Protection of wood against marine borers
The Amazon
A report to the Government of India has recently been issued by Professor a. Becker engaged by FAO to advise on the protection of wood against the attack of marine borers and to demonstrate at the Forest Research Institute Dehra Dun, the latest developments in research and control.
Deterioration of wood ill sea water is caused by two groups of marine organisms; molluscs and crustaceans. The molluscs belong to the genera Teredo, Bankia and Nausitora of the Teredinidae family, and the genera Martesia and Pholas of the Pholadidae family. Of crustaceans the most important genera, Limnoria and Sphaeroma, are Isopoda; the genera Chelura, Metaponorthus and others belonging to different crustaceae families are of minor importance.
Teredinidae got their name "shipworms" from the long bodies of the adults. Some species grow to 1 meter. The shells cover only the foremost part of the body (Figures 1 and 2) and work as a rasping and boring apparatus to grind the wood. The boring tunnel with the calcareous coating of its inner surface protects the stretched, soft-skinned body. Two siphons ingest and egest the sea water (Figure 3). These siphons can be retracted and closed firmly by means of two calcareous appendages to the body, the so-called pallets. In this state, shipworms are able to survive in spite of removal from sea water or in water of a very low salinity for a period of days to weeks. Propagation of shipworms takes place by freely swimming larvae. Some of the species ejaculate eggs and sperm into the water, of others the larvae develop in the interior of the females, so that the swarming period of the larvae is shortened. The deterioration pattern of Teredinidae is characterized by the long boring tunnel which looks circular in cross section and often rims parallel to the wood fibers (Figure 4).
The shells cover only the foremost half of the body of the Teredinidae, and work as wood-boring apparatus.
FIGURE 3. - Two siphons ingest and egest the sea water.
FIGURE 4. Characteristic long boring tunnel of Teredinidae.
FIGURE 5. - Bivalve shape of Martesia genus of Pholadidae.
The shape of Pholadidae is more like a common bivalve; this is especially true for the Martesia genus, which is very important in tropical waters (Figure 5). These "piddocs" are not fixed on to the wood. The holes they make within the timber correspond to the length of their bodies. The pointed back end with its short siphons extends somewhat out of the tunnel. Martesia grows to a length of about 4 centimeters. Pholadidae also propagate by freely swimming larvae. Though the tunnels - compared with those of Teredinidae - are relatively short (Figure 6), they cause considerable damage; for the deterioration proceeds deeper into the wood from one generation to another.
Limnoria, the so-called "gribble," belonging to Isopoda, is 3 to 6 millimeters in length, flat and unpretentious, and able to roll itself together like a terrestric isoped (Figure 7). The gribbles can leave their tunnels at random, swim about and select new breeding places. Newly infested timber is mostly attacked by young and middle-sized organisms with a peak at certain seasons. Limnoria eats its tunnels quite close to the surface of the wood (Figure 8). Though small in size it completely deteriorates the wood (Figure 9), but takes longer, of course, than the shipworm.
The species of the Sphaeroma genus ("pill bugs") are considerably longer. They grow up to 10 millimeters; their shape is more rounded than that of Limnoria. They, too are able to roll themselves together like other isopods. They are also able to leave their tunnels, creep about on the surface of the wood and swim. Their boring tunnels are never less than twice the length of their bodies but, when occurring densely, they cause serious damage (Figure 10).
All other wood-inhabiting crustaceans are of minor economic importance.
FIGURE 7. - The Limnoria, which is able to roll itself together like a terrestric isoped.
FIGURE 8. - Limnoria boring tunnels are close to the wood surface.
FIGURE 9. - Wood deterioration by Limnoria is complete.
FIGURE 10. - Dense occurrence of Limnoria boring tunnels, cause serious damage.
The FAO officer (Mr. V. Hasek), in charge of the sawmilling training center at Santarem on the Brazilian Amazon, has sent the photograph shown on this page.
At the logging demonstration center at Curua Camp on the Curua tributary of the Amazon, roads have been constructed with mechanized equipment brought in and maintained with some difficulties. Repair of machinery takes a large amount of time and occasionally strong language. The first few compartments have been felled in accordance with prescribed methods. Some of the logs are being cut on a portable sawmill in the forest for use in construction of living quarters which will be somewhat more permanent than the present tents and thatch-covered frames. But most logs will be hauled to the river to the loading-dock being constructed, for transport to the sawmill at Santarem.
Communications, food supply, and transport of tools, parts, and personnel between Curua Camp and Santarem are dependent on a motorboat and steam launch. The motorboat takes about four hours from Santarem to Curua, and about five or six hours against the Amazon current for the return trip. The slower launch requires about 10 hours and 12 hours for the same trips. The technical assistance team must therefore not only be expert in logging, silviculture, and sawmilling, but also in marine motors and navigation, and must possess, as they do, an abundance of patience in dealing with balky motors, water in the petrol, and shifting river channels, not to mention mosquitoes, humid heat, and difficulty in obtaining drinking water, and fresh food.
A vegetable garden is maintained in wooden boxes on stilts at the logging camp. The camp cook is particularly efficient in catching fish, including the edible varieties of the flesh eating piranha, and also in preparing these fish, and the fowl and animals brought in from hunting in the forest. This is a particularly important factor in keeping up the morale and spirits of the road and logging crews.
The other forestry members of the FAO Amazon mission are Mr. G. G. Gray who heads the team, Mr. C. J. Pitt as silviculturist, Mr. B. B. Glerum in charge of forest inventory operations, and Mr. W. O. Hopf, logging instructor. Mr. D. Heinsdjik, who initiated the extensive inventory work carried out over selected areas, has been transferred to Rio de Janeiro to help to organize a federal forest inventory service.
A center for training Indian boys in forestry work has been started at Aychapichu, located 45 kilometers to the south of Quito at an altitude of 3,000 meters. This is a very modest establishment but the history of its origin is highly significant and interesting and deserves to be put on record.
There is a semiautonomous charitable organization working under the Ministry of Social Welfare which is called the Asistencia Pública and owns haciendas (landed estates) out of the profits of which hospitals, orphanages and old people's homes are maintained. It also runs shops to issue some consumer goods and drugs to poor people at cheap prices.
This organization owns the particular hacienda where the forestry training centre is located. The administration of the organization was persuaded by the forestry technical assistance officer in Ecuador, Mr. Gonzalez de Moya, with the help of the then Director of Forests, who was acting as his counterpart, to start a center for the establishment of a forest nursery. This did not succeed for lack of whole-time skilled labor to attend to the work. It was then suggested that some Indian boys, mainly orphans recruited from the Oriente area from missionary societies, be trained here in forestry work. This is how the idea grew.
There are now six boys under training for nine months. They stay at the center and, although the feeding and lodging arrangements are primitive, great credit goes to the organizers for building up this potentially valuable institution from very humble beginnings.
The boys had already received elementary education from the missionary societies. At the center they have been receiving lectures and practical training in elementary forestry subjects as well as in civics, mathematics and geography. They are all likely to find employment in the Government's Forestry Department.
This is attracting the attention of responsible authorities among the public and in the Government. What is particularly satisfying is the fact that this work did not fall strictly within the terms of reference of the FAO forestry officer. He now hopes that the program can eventually be developed into a properly established forestry training institution for Ecuador. For this purpose it is proposed to shift the center to some land belonging to the Forestry Department nearer Quito.
