We describe literature-based research on the viability of whole-culm bamboo as a construction technology for South Africa. South Africa has one bamboo species considered suitable for construction, namely Bambusa balcooa, found in various parts of the country. Quantitative production figures are not currently available; however, local reports indicate that South Africa can expand its bamboo growth industry to meet any possible expected demand. Although the South African bamboo plant has not yet been evaluated in terms of its material properties, engineering design approaches and material properties from the literature indicate that this species is a viable construction material. The limitations for bamboo design and construction are not unique to South Africa but are common to countries involved in bamboo construction. Their experience in overcoming these limitations can be transferred to the use of bamboo in South Africa, making bamboo construction a potentially viable construction technology in South Africa. Significance: • Whole-culm bamboo can be used as a structural material in buildings and other specialised structures such as bridges, assembly halls, and the like. • South Africa has a bamboo species that should potentially be suitable for the construction of structures that lend themselves to this type of construction. • The information given here should allow designers, engineers and technologists to assess the viability of bamboo construction in South African situations.

A colheita seletiva de madeira pode vir a ser uma forma sustentável de uso da terra para ecossistemas florestais da Amazônia, uma vez que permite a manutenção de parte considerável da biomassa florestal, diminuindo, assim, a perturbação nas áreas exploradas. Neste sentido, o presente estudo teve como objetivo avaliar o efeito da exploração seletiva de madeira sobre as características físicas de um Latossolo Amarelo. A área de estudo localiza-se a cerca de 80 km ao norte de Manaus e a vegetação é do tipo Floresta Ombrófila Densa. O número de árvores retiradas com um trator de esteiras D6, por arraste, em 1993, variou de sete a dez árvores/ha (DAP > 55 cm). O delineamento experimental foi do tipo blocos ao acaso, com três repetições. Seis tratamentos foram avaliados, equivalendo às seguintes classes de perturbação identificadas na área: trilha de trator, centro de clareira, borda da clareira/floresta, borda da floresta/clareira, floresta remanescente e floresta-controle. A colheita seletiva de madeira provocou modificações nas características físicas do solo, principalmente nas trilhas de trator, e representou, em média, 13,8 % da área total explorada. Os valores de densidade do solo e resistência à penetração foram maiores para o solo sob estas áreas, enquanto a macroporosidade e o volume de água disponível para as plantas apresentaram-se menores do que nas demais classes de perturbação. Estas classes foram menos afetadas, não se estabelecendo diferenças significativas para as características físicas do solo entre estas e a floresta-controle, indicando, assim, a colheita seletiva como uma prática de menor impacto para o solo dos ecossistemas florestais da Amazônia.

Selective logging may become a form of sustainable use of Amazon forest ecosystems since most part of the forest biomass is maintained and the impacts on the exploited area are lower than in comparison to those under other land uses. The objective of this study was to evaluate the effects of selective logging on some soil physical characteristics. The study area lies about 80 km north of Manaus and the vegetation is a humid tropical rainforest. Seven to ten trees/ha (DAP > 55 cm) were felled and removed by a D6 bulldozer, in 1993. Six disturbance classes were defined in the logged plots, with three replicates each: tractor track, center of clearing, edge of clearing, edge of forest, remaining forest and control forest. Soil under tractor tracks represented 13.8 % of the exploited area, and showed higher values of bulk density, and penetration resistance, and lower macroporosity and available water for plants than the other disturbance classes. The other classes were less affected and no significant differences were observed between their soil properties and the control forest, indicating selective logging as a practice that causes less impact on soils of Amazon forest ecosystems.

Variáveis físicas do solo foram investigadas em parcelas de floresta de terra firme submetidas à extração seletiva de madeira na Amazônia central. Foram obtidas curvas de retenção de água no solo, juntamente com medidas de água disponível no solo às plantas, densidade do solo e porosidade total. Medidas de temperatura do solo foram realizadas por mais de 13 meses, considerando seis tratamentos: controle, centro da clareira, borda da clareira, borda da floresta remanescente, floresta remanescente e trilha do trator. Medidas de condutividade hidráulica de solo saturado foram feitas na floresta e em clareiras, sem distinguir os tratamentos. O solo revelou baixa capacidade de armazenar água disponível: apenas 11 a 18% da água pode estar disponível às plantas, num perfil de 1 m de profundidade. A temperatura das camadas superiores do solo foi influenciada pela extração seletiva de madeira: nas clareiras abertas, a luz chega com mais intensidade no solo, proporcionando temperaturas mais elevadas no centro e nas bordas das clareiras do que no controle e na floresta remanescente.

Soil physical variables were investigated in forest plots submitted to selective logging in Central Amazonia. After logging, soil samples were collected to obtain soil water retention curves and measure: available soil water to the plants, soil density, and total porosity. Temperature measurements were carried out for 13 months, considering six treatments: control, center of the gaps, edge of the gaps, edge of the remaining forest, remaining forest and tractor tracks. Hydraulic conductivity measurements on saturated soil were conducted both on the control forest as well as on the logged plots, with no treatment distinction. The soil showed a low available water storage capacity: only 11 to 18% can be available to the plants, up to 1 meter depth. The temperature of the soil upper layers was influenced by logging, i. e., through the opening of the gaps, light reaches the soil more intensely in the center and edge of gaps, increasing temperatures in relation to the control and the remaining forest.