Neo-Colonisation

by Angela Hijjas

From The Malaysian Naturalist, vol. 53 no. 3.

For the naturalist gardener to transform a bare patch of ground to forest, one needs to simulate the natural processes of plant colonization. The inexperienced gardener who plants durian seedlings and expects the fruit exactly on cue seven or so years later invariably finds that the tree does poorly unless it has lots of company around to shade and protect it. For a forest species, an exposed site has too many extreme conditions of light and humidity, as well as being the most succulent thing around for the local munchers.

In the natural system of plant regeneration in Malaysia, lalang (Imperata cylindrica) and ferns are usually the first plants to colonize an exposed patch; wind delivered seeds and spores set quickly and cover the entire area, anchoring the soil and providing an acceptable environment for the next wave of colonists, like senduduk, or Melastoma (below), which will find a niche amongst the tough grass roots to emerge another foot or so higher than the lalang. Their seeds are dropped by birds like the yellow vented bulbul that frequent open spaces. Trees that can tolerate the hot extreme conditions, like Macarangga, Malotis and Pulai, are the next species on the scene with their energy concentrated on producing soft, light timber to gain a height advantage.

These colonists are not long livers but they attain maturity quickly and can flower and fruit within a short space of time, exploiting the window of oppor tunity as well as modifying the environment for the next succession of plants. In a way, the success of the colonizing individuals does not bode well for successive generations of the same species, as the parents change the habitat so that it is not so suitable for their offspring, a process not unlike pushing the young out of the nest. The successive waves of colonizing plants are constantly on the move, seeds transported by wind or animals, distributed widely to take advantage of any suitable forest opening.

Then come the herbaceous creepers, creating a net that encloses the planting that has emerged so far, providing soil litter, shade and higher humidity for the germination of seeds blown or brought in from surrounding forest.

Like every species the creepers exploit a competitive advantage over other plants, but can only achieve it within the timetable of regeneration. Before there is any height provided by the colonizing soft woods, their climbing habit provides no advantage, and once the canopy is too high they lack the structural strength to reach the sunlight. However, within that opening they are well nigh impossible to eradicate.

In the replanting programme of the Sabah Foundation’s reserves around the Danum Valley, saplings are not planted o ut for two decades after logging, as the foresters wait for the creepers to subside, a long time when considering the growing period required before harvesting, but an essential duration to restore the appropriate conditions for soil and micro-climate.

The common simpoh air, Dillenia sufruticosa, flowers and fruits prolifically soon after planting. As a garden species, it is pretty but can quickly squeeze out less aggressive competitors and form dense thickets.

With each successive stage of colonization, there is a gradual increase in two important factors: the number of species present in the area, and the height above ground of the vegetation, representing the slow but inexorable progress back to forest status. However, this makes the assumption, not often fulfilled in the real world, that there is a source of seeds within a reasonable distance so that new species can be reintroduced when the time is appropriate.

In Malaysia, we are led to believe that we inhabit a green nation because we have a such a large proportion of country side covered by plants, but these figures include mono-cultural plantations that are mocked by the diversity of a true forest. If we are concerned about conserving natural habitats, the rule of thumb is that the height of the canopy will determine the conservation potential or the richness of species and habitat diversity present on a given site. This is the information that should be mapped, not a mere swathe of plantations, to give a true indication of how green is our country.

As a gardener, my life span cannot be measured along side the forest and I am impatient to see results sooner rather than later; short cuts are in order. I weed away the creepers and hope that lavish spreadings of cocopeat will simulate a natural environment for soil formation and water retention; I plant bananas as a ‘nurse species’ around the durian seedlings but I suspect this is not enough and that before too long I will have to relent and interplant with some ‘temporary’ shade trees.

All this leads to a ‘garden’ that could not be further from the DBKL landscape, in fact many would not even consider it to be a garden but an illogical mass of impossible mix. I plant densely in full knowledge that perhaps only a handful will ultimately flourish and carefully protect anything that somehow finds its way into the garden without me having to introduce it. So far my only prize in this category is the lembah, a small herb with palm-like pleated leaves; its fruit is eaten by the Orang Asli to stimulate the taste for sweetness.

Unfortunately my kampong is too far from any remaining forest to benefit from the natural progression of colonizing plants, so I manually introduce everything from all stages of the colonization spectrum, including the forest hardwoods that are so slow to grow as they concentrate their energy in producing the hardest timber for long term structural strength and leaves with complex chemicals that prevent insect attack. A belian tree in Rimba Ilmu that is a quarter century old is barely 30 feet high with a trunk of only 6″ diameter; its leaves are not attacked at all, but it offers a critical clue to the time span necessary to reach fruiting maturity.

My efforts are trying to short cut the natural progression of the colonizing species, even though I know it is illogical and that I am trying to control nature by eliminating even the first process of lalang: cow grass demands more nutrients than lalang and can be a major drain on the soil placing other plants at a disadvantage, so then one must clear around the saplings and ensure that there is some nutrient substitution. Gardening is all about controlling nature, but on the grand spectrum I see my process being a little closer to nature than the clipped minutiae of DBKL, my version of neo-colonization.

The round of the naturalist gardener becomes a routine one, but the rewards are immense: to enjoy the shade of a tree planted just a few years earlier, to watch birds feed on its fruit, even to begrudgingly admire the tenacity of the squirrels as they penetrate the durians or coconuts to reach the succulent flesh, provides the greatest satisfaction.