected and their populations are reduced to only a single location. Stemonoporus mooniicommonly known as Hora wel is one such species which is reported only from a single location. In is important to note that the entire genus Stemonoporus is endemic to Sri Lanka. This species, listed as Critically Endangered in the IUCN Global Red list and in both 2012 and 2020 National Red Lists, is found only in a privately owned site in Walau watte, Wathurane near Bulathsinhala .

Kayea stylosa, commonly known as suwanda in Sinhala, is also another such species which is also reported only from a the same location. This species, which is closely related to our national tree, Mesua ferrea (na), is also listed as Critically Endangered in the IUCN Global Red list and in both2012 and 2020 National Red Lists

“As the populations of these species are reduced to only a few individuals it is extremely important to propagate those and multiply the number of individuals to help develop a healthy population to conserve the genetic diversity. It is also necessary to introduce those propagated plants into suitable habitats.”

WNPS has provided Prof. Wijesundera and the team financial assistance to conserve these two species. “I am conducting this project with Dr. Himesh Jayasinghe, of NIFS and with Dr Achala attanayake of Peradeniya Royal Botanic Gardens.”

 Ex-situ conservation

Ex-situ conservation involves the collecting, handling and management (including research) of living germplasm, its storage, regeneration, characterization/evaluation, documentation and dissemination to users. In short, it is conservation of biodiversity in a safe place outside natural habitats.

Numerous plant species, found a sanctuary of existence exclusively in the living plant collections of the Royal Botanic Gardens, Peradeniya. Among these botanical rarities which are believed to be extinct in the wild are Alphonsea hortensisfrom the Annonaceae family and Eugenia xanthocarpafrom the Myrtaceae family.

The 2012 National Red List listed the five plants as extinct. They are:

1. Rinorea decora (Violaceae)

2. Rinorea benghalensis (Violaceae)

3. Strobilanthes caudata (Canthaceae)

4. Blumea angustifolia (Asteraceae)

5. Crudia zeylanica (Fabaceae)

Fortunately, a glimmer of hope emerged as the two Rinoreaspecies and Crudia zeylanicawere rediscovered, leading to a reduction in the count of extinct plants to two.

Cultivated within the Royal Botanic Gardens, Peradeniya, these three species serve as living testimonials to the success of conservation efforts. Additionally, the botanical garden has several other critically endangered plants, including:

1. Vanda thawaitesii(Orchidaceae)

2. Kayea stylosa(Mesua stylosa) and

3. Sophora rubriflora (Fabaceae)

4. Diospyros atrata(Ebenaceae)