Johan C. Zweede

Financial and ecological indicators of reduced impact logging performance in the eastern Amazon

Abstract Reduced impact logging (RIL) systems are currently being promoted in Brazil and other tropical countries in response to domestic and international concern over the ecological and economic sustainability of harvesting natural tropical forests. RIL systems are necessary, but not sufficient, for sustainable forest management because they reduce damage to the forest ecosystem during the initial forest entry. If conditions were identified where RIL costs were clearly less than conventional logging (CL) costs, then a strong incentive for RIL adoption would exist. In this paper, a comparison of costs and revenues was made for typical RIL and CL operations in the eastern Amazon. An economic engineering approach was used to estimate standardized productivity and cost parameters. Detailed data on productivity, harvest volume, wasted wood and damage to the residual stand were collected from operational scale harvest blocks. Productivity and cost data were also collected using surveys of forest products firms. The major conclusion of the study was that RIL was less costly, and more profitable, than CL under the conditions observed at the eastern Amazon study site. Full cost accounting methods were introduced to capture the direct and indirect costs associated with wasted wood. The impact of wasted wood on effective stumpage price provided the largest gain to RIL. Large gains attributable to RIL technology were also observed in skidding and log deck productivity. In addition, investment in RIL yielded an “environmental dividend” in terms of reduced damage to trees in the residual stand and reduction of the amount of ground area disturbed by heavy machinery. Developing institutions that can monetize the value of the environmental dividend remains a major challenge in the promotion of sustainable forest management in the tropics.

Remote sensing of selective logging in Amazonia Assessing limitations based on detailed field observations, Landsat ETM+, and textural analysis

We combined a detailed field study of forest canopy damage with calibrated Landsat 7 Enhanced Thematic Mapper Plus (ETM+) reflectance data and texture analysis to assess the sensitivity of basic broadband optical remote sensing to selective logging in Amazonia. Our field study encompassed measurements of ground damage and canopy gap fractions along a chronosequence of postharvest regrowth of 0.5–3.5 years. We found that canopy damage and regrowth rates varied according to the logging method used, either conventional logging or reduced impact logging. Areas used to stage felled trees prior to transport, log decks, had the largest gap fractions immediately following cutting. Log decks were quickly colonized by early successional plant species, resulting in significant gap fraction decreases within 1.5 years after site abandonment. Although log decks were the most obvious damage areas on the ground and in satellite imagery, they accounted for only 1–2% of the total harvested area of the blocks studied. Other forest damage features such as tree-fall gaps, skid trails, and roads were difficult to recognize in Landsat reflectance data or through textural analysis. These landscape features could be only crudely resolved in the most intensively logged forests and within about 0.5 years following harvest. We found that forest damage within any of the landscape strata (decks, roads, skids, tree falls) could not be resolved with Landsat reflectance or texture data when the canopy gap fraction was <50%. The basic Landsat ETM+ imagery lacks the resolution of forest structural features required for quantitative studies of logging damage. Landsat textural analyses may be useful for broad delineation of logged forests, but detailed ecological and biogeochemical studies will probably need to rely on other remote sensing approaches. Until spatial gradients of canopy damage and regrowth resulting from selective logging operations in tropical forests in the Amazon region are resolved, the impacts of this land use on a continental scale will remain poorly understood. D 2002 Elsevier Science Inc. All rights reserved.

Forest canopy damage and recovery in reduced-impact and conventional selective logging in eastern Para, Brazil

Abstract We investigated ground and canopy damage and recovery following conventional logging and reduced-impact logging (RIL) of moist tropical forest in the eastern Amazon of Brazil. Paired conventional and RIL blocks were selectively logged with a harvest intensity of approximately 23xa0m 3 xa0ha −1 (geometric volume) in the dry seasons (July–December) of 1996 and 1998. Ground damage (roads+skid trails+log decks) in the conventional logging treatments occupied 8.9–11.2% of total operational area. In contrast, ground damage in RIL treatments ranged from 4.6 to 4.8% of the total area. Forest canopy damage was assessed using gap fraction measurements collected with an automated optical canopy analyzer (LAI-2000; Licor Inc.) in March 1999. Canopy opening varied by time since logging. The recently logged (1998) blocks had integrated canopy gap fractions of 21.6 and 10.9% of total area for conventional and RIL blocks, respectively. The blocks logged in 1996 had more closed canopies with 16.5 and 4.9% gap fraction for conventional and RIL blocks, respectively. For comparison, undisturbed forest had a canopy gap fraction of 3.1%. Measurements of ground disturbance and gap fraction using the Licor LAI-2000 generally agree with other field evaluations of RIL and conventional logging. Detailed understanding of canopy structural changes resulting from different logging intensities are critical to the prospect of logging damage estimation using current and future remote sensing products.

CANOPY DAMAGE AND RECOVERY AFTER SELECTIVE LOGGING IN AMAZONIA: FIELD AND SATELLITE STUDIES

We combined a detailed field study of canopy gap fraction with spectral mixture analyses of Landsat 7 ETM1 satellite imagery to assess landscape and regional dynamics of canopy damage following selective logging in an eastern Amazon forest. Our field studies encompassed measurements of ground damage and canopy gap fractions along multitemporal sequences of post-harvest regrowth of 0.5-3.5 yr. Areas used to stage har- vested logs prior to transport, called log decks, had the largest forest gap fractions, but their contribution to the landscape-level gap dynamics was minor. Tree falls were spatially the most extensive form of canopy damage following selective logging, but the canopy gap fractions resulting from them were small. Reduced-impact logging resulted in consistently less damage to the forest canopy than did conventional logging practices. This was true at the level of individual landscape strata such as roads, skids, and tree falls as well as at the area-integrated scale. A spectral mixture model was employed that utilizes bundles of field and image spectral reflectance measurements with Monte Carlo analysis to estimate high spatial resolution (subpixel) cover of forest canopies, exposed nonphotosynthetic vegetation, and soils in the Landsat imagery. The method proved highly useful for quantifying forest canopy cover fraction in log decks, roads, skids, tree fall, and intact forest areas, and it tracked canopy damage up to 3.5 yr post-harvest. Forest canopy cover fractions derived from the satellite observations were highly and inversely correlated with field-based canopy gap fraction. Subsequent regional-scale estimates of forest gap fraction were derived from the combi- nation of field- and satellite-based measurements. A 450-km 2 study of gap fraction showed that approximately one-half of the canopy opening caused by logging is closed within one year of regrowth following timber harvests. This is the first regional-scale study utilizing field measurements, satellite observations, and models to quantify forest canopy damage and recovery following selective logging in the Amazon.

Timber production in selectively logged tropical forests in South America

Selective logging is an extensive land-use practice in South America. Governments in the region have enacted policies to promote the establishment and maintenance of economically productive and sustainable forest industries. However, both biological and policy constraints threaten to limit the viability of the industry over the long term. Biological constraints, such as slow tree growth rates, can be overcome somewhat by management practices. In order to improve the likelihood of success for sustainable management, it is important to accept that forests change over time and that managed forests may be different than those of the present. Furthermore, education campaigns must convince decision makers and the public of the value of forest resources. We recommend that the forest sector be governed by simple, understandable regulations, based on sound science and consistent enforcement, and that governments work with, instead of against, industry. Problems of tropical forest management are far from being solv...

Compliance with reduced-impact harvesting guidelines by timber enterprises in terra firme forests of the Brazilian Amazon

SUMMARY The paper presents the results and main conclusions of an assessment of compliance with technical guidelines for Reduced Impact Harvesting (RIH) in terra firme forests of the Brazilian Amazon. The assessment was carried out in two certified timber enterprises in the State of Para, Brazil applying the RIH-guidelines for a period of over three years. From a tool developed for Amazonian forest enterprises to monitor the sustainability of their harvesting operations, which uses a set of criteria and indicators (C&I), a total of 190 verifiers were selected for assessing the 61 RIH-guidelines. The assessment revealed valuable information with regard to the state of implementation and quality of the forest operations in the two enterprises and important insights for improvement of the RIH-guidelines. Two thirds of the RIH-guidelines were fully implemented. Their acceptance, however, differed according to the situation and interest of the enterprises. Among the reasons for incomplete implementation of the RIH-guidelines, the lack of systematic monitoring, insufficient training and qualification, and inadequate equipment appeared to be most important. The study also showed the need for the continuous assessment of the quality and relevance of RIH-guidelines.

Three Years After: Early Stand Re-Entry in Reduced Impact Logging of Neo-Tropical Forests

Several polycyclical harvest systems define the process of reduced impact logging (RIL) in the neo-tropics. As a rule, after the first RIL harvest, the area is left undisturbed for 25 to 35 years or the chosen rotation. This constraint reduces the ability of the forest manager to adjust to changes. The option to re-enter a stand after a given period but before the planned rotation age would allow the forest manager to examine trends in timber prices harvesting when prices are high or delaying harvest when prices are low and to accommodate changes in species demand, harvesting species that were previously noncommercial. Indeed, to accommodate delays due to problems such as heavy rain or broken machinery, current forest legislation in Brazil allows for re-entry into a harvested stand for up to one year. Although an anathema to many RIL advocates, a re-entry harvest would introduce muchneeded flexibility into the system.