Individual carbon nanotubes are like minute bits of string, and many trillions of these invisible strings must be assembled to make useful macroscopic articles. We demonstrated such assembly at rates ...above 7 meters per minute by cooperatively rotating carbon nanotubes in vertically oriented nanotube arrays (forests) and made 5-centimeter-wide, meter-long transparent sheets. These self-supporting nanotube sheets are initially formed as a highly anisotropic electronically conducting aerogel that can be densified into strong sheets that are as thin as 50 nanometers. The measured gravimetric strength of orthogonally oriented sheet arrays exceeds that of sheets of high-strength steel. These nanotube sheets have been used in laboratory demonstrations for the microwave bonding of plastics and for making transparent, highly elastomeric electrodes; planar sources of polarized broad-band radiation; conducting appliqués; and flexible organic light-emitting diodes.
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In an earlier special issue of this journal, Marsh & Greer summarized forest land use in Sabah at that time and gave an introduction to the Danum Valley Conservation Area. Since that assessment, ...during the period 1990—2010, the forests of Sabah and particularly those of the ca 10 000 km 2 concession managed on behalf of the State by Yayasan Sabah (the Sabah Foundation) have been subject to continual, industrial harvesting, including the premature re-logging of extensive tracts of previously only once-logged forest and large-scale conversion of natural forests to agricultural plantations. Over the same period, however, significant areas of previously unprotected pristine forest have been formally gazetted as conservation areas, while much of the forest to the north, the south and the east of the Danum Valley Conservation Area (the Ulu Segama and Malua Forest Reserves) has been given added protection and new forest restoration initiatives have been launched. This paper analyses these forest-management and land-use changes in Sabah during the period 1990—2010, with a focus on the Yayasan Sabah Forest Management Area. Important new conservation and forest restoration and rehabilitation initiatives within its borders are given particular emphasis.
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A convincing body of evidence shows that as it is presently codified, sustainable forest-management (SFM) logging implemented at an industrial scale guarantees commercial and biological depletion of ...high-value timber species within three harvests in all three major tropical forest regions. The minimum technical standards necessary for approaching ecological sustainability directly contravene the prospects for financial profitability. Therefore, industrial-scale SFM is likely to lead to the degradation and devaluation of primary tropical forests as surely as widespread conventional unmanaged logging does today. Recent studies also show that logging in the tropics, even using SFM techniques, releases significant carbon dioxide and that carbon stocks once stored in logged timber and slash takes decades to rebuild. These results beg for a reevaluation of the United Nations Framework Convention on Climate Change proposals to apply a Reducing Emissions from Deforestation and Forest Degradation subsidy for the widespread implementation of SFM logging in tropical forests. However, encouraging models of the successful sustainable management of tropical forests for timber and nontimber products exist at local-community scales.
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Gmelina arborea is a forest species of increasing use in the establishment of commercial plantations in Colombia. The areas where it is currently planted are deficient in nutrients, so the use of ...Arbuscular Mycorrhizal Fungi (AMF) can be an alternative to improve phosphoric fertilization. The aim of this work was to determine the mycorrhizal dependency, colonization, and growth of G. arborea when it is inoculated with Rhizoglomus fasciculatum, Rhizoglomus aggregatum, Rhizoglomus irregulare, Glomus fistulosum, and Entrophospora colombiana, under different concentrations of phosphorus (P) in a soil solution. A completely randomized design was used with a 6×3 factorial arrangement, five AFM strains + control (uninoculated) and three P doses (0.002, 0.02, and 0.2 mg L-1) with five replicates per each treatment and twice through time. Mycorrhizal colonization and dependency, foliar concentration of P, dry biomass, leaf area, and height were evaluated. A moderate mycorrhizal dependency was obtained under a P concentration of 0.002 and 0.02 mg L-1 and inoculation with R. fasciculatum, R. aggregatum, and R. irregulare while inoculation with G. fistulosum and E. colombiana produced a marginal dependency. It was found a negative effect on G. arborea inoculated with all AMF strains under 0.2 mg L-1 of P. Mycorrhizal colonization presented values between 62.5 - 2.5% for all the AMF evaluated, influenced by AFM strains and P concentration. Plants inoculated with R. fasciculatum, R. aggregatum, and R. irregulare showed a significant increase (P<0.05) in their growth. Mycorrhizal dependency and colonization in G. arborea and its growth were highly influenced by species of AMF and amount of P.
Restoration of Degraded Tropical Forest Landscapes Lamb, David; Erskine, Peter D; Parrotta, John A
Science (American Association for the Advancement of Science),
12/2005, Volume:
310, Issue:
5754
Journal Article
Peer reviewed
The current scale of deforestation in tropical regions and the large areas of degraded lands now present underscore the urgent need for interventions to restore biodiversity, ecological functioning, ...and the supply of goods and ecological services previously used by poor rural communities. Traditional timber plantations have supplied some goods but have made only minor contributions to fulfilling most of these other objectives. New approaches to reforestation are now emerging, with potential for both overcoming forest degradation and addressing rural poverty.
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In some countries across the globe, tropical forest cover is increasing. The national-scale reforestation of Vietnam since 1992 is assumed to contribute to this recovery. It is achieved, however, by ...the displacement of forest extraction to other countries on the order of 49 (34-70) M m³, or almost equal to39% of the regrowth of Vietnam's forests from 1987 to 2006. Approximately half of wood imports to Vietnam during this period were illegal. Leakage due to policies restricting forest exploitation and displacement due to growing domestic consumption and exports contributed respectively to an estimated 58% and 42% of total displacement. Exports of wood products from Vietnam also grew rapidly, amounting to 84% of the displacement, which is a remarkable feature of the forest transition in Vietnam. Attribution of the displacement and corresponding forest extraction to Vietnam, the source countries or the final consumers is thus debatable. Sixty-one percent of the regrowth in Vietnam was, thus, not associated with displacement abroad. Policies allocating credits to countries for reducing deforestation and forest degradation should monitor illegal timber trade and take into account the policy-induced leakage of wood extraction to other countries.
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Los factores que regulan la diversidad de organismos a través de las redes tróficas han sido muy estudiados, aunque el componente ambiental no suele ser tenido en cuenta. En el marco de los cambios ...ambientales dados por el uso de la tierra y de su influencia sobre la biodiversidad, es clave considerar cómo esos cambios influyen sobre la regulación de las redes tróficas. Aquí nos propusimos investigar el efecto de la diversidad y la abundancia de presas sobre la diversidad de depredadores (arañas) en distintas condiciones ambientales dadas por el uso de la tierra. Se establecieron parcelas en sitios con cultivos de soja y plantaciones forestales. A la mitad de ellas se las trató aplicando cebo atractivo para presas potenciales de arañas, y el resto sin tratar sirvió de control. Se colectaron presas potenciales mediante trampas pegajosas, y arañas mediante trampas de caída. La respuesta de la riqueza específica, la diversidad funcional y los rasgos particulares de las arañas al tipo de uso de la tierra y al tratamiento con cebo se estudió por medio de modelos lineales generalizados mixtos incluyendo la interacción entre factores. La riqueza específica de arañas fue similar entre usos de la tierra y tratamiento con y sin cebo, aunque su abundancia fue mayor en campos de soja que en plantaciones. En éstas, la diversidad funcional resultó menor en las parcelas con cebo que en los controles. Los diferentes rasgos examinados mostraron respuestas variadas a los factores. Los cultivos de soja y las plantaciones de eucalipto parecen limitar la riqueza específica de arañas de manera similar, pero no la diversidad funcional, aun en presencia de mayor diversidad de recursos alimenticios.
This study determines whether the establishment of tropical protected areas (PAs) has led to a reduction in deforestation within their boundaries or whether deforestation has been displaced to ...adjacent unprotected areas: a process termed neighbourhood leakage. Sumatra, Indonesia. We processed and analysed 98 corresponding LANDSAT satellite images with a c. 800 m² resolution to map deforestation from 1990 to 2000 across 440,000 km² on the main island of Sumatra and the smaller island of Siberut. We compared deforestation rates across three categories of land: (1) within PAs; (2) in adjacent unprotected land lying with 10 km of PA boundaries; and (3) within the wider unprotected landscape. We used the statistical method of propensity score matching to predict the deforestation that would have been observed had there been no PAs and to control for the generally remote locations in which Sumatran PAs were established. During the period 1990-2000 deforestation rates were found to be lower inside PAs than in adjacent unprotected areas or in the wider landscape. Deforestation rates were also found to be lower in adjacent unprotected areas than in the wider landscape. Sumatran PAs have lower deforestation rates than unprotected areas. Furthermore, a reduction in deforestation rates inside Sumatran PAs has promoted protection, rather than deforestation, in adjacent unprotected land lying within 10 km of PA boundaries. Despite this positive evaluation, deforestation and logging have not halted within the boundaries of Sumatran PAs. Therefore the long-term viability of Sumatran forests remains open to question.
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Aim A range of approaches and philosophies underpin national-level strategies for managing invasive alien plants. This study presents a strategy for the management of taxa that both have value and do ...harm. Location South Africa. Methods Insights were derived from examining Australian Acacia species in South Africa (c. 70 species introduced, mostly > 150 years ago; some have commercial and other values; 14 species are invasive, causing substantial ecological and economic damage). We consider options for combining available tactics and management practices. We defined (1) categories of species based on invaded area (a surrogate for impact) and the value of benefits generated and (2) management regions based on habitat suitability and degree of invasion. For each category and region, we identified strategic goals and proposed the combinations of management practices to move the system in the desired direction. Results We identified six strategic goals that in combination would apply to eight species categories. We further identified 14 management practices that could be strategically combined to achieve these goals for each category in five discrete regions. When used in appropriate combinations, the prospect of achieving the strategic goal will be maximized. As the outcomes of management cannot be accurately predicted, management must be adaptive, requiring continuous monitoring and assessment, and realignment of goals if necessary. Main conclusions Invasive Australian Acacia species in South Africa continue to spread and cause undesirable impacts, despite a considerable investment into management. This is because the various practices have historically been uncoordinated in what can be best described as a strategy of hope. Our proposed strategy offers the best possible chance of achieving goals, and it is the first to address invasive alien species that have both positive value and negative impacts.
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Bamboo is widely distributed in Southeast Asia, Africa, and Latin America. As a major non-wood forest product and wood substitute, bamboo is of increasing interest to ecologists owing to its rapid ...growth and correspondingly high potential for mitigating climate change. With a long history of production and utilization of bamboo, China is one of the countries with the richest bamboo resources and largest area of bamboo forest, and has paid unprecedented attention in recent decades to management of its bamboo forests. This review summarizes the versatility of bamboo in terms of its ecological benefits including carbon sequestration, water and soil conservation, its benefits for socioeconomic development, and its potential to mitigate climate change. Current problems, and the future potential of and challenges to rapidly expanding bamboo forests under both wider use of intensive management and the effects of global warming, are also discussed.
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