An Attempt to Predict Which Amazonian Tree Species May be Threatened by Logging Activities

Abstract

The impacts of logging on Amazonian ecosystems has been the focus of considerable attention both within and outside of Amazonia. However, the impacts of logging on individual timber species has not been at all adequately investigated. Logging affects timber species by: (1) removing mature individuals that are important sources of seeds; (2) damaging seedlings and saplings (i.e future generations of canopy adults); and (3) creating conditions that favour fire by opening the canopy and leaving slash as fuel on the forest floor.In this study we summarize information on the ecological characteristics of 305 timber species in Brazilian Amazonia. We identify seven ecological parameters that are useful in evaluating a species' ability to resist the negative impacts of logging. These characteristics are: (1) effective long-distance dispersal ability; (2) abundance of saplings in forest regeneration; (3) rapid growth; (4) ability to resprout; (5) capacity to withstand fire; (6) broad geographic distribution; and (7) high density of adults. We hypothesize thai species with characteristics opposed to these parameters and subjected to intense logging pressure will have difficulty in maintaining their populations in logging regions.We use a simple scoring system to rank species with regard to their hypothesized ability to withstand logging impacts. Among the species that are potentially susceptible to logging impacts are Euxylophora paraensis (‘Pau Amarelo’) and Swietenia macrophylla (American Mahogany). The sawn lumber from these two species goes principally to European and North American buyers, revealing a direct link between First World consumption and possible biodiversity impoverishment in the Brazilian rain-forest. These two species, and others that might experience population reductions as a result of logging, merit special study.

Efeito da exploração madeireira sobre o número de indivíduos férteis de três espécies arbóreas comerciais na Amazônia oriental

“…efeito da exploração madeireira sobre o número de indivíduos férteis de três espécies arbóreas comerciais na amazônia oriental está sujeita, sua importância para a fauna e/ou para a estrutura florestal e a susceptibilidade potencial aos efeitos da exploração (avaliada através de critérios como distribuição geográfica, síndrome de dispersão das sementes, taxa de crescimento, entre outros; Martini et al, 1994). Tais estudos devem subsidiar o aperfeiçoamento das práticas de manejo e favorecer, portanto, a sustentabilidade do manejo florestal.…”

The Effects of Selective Logging Behaviors on Forest Fragmentation and Recovery

“…In the Amazon basin, harvesting timber species of high value (e.g., mahogany) may have a smaller impact on forest structure and function than harvesting timber species of low value, which are more abundant and are extracted at much higher volumes [48]. Sawmills in the Amazon are involved in the processing of more then 100 tree species [67,68] and the volume of timber species of high value makes up only a small percentage of the total production (e.g., mahogany is 5% of the total timber production) [48].…”

Environmental variables and tree population structures in deciduous forests of central Brazil with different levels of logging

“…Lianas differ from invasive herbs in competitive ability because: (1) they climb seedling or juvenile tree stems (Putz, 1991;Alvira et al, 2004), (2) they are perennial, while the sampled invaders only occur in the rainy season, and (3) they reduce the amount of light that reaches the herbaceous stratum. Implications for management and conservationThe evaluation of threat to a species population must take into account the seed dispersal, abundance of recruits, growth rate, sprouting capacity after felling or damage, resistance to fire, geographical range and abundance of adults (Martini et al, 1994). Large-seed species, which include Eugenia, Swartzia and Cavanillesia, have low seedling densities.…”