Uprooting and snapping of trees: structural determinants and ecological consequences

Journal ArticleThe influence of mechanical and architectural properties of trees on growth rates, mortality rates, and relative probabilities of snapping and uprooting were examined on Barro Colorado Island, Republic of Panama. Of 310 fallen trees, 70% snapped, 25% uprooted, and 5% broke off at ground level. Stepwise discriminant analysis between snapped and uprooted trees indicated that of the variables measured, wood properties were the most important factors determining the type of death in trees. Uprooted trees tended to be larger, shorter for a given stem diameter, and to have denser, stiffer, and stronger wood than snapped trees. There were no significant differences between trees that snapped and trees that uprooted in the extent of buttress development or in the slope of the ground upon which they grew. Trees with low density wood grew faster in stem diameter than those with high density wood but also suffered higher mortality rates. After damage, many of the snapped trees sprouted; small trees sprouted more frequently than large trees. Sprouting is proposed as a means by which weak-wooded fast-growing trees partially compensate for being prone to snapping

A Sustainable Forest Future?

Concern about the rate at which the world's forests are being depleted is wide-spread. Recent international calls for radical efforts to reduce deforestation include the United Nations Inter-governmental Forum on Forests of the UN Commission on Sustainable Development (1999), and the World Commission on Forests and Sustainable Development (1999). This concern reflects an appreciation of the ecological and economic functions of forests: as providers of timber and many non-timber predicts, as the habitat for much of the world's biological diversity, and as regulators of local, regional and global environments. These functions are at risk. Most of the forest clearance is in areas of high forest cover and high human population pressure in tropical areas for agriculture. In temperate and boreal areas the pressures from logging are more important. But in all areas, forestry itself has an important role to play both as a partial cause of deforestation, and, if practiced wisely, as a potential source of salvation for at least some of the world's forests. In terms of its causal role, forestry tends to open up primary forest areas, enabling colonists to move in, using roads forged by the timber companies. In some parts of the world, forests are converted not to agriculture but to biomass plantations of fast growing trees or to other agro-industries based on tree-crop plantations such as palm oil and rubber. Here the primary agent is not the peasant, but the richer elements of local and international society. How, then, can the world's forests be used more wisely? It is this admittedly grand and complex question that we seek to answer in this paper. Some argue for outright protection, caricatured perhaps in the phrase 'fence and forget'. Others argue for 'sustainable forest management', and still others for systems of forest management that rely on acceptance of an initial period of exploitation of valuable species followed by outright protection. The issue, then, is the optimal use of forested land , which begs the question of what is meant by 'optimal'. This is addressed shortly

Is Sustainable Forestry Economically Possible?

Concern about the rate at which the world's forests are being depleted is wide-spread. Recent international calls for radical efforts to reduce deforestation include the United Nations Inter-governmental Forum on Forests of the UN Commission on Sustainable Development, and the World Commission on Forests and Sustainable Development. This concern reflects an appreciation of the ecological and economic functions of forests: as providers of timber and many non-timber predicts, as the habitat for much of the world's biological diversity, and as regulators of local, regional and global environments. These functions are at risk. Most of the forest clearance is in areas of high forest cover and high human population pressure in tropical areas for agriculture. In temperate and boreal areas the pressures from logging are more important. But in all areas, forestry itself has an important role to play both as a partial cause of deforestation, and, if practiced wisely, as a potential source of salvation for at least some of the worldââ‰��������s forests. In terms of its causal role, forestry tends to open up primary forest areas, enabling colonists to move in, using roads forged by the timber companies. In some parts of the world, forests are converted not to agriculture but to biomass plantations of fast growing trees or to other agro-industries based on tree-crop plantations such as palm oil and rubber. Here the primary agent is not the peasant, but the richer elements of local and international society. How, then, can the world's forests be used more wisely? It is this admittedly grand and complex question that we seek to answer in this chapter

Sustainable Forestry in the Tropics: Panacea or Folly?

The profitability of uncontrolled logging can be a significant obstacle to sustainable forest management, especially in the tropics. Rice et al. (1997) have argued that not only does traditional selective logging provide higher returns but also incurs less damage to forests than sustainable forest management systems that involve harvesting of many species and the creation of large gaps in the forest canopy to foster regeneration of light-demanding species. They claimed that protected areas were the only viable way to conserve forest ecosystems and proposed that loggers be allowed to log forests selectively once, after which the forests should become parks. Here we respond to the challenge posed by Rice et al. by exhaustively reviewing the evidence regarding the viability and desirability of sustainable forest management in the tropics. Following Rice et al., we use the term conventional timber harvesting to refer to existing practice, which typically pays little attention to maintaining long-term timber supply. Sustainable timber management implies taking steps to ensure forests continue to produce timber in the longer term, while maintaining the full complement of environmental services and non-timber products of the forest. Empirical studies tend to confirm the conclusion of Rice et al. (1997) that although sustainable timber management sometimes provides reasonable rates of return, conventional timber harvesting is generally more profitable. This implies that without additional incentives, one cannot expect companies to adopt sustainable management. The shortsightedness of many loggers, the slow rise in international timber prices, political uncertainty, and tenure insecurity simply reinforce this tendency. However, we reject the claim that sustainable timber management generally damages forests more than conventional logging. Rice et al. base their conclusion largely on the particular case of mahogany extraction in Bolivia, and even there it may not hold. In many cases, sustainable timber management performs better in terms of carbon storage and biodiversity conservation than conventional logging approaches, as well as producing more timber. If new carbon markets emerge, sustainable forest management might compete effectively with conventional timber harvesting. Timber certification systems may also provide a sufficient incentive for sustainable forest management in certain circumstances

Community ecology and management of lianas

In this investigation, the basic pigment component, or anthocyanidin, of the ten most common spots was identified using paper and thin layer chromatographic techniques