Peninsular Malaysian rainforests

• Category: Forest Biomes
• Geographic Location: Southeast Asia
• Summary: These biologically diverse rainforests feature continental Asiatic and Australasian floristic elements.

Peninsular Malaysia in southeast Asia was once fully covered by tropical rainforests before the arrival of humans, and even now, about half of the tropical rainforest formations are still present. The rich biological diversity in this biome may be attributed to geographical history and to the complex terrain and soil conditions present on the peninsula.

Geographically, peninsular Malaysia is the southernmost extreme of the Asian continent. Some geological evidence suggests that a broad continuous mountain range connected eastern Asia to the Indonesian islands via peninsular Malaysia in the early Tertiary period, about 60 million years ago. This land connection permitted many mainland Asiatic flora to migrate to the southern latitude during the global cooling event by the mid-Tertiary.

In the Middle Miocene, about 10 million years ago, after the Australian Plate fully collided with the Asian Plate, some of the original Australian taxa crossed the shallow sea that was present at that time, and entered mainland Asia via peninsular Malaysia. Thus, peninsular Malaysia was an important pathway for the exchange of biological elements from two continents, and acquired some of its rich biological resources through those biogeographical events.

Biodiversity

The ever-wet tropical climate, with annual rainfall exceeding 98 inches (2,500 millimeters), and rather uniform diurnal temperature throughout the year of approximately 7991 Fahrenheit (2633 Celsius), permits many tropical plant species to establish and grow in the region. Except for the extreme northwestern region of peninsular Malaysia, which experiences a few dry months every year, the dry spells in a large part of the peninsula are usually short. Hence, in such humid tropical conditions, the changes in land relief, soil type, and soil water level are among the key environmental factors that regulate the distribution and pattern of the vegetation in peninsular Malaysia.

The lowland evergreen rainforest is the main forest formation found in lowland peninsular Malaysia, and it sustains the highest biological diversity compared to any other vegetation type. The forest here developed on well-drained soils, and is dominated by members of a single tree family, Dipterocarpaceae; hence, the forest is often referred to as a Dipterocarp forest. The forest is well known for its intense plant diversity, with numerous plant species growing together but usually occurring in low numbers.

The main mountain range runs along the length of the peninsula, with its maximum height of about 6,890 feet (2,100 meters) above sea level. Most of the mountains in the peninsula are granitic; in fact, two-fifths of the peninsula is comprised of granitic rocks. Granitic rocks are coarse-grained, crystalline igneous rocks that are found in the continental crust around the world. Change in land relief has a significant influence on the local temperature and rainfall distribution, which consequently shapes the vegetation found there. On this mountainous region, lowland evergreen forest is replaced by lower mountain forest, with upper mountain forest occupying the summit region.

Beach forests are found along the east coast of Peninsular Malaysia, with mangroves more common along the western coasts. Among the mangrove swamps, brackish water vegetation is common, especially in areas where fresh and saltwater mixes during high tides. Peat swamp forests develop in areas that are permanently waterlogged, and the soil there is highly acidic and mineral deficient. The tualang tree is one of the tallest trees found in the Peninsular Malaysian Rainforest biome. It can reach heights of over 250 feet (75 meters). Over 6,000 species of trees have been identified here, making the area quite rich in flora.

Animal species found throughout the rainforest include about 450 species of birds, such as the crestless fireback pheasant and other pheasants, woodpeckers, hornbills, and pigeons. Asian elephants, rhinos, and other large mammals lumber through the forests, while the endangered Sunda otter-civet preys upon local amphibians. The Malaysian tapir and brush-tailed porcupine are also found in this rainforest. This area is also one of the few remaining natural habitats for the rare Malayan tiger.

Threats

In Peninsular Malaysia, forest loss is traditionally associated with commercial agricultural development, timber extraction, and mining. Between 1971 and 1989, during the peak of agricultural expansion, the forest area declined by almost 50 percent. With the global rise in demand for palm oil in the twenty-first century, this deforestation continued to increase as Indonesia became one of the world's top palm oil suppliers. Between 2000 and 2012, Malaysia had the highest rate of deforestation in the world, losing 18,244 square miles (47,278 square kilometers) of forest. The rate of deforestation declined from the mid-2010s, but by the 2020s, palm oil plantations covered 47 percent of the country's planted area, representing 17 percent of the country's total land area. Although logging restrictions exist, the Indonesian government allows forests to be cleared if they are linked to certain types of development, such as a palm oil plantation. Around 85 percent of the country's forests were protected regions by the 2020s, but palm oil companies continued to clear the land, primarily in Pahang, Kelantan, Terengganu, and Johor.

However, timber and forest-related products are still important export commodities that bring significant revenue to Malaysia. Of the 14.6 million acres (5.9 million hectares) of forested area (40.7 percent of Peninsular Malaysia’s total land area), at least half is categorized as “production forest,” meaning it is still subjected to timber extraction, albeit with appropriate forest management schemes to be followed and monitored.

Individual Malaysian states have complete jurisdiction over forestry matters; forest commodities have been critical in providing revenue for state budgets. Although a central body, the National Forestry Council was set up by the federal government to serve as a forum for discussing and coordinating the forestry policies among the eleven states in peninsular Malaysia. There has been considerable variation in actual implementation and enforcement by different state governments.

However, the fact remains that the high biodiversity found in the Peninsular Malaysia Rainforest biome is largely attributed to the region's terrain and soil complexities. A proper federal management plan that considers the protection of various natural ecosystems found in different states in the context of climate change is essential to safeguard the extreme range of habitats. Average rainfall began declining in 1990, and the number of drought events experienced in the region began increasing in 1980. A pattern of increasing temperatures are likely to increase the number of heatwaves the area experiences, and variations in precipitation may increase the frequency of droughts and floods in the region. These types of changes impact patterns of seed germination, food availability, and breeding seasons and, thus, present new stresses for the rainforest's plants and animals. Poaching is also a threat in the area. In 2010, the Sumatran rhinoceros was declared extinct in the Peninsular Malaysian region, and its population decline was attributed to poachers who killed the species for their horns.

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