Silvicultural techniques generally require relatively large capital investments and intensive management. One recent study of the Chimanes forest in Bolivia concludes that such methods are often not systematically applied because of the associated high costs and uncertain return on the loggers’ investment. In addition, stimulating regeneration of valuable commercial species, such as mahogany requires large areas of forest to be cut down, significantly enlarging the affected area. [50]
Similar trends are evident in Venezuela’s forests. Because of the high costs involved, concessionaires operating in Venezuela do not systematically apply prescribed silvicultural treatments. [51] Furthermore, this system of forest management has been found to be inflexible, especially in its incapacity to adapt to the different forest ecosystems of the Guayana region and to ensure natural regeneration of some valuable commercial species. [52]
Scientific research documenting the impact of logging on the forests of the Guayana region indicates that extraction and enrichment strip planting practices have resulted in fragmentation of the remaining forest, as well as a decrease in biodiversity. [53] In fact, to establish enrichment strips, an average of 1,200 trees (>10 cm dbh) per hectare were felled to plant an additional 400 commercial saplings. [54] Thus, virtually all trees greater than 10 cm dbh were cut in this area. [55]. Furthermore, the remaining stands of valuable species were also damaged and subject to fungal infection during the extraction of nearby trees, which eliminated the remaining adult parent trees in two or three years. [56] According to the results of two studies of fauna in the Imataca Forest Reserve, [57] the composition of bird and mammal communities was significantly modified by logging activities. Even though some wildlife species can take advantage of secondary habitats, an important number of taxa declined in abundance and others were eliminated from logged forests.
Although the Venezuelan forest service requires timber concessionaires to apply silvicultural techniques, it does not prescribe reduced-impact logging. Studies conducted in the Ticoporo and Caparo Forest Reserves of the Llanos region show that selective cutting, felling, and hauling practices are not conducted in a careful and well-planned manner, which damages remaining stands. [58] Timber extraction methods in both the western Llanos and the Guayana regions do not incorporate such reduced-impact logging techniques as directional felling or planned skidder trails and road development. Indeed, workers on timber concessions often work without maps, finding instead the most direct way to haul timber from the forest.
The United Nations Food and Agriculture Organization has developed guidelines that address methods for reducing environmental impacts in forestry operations. The Forest Stewardship Council (FSC) has developed additional criteria that might also help Venezuelan policy-makers define national standards for logging. The FSC is an international body that provides a framework for organizations certifying sustainable logging operations (See Guidelines for Reducing the Impacts of Logging).
References and notes
50. R. Rice et al., “Can Sustainable Management Save Tropical Forests?” Scientific American (April 1997). For a more global discussion of policy failures in forest management, see R. Repetto and M. Gillis, Public Policies and the Misuse of Forest Resources (Washington, DC: World Resources Institute, 1988).
51. Vincent et al., “Evoluci¢n hist¢rica y desarrollos recientes de la silvicultura del bosque tropical alto en Am‚rica” paper presented at CIFOR workshop: Pucallpa, Peru, 17-21 June 1996); H. Finol, “Ponencia en el taller de manejo forestal en la Guayana venezolana,” workshop on Forest Management (Upata, Bol¡var state, June 17, 1994).
52. E.J. Segovia, “Evaluaci¢n de los sistemas silviculturales aplicados en las unidades de manejo de las reservas forestales y lotes boscosos,” final report. (MARNR/ Direccion General Sectorial de Informaci¢n e Investigaci¢n del Ambiente: Caracas, 1989).
53. For a discussion of the impacts of enrichment strip planting on birds, see D. Mason, “Responses of Venezuelan Understory Birds to Selective Logging, Enrichment Strips, and Vine Cutting,” Biotr¢pica (vol. 28:296-309, 1996). For an analysis of the effects of selective logging and enrichment strip planting on bats, see J. Ochoa G., “Sensibilidades potenciales de una comunidad de mam¡feros en un bosque productor de maderas de la Guayana venezolana,” Interciencia (vol. 22: 112-122, 1997).
54. J. Ochoa G. “El aprovechamiento forestal en la Guayana venezolana: evaluaci¢n ecol¢gica e implicaciones para la conservaci¢n de los mam¡feros de la region,” doctoral thesis (Universidad de Los Andes: M‚rida, 1997); J. Ochoa G. “Sensibilidades potenciales de una comunidad de mam¡feros en un bosque productor de maderas de la Guayana venezolana,” Interciencia (vol. 22: 112-122, 1997).
55. The density of trees greater than 10 centimeters diameter at breast height (dbh) varies from between 300 to 1200 individuals per hectare. See Franco et al., “La situaci¢n actual de la reserva forestal Imataca y propuestas para orientar su ordenamiento,” report commissioned by the Ministry of Energy and Mines (Caracas, 1997); L. Hern ndez, “Bosques,” Chapter 5.2 in “Ecolog¡a de la altiplanicie de la gran sabana (Guayana venezolana) I”. Dezzeo N. (ed.), Scientia Guaianae (no. 4: 80-94, Caracas, 1994); M. Euler and A. Chaviel, “La vegetaci¢n: bosques de tierra firme,” in J. Rosales and O. Huber (eds.) Scientia Guaianae: Ecolog¡a de la cuenca del r¡o Caura, I, caracterizaci¢n general (no. 6: 60-65, 1996).
56. E. Sanoja, Universidad Nacional Experimental de Guayana, personal communication, 1994.
57. D. Mason, “Responses of Venezuelan Understory Birds to Selective Logging, Enrichment Strips, and Vine Cutting,” Biotr¢pica (vol. 28: 296-309, 1996); J. Ochoa G. “Sensibilidades potenciales de una comunidad de mam¡feros en un bosque productor de maderas de la Guayana venezolana,” Interciencia (vol. 22: 112-122, 1997); J. Ochoa G. “El aprovechamiento forestal en la Guayana venezolana: evaluaci¢n ecol¢gica e implicaciones para la conservaci¢n de los mam¡feros de la regi¢n,” doctoral thesis (Universidad de Los Andes: M‚rida, 1997).
58. M. Plonczak, “Die Nutzung der Naturwaelder in Venezuela,” Allg. Forst-und Jagdzeitung (168: 1997); L. Kammesheidt, “Bestandesstruktur und Artendiversitaet in selektiv genutzten Feutchwaelder der westlichen Llanos Venezuela, unter besonderer Beruecksichtigung einiger autooekologischer Merkmale wichtiger Baumarten,” G”tt. Beitr. Land-Forstw. Tropen Subtropen, (vol. 100: 1994); E. Arends, “Impacto ecol¢gico de la explotaci¢n selectiva en bosques de la reserva forestal de Caparo,” summary of presentation, Asovac, Coro (M‚rida: Instituto de Silvicultura, Facultad de Ciencias Forestales, Universidad de los Andes, 1994)
