Kayan River tributary, Bulungan, North Kalimantan, Indonesia

Environment

Surrounding area

The Bulungan region of North Kalimantan is a remote, forested area characterized by dense tropical mountain forest. In this region is the majestic Kayan River, which extends for 576 km through valleys, mountains and dense jungles. The river is distinguished by its abundant boulders of karst origin and muddy banks full of minerals that pile up due to the fluctuations of its current. The area is located at 2300m above sea level, providing a unique habitat for rich biodiversity.

Weather conditions: Temperature: Ranges between 17º to 27ºC.

Tropical mountain climate with two marked seasons:

• Wet season: from November to April, during which heavy torrential rains wash away trunks and leaves, slightly staining the river waters with tannins from organic matter.
• Dry season: from May to September, in which the river water goes from its natural crystalline state to acquire a whitish color due to the accumulation of deposited minerals and sediments.

Aquarium plants:
In this area, one can find some of the most appreciated plants in aquariums:

1. Bucephalandra sp. (Araceae). Size: 5-20cm high. Leaves: small, elongated and leathery, dark green sometimes with reddish, brown or bluish tones. Habitat: grows on rocks and logs in slow-flowing rivers.
2. Dipteris lobiana (Dipteridaceae). Size: up to 1m high. Leaves: large, lobed fronds. Habitat: prefers shady and humid areas.
3. Homalomena sp. (Araceae). Size: from 30 cm to 1 meter high. Leaves: large, heart-shaped, deep green. Habitat: grows in soils rich in organic matter.
4. Homalomena humilis (Araceae). Size: smaller than other Homalomena sp. Leaves: dark green, lance-shaped. Habitat: shaded and humid areas.
5. Taxiphyllum sp. (Hypnaceae). Size: can grow several centimeters in length. Leaves: small and green, densely arranged along thin stems. Habitat: grows on surfaces submerged in slow running water.

Terrarium flora: On the banks of the river there are also highly appreciated species for terrariums:

1. Macodes sp. (Orchidaceae) – Jewel Orchid. Size: small terrestrial orchids. Leaves: decorative, with shiny veins in distinctive patterns. Habitat: they prefer humid and shady environments.
2. Dendrobium spp. (Orchidaceae). Size: varies depending on the species. Leaves: elongated and arranged in canes. Flowers: various shapes and colors, highly appreciated for their beauty. Habitat: epiphytes grow on trees or rocks, in humid and shady areas.

Conservation: it is crucial to protect these areas due to their biodiversity and the presence of unique and threatened species.
Ecological importance: the forests and rivers of this region are not only vital for local flora and fauna, but also have a significant impact on climate regulation and the water cycle.

Terrestrial vegetation:

• Dipterocarpus merandi (Dipterocarpaceae)
• Shorea spp. Meranti lauan (Dipterocarpaceae)
• Agathis borneensis (Araucariaceae)
• Ficus spp. (Moraceae)
• Eusideroxylon zwageri (Lauraceae)

Conclusion: The Bulungan region of North Kalimantan is a complex and vital ecosystem that is home to rich biodiversity, including plants prized in both aquariums and terrariums. Its conservation is essential to maintain ecological balance and preserve the natural beauty of Borneo.

Underwater landscape

The Kayan River, which spans 576km in the Bulungan region of North Kalimantan, offers a fascinating and diverse underwater environment. Below is a detailed description of this aquatic ecosystem:

Wet season (November – April): during the rainy season, the clarity of the water is affected by the presence of tannins carried by organic matter, such as trunks and leaves, which gives an amber tone to the river waters. Visibility may be reduced, and the water surface may appear cloudy and dark due to suspended sediment.

Dry season (May – September): in the dry season, visibility improves considerably. The crystal clear waters of the river turn slightly whitish due to the accumulation of minerals and sediments deposited on the river bed during the drought.

River bed: the river bed is composed of a mixture of karstic pebbles, sand and fine sediments. The boulders of karst origin form an irregular surface, with large stones and rocks that provide shelter and habitat for various aquatic species.

Muddy banks: the banks of the river have muddy areas full of minerals that pile up due to current fluctuations. These mineral deposits can create mud and mud formations that are important for the formation of specific aquatic habitats.

Aquatic plants: the river is home to a variety of aquatic plants that thrive in its waters. Among them are species such as Bucephalandra sp., which grows on submerged rocks, and Taxiphyllum sp., which adheres to underwater surfaces. These plants not only provide shelter and food for aquatic organisms, but also contribute to the stability of the substrate.

Fishes: the ichthyological fauna includes a variety of species adapted to fluctuations in water flow and variability in water clarity. Fish move between spaces in rocks and sandy beds, seeking food and shelter in the complex environment of the river.

Invertebrates: such as aquatic insects and mollusks are found in the river bed and aquatic vegetation, which play crucial roles in the food chain and in the decomposition of organic matter.

Currents: the river has a variable flow, with faster currents in the steeper sections and areas of calm water in the flatter sections. These currents shape the substrate and create diverse habitats for different aquatic species.

Level fluctuations: seasonal fluctuations in water level affect the dynamics of the river, modifying the extent of flood zones and the extent of sedimentation and mineral accumulation areas.

Natural refuges: rocks, submerged logs and boulder formations create diverse microhabitats that offer shelter and feeding areas for aquatic organisms. These refuges also provide breeding and nursery areas for various species of fish and invertebrates.

Conclusion: the underwater environment of the Kayan River is a vibrant and dynamic ecosystem, characterized by its seasonal variability in water clarity, diverse substrate and aquatic vegetation. The interaction between currents, mineral deposits and vegetation creates a complex habitat that supports rich aquatic biodiversity. This environment is not only essential for local aquatic life, but also contributes to the ecological balance of the region.

Fishlist:

• Betta sp. Antuta/Bulungan (Osphronemidae)

Crustaceans:

• Caridina sp. (Atyidae)

Aquatic plants:

• Homalomena sp. (Araceae)
• Bucephalandra sp. (Araceae)

Aquatic mosses:

• Versicularia sp. (Hypnaceae)

Aufwuchs:

• Dipteris lobiana (Dipteridaceae)

Threats to ecology

The Bulungan region of Borneo faces several ecological threats that put its rich biodiversity and unique ecosystems at risk. These threats have significant impacts on both the natural environment and local communities. The main ecological threats are detailed below:

1. Deforestation: the indiscriminate felling of forests for the expansion of oil palm plantations, wood and other agricultural products.
Impact: loss of habitats for many species, alteration of hydrological cycles and reduction of biodiversity. Deforestation also contributes to the loss of carbon stored in forests, exacerbating climate change.

2. Mines and exploitation of natural resources
Cause: mining of coal, minerals and other natural resources.
Impact: pollution of waters with heavy metals and sediments, destruction of natural habitat and alteration of the landscape. Mining can also lead to soil degradation and loss of biodiversity.

3. Climate changes
Cause: global climate change affecting temperatures and precipitation patterns.
Impact: alteration of ecosystems and climatic seasons, which affects local flora and fauna. Rising temperatures can intensify extreme events such as droughts and heavy rains, affecting water availability and the health of forests.

4. Forest burning
Cause: use of fire to clear land for agriculture and plantations.
Impact: burning forests not only destroys large areas of natural habitat, but also contributes to air pollution and greenhouse gas emissions. Burns can have devastating effects on the health of aquatic and terrestrial ecosystems.

5. Introduction of Invasive species
Cause: the accidental or intentional introduction of non-native species.
Impact: invasive species can displace native species, altering ecosystem dynamics and competing for resources. This can lead to the decline or extinction of local species.

6. Hunting and wildlife trafficking
Cause: illegal hunting and trafficking of exotic species.
Impact: reduction in wildlife populations, disruption of food chains and loss of biodiversity. Hunting and wildlife trafficking also affect the ecological balance and health of ecosystems.

7. Pollution: industrial and agricultural discharges, including pesticides and fertilizers.
Impact: pollution of rivers and soils, affecting the health of aquatic and terrestrial species. The accumulation of pollutants can have harmful effects on human health and ecosystems.

8. Urban expansion and infrastructure development
Cause: construction of infrastructure such as roads, dams and urbanization.
Impact: habitat fragmentation, alteration of fauna migration corridors and reduction of ecological connectivity. Development can lead to the loss of natural areas and alteration of ecosystems.

9. Overexploitation of natural resources
Cause: excessive extraction of wood, medicinal plants and other resources.
Impact: degradation of ecosystems and reduction in populations of key species. Overexploitation can lead to the loss of essential ecosystem services, such as climate regulation and the provision of clean water.

Mitigation measures: to address these threats, it is essential to implement conservation and sustainable management strategies, including:

• Protection of critical areas: establishment of protected areas and reserves to conserve key habitats and biodiversity.
• Regulation and monitoring: implementation of laws and regulations to control the exploitation of natural resources and wildlife trafficking.
• Ecosystem restoration: reforestation and habitat restoration projects to recover degraded areas.
• Education and awareness: educational programs to raise awareness in local communities and promote sustainable practices.
• Research and monitoring: continuous studies to evaluate the state of ecosystems and the effectiveness of conservation strategies.

Preserving the Bulungan region of Borneo requires an integrated approach that addresses these threats and promotes environmental sustainability.

Bibliography

• → Biodiversity and Conservation of the Tropical Rainforests of Borneo - Journal of Tropical Ecology by M.A. Wilkie, J. B. Houghton, et al.
  
• → Conservation Biology - Impact of Deforestation on Tropical Biodiversity in Borneo by S. E. Houghton, P. D. Thompson
  
• → Ecological Research - Ecology of the Kayan Mentarang National Park, Borneo by T. L. Kuswanto, R. H. Evans
  
• → by FishBase
  
• → Betta Macrostoma: The World of the Giant Betta by Horst Linke
  ISBN 978-1495363732
  

Sitography

Comment by the expert