As a vulnerable small island, Sri Lanka is highly exposed to the threats emanating from climate change, which affects every aspect of ecosystems: flora, fauna, and the environment. Its truly rich biodiversity, known internationally for high species density within flowering plants, amphibians, reptiles, and mammals, is seriously in jeopardy. The main threats include habitat loss, invasive species, deforestation, and environmental pollution-all of which are further exacerbated by climate change and threaten nothing less than the survival of endemic species, a loss that would prove irreparable globally. Let’s find out about the climate changes in Horton Plains, which was inherited such a valuable biodiversity like heart of Sri Lanka.
Overview of Horton Plains
Horton Plains National Park is situated in the central highlands of Sri Lanka, some 5-6 drive from Colombo. The plateau rises over 2,000m above sea level and is enveloped by fog almost throughout the year. The park is accessible via 02 primary entrances, namely Pattipola, Ohiya and most of the visitors come here to see the famous World’s End, the precipice around 4,000-foot drop with breathtaking views of the landscape. Another primary attraction is the 22m high Baker’s Falls discovered in 1845 by Samuel Baker. The park has several trekking trails. The history of Horton Plains includes its first European observations in 1834 by Lieutenant William Fisher and Albert Watson, which led to its naming after British Governor Sir Robert Wilmot Horton. Before this, it was locally known as “Maha Eliya Thanna” meaning Great Light. The area has evidence of early human habitation and was used as a hunting ground by British colonists after its discovery. Notables like Samuel Baker wrote about Sambar deer hunting in the region. The flora of the Horton Plains is tropical montane cloud forest and montane grassland. This attracted the attention of the botanists since the late 1880s. Several theories linked it to the historical burning by herders. As part of the cloud forests, it provides a home for many plants and animals that are endemic, and the area forms the catchment for three major rivers in Sri Lanka. It is considered a UNESCO World Heritage Site due to the richness in biodiversity it holds as a sensitive ecosystem.
The Creative History of Horton Plains Cloud Forest
It is also a biodiversity hotspot in Sri Lanka, home to the oldest cloud forest in the world. Geological and climatic history such as these forests relates directly to the movement of the Earth’s continental plates.
What is now Sri Lanka was part of the supercontinent Gondwana, also comprising of present-day Antarctica, Africa, South America, and India, many millions of years ago. When the plates began their autonomous drift, Sri Lanka moved north across the warming equator. Unlike other landmasses that eventually collided with Asia, Sri Lanka remained an isolated fragment. This isolation preserved the unique climatic and ecological conditions of its highlands.
This unusually climatic zone has hardly altered over several million years, and though Sri Lanka went through tropical conditions when it drifted across the equator, the peaks of the mountains which form the Horton Plateau kept the temperature temperate. As a result of this continuity, this area has preserved its flora and fauna generally unchanged and forms a living museum of ancient biodiversity.
The Horton area is ever draped in fog and cloud cover, giving cloud forests perpetual moisture. This perpetuates a broad array of plant and animal life, many of which are endemic and found nowhere else on the planet. The direct descendants of ancient-perhaps millions of years old-forests, they avail gateways into Earth.
Climate of Horton
Within Sri Lanka are found Horton plains with a cool and temperate climate. Average temperatures range between 12°C to 16°C, while at night the temperature is about 5°C/41°F. The Horton Plain gets heavy rainfall, an average amount of about 2,000 to 2,500 mm/78 to 98 in annually. On the plain, there are two monsoon seasons; most of the rain falls between October and December and from April until June. Apart from that, it has a dry period throughout February and during the oncoming monsoon rains in addition to occasional hailstorms. Generally, Horton Plains have high humidity most of the time; it can be from 80% to 90% due to its elevation and surrounding forest. These climates have, over time proved to be critical for a number of major watersheds.
Climate Change Impacts on Flora in Horton plains
The climatic conditions of the Horton Plains have not changed markedly as the area receives rain throughout the year. But several environmental changes are taking place due to years of climate. Climate change has presented a significant threat to the highly fragile plant assemblage in Horton Plains National Park, one of the most ecologically and biologically important Montane ecosystems in Sri Lanka. A rise in temperatures and change in precipitation patterns is damaging the plant life of the park. Global warming may badly affect the growth, reproduction, and overall survival of the plants due to heat-stress; the result is extinction of a vast majority of species evolved to tolerate temperature within certain limits. Drier weather with higher temperatures can also promote wildfires that will lead to total plant population destruction.
• Invasive plant growth
Horton Plain habitats are changing due to disturbed ecosystems and the spread of invasive alien plant species (IAS) driven by climate change. Major invasive plants include the invasive gorse (Ulex europeus), mist flower (Ageratina riparia), Suddha (Austroeupatorium inulifolium) and Crofton weed (Eupatorium adenophorum) introduced by the British in the 19th century. Rising temperatures and extreme weather conditions create ideal conditions for these invasive plants.
This has also affected the ‘Nelu’ (Strobilanthes) plantations in the Horton plains, which is an endemic plant species. Especially known for its large blooms that occur every 12 years, changes in temperature and rainfall patterns can disrupt its growth and flowering, affecting the plant’s survival and overall biodiversity in the region.
• Forest Dieback
Research shows that deforestation, first observed in the 1970s, has increased to 30% by 1998. This phenomenon has changed the vegetation composition of disturbed areas with periodic fires. Deforestation at Horton Plains Ferry Hill and Anderson Sites Nos. 1 and 2 results in gradual decline in tree health and death. This increase is notable due to higher traffic in April and the resulting carbon dioxide emissions have been a major cause.
Climate change is causing significant damage to Horton Plains National Park in Sri Lanka, causing heat stress, wildfires, and extinction of species that withstand specific temperature ranges, affecting plant growth, reproduction, and survival. Changes in precipitation patterns and rising temperatures can lead to water scarcity, affecting plant survival and growth, and exacerbated erosion, affecting wetland environments. This affects Horton Plains, causing the disappearance of endemic plant species and distinct plant communities.
Climate change threatens alpine grasslands in Horton Plains, potentially causing species extinction and ecosystem services loss, and potentially causing shrub encroachment and ecosystem structure changes.
These cloud forests of Horton Plains are important in ecosystem services like soil retention and carbon sequestration, and thus, because of climate change, may become extinct and pose a threat to the biodiversity of the unique plant groups of the park. However, less than 5% of Sri Lanka’s original cloud forest remains today, and the park has suffered from deforestation due to natural and man-made causes.
Climate Change Impacts on Fauna in Horton Plain
Situated in Sri Lanka’s central highlands, Horton Plains National Park houses various montane ecosystems and species. The serious threats to its fragile ecosystem are climate change, among others, that even alter its rich biodiversity. An important worry is rising temperatures, especially for species that are acclimated to the park’s chilly, high-altitude environment. The Sri Lankan Leopard for example, is dependent on a finely balanced diet of available prey and stable habitat. The distribution of prey species can be upset by rising temperatures, which can also cause habitat fragmentation and impact the leopard’s hunting areas. Similarly to that, the Horton Plains Frog (Nannophrys marmorata) is very sensitive to temperature changes. High temperatures can be a cause of disruption in their reproductive cycles their immunity will decrease due to that, which will also cause them to get ill and therefore will minimize their survival chances. The changing patterns of vegetation brought about by climate change also impact species that depend on plant species. Due to their reliance on specific tree species for food, Purple-faced Langurs may have to migrate to less hospitable locations or experience nutritional hardship if vegetation changes. Comparably, as plant communities change, the Wild Boar (Sus scrofa) may encounter difficulties that affect their survival and foraging habits. These difficulties are exacerbated by variations in water supply brought on by shifting patterns of precipitation and rising temperatures. Because it hunts in aquatic habitats, the Fishing Cat may suffer from decreased water levels and altered aquatic ecosystems. Changes in the availability and quality of water may pose a potential threat to otters, which rely on stable, clean-water habitats.
Habitat loss and fragmentation due to climate change could result in some population isolation and reduction in genetic variability. The Sri Lankan Elephant (Elephas maximus maximus), while less prevalent in Horton Plains, may experience changes in migratory patterns and a rise in human-wildlife conflicts as their habitats in grasslands and forests decline. Dispersed habitats may limit the migration of the Toque Macaque and increase competition for resources. Notable behavioral and biological alterations include possible adjustments in the time of migration and breeding success in species such as the Sri Lankan Bush Warbler and Whistling Thrush. Changes in temperature and ecological conditions influence the reproductive cycles and survival rates of amphibians and reptiles in a similar way. Disruptions to an ecosystem can have repercussions for species that depend on insects and pollinators, hence altering the food chain.
A comprehensive strategy including continual monitoring, habitat preservation and restoration, and adaptive management techniques is needed to address these climate change implications. Conservationists can guarantee the resilience of Horton Plains’ species in the face of climate change, conserve the region’s distinctive biodiversity, and lessen some of the negative effects of climate change by putting these measures into practice.
Impact of Climate Change on Horton Plains Water Resources
The climate crisis has affected not only the water resources but also the aquatic biodiversity of Horton Plains, a vital catchment in Sri Lanka that feeds major rivers including Mahaweli, Walawe and Kelani Rivers. This unique montane plateau is also home to the cloud forests and montane grasslands which help in the hydrological cycle, but these have been altered by climate change affecting rainfall patterns, temperatures and the frequency of extreme climatic conditions.
This lesser provision of water for people in the short run is an immediate effect of floods and including the more long-term one – drought. One of the most notable impacts is the change in precipitation patterns. Through the years, Horton Plains, known for its frequent mist and cloud cover, has been experiencing erratic rainfall due to climate change. One such problem is the occurrence of a prolonged dry season or on the contrary, a wet season with heavy precipitation, but for a shorter duration than usual. Such variations can disturb the natural distribution of water. During the dry season, sediments are left dry with bared bottoms or slow moving waters without any current for long periods. This can aggravate water related crises to people, as well as animal, mostly in dry zone regions that are reliant upon the up streams.
Such changes in water abundance also have a direct impact on the aquatic fauna and flora existing within Horton Plains. Different studies show that reduced water levels, reduced rates of flow in streams and rivers, and higher temperature of still waters, result to excessive heat and low oxygenation that is harmful to many creatures inhabiting such waters. This would exert stress on those species which includes the endemic fish (Schistura notostigma) and the frog (Micrixalus fuscus), both of whom are dependent on cool, well oxygenated water.
Moreover, the issue of forest dieback, partly made worse by climate change, has led to the destruction of cloud forests which are important in the maintenance of the water resources within the Horton Plains. Implication being that, as forests become sicker, they become less functional with a lower ability to hold and filter water resulting in degradation on the quality and levels of water passing through the system. Such water quality affects water containing an ecosystem making it more vulnerable to disease causing organisms thereby reducing the populations of the species.
As if climate change is not enough of a threat to Horton Plains’ water bodies, the invasive species problem too has been exacerbated by the phenomenon. Instances of invasive species like gorse (Ulex europaeus), that have enveloped the land, may also change the soil and the water holding capacity in the area thereby diminishing the capacity for water recharge and altering stream patterns. The situations, together with the consequences of climate change, can make it hard for indigenous water species to prosper.
Therefore, Horton Place, like the stroke of a mindless artist, is a valley that quietly hides secrets. Cloud forests are characterized by unique flora and fauna, and many species are endemic to the region and maintain rare populations. The living and non-living evolutions that were created by the climate and buried by it, have made this unique land so unique that it cannot be found anywhere else in the world.
This note is placed by : SSCCA Team 12
Sabaragamuwa University of Sri Lanka
Leave a Reply