Strategists
According to MacArthur and Wilson's (1967) theory of island biogeography, there are two kinds of ways which plants can adapt and strategize to adapt to their conditions. The so called r-strategists are herbs which are short lived, light demanding, and have biomass mostly to produce large amounts of seeds. On the other hand, ideal K-strategists are slow growing long-lived trees with biomass used to produce a large stature, and have shade tolerant seedlings, and have larger, fewer and poorly dispersed seeds. The former is adapted to rapidly changing environments, being able to quickly grow and disperse its seeds so that at least some may survive to continue the lineage, while the latter is adapted to stable, unchanging environments. As can be seen, belukar plants are more r-strategists. They are adapted in many ways to survive and be more successful in the belukar environment. As mentioned above, there are many environmental factors they have to contend with.
Water
To deal with the low amounts of water available to them, belukar plants have thick and small leaves, (Turner & Tan, 1991) with more dry weight per unit area than primary rainforest plants, which, according to Whitmore (1975), tend to have large and thin leaf laminas. Furthermore, Adinandra belukar plants have tough and sclerophyllous leaves in comparison with Trema belukar plants (Boo, 1996), most likely since the latter have more water available to them in a more humid environment. According to Chee (1987), rhizosclereids can be found in Adinandra, and astrosclereids in Fagraea. He also reports the texture of most belukar plants as coriaceous or chartaceous, qualitatively confirming the tough nature of the leaves. Having tough leaves may also be a form of protection against animals consuming the foliage, as they would tend to choose softer and tender leaves for consumption. (Choong et al, 1992) Furthermore, pioneer plants tend to have low resistance to water transport (Bazzaz, 1996). Adinandra, Melastoma, and Ploiarium also have young in-curled leaves, possibly to reduce water loss by transpiration by creating a small zone of more humid air around the leaves. In addition, most important belukar species have about 2 layers of cells in the upper palisade mesophyll layer in their leaves, except for Vitex (1) and Fagraea (4-5). This is probably also another means of preventing water loss through the leaves. Dicranopteris, the sun loving fern, has a waxy cuticle layer on both sides of its fronds, as well has having a closely arranged palisade mesophyll layer, a tactic to save water. In addition, the stomata in Dicranopteris fronds are sunken and surrounded by raised cells, which create pockets of humid air around stomata to reduce water loss. The waxy cuticle on the underside of Dicranopteris is flaky, and hence may act as 'heat fins' to dissipate excess heat as the plant is often in direct sunlight. (Silachart, 1995)
Growth and Photosynthesis
In order to have successful establishment and dispersal, belukar plants mature very fast. For example, 6 day old Adinandra and Fagraea plants already have primary roots covered in root hairs. Macaranga spp., another common pioneer plant, produces lateral roots when only 1-4 days old. (Chin, 1970) Fast root growth is important to get water, which is more important for young seedlings than mature plants. Belukar seedlings are also light demanding, needing a lot of light for good growth. This gives them an advantage over the shade-loving forest-floor herbs found in the understorey of primary forests. Their rapid growth results in the mature plants being tall and thin, almost pole like. Hence venturing into a belukar forest is somewhat like walking into a forest of poles. Turner et al (1994) report that primary forest herbs are rarely found in mature secondary forest in the Central Catchment area, perhaps due to their aversion to such environments. They have high photosynthetic rates, and high light saturation intensities. Their maximal photosynthetic rates are higher than primary plants. Hence, they can better cope with the greater light exposure in belukar, and the high rate of photosynthesis means that the plant can generate more biomass quickly and grow rapidly. However, the photosynthetic apparatus of belukar plants is not very efficient, and Boo (1996) suggests that this might be due to insufficient nutrients being channeled to it. Interestingly, a light-demanding plant like Dicranopteris may experience having too much light as it tends to grow in exposed places, hence to cope with that problem it has undulations on the surface of its fronds that reflect of some of the incident light, reducing light intensity and the possibility of photodamage to plant cells. (Silachart, 1995)
Nutrition
Nutritionally, the soils are deficient. Therefore, the plants which grow in belukar need to survive on low nutrient concentrations. In fact, high nutrient concentration may even be toxic to belukar plants. Nepenthes spp. attempt to supplement the little nitrogen they can get from the soil by having developed pitchers, which are mentioned above. They digest insects and even small animals (although some creatures can survive in the pitchers) to give more nutrients. Their presence in belukar is a very good indicator of the nutrient poverty of the soil. Although legumes (except for the exotic Acacia) are not commonly found in belukar, Myrica esculenta, a common plant on the Ridge, forms an association with Frankia (an actinomycete) that forms root nodules that fix nitrogen (Sim, 1991).