Acknowledgment

We would like to express our sincere gratitude for the invaluable guidance and support provided during
our field visit to the Sinharaja Rain Forest, conducted as part of our study on the biodiversity of this
unique ecosystem.
First and foremost, we extend our heartfelt thanks to Prof. E.P. Kudavidanage and Prof. Sanjaya for
their expert guidance, insightful explanations, and constant encouragement throughout the visit. Their
dedication and passion for biodiversity conservation greatly enriched our learning experience.
We would also like to thank the demonstrators, whose assistance and support in organizing activities,
data collection, and field observations played a vital role in the success of the visit.
This field experience not only enhanced our academic knowledge but also deepened our appreciation
for the rich biodiversity and ecological significance of the Sinharaja Rain Forest.

Introduction
The Sinharaja Rain Forest, situated in the southwest lowland wet zone of Sri Lanka and spanning the
Sabaragamuwa and Southern provinces, stands as one of the island’s most vital and biologically diverse
ecosystems. Covering an area of approximately 8,864 to 11,187 hectares and ranging in elevation from
90 to 1,170 meters, Sinharaja is internationally recognized for its remarkable biodiversity and high
degree of endemism among both plant and animal species.
This field report is the result of an educational visit aimed at exploring and documenting the rich
biodiversity and ecological features of Sinharaja. The objectives of the trip included observing the
unique plant associations-such as Dipterocarpus species in the valleys and Mesua-Doona on the upper
slopes-studying the forest’s structural characteristics, and understanding the complex interactions within
its ecosystem. The report details the dominant vegetation, which consists of tall, straight trees with
abundant regeneration and high species diversity, as well as the sparse undergrowth typical of
undisturbed rainforest canopies.
Sinharaja’s climate is characterized by high annual rainfall (3,000–6,000 mm), a mean temperature
range of 18–27°C, and humidity levels between 75–90%, all of which contribute to the lushness and
productivity of the forest. The area’s rolling topography, with its network of ridges, valleys, and
streams, supports a variety of habitats and is the source of major rivers such as the Gin Ganga and Kalu
Ganga. Geologically, the forest lies within a transition zone of two major Sri Lankan rock types, and its
soils are lateritic and rich in organic matter, providing an ideal substrate for tropical rainforest
vegetation.
The animal life of Sinharaja is equally impressive, with over half of Sri Lanka’s endemic mammals, a
significant number of endemic bird species (including the Sri Lanka blue magpie and red-faced
malkoha), and a diverse array of reptiles, amphibians, and fish. The forest is also closely linked to the
livelihoods of approximately 5,000 people living in 22 surrounding villages, who depend on its
resources for water, medicinal plants, eco-tourism, and traditional agriculture.
This report not only documents the ecological and biological wealth of Sinharaja but also reflects on the
challenges of conservation and the importance of community involvement in protecting such
irreplaceable natural heritage. The insights gained during this visit reinforce the critical role of field
studies in bridging theoretical knowledge with real-world environmental stewardship, fostering a deeper
appreciation for the complexities of tropical rainforest ecosystems and the urgent need for their
preservation

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Objectives
- To explore the biodiversity of the Sinharaja Rainforest.
- To understand the relationship between forest ecosystems and surrounding village communities.
- To conduct a mini-research project on herbivory and its effects on plant species.
- To participate in birdwatching activities to observe avian diversity.

Forest exploration
Field Detail
Characteristics of Sinharaja rain forest
Location
 Sinharaja Rainforest is located in the southwest lowland wet zone of Sri Lanka, spanning the
Sabaragamuwa and Southern provinces, between latitudes 6°21'–6°27'N and longitudes 80°21'–
80°34'E
 The forest covers approximately 8,864–11,187 hectares, with an elevation ranging from 90 to
1,170 meters.
Climate
The Sinharaja Rain Forest experiences a tropical ever-wet climate, characterized by high humidity,
consistent rainfall, and moderate temperature variations throughout the year. The average annual rainfall
ranges from 3,000 mm to over 6,000 mm, primarily influenced by both the southwest and northeast
monsoons. Rainfall is fairly well-distributed, though the wettest period typically occurs from May to
September, with additional rainfall from October to November. The forest rarely experiences a
completely dry month, maintaining a moist environment year-round. Average temperature in the region
varies between 19°C and 27°C, with cooler conditions in the higher elevations. Relative humidity
remains high, often exceeding 90%, especially during early mornings and after rainfall. These stable and
humid climate conditions play a crucial role in supporting the dense evergreen vegetation and high
biodiversity found in Sinharaja.
Topography
 The forest consists of rolling terrain with a series of ridges and valleys, drained by an intricate
network of streams.
 Major rivers originating from Sinharaja include the Gin Ganga and Kalu Ganga.
Geology & Soil of Sinharaja Rain Forest
The Sinharaja Rain Forest, located in the south-western region of Sri Lanka, lies within the
southwestern group of the central highlands, which is geologically part of the Highland Complex. This
complex is predominantly composed of Precambrian metamorphic rocks, dating back over 1.5 to 2
billion years. The major rock types found in the area include charnockites, garnet-hornblende gneisses,
quartzite, and granulites, which form the bedrock of the forest.
The soils in Sinharaja are mostly lateritic and reddish-brown earths, formed from the intense weathering
of metamorphic rocks under tropical conditions. These soils are typically acidic, with low fertility due to
heavy leaching caused by high rainfall. However, they support rich biodiversity due to the long-standing
adaptation of flora to these conditions. Organic matter content in the topsoil is relatively high due to
continuous leaf litter and forest debris.

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The interaction between geology, soil, and the high rainfall regime plays a crucial role in shaping the
structure and diversity of the Sinharaja ecosystem.

Birds watching
Birds in the Sinharaja Rainforest exhibit a rich diversity of features shaped by the unique environment
of this tropical wet zone. Many species are endemic to Sri Lanka, found nowhere else in the world, and
have evolved to thrive in the dense, humid canopy. These birds often display vibrant plumage, loud and
varied vocalizations for communication within the thick forest, and specialized behaviors like canopy
foraging, insect-hawking, or ground scratching. Social behavior is common, with several species
moving in mixed-species flocks. Their diets are typically omnivorous, consisting of insects, fruits, small
vertebrates, and even other birds’ nestlings. Adaptations such as strong claws, short bursts of flight, and
agility in navigating dense foliage are also prevalent.

01. Sri Lanka Junglefowl (Gallus lafayettii)

also known as the Ceylon Junglefowl, is the national bird of Sri Lanka and is endemic to the island.
Distinctive Appearance-
Male (Rooster)
Bright orange-red body with dark purple wings and back. A striking
golden-yellow comb (unlike the red comb of domestic chickens).
Long, arched tail feathers with a black-and-white pattern. Red wattles
and a yellow patch on the neck.
Female (Hen)
Smaller and duller in color, with brown and mottled plumage for camouflage. Lacks the long tail and
bright colors of the male.
Unique Behaviors-These birds exhibit several unique behaviors that distinguish them from their
domestic counterparts. They engage in terrestrial foraging, scratching the forest floor in search of seeds,
insects, and small invertebrates. Unlike domestic chickens, they are strong flyers, capable of short bursts
of flight which they use to escape predators or to roost in trees. Additionally, the males produce loud,
distinctive calls, most notably a "kuk-ku-koo" crow that sets them apart from the typical crow of
domestic roosters.
Breeding and nesting -Breeding and nesting behaviors in these birds are quite distinctive. Males engage
in elaborate courtship displays that include wing-flapping and vocalizations to attract females. Once
mated, females lay 2–4 eggs in ground nests that are carefully hidden within dense vegetation for
protection. The chicks are precocial, meaning they are capable of moving around and feeding on their
own shortly after hatching, which enhances their chances of survival in the wild.

02. Sri Lanka Blue Magpie (Urocissa ornata)

also known as the Ceylon Magpie, is a stunning and rare bird endemic to Sri
Lanka.
Appearance -Vibrant Colors, bright azure blue plumage with a chestnut head
and wings, a long, graduated blue tail, and a white-tipped tail. Red Bill & Legs,

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its bold red beak and red legs contrast sharply with its blue feathers. White Underparts, the throat and
breast are white, blending into blue on the lower body.
Unique Behaviors- These birds are known for their social and noisy nature, often seen moving in small
flocks and communicating through loud, metallic "kink-kink" calls. They are highly agile, actively
navigating through the forest canopy with quick hops and short bursts of flight. Their omnivorous diet is
diverse, including insects, frogs, small reptiles, fruits, and even the nestlings of other bird species,
showcasing their adaptability and opportunistic feeding habits.
Habitat & Range-Endemic to Sri Lanka, these birds are primarily found in the island’s wet zone forests,
with a strong presence in the Sinharaja Forest Reserve. They prefer undisturbed rainforests with a dense
canopy and typically inhabit elevations ranging from 150 to 2,100 meters above sea level, where they
thrive in the lush, humid environment.
Conservation Status- Classified as Endangered by the IUCN, this species faces a significant threat from
habitat loss due to deforestation and human encroachment. Their population is critically low, with
estimates suggesting fewer than 10,000 individuals remain in the wild, making conservation efforts
essential for their survival.
03. The Indian Peafowl (Pavo cristatus),
Commonly known as the peacock, is one of the most visually striking birds in Sri Lanka and across the
Indian subcontinent. It is easily recognized by the male’s brilliant iridescent blue and green plumage,
along with a long train of elongated upper tail feathers, each decorated with vivid eye-spots. In contrast,
the female (peahen) is much duller in color, usually brown with a shorter tail, allowing for better
camouflage in the wild.
Behavior Peafowls are also well known for their distinctive and loud calls, especially during the
breeding season. These calls are often heard before dawn or in response to disturbances. During
courtship, males perform an elaborate display, fanning their trains into a shimmering fan while vibrating
them to catch the attention of nearby females.
Habitat- the Indian Peafowl typically prefers forest edges, open scrublands, and areas near water bodies.
While they are not considered rainforest specialists, they are occasionally seen near the edges of
Sinharaja, particularly in adjacent open areas or secondary growth zones. As omnivores, they feed on
seeds, insects, small reptiles, and plants, contributing to seed dispersal and insect population control in
their habitats.
04. The Black Bulbul (Hypsipetes leucocephalus)
Distinctive Features- The Black Bulbul (Hypsipetes leucocephalus) is easily recognizable by its dark
grey to entirely black plumage, often accompanied by a slight crest on the head, giving it a sleek and
elegant appearance. One of its most striking features is its bright red beak and legs, which contrast
sharply with its dark body, making it stand out in the forest canopy.
Behavior- This species is known for being highly vocal, producing a wide range of whistles, chatter, and
harsh calls that contribute to the lively soundscape of the forest. Black Bulbuls are social birds, often
seen in noisy flocks, particularly during feeding. They feed mainly on fruits, berries, and insects, and
play an important role in seed dispersal within the forest ecosystem.
Habitat- The Black Bulbul prefers montane and submontane forests, but can also be found in wooded
areas and forest edges. While it is more common in Sri Lanka’s central highlands, it can occasionally be
observed in higher elevations and open forest zones near Sinharaja, especially where fruiting trees are
abundan
05. The Red-vented Bulbul (Pycnonotus cafer)

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Distinctive Features- The Red-vented Bulbul (Pycnonotus cafer) is a medium-sized songbird with a
brownish-grey body, a distinct black head, and a short crest that gives it a slightly pointed silhouette.
One of its key identifying features is the small red patch beneath its tail, known as the vent, which
becomes visible when the bird is perched or in flight.
Behavior -Red-vented Bulbuls are known for their aggressive and territorial behavior. They are often
seen in pairs or small family groups, actively chasing away intruders from their feeding or nesting areas.
They are omnivorous, feeding on a wide range of food sources including fruits, nectar, small insects,
and even flower petals, making them highly adaptable in various environments.
Habitat- This species is highly adaptable and commonly found in a variety of habitats, including forests,
home gardens, agricultural fields, and even urban areas. In the Sinharaja Rain Forest, they are more
often seen in disturbed areas, forest edges, and open spaces rather than in the dense interior, where they
take advantage of human-altered landscapes and fruiting trees.
06. The Red-vented Bulbul (Pycnonotus cafer)
Distinctive Features- The Red-vented Bulbul (Pycnonotus cafer) is a medium-sized songbird with a
brownish-grey body, a distinct black head, and a short crest that gives it a slightly pointed silhouette.
One of its key identifying features is the small red patch beneath its tail, known as the vent, which
becomes visible when the bird is perched or in flight.
Behavior- Red-vented Bulbuls are known for their aggressive and territorial behavior. They are often
seen in pairs or small family groups, actively chasing away intruders from their feeding or nesting areas.
They are omnivorous, feeding on a wide range of food sources including fruits, nectar, small insects,
and even flower petals, making them highly adaptable in various environments.
Habitat- This species is highly adaptable and commonly found in a variety of habitats, including forests,
home gardens, agricultural fields, and even urban areas. In the Sinharaja Rain Forest, they are more
often seen in disturbed areas, forest edges, and open spaces rather than in the dense interior, where they
take advantage of human-altered landscapes and fruiting trees

Funa observation
The Sinharaja Rain Forest harbors an exceptionally rich and diverse array of animal life, many of which
are endemic to Sri Lanka and found nowhere else in the world. The forest is home to over 50% of Sri
Lanka’s endemic mammals, including species such as the Purple-faced Leaf Monkey (Trachypithecus
vetulus), Sri Lankan Leopard (Panthera pardus kotiya), and the Sri Lankan Giant Squirrel (Ratufa
macroura). It is a vital habitat for over 147 species of birds, of which more than 30 are endemic,
including the iconic Sri Lanka Blue Magpie (Urocissa ornata), Red-faced Malkoha (Phaenicophaeus
pyrrhocephalus), and Green-billed Coucal (Centropus chlororhynchos). Reptile and amphibian diversity
is also high, with many species adapted to the moist, shaded environment. Notable reptiles include the
Hump-nosed Lizard (Lyriocephalus scutatus) and various endemic snakes, while amphibians such as Sri
Lanka Tree Frogs are abundant, especially after rainfall. The forest also supports a rich invertebrate
population, including rare butterflies, spiders, and beetles. Many of these species are adapted to the
forest’s complex microhabitats, making Sinharaja a globally important biodiversity hotspot.
Mammal

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The Sinharaja Rain Forest supports a rich diversity of mammals, many of which are endemic and
threatened. Around 40 species of mammals have been recorded in the forest, with over half being
endemic to Sri Lanka. One of the most notable is the Purple-faced Leaf Monkey (Trachypithecus
vetulus), an endangered species often seen in the canopy. The elusive Sri Lankan Leopard (Panthera
pardus kotiya), although rarely spotted, is the top predator in the ecosystem. Other important mammals
include the Sri Lankan Giant Squirrel (Ratufa macroura), Layard’s Striped Squirrel (Funambulus
layardi), and the Toque Macaque (Macaca sinica). Small mammals such as Indian Pangolin (Manis
crassicaudata), Jungle Striped Squirrel, and various shrews and bats also inhabit the forest. Many of
these species are nocturnal and shy, making them difficult to observe during the day. The mammal
population plays vital ecological roles in seed dispersal, pollination, and maintaining the balance of
predator-prey relationships in the forest ecosystem. Due to habitat specificity and small population
sizes, many of these mammals are classified as vulnerable or endangered, emphasizing the importance
of Sinharaja for conservation.
01. Purple-faced Leaf Monkey (Trachypithecus vetulus)
also known as the Purple-faced Langur, is an endemic primate species found in Sri Lanka.
Appearance- This species is known for its striking physical characteristics. Adults possess a dark brown
to black coat with a distinctive purplish-gray face, which contributes to their common name. In contrast,
infants are born with vibrant golden-orange fur that gradually darkens with age. Their facial features
include prominent white or light gray sideburns and a beard, set against a hairless, dark face with a
short, rounded muzzle. Males are notably larger, with head-body lengths ranging from 50–67 cm and
tails extending 67–85 cm, while females are slightly smaller.
Adaptations for Arboreal Life-Perfectly adapted to life in the trees, these primates have long tails that
aid in balance as they leap between branches. Their strong limbs are well-suited for climbing and
navigating the forest canopy. Their diet is primarily folivorous, consisting mainly of leaves, but they
also consume a variety of fruits, flowers, and seeds, allowing them to make the most of their rainforest
habitat.
Behavior -They are highly social animals, living in small groups of 2 to 12 individuals. These groups
typically include one dominant male, several females, and their offspring. Communication within the
group is maintained through loud, guttural calls, which also serve as a means of defending their
territory. They are diurnal and spend most of their time in the treetops, rarely descending to the ground.
Conservation Status & Threats- Listed as Endangered on the IUCN Red List, this species faces serious
threats due to habitat loss caused by deforestation and expanding urban development. The Sinharaja
Rain Forest remains one of their last strongholds, offering dense canopy cover and a safe environment
critical for their survival and reproduction.

Reptiles -
The Sinharaja Rain Forest is home to a diverse range of reptile species, many of which are endemic to
Sri Lanka and specially adapted to the forest’s moist, shaded environment. Over 45 species of reptiles
have been recorded in the forest, with a significant number being forest-dwelling and tree-loving
(arboreal). One of the most iconic reptiles of Sinharaja is the Hump-nosed Lizard (Lyriocephalus
scutatus), which is endemic and easily spotted on tree trunks. Other notable lizards include the Green
Garden Lizard (Calotes calotes), Whistling Lizard (Calotes liolepis), and Ceratophora aspera, a rare
horn-nosed lizard found only in wet zone forests. The forest is also rich in snake diversity, including
Green Pit Vipers (Trimeresurus trigonocephalus), Cat Snakes (Boiga ceylonensis), and various species
of non-venomous tree snakes. Most snakes are shy and nocturnal, often hiding in leaf litter or

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vegetation. The humid environment also supports several gecko species, such as the Leaf-nosed Gecko
(Hemidactylus depressus). The reptile fauna plays key roles in controlling insect populations and
serving as both predator and prey within the food web. Due to their restricted ranges and habitat
sensitivity, many Sinharaja reptiles are considered threatened or endangered.

Butterflies
The Sinharaja Rain Forest is an important habitat for a wide variety of butterflies, including many
endemic and rare species. Over 70 species of butterflies have been recorded in the forest, making it a
hotspot for butterfly diversity in Sri Lanka. The Sri Lanka Birdwing (Troides darsius), which is the
largest butterfly in the country, is one of the most spectacular and commonly seen species in Sinharaja.
Other notable butterflies include the Sri Lanka Tree Nymph (Idea iasonia), the Clipper (Parthenos
sylvia), and the Blue Mormon (Papilio polymnestor). Many of these species are found fluttering along
forest paths, near streams, and in sunny clearings where flowering plants are abundant. The forest also
hosts several species of skippers, swallowtails, and pierids, each playing an important role in pollination
and indicating the health of the ecosystem. Some butterflies, such as the Red Helen (Papilio helenus)
and Common Rose (Pachliopta aristolochiae), have specific host plants, which makes their survival
closely tied to the undisturbed forest habitat. Due to their beauty, sensitivity to environmental changes,
and ecological roles, butterflies are among the most studied and admired insects in Sinharaja.
Amphibians - Many rare and endemic frogs, such as the Sinharaja shrub frog 5 2.
Fish -Several endemic species inhabit the streams and rivers within the reserve
Spiders
The Sinharaja Rain Forest is home to a diverse and fascinating array of spiders, many of which are
endemic to Sri Lanka and play crucial roles in the ecosystem. Over 100 species of spiders have been
recorded in and around the forest, with many still awaiting formal identification due to their cryptic
nature. One of the most iconic is the Giant Wood Spider (Nephila pilipes), known for its large size and
impressive golden web, often seen stretched between trees along forest trails. The forest also supports a
variety of orb-weaver spiders, jumping spiders, trapdoor spiders, and wolf spiders, each occupying
different niches from tree trunks and leaf litter to stream banks and the forest canopy. Many spider
species in Sinharaja are nocturnal, using web-building or active hunting techniques to capture prey.
These arthropods are vital in controlling insect populations, maintaining ecological balance, and serving
as food for birds and reptiles. Due to the dense vegetation and high humidity, the forest provides ideal
conditions for the survival of rare and specialized spider species, making it a key location for
arachnological research and biodiversity conservation.

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Flora observation
The Sinharaja Rain Forest is home to a wide variety of plant species that display unique characteristics,
many of which were observed during our field visit. One of the most striking features is the high level
of endemism. Over 60% of the tree species in Sinharaja are endemic to Sri Lanka, with some species
being exclusive to this forest. Examples include Shorea trapezifolia, Doona congestiflora, and Mesua
nagassarium. These species contribute to the ecological uniqueness and global importance of Sinharaja
as a biodiversity hotspot.
The forest structure is vertically stratified into several layers. The tallest trees, often reaching over 40
meters, form the emergent layer, represented by large dipterocarps. Below this lies the canopy layer,
where the crowns of medium-sized trees form a dense cover, regulating light penetration. Beneath the
canopy, the understory supports a variety of shade-tolerant shrubs, saplings, and small trees, while the
forest floor is home to ferns, seedlings, and mosses adapted to low-light, moist conditions.
Plants in Sinharaja show several adaptations to the tropical climate, particularly the high rainfall. Many
leaves possess drip tips, which help in shedding excess water and preventing fungal growth. A waxy
cuticle on leaf surfaces serves a similar purpose and also reduces water loss. These adaptations are
essential for survival in the humid and wet environment of the rainforest.
Another noticeable characteristic is shade tolerance, especially among understory plants. These species
tend to have broad, dark green leaves that maximize photosynthesis under low-light conditions. This
adaptation allows them to thrive despite limited exposure to direct sunlight beneath the dense canopy.
Large trees often feature buttress roots, which provide extra support in the shallow, nutrient-poor soils
of the forest. These visible root structures help anchor the trees and also increase nutrient absorption
from the topsoil layer. The root systems are generally shallow due to the high leaching rate caused by
heavy rainfall.
In addition, Sinharaja hosts a wide range of epiphytes and climbers. Epiphytes such as orchids, ferns,
and mosses grow on the trunks and branches of larger trees, utilizing them for support without
extracting nutrients. Lianas and woody climbers are also common and contribute to the forest’s
structural complexity.
Many plants in Sinharaja also have medicinal and economic value. For example, Coscinium fenestratum
(locally known as Weniwel) is used in traditional medicine. Other species like wild cardamom and
native pepper vines are economically significant for local communities.
Lastly, most of the plant species in Sinharaja are evergreen, maintaining their foliage throughout the
year. This is a typical feature of tropical rainforests, where constant temperature and moisture levels
allow for continuous photosynthesis and growth.
Some specific features of selected plants species
1. Shorea trapezifolia (Sinharaja Dun)

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Shorea trapezifolia is one of the most significant and dominant tree species in Sinharaja, and it is
endemic and critically endangered. Belonging to the Dipterocarpaceae family, this majestic emergent
tree can grow over 40 meters in height. It has thick, leathery leaves and produces winged seeds that are
dispersed by wind. This species plays a key role in forming the upper canopy layer of the forest,
providing essential habitat and shade for the plant and animal species beneath it. Although it has been
heavily logged in the past due to its high-quality timber, it is now protected due to its conservation
importance.
2. Mesua nagassarium (Diya Na)
Mesua nagassarium, known locally as Diya Na, is a native tree species commonly found along stream
banks and wet lowland areas of Sinharaja. It belongs to the Calophyllaceae family and is easily
recognized by its glossy green leaves and large, fragrant white flowers. This species thrives in riparian
zones and plays a crucial role in preventing soil erosion and maintaining water quality. Besides its
ecological functions, Mesua nagassarium also has ornamental value and is used in traditional medicine
for its anti-inflammatory and antimicrobial properties.

3. Coscinium fenestratum (Weniwelgata)

Coscinium fenestratum, locally known as Weniwelgata, is a woody climber native to the wet zone
forests of Sri Lanka and is considered endemic and threatened. It belongs to the Menispermaceae family
and is easily identifiable by its bright yellow stem and heart-shaped leaves. This plant winds around
larger trees, forming part of the forest’s vertical structure. It is highly valued in traditional Ayurveda,
where the stem extract is used to treat ailments such as fever, diabetes, and digestive disorders. Due to
overharvesting and habitat loss, this species faces conservation concerns.

4. Stemonoporus affinis
Stemonoporus affinis is a rare and endangered endemic tree species found exclusively in the lowland
rainforests of Sri Lanka, including Sinharaja. It belongs to the Dipterocarpaceae family and is known for
its rough bark, tall trunk, and elliptical leaves. As a part of the canopy layer, this species contributes to
the structural integrity and biodiversity of the forest. It provides habitat and food for numerous insects,
birds, and mammals. While it has no major commercial value due to its rarity, its ecological importance
in sustaining the health of Sinharaja’s ecosystem is significant.

Microhabitats
The Sinharaja Rainforest in Sri Lanka is a biodiversity hotspot with a complex mosaic of microhabitats,
each supporting unique flora and fauna. The forest floor is damp and shaded, covered with decomposing
leaf litter, fallen logs, and fungi, providing shelter for amphibians like the Sri Lankan hourglass tree
frog, reptiles such as the green pit viper, and ground-dwelling birds like the grey-capped emerald dove.
The undergrowth layer, dense with shrubs, ferns, and saplings, is home to endemic species like the Sri
Lankan junglefowl and small mammals, including the purple-faced langur, which forages here for fruits
and leaves. The mid-canopy is a bustling zone with tangled lianas, epiphytes, and orchids, hosting birds
like the Sri Lanka blue magpie and insects such as the Sri Lankan birdwing butterfly. The upper canopy,
dominated by towering dipterocarp trees, is alive with mixed-species bird flocks, including the red-
faced malkoha and legge’s flowerpecker, while flying squirrels and giant squirrels glide between
branches. Along streams and marshes, specialized species like the green forest lizard and freshwater
crabs thrive, while the moss-covered rocks and tree trunks support rare mosses, lichens, and micro-

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endemic land snails. This intricate layering of microhabitats makes Sinharaja a vital refuge for endemic
and endangered species, sustaining one of the world’s most ecologically rich rainforests.

Ecosystem interactions
Sinharaja Rainforest exhibits complex and dynamic ecosystem interactions involving biotic (living) and
abiotic (non-living) components. These interactions ensure ecological balance, energy flow, and nutrient
cycling in the forest.
 Producer-Consumer Interactions (Food Web)
Primary producers- Large canopy trees (e.g., Shorea spp.), understory plants, ferns, and mosses convert
sunlight into energy.Primary consumers- Herbivores like leaf-eating insects, purple-faced langurs
(Semnopithecus vetulus), and deer feed on plants. Secondary/Tertiary consumers: Birds like the Sri
Lanka crested drongo (Dicrurus paradiseus), snakes, and small mammals prey on herbivores and
insects.
Decomposers- Fungi, termites, and soil bacteria break down organic matter and recycle nutrients.
 Symbiotic Relationships
Mutualism
Mycorrhizal fungi and tree roots exchange nutrients. Flowering plants and pollinators (e.g., bees, birds)
benefit each other.
Commensalism
Epiphytic plants (orchids, ferns) grow on trees without harming them.
Parasitism
Parasitic plants or insects exploit host plants or animals.
 Predator-Prey Dynamics
Carnivorous animals like snakes and jungle cats prey on smaller animals. Helps control population sizes
and maintain ecological balance.
 Competition
Trees and understory plants compete for light, water, and nutrients. Animal species may compete for
food or nesting sites.
 Abiotic-Biotic Interactions
Rainfall and humidity influence seed germination, fungal growth, and amphibian reproduction. Soil type
affects plant diversity and forest structure.
 Human-Environment Interactions
Ecotourism, scientific research, and conservation efforts impact the ecosystem. Illegal logging and
encroachment can disrupt ecological interactions

Mini project
Key learning
Conclusion

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