Regenerating Logged Forests

Background

Solomon Islands has endured sustained, high intensity logging over a large percentage of the land mass for over 40 years with many logged areas having been re-logged, some twice. This has an enduring effect on the structure of the forest and while, if left completely alone for a considerable period (probably centuries), the forest will regenerate, the immediate effect of logging is devastating. Problems associated with logging include the pollution of waterways from erosion, loss of habitat for native animals, and birds, and loss of amenity for the local communities. Areas that were actively used by communities for hunting, for gathering food and fibre, for medicine and traditional practices and for the very building materials for village life are left abandoned. Logged forest has been described as a "wasteland" by members of local communities that the project team has discussed the issue with.

Research

The project had the opportunity to establish a small trial on an island where logging had ceased 3 months earlier. The island is called Vasavasara and is situated in Vonavona lagoon in Western Province. It is a small island of approximately 77 ha in size but had been logged as it had a high concentration of Vitex cofassus, a timber that is sought after for both local use and as a valued export timber.

Three areas of 0.1 ha were cleared of all but the regenerating seedlings of commercial species of timber including Flueggea flexuosa, Vitex cofassus and Pomatia pinnata. Regular visits were made to the area for weed control and to measure the trees. After 3 years the trees were thinned as the regrowth was dense enough to cause competition for resources. The Vitex was measured at 15 m in height and weeding was no longer needed.

A further three areas were given the same treatment to see if a similar response could be gained in areas that had been overgrown following logging. These areas had not been touched in the three years following logging and had been overrun with weedy species and so choked up with growth they were virtually impenetrable. It took a concerted effort over two days to clear out the weed species and the keen eyes of experienced forest officers to spot the small seedlings of the species we wished to preserve. Three months later active weed control had resulted in a positive growth response from existing seedlings and the sprouting of more from the soil seed bank. In much they same way that the forests respond when cyclone damage clears an opening , the suppressed seedlings and the soil seed bank provided a vigorous re-growth of the species we were trying to encourage. The response from the new areas has been encouraging and 18 months following establishment, we are looking at thinning and selection of the most promising trees.

Conclusion

The project has shown that, with a minimal amount of effort, it is possible to return the value back to logged areas far faster than previously thought. By careful selection of species the forest can be regenerated to suit the purposes of the community, be it for traditional or commercial use. By promoting the growth of Vitex, the trees are now growing at a higher density than prior to the logging, the area is accessible as the rampant weed growth is now controlled naturally through shading and the only maintenance that will be required will be thinning of the trees to reduce competition for resources.

While this operation is most easily accomplished immediately after logging, it is not too late even 3 years later, though the amount of work required to clear the area is considerably more. Controlled natural regeneration is a viable alternative to plantation establishment, can achieve multiple outcomes dependent upon species selection, and requires no seeds, no nurseries and no ground preparation.