About the Reforestation Process

The tropical rainforest is one of the oldest and most diverse ecosystems in the world. Some places in the rainforest have over 160 tree species per hectare and over 1000 individual trees per hectare (excluding seedlings under 10 centimeters in diameter).

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In northeastern Queensland, over 800 species of tree have been identified. Add other plants like ferns, orchids, palms, mosses, and lichens, and that number jumps to the thousands. In the Daintree, there are over 400 species, many of which exist only locally. The most diverse area is in Cape Tribulation, where we stayed.

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Needless to say, this is a treasure of land rich and abundant in life. Under normal circumstances, the area has an amazing ability to regenerate itself and recover from natural disasters and other setbacks. However, when human activity like clearing for agriculture takes place, the recovery process is severely hindered or even becomes impossible. Nevertheless, with the right conditions, seedlings exposed to sunlight from the break in the canopy can rise up and initiate the regeneration process.

Daintree: Jewel of Tropical North Queensland, by Lloyd Nielsen, outlines the four distinct stages of regeneration:

The first is the prompt appearance of small weedy annuals. The next is one in which longer-lived weedy plants replace the annuals. These may live for four or five years. The third stage is one where pioneer species dominate. This stage consists of trees such as Milky Pine, Sarsaparilla, White Cedar, Bleeding Heart, Blackwood and others. All are short-lived, their life spans rarely exceeding 25 to 50 years. It is this stage, sometimes combined with the second stage, which some people mistakenly interpret as a poor type of rainforest, referring to it as 'rubbish' or 'second growth'. It is in fact a vital part of rainforest regeneration. The final stage, the so-called mature stage, is one in which the pioneers give way to the long-lived tree species which eventually return to the rainforest to a pristine condition. It may take 600 to 800 years or more for some of these to reach the mature proportions of their predecessors.

For the first three stages, germinating seeds can come by wind, birds and other animals, and water. Each plant produces a myriad of seeds that can span the entire rainforest, waiting for a break in light to germinate. During the final stage, seedlings of many trees are unable to grow because they lack sunlight, but are capable of remaining alive in the shade for years, waiting for the canopy to open. When they do finally get light, the competition to spurt to the top of the canopy is fierce and few survive. The cycle repeats when the seedlings from the canopy trees fight for survival and sunlight blocked by their own parent trees.

For us, it was important to restore the imbalance in every part of the reforestation process. Weeds exposed to sunlight grow too fast, impeding the growth of seedlings. Overgrowth of vines strangle young trees and prevent them from growing. Seedlings receive an overkill of sunlight, too much without rain or partial shade from the canopy. It was our job to aid the seedlings by giving them a head start against all the natural obstructions. Furthermore, it was important to identify which species were important for which stage of the reforestation process. Certain pioneer species needed to be planted first in order for primary and secondary successional species to follow. Plants would fail if they were introduced in the wrong part of the process, making it key to identify which trees were which.

Identifying seedlings of pioneer species for potting and replanting