Mulu and Gunung Buda National Parks in Sarawak are biodiversity-rich areas with rare plants and unique ecosystems. Professor Dr Wong Sin Yeng’s research highlights their importance, while tourism and local communities contribute to conservation but require sustainable management.
Mulu: Nature’s Living Masterpiece of Biodiversity
This is part three of a five-part series on the natural wonders of Mulu.
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Mulu National Park is not just a place on the map; it is evidence of the resilience of nature and the stories woven into it by explorers, indigenous communities, and conservationists.
The park, spanning 528.64 square kilometres, and its adjacent neighbour, Gunung Buda National Park (66.2 square kilometres), have drawn scientists and travellers alike, captivated by the kaleidoscope of biodiversity against awe-inspiring karst formations.
For Professor Dr Wong Sin Yeng, Deputy Director at the Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak (UNIMAS), Mulu’s story is both scientific and deeply personal.
Wong’s journey into botany began during her undergraduate studies at Universiti Putra Malaysia (UPM), where she was first introduced to the world of plants.
Although she initially explored the timber industry, it wasn’t until 2005, after attending a lecture by renowned botanist Peter Boyce at UNIMAS, that she fully embraced the field.
Since then, Wong has dedicated her research to taxonomy (the scientific study of classifying organisms based on shared characteristics), phylogeny (the study of the evolutionary history of organisms), pollination biology, and botanical nomenclature (the scientific naming of plants, and the rules and principles that govern the process), with a special focus on Borneo’s unique plant life.
Her recent publication, The Flora of Borneo — the first complete list of plants for the island in a century — testifies to her dedication to the field.
In collaboration with Boyce, Wong has published over 250 new species, 27 new genera, and even a new plant tribe in more than 200 indexed and refereed journal articles.
Unique Ecosystem
Mulu National Park and Gunung Buda National Park are two of the most ecologically significant regions in Sarawak.
Mulu National Park is home to eight distinct forest types, including peat swamp, heath, mixed dipterocarp, moss forest, and stunted upper montane vegetation.
The park contains 17 different vegetation zones, supporting a remarkable diversity of plant life with 2,142 species of non-flowering plants and over 2,000 species of flowering plants, including 182 orchids and 15 species of carnivorous pitcher plants.
The park’s wildlife includes 116 mammal species — 54 of which are bats — 305 bird species, 100 reptiles, 97 amphibians, and 48 fish species.
The estimated richness of invertebrates is around 20,000 species, comprising 360 species of spiders, 147 species of dragonflies, 281 species of butterflies, approximately 3,000 species of moths, 458 species of ants, and roughly 4,000 species of beetles.
Meanwhile, Gunung Buda National Park is in the Limbang division, and the park’s landscape is characterised by towering karst formations, dense lowland dipterocarp forests, and a variety of forest types, including limestone forest, heath forest (kerangas), and upland dipterocarp forest.
This diverse environment supports a wide array of flora and fauna, including at least 300 species of birds, numerous primates, over 2,500 species of trees, and 60 species of snakes.
Together, Mulu National Park and Gunung Buda National Park form a vivid tapestry of diverse habitats, each shaped by unique geological and environmental conditions.
Wong said the landscape here is as complex as it is beautiful — towering karst cliffs, shaped by millions of years of erosion, create steep rock faces that shelter numerous microhabitats.
“In Mulu, these karst cliffs serve as more than just dramatic scenery; they support ecosystems that transition rapidly from sun-baked, arid limestone on the exposed surfaces to perpetually wet seepages hidden deep within the rock face crevices.
“These cliffs, along with karst outcroppings rising from peat swamp forests, create ‘dry islands’ separated from their neighbours by deep, saturated peat, sandstone, limestone, and shale riverbeds running parallel to one another, each supporting its own geologically obligated riverine flora, and much else,” she explained.
Touching on the specific adaptation strategies that flora in Mulu have developed over time to thrive in its unique karst and forest environments, Wong said there are countless examples, including the accretion of calcium in the leaves of many of the karst-obligated plants and niche specialisations, where different species within the same genus each have their own place within an ecology.
“The one-leaf plants of the genus Monophyllaea, in particular, display a wide range of rigid distributions. For instance, Monophyllaea pendula is only found on the cliff face, whereas M. insignis is only on the dripline at the base of the cliff in Clearwater Cave,” she said.
Exclusive Flora of Mulu and Gunung Buda
The unique ecosystems of Mulu and Gunung Buda National Parks support an extraordinary array of flora, much of which is found nowhere else on Earth.
Within Wong’s field of expertise — primarily terrestrial herbs of the forest understory and plants adapted to the fast-moving streams and rivers of the spate zone — approximately 75 per cent of these species are endemic to Mulu and Buda.
“Of these, more than 80 per cent have been described as species new to science in the last 20 years,” she said.
Among the standout examples is the Begonia genus, with 22 species recorded in Mulu alone, 20 of which are found nowhere else.
Of these, 18 were identified as new to science since 2013, demonstrating the region’s significance as a site for ongoing botanical discovery.
Another fascinating genus is Monophyllaea, the “one-leaf plants”.
Mulu hosts seven species of Monophyllaea, six of which are exclusive to the area, showing how highly specialised these plants are to the local conditions.
Wong pointed out that several particularly rare species have adapted to very specific environments within the park.
Burttianthus hansenii, for example, is restricted to the sandstone riverbeds at 1,300 metres on Gunung Mulu, thriving in the altitude and unique river conditions there.
Meanwhile, Bau multinervia and B. pellucida are found only on limestone outcrops that are both permanently shaded and permanently damp, conditions that allow them to flourish but limit their distribution.
Another species, Homalomena hottae, has adapted to wet seepages on the lower parts of limestone cliffs, taking advantage of the moisture and cool temperatures provided by the cliffside habitat.
“These plants are not only beautiful and unique; they also represent specialised adaptations that illustrate the broader ecological richness of Mulu and Buda. Each species, with its distinct ecological niche, showcases the importance of these parks as irreplaceable reservoirs of biodiversity,” she said.
A Legacy of Exploration and Research
Since the 1930s, Mulu has attracted the attention of international scientists.
The first significant scientific study, the Oxford University Expedition in 1932, set the stage for later exploration.
The expedition’s findings established Mulu as one of the world’s most diverse ecologies, producing the park’s first species list of plants and animals discovered at that time.
This was followed by the Kyoto University Expedition in 1968-1969, which added significantly to the growing body of knowledge about Mulu’s unique environment.
The expedition also provided some of the first scientific documentation of Mulu’s complex karst landscape.
These studies highlighted the geological significance of the area, emphasising the role of these formations in supporting Mulu’s diverse ecosystems.
In addition to geological insights, the Kyoto team conducted thorough botanical surveys, cataloguing and describing a variety of plant species within the park.
They documented several distinct vegetation zones and noted the presence of endemic plants such as orchids and ferns.
However, it was the Royal Geographical Society Expedition in 1977-1978 that truly elevated Mulu’s reputation as a world-class site for biological, caving, and ecological research. This extensive 15-month expedition involved over 100 scientists who conducted comprehensive studies across various disciplines.
The expedition’s findings laid a strong foundation for future research, inspiring continued scientific interest and supporting conservation efforts that would eventually lead to Mulu’s designation as a UNESCO World Heritage Site.
Their efforts led to the identification of more than 2,500 plant species, 60 mammal species — including the world’s smallest, Savi’s pygmy shrew — over 260 bird species, and 320 fish species.
Insects were estimated to number around 12,000 species, and fungi over 8,000.
The expedition explored and mapped over 50 kilometres of cave passages, including the vast Deer Cave and the Clearwater Cave system, revealing some of the world’s most extensive and unique subterranean landscapes.
These expeditions have been instrumental in uncovering the intricate dynamics of Sarawak’s rainforests and highlighting Mulu’s critical role in global biodiversity.
As such, the park is recognised as a natural laboratory, where researchers continue to study the relationships between geology, climate, and the species that depend on this unique environment.
Biodiversity Hotspot and Indicator of Sarawak’s Ecological Health
Though Mulu and Buda cover only about 0.5 per cent of Sarawak’s land area, they represent an invaluable microorganism of the region’s biodiversity.
Wong said this makes them essential indicators of Sarawak’s overall ecological health.
“The biodiversity contained within these parks is nothing short of remarkable. As easily accessible showcases of Sarawak’s immense biological wealth, Mulu and Buda offer rare insight into the ecosystems that once covered much of Borneo.
“Mulu and Buda’s lowland riverine and hill forests remain largely untouched by deforestation and other human impacts, making them a haven for species that have disappeared from other parts of Borneo,” she explained.
The parks are home to an impressive array of tree species, including the vital dipterocarps — the tree family that includes meranti and selangan batu, valuable not only for their timber but for their role in forest ecology.
In Mulu’s lowlands, Parashorea macrophylla (a member of the dipterocarp family) dominates, providing a dense canopy that helps sustain the forest ecosystem below.
These trees play an irreplaceable role in forest regeneration and habitat creation, supporting countless other species, from insects to larger mammals.
Adding to Mulu’s ecological richness are the large stands of Bornean ironwood (Potoxylon melagangai), an endemic species with large populations crucial for wider-range seed dispersal.
Ironwood’s presence, in turn, aids in maintaining the stability of Mulu’s forests, as these trees have a significant impact on the surrounding soil and forest floor composition.
Their seeds and nutrients spread across the area, helping to regenerate and stabilise forest systems even during environmental stresses.
“Mulu is not just a park; it is a living indicator of ecological balance. The diversity here reflects the health of Sarawak’s greater environment and provides invaluable insights for conservationists,” she added.
Balancing Tourism and Conservation
Even though Mulu and Gunung Buda National Parks are incredible natural sanctuaries, they face a complex balance between preservation and the pressures of modern tourism.
Among the long-term threats to these parks is climate change. Wong said the potential for shifting rainfall patterns could impact Mulu’s delicate limestone flora.
“At the current time, there aren’t any irrefutable impacts from climate change visible. However, the limestone biomes in Mulu are some of the most sensitive.
“If significant changes in water availability occur, the impact on these ecosystems could be profound,” she said.
Ironically, one of the more immediate challenges stems from tourism itself.
While tourism generates vital funding and raises global awareness of Mulu’s ecological value, Wong said it also creates direct risks to the park’s delicate environment.
“Some visitors, straying from marked trails, have caused erosion and damaged sensitive areas like the Paku Waterfall trail. This is a reminder of how important it is to balance public access with preservation,” she said.
As such, Wong stressed the importance of proactive tourism management.
“Mulu and Gunung Buda are some of the best-managed protected areas in Sarawak, but they are also some of the most popular for tourism. The impact of visitors cannot be underestimated.
“Managing this impact is particularly challenging given Mulu’s logistical constraints. It’s an ecologically sensitive area, accessible only by river and air.
“Providing sustainable accommodation that meets international standards, while keeping the natural landscape undisturbed, is no small task,” she said.
Beyond the park boundaries, Wong pointed out that agricultural and plantation activities could present a further threat.
Although these areas technically lie outside protected zones, she said they pose risks if not carefully regulated.
“Encroachment into park land could disrupt sensitive ecosystems, thus threatening Mulu and Gunung Buda’s unique biodiversity,” she said.
One of Mulu’s strengths lies in its collaborative relationship with local indigenous communities, whose traditional knowledge and cultural ties make them natural stewards of these lands.
However, Wong said this relationship may occasionally pose challenges, particularly in managing forest produce collection.
“The local communities are a vital part of Mulu’s management, but it requires a careful balance to protect these resources while respecting their traditional practices,” she said.
Inspiring the Next Generation of Conservationists
For those passionate about conservation, Wong emphasised the importance of genuine long-term enthusiasm and a determination to take the time to truly learn as much as possible about biodiversity, ecology, and potential threats.
She also said aspiring conservationists must understand that biodiversity work often means extended periods in remote locations, sometimes cut off from modern conveniences.
“Biodiversity study in all its numerous facets is not a 9-to-5 job with weekends free. Field research demands dedication, patience, and a willingness to spend time immersed in nature, observing its rhythms and subtleties,” she said.
Looking toward the future, Wong highlighted the importance of equipping young conservationists with the skills to balance conservation goals with practical challenges.
“Conservation in places like Mulu requires a blend of scientific knowledge, community engagement, and sustainable practices,” she added.
Mulu is a living masterpiece of nature’s resilience and evolution, where ancient landscapes and rich ecosystems reveal the intricate dance between geology, climate, and biodiversity.
Each trail, tree, and cavern in Mulu offers a glimpse into the dynamic processes that have shaped our planet, inviting scientists, explorers, and visitors alike to witness a world where nature thrives in its most extraordinary forms.
