Jeffrey J. Gerwing

Integrating liana abundance and forest stature into an estimate of total aboveground biomass for an eastern Amazonian forest

This study provides an estimate of aboveground live biomass for an intact eastern Amazonian forest. An allometric regression biomass equation was developed to estimate the aboveground biomass of live lianas. This equation, together with a previously published equation for trees, was then used to estimate the contributions of lianas and trees to the total biomass of forest patches in four stature classes: gap (openings in the canopy of at least 25 m 2 with the dominant vegetation 25 m canopy height). Total stand-level biomass was estimated as the weighted average of the stature classes. In 130 ha of surveyed forest, forest stature classes were found in the following proportions: gap phase 8%; low stature 31%; medium stature 44%; and high stature 17%. Total aboveground biomass was found to be three times higher in high stature forest than in low. Liana biomass, however, showed the opposite result, being three times higher in low stature forest. Stand-level aboveground live biomass was estimated at 314 t ha -1 of which 43 t ha -1 (14%) was lianas. Liana leaf area index (LAI) ranged from 1.3 m m -2 in high stature forest to 5.3 m m -2 in low stature. Abundant lianas are generally interpreted as a sign of past forest disturbance. As forests throughout the Amazon basin are increasingly disturbed through human activities, it is likely that their biomass will be underestimated if the contribution of lianas is ignored.

Natural Resource Management in the Brazilian Amazon An integrated research approach

he Amazon region of Brazil contains billions of cubic meters of high-quality wood whose overall value after sawing would be several trillion dollars. Given this timber wealth, it is common to consider forestry as the natural vocation for Amazonia (Pandolfo 1974). Already, well over half of the wood consumed in Brazil comes from Amazonia, and this domestic demand for Amazonian roundwood is expected to grow (Verissimo et al. 1992). Foreign consumption of Amazonian wood, although low at present, is also likely to increase as Asian tropical hardwood stocks decline. Brazil, which possesses almost one-third of the worlds rain forest

Vine management for reduced-impact logging in eastern Amazonia

Abstract The presence of vines interconnecting the canopies of tropical forest trees has been thought to increase the damage to neighboring trees when a tree is felled during selective logging, resulting in larger canopy gaps and possibly prejudicting future timber harvests. To ameliorate this problem, vine cutting prior to logging has been recommended as a forest management tool. However, at present, little information exists on the economic and ecological impacts of vine cutting on tropical forest management. We undertook a study of vine management in a 210 ha forest stand. Our first objective was to determine vine species composition, stem densities, and the abilities of different vine species to resprout following cutting. Secondly, we assessed the degree of tree canopy connectedness due to vines and the amount of damage associated with felling trees with intercrown vine connections. Finally, we looked at the costs of vine cutting as a forest management tool. Vine density was found to differ among forest phases, being three times greater in young building phase forest than in mature forest. We encountered 63 species of vines in two (2 × 1400 m) transects and among the most common species, the degree of resprouting following cutting differed significantly. Typically, vines connected each tree to the crowns of from three to nine other trees. Felling trees with many vine connections resulted in canopy gaps that were twice as large as those created in the felling of vine-free trees. Although vine cutting prior to logging can reduce logging damage, it costs approximately

Pre-logging liana cutting reduces liana regeneration in logging gaps in the Eastern Brazilian Amazon

16 ha −1 , on average. This is equivalent to 8% of the profits of a typical logging-only operation in the region. Reductions in the cost of vine cutting could come with the development of species-specific cutting prescriptions that would reduce the total number of vine stems cut by focusing cutting efforts on aggressive species likely to cause silvicultural problems.

Degradation of forests through logging and fire in the eastern Brazilian Amazon

The cutting of all lianas prior to logging is a reduced-impact logging technique that is predicted to reduce liana proliferation in logging gaps. This study compares liana abundance and species composition in gaps created during conventional and reduced-impact logging in a forest of the eastern Brazilian Amazon. Logging treatments were conducted in side-by-side plots. Shortly following logging, 50-m2 plots were located in the approximate centers of four single treefall and four multiple treefall gaps in each logging area. Six years following logging, there were ∼40% fewer climbing lianas in reduced-impact gaps than in conventional logging gaps. In both logging areas multiple-tree gaps had higher liana densities and a higher proportion of lianas recruiting from seed than single tree gaps, where sprouts from cut or fallen lianas were more common. The mean number of liana species encountered per plot did not differ among treatments nor was there any significant difference in species diversity (Fishers α) be...