José Natalino Macedo Silva

Condition and fate of logged forests in the Brazilian Amazon

The long-term viability of a forest industry in the Amazon region of Brazil depends on the maintenance of adequate timber volume and growth in healthy forests. Using extensive high-resolution satellite analyses, we studied the forest damage caused by recent logging operations and the likelihood that logged forests would be cleared within 4 years after timber harvest. Across 2,030,637 km2 of the Brazilian Amazon from 1999 to 2004, at least 76% of all harvest practices resulted in high levels of canopy damage sufficient to leave forests susceptible to drought and fire. We found that 16 ± 1% of selectively logged areas were deforested within 1 year of logging, with a subsequent annual deforestation rate of 5.4% for 4 years after timber harvests. Nearly all logging occurred within 25 km of main roads, and within that area, the probability of deforestation for a logged forest was up to four times greater than for unlogged forests. In combination, our results show that logging in the Brazilian Amazon is dominated by highly damaging operations, often followed rapidly by deforestation decades before forests can recover sufficiently to produce timber for a second harvest. Under the management regimes in effect at the time of our study in the Brazilian Amazon, selective logging would not be sustained.

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.

Growth rate of a terra firme rain forest in Brazilian Amazonia over an eight-year period in response to logging

E analisado o crescimento de 257 especies arboreas, considerando individuos com DAP > 5cm, na Floresta Nacional do Tapajos, em um periodo de oito anos. Em 1981 foram estabelecidas parcelas permanentes, e medidas pela primeira vez. Em 1982 a area foi explorada. Medicoes apos a exploracao foram realizadas em 1983, 1987 e 1989. Considerando todas as especies juntas, o incremento em diâmetro foi similar nas duas intensidades de exploracao, ate o quinto ano apos a colheita. As especies intolerantes a sombra mostraram crescimento significativamente maior do que as especies tolerantes a sombra na floresta explorada, com maior incremento na area de exploracao mais pesada. Especies comerciais tambem tiveram crescimento maior nessa mesma intensidade de exploracao, embora tenham sido significantemente diferentes apenas entre o primeiro e o quinto ano apos a exploracao. Na floresta nao-explorada, as arvores com diâmetros maiores apresentaram maior crescimento. Em nivel de especies, o crescimento variou entre e dentro das diferentes intensidade de exploracao, assim como entre as arvores dento de uma mesma especie, dependendo principalmente do grau de abertura do dossel. A exploracao favoreceu o crescimento de especies comerciais, principalmente intolerantes a sombra. Se as mesmas condicoes de crescimento continuarem sendo proporcionadas, por exemplo atraves de tratos silviculturais, para essas especies de interesse, a floresta atingira um estoque disponivel para nova colheita cerca de 30 anos apos a exploracao. Entretanto, a alta variacao na taxa de incremento indica que o periodo de oito anos nao e suficiente para permitir predicoes seguras quanto a ciclos de corte ou sistemas de manejo policiclico para a floresta estudada.

Essential oils of Toona and Cedrela Species (Meliaceae): taxonomic and ecological implications

Os oleos essenciais de Toona ciliata, Cedrela odorata e C. fissilis foram analisados por CG-EM. Cedrela apresentou em maior percentagem sesquiterpenos formados a partir do precursor pirofosfato de cis- e trans-farnesila. Ja Toona mostra uma tendencia em produzir principalmente sesquiterpenos derivados do pirofosfato de trans-farnesila. Estes resultados confirmam que a classificacao destes dois generos em uma mesma tribo, Cedreleae, continua problematica. As respostas em eletroantenogramas medios (EAGs) dos oleos essenciais de T. ciliata e C. odorata, em femeas de Hypsipyla grandella, foram significativamente maiores que aquelas obtidas em machos, sugerindo que as femeas utilizariam os odores destes oleos para a selecao da planta hospedeira (generos de Swietenioidea) e na escolha de locais para oviposicao.

Simulação de estratégias de manejo florestal na Amazônia com o uso do modelo SYMFOR

The SYMFOR model was used to simulate the ecological processes of tree growth, mortality and recruitment, and the forest management processes, in the terra firme forests of the eastern Amazon. The simulation utilized all the trees that have a diameter greater than 5 cm, from 40 permanent sample plots of 1 ha each (36 logged and 4 unlogged). The stand was measured in 1984, logged in 1985 and remeasured in 1986, 1988, 1990, 1994, 1996 and 2004. Ten species groups are used to describe the natural processes affecting tree behavior. Model performance compares the simulation results with real data describing the forest recovery for 19 years following logging. The treatments, combinations of logging intensities (15%, 25% and 35% of the total volume of the trees higher than 60 cm of DBH had been tested) and thinning intensities (0%, 30%, 50% and 70% of the original basal area) were analyzed as management strategies. The model was applied to simulate current forest management practice in the Brazilian Amazon, with 30 m3 ha−1 of timber extracted with a cutting cycle of 30 years. Results show that the similarity among observed and simulated data for SYMFOR validated the model to represent the dynamics of the unlogged forest. In the simulation of the current management practice applied in the Amazon forest, it is suggested that the financial benefits decrease with successive harvests and, consequently, the timber volume cannot be sustained.

Predição da distribuição diamétrica de uma floresta manejada experimentalmente através de um Sistema de Equações Diferenciais

The aim of this study was to evaluate the prognosis of the diameter structure of an experimentally managed forest, utilizing a system of differential equations of the first order, adjusted for each treatment. The basic data were obtained from the Bom Manejo Projet (Embrapa Eastern Amazon/CIFOR/ITTO), carried out in the Monte Dourado Forest Company (Jari) area, Vitoria do Jari, Amapa, Brazil. The statistical delineation was designed as random blocks with three replications. The treatments applied were combinations of logging intensities (15%, 25% and 35% of the total volume of the trees larger than 60 cm of DBH) and thinning intensities (0%, 30%, 50% and 70% of the original basal area). The non-logged forest was used for the control plots. Stand development was monitored through 40 permanent sample plots of 1 ha each (36 logged and 4 unlogged). The stand was measured in 1984, logged in 1985 and remeasured in 1986, 1988, 1990, 1994, 1996 and 2004. All the trees with DBH ≥ 20 cm were measured. While keeping the same simplicity of transition matrix based models, the proposed model allows for determining the state of the system for any given point in time, not being confined just for multiplying time intervals as was the former. This method was verified for different evaluation periods and the results showed that not even the longer periods of projections (break-even point) will be enough to restore the initial conditions of the stand.

Estoque de duas espécies arbóreas ameaçadas de extinção aos 30 anos após a exploração na Amazônia oriental

Sustainable management of species threatened with extinction should be used as a conservation strategy. It is essential to know the behavior of these species in relation to forest logging and the recovery rate of its stock over the cutting cycle established for the forest. Thus abundance, basal area, volume and diameter distribution of Hymenaea parvifolia Huber and Hymenolobium excelsum Ducke, considered species threatened with extinction and which were harvested for timber at Embrapa Amazônia Oriental’s experimental sites at Km 1Pesquisadora Doutora. SEMAS/PA – Secretaria do Estado de Meio Ambiente e Sustentabilidade. Travessa Lomas Valentinas, 2717 – 66.093-677 – Belém, PR, Brasil. E-mail: jaquelinemacedogomes@hotmail.com. 2Professor do Programa de Pós-Graduação em Ciências Florestais. UFRA – Universidade Federal Rural da Amazônia. Av. Presidente Tancredo Neves, 2501 – 66.077-530 – Belém, PR, Brasil. E-mail: olegario@pq.cnpq.br; silvanatalino734@gmail.com. 3Pesquisador Doutor. EMBRAPA Amazônia Oriental – Empresa Brasileira de Pesquisa Agropecuária. Trav. Dr. Enéas Pinheiro s/n – Caixa Postal: 48 66.095-100 – Belém, PA, Brasil. E-mail: ademir.ruschel@embrapa.br; lucas.mazzei@embrapa.br. 4Professor Associado do Departamento de Ciências Exatas e Naturais. UFRA – Universidade Federal Rural da Amazônia. Av. Presidente Tancredo Neves, 2501 – 66.077-530 – Belém, PR, Brasil. E-mail: ramosedson@gmail.com. 5Doutoranda em Ciências Florestais. UFRA – Universidade Federal Rural da Amazônia. Av. Presidente Tancredo Neves, 2501 – 66.077-530 – Belém, PR, Brasil. E-mail: ccastro.tatiana@gmail.com. 6Pesquisador Mestre em Ciências Florestais. TNC – The Nature Conservancy. Av. Nazaré, 280 – 66.035-170 – Belém, PA, Brasil. E-mail: ithompson@tnc.org. Gomes et al. – Estoque de duas espécies arbóreas ameaçadas de extinção aos 30 anos após a exploração na Amazônia oriental 42 Sci. For., Piracicaba, v. 46, n. 117, p. 41-52, mar. 2018 DOI: dx.doi.org/10.18671/scifor.v46n117.04 114 and Km 67 of BR 163 in the Tapajos National Forest, municipality of Belterra, Pará were studied. Data from 100% inventories from Km 114 (from 1981one year before logging and in 201432 years after logging) and from Km 67 (in 1975 four years before logging and in 200930 years after logging) were evaluated. Diameter distribution of abundance, basal area and volume were compared between the two inventories of each site. The period of 30 years after logging was not sufficient for Hymenaea parvifolia to recover prelogging tree numbers, basal area or volume in both sites, due to the high logging intensity applied. The species has a volume available for harvesting at Km 67; however it does not have a growing stock that could ensure new harvests in the near future, thus needing special management attention of the population. At Km 114, the species showed a stock to support the second harvest, but we recommend its harvest after recovering its pre-logging population structure. The high logging intensity meant that Hymenolobium excelsum did not recover pre-logging tree numbers at both sites in the 30 years. However the species showed growing stock that could guarantee its future logging, following current legislation, but we also recommend its harvest after recovering its pre-logging population structure.

A AUTOCORRELAÇÃO TEMPORAL DO INCREMENTO EM DIÂMETRO E AS DIFERENÇAS DE CRESCIMENTO ENTRE GRUPOS DE ESPÉCIES EM UMA FLORESTA OMBRÓFILA DENSA

 RESUMO: O objetivo deste estudo foi verificar a existência de autocorrelação temporal entre dois períodos consecutivos de medição do incremento diamétrico (1984-1994 e 1994-2004) e identificar padrões de taxas de crescimento diamétrico entre diferentes grupos de espécies de espécies. O estudo foi desenvolvido na área de manejo florestal da empresa Jari Florestal S.A., no município de Vitória do Jari, AP. Foram empregadas três parcelas permanentes de um hectare cada uma (100 × 100 m), onde foram medidos todos os indivíduos arbóreos com DAP ≥ 20,0 cm. A correlação de Pearson foi empregada para verificar a existência da autocorrelação do crescimento, bem como entre as classes diamétricas. O agrupamento das espécies baseou-se em construir um gráfico de dois eixos relacionando o incremento diamétrico médio e o diâmetro percentil 0,95. A análise de variância (α= 0,01) e o teste Tukey (α=0,05) foram utilizados para checar as diferenças entre os incrementos. O resultado desta análise detectou a autocorrelação temporal do crescimento e de diferentes padrões de crescimento entre algumas classes diamétricas. O agrupamento de espécies mostrou ser uma ferramenta útil na identificação de grupos de espécies e as análises indicaram existir diferenças de crescimento entre alguns grupos.

Disturbance intensity is a stronger driver of biomass recovery than remaining tree‐community attributes in a managed Amazonian forest

Forest recovery following management interventions is important to maintain ecosystem functioning and the provision of ecosystem services. It remains, however, largely unclear how above‐ground biomass (AGB) recovery of species‐rich tropical forests is affected by disturbance intensity and post‐disturbance (remaining) tree‐community attributes, following logging and thinning interventions. We investigated whether annual AGB increment (∆AGB) decreases with management‐related disturbance intensity (disturbance hypothesis), and increases with the diversity (niche‐complementarity hypothesis) and the community‐weighted mean (CWM) of acquisitive traits of dominant species (biomass‐ratio hypothesis) in the remaining tree community. We analysed data from a long‐term forest‐management experiment in the Brazilian Amazon over two recovery periods: post‐logging (1983–1989) and post‐thinning (1995–2012). We computed the ∆AGB of surviving trees, recruit trees and of the total tree community. Disturbance intensity was quantified as basal area reduction and basal area remaining. Remaining diversity (taxonomic, functional and structural) and CWM of five functional traits linked to biomass productivity (specific leaf area, leaf nitrogen and phosphorous concentration, leaf toughness and wood density) were calculated for the post‐intervention inventories. Predictors were related to response variables using multiple linear regressions and structural equation modelling. We found support for the disturbance hypothesis in both recovery periods. AGB increment of survivors and of the total tree community increased with basal area remaining, indicating the importance of remaining growing stock for biomass recovery. Conversely, AGB increment of recruit trees increased with basal area reduction because changes in forest structure increased resource availability for young trees. We did not find consistent support for the niche‐complementarity and biomass‐ratio hypotheses, possibly because of a high redundancy in these extremely species‐rich forests. Synthesis and applications. The intensity of disturbance through management, expressed as basal area reduction and basal area remaining, was consistently more important for explaining forest biomass recovery following harvesting and thinning than remaining diversity or trait composition. This points to the importance of controlling logging and thinning intensity in forests of the eastern Amazon. Given the high intervention intensities applied in this experiment, it is likely that low to moderate harvesting intensities permitted by the current legislation for the Brazilian Amazon (30 m³/ha) will not impair biomass recovery in these forests.

DIAMETER DISTRIBUTION OF WOOD RESIDUES IN LOGGED AND UNLOGGED FOREST AREAS OF THE EASTERN BRAZILIAN AMAZON

This study aimed to investigate the patterns of diameter distribution of residual wood pieces found on the forest ground (e.g. tree branches, sound and hollowed trunks, log trimmings) of an unlogged and of a logged forest area one year after logging operations with impact reduction techniques (EIR), by setting up a mathematical model. Diameters were field measured of wood residue pieces in 48 sampling units systematically distributed across the experimental area, 24 units for each situation, that is, unlogged (FNE) and logged forest (FE), with sampling errors of 8.32% and 7.58% respectively for the variable volume (m³.ha-1), applying the line intercept sampling method proposed by Wagner (1968). In both situations, the diameter distribution of the wood residue pieces was decreasing and reverse J-shaped, similarly to the DBH distribution occurring in native forests of the Amazon. A highly significant linear correlation exists between the diameter class midpoints and the number of wood residue pieces. Distributions were modeled using the exponential equation proposed by Meyer (1952), whose adjusted coefficients of determination (r²aj.) were 98.6% and 94.8%, for unlogged and logged forest areas respectively.