Lesser-known timbers for maritime and riverine construction

Abstract

Dense tropical hardwoods are commonly used in maritime and river structures because they have the necessary strength and display some required durability including good resistance to abrasion and to attack by marine borers. Owing to environmental concerns about the sustainability of forest products, responsible procurement regimes now require that tropical hardwoods are certified from a sustainable and legal origin. However, timber is generally selected from a restricted number of species with proven track records of in-service performance, for example greenheart and ekki. There are concerns that over-reliance on a small number of timber species is exerting disproportionate environmental pressure on these species in their forests of origin and could encourage removal of timber that is not produced legally or sustainably. The present research sought to find alternative lesser-used timber species that are commercially available, can be legally and sustainably sourced and would display appropriate performance for maritime and riverine applications. A desk study first established a long list of potential lesser-used timber species. These were screened for resistance to attack by maritime gribble and to abrasion. The resulting shortlist of candidate species has been screened for resistance to shipworm through in situ exposure at a site known for its aggressive shipworm population. In addition to these results, the proposed approach to assess the actual full-scale performance of lesser-used timber species is introduced