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141.
Sean P Healey Jock A Blackard Todd A Morgan Dan Loeffler Greg Jones Jon Songster Jason P Brandt Gretchen G Moisen Larry T DeBlander 《Carbon balance and management》2009,4(1):9
Background
Although significant amounts of carbon may be stored in harvested wood products, the extraction of that carbon from the forest generally entails combustion of fossil fuels. The transport of timber from the forest to primary milling facilities may in particular create emissions that reduce the net sequestration value of product carbon storage. However, attempts to quantify the effects of transport on the net effects of forest management typically use relatively sparse survey data to determine transportation emission factors. We developed an approach for systematically determining transport emissions using: 1) -remotely sensed maps to estimate the spatial distribution of harvests, and 2) - industry data to determine landscape-level harvest volumes as well as the location and processing totals of individual mills. These data support spatial network analysis that can produce estimates of fossil carbon released in timber transport. 相似文献142.
Scott J Goetz Alessandro Baccini Nadine T Laporte Tracy Johns Wayne Walker Josef Kellndorfer Richard A Houghton Mindy Sun 《Carbon balance and management》2009,4(1):2-7
Mapping and monitoring carbon stocks in forested regions of the world, particularly the tropics, has attracted a great deal
of attention in recent years as deforestation and forest degradation account for up to 30% of anthropogenic carbon emissions,
and are now included in climate change negotiations. We review the potential for satellites to measure carbon stocks, specifically
aboveground biomass (AGB), and provide an overview of a range of approaches that have been developed and used to map AGB across
a diverse set of conditions and geographic areas. We provide a summary of types of remote sensing measurements relevant to
mapping AGB, and assess the relative merits and limitations of each. We then provide an overview of traditional techniques
of mapping AGB based on ascribing field measurements to vegetation or land cover type classes, and describe the merits and
limitations of those relative to recent data mining algorithms used in the context of an approach based on direct utilization
of remote sensing measurements, whether optical or lidar reflectance, or radar backscatter. We conclude that while satellite
remote sensing has often been discounted as inadequate for the task, attempts to map AGB without satellite imagery are insufficient.
Moreover, the direct remote sensing approach provided more coherent maps of AGB relative to traditional approaches. We demonstrate
this with a case study focused on continental Africa and discuss the work in the context of reducing uncertainty for carbon
monitoring and markets. 相似文献
143.
144.
Jane Bemigisha John Carranza rew K. Skidmore Mike McCall Chiara Polce Herbert H.T. Prins 《Transactions in GIS》2009,13(3):273-293
In a project to classify livestock grazing intensity using participatory geographic information systems (PGIS), we encountered the problem of how to synthesize PGIS-based maps of livestock grazing intensity that were prepared separately by local experts. We investigated the utility of evidential belief functions (EBFs) and Dempster's rule of combination to represent classification uncertainty and integrate the PGIS-based grazing intensity maps. These maps were used as individual sets of evidence in the application of EBFs to evaluate the proposition that " This area or pixel belongs to the high, medium, or low grazing intensity class because the local expert(s) says (say) so ". The class-area-weighted averages of EBFs based on each of the PGIS-based maps show that the lowest degree of classification uncertainty is associated with maps in which "vegetation species" was used as the mapping criterion. This criterion, together with local landscape attributes of livestock use may be considered as an appropriate standard measure for grazing intensity. The maps of integrated EBFs of grazing intensity show that classification uncertainty is high when the local experts apply at least two mapping criteria together. This study demonstrates the usefulness of EBFs to represent classification uncertainty and the possibility to use the EBF values in identifying and using criteria for PGIS-based mapping of livestock grazing intensity. 相似文献
145.
T. Ch. Malleswara Rao G. Jai Sankar T. Roopesh Kumar 《Journal of the Indian Society of Remote Sensing》2012,40(2):191-200
The focus of this work is on developing a new hierarchical hybrid Support Vector Machine (SVM) method to address the problems
of classification of multi or hyper spectral remotely sensed images and provide a working technique that increases the classification
accuracy while lowering the computational cost and complexity of the process. The paper presents issues in analyzing large
multi/hyper spectral image data sets for dimensionality reduction, coping with intra pixel spectral variations, and selection
of a flexible classifier with robust learning process. Experiments conducted revealed that a computationally cheap algorithm
that uses Hamming distance between the pixel vectors of different bands to eliminate redundant bands was quite effective in
helping reduce the dimensionality. The paper also presents the concept of extended mathematical morphological profiles for
segregating the input pixel vectors into pure or mixed categories which will enable further computational cost reductions.
The proposed method’s overall classification accuracy is tested with IRS data sets and the Airborne Visible Infrared Imaging
Spectroradiometer Indian Pines hyperspectral benchmark data set and presented. 相似文献
146.
Recent advances in accessibility research: Representation,methodology and applications 总被引:22,自引:0,他引:22
Mei-Po Kwan Alan T. Murray Morton E. O'Kelly Michael Tiefelsdorf 《Journal of Geographical Systems》2003,5(1):129-138
In this article we examine recent advances in accessibility research and their implications for future studies. We base our
discussion on three intersecting dimensions that are useful for evaluating the contribution of recent studies: representation,
methodology and applications. Various examples are selected to show that research concerned with representation and methodological
problem solving is often applied to issues of broad concern in policy and planning. It is, however, not clear that the simultaneous
treatment of representation, methodological and application issues has ever been fully worked out. The questions raised in
this article may serve as a foundation for addressing issues pertinent to accurate representation, improved model building,
and more rigorous applications in accessibility research.
Received: 9 December 2002 / Accepted: 10 February 2003 相似文献
147.
148.
C. Vigny J. Chéry T. Duquesnoy F. Jouanne J. Ammann M. Anzidei J.-P. Avouac F. Barlier R. Bayer P. Briole E. Calais F. Cotton F. Duquenne K. L. Feigl G. Ferhat M. Flouzat J.-F. Gamond A. Geiger A. Harmel M. Kasser M. Laplanche M. Le Pape J. Martinod G. Ménard B. Meyer J.-C. Ruegg J.-M. Scheubel O. Scotti G. Vidal 《Journal of Geodesy》2002,76(2):63-76
The Western Alps are among the best studied collisional belts with both detailed structural mapping and also crustal geophysical
investigations such as the ECORS and EGT seismic profile. By contrast, the present-day kinematics of the belt is still largely
unknown due to small relative motions and the insufficient accuracy of the triangulation data. As a consequence, several tectonic
problems still remain to be solved, such as the amount of N–S convergence in the Occidental Alps, the repartition of the deformation
between the Alpine tectonic units, and the relation between deformation and rotation across the Alpine arc. In order to address
these problems, the GPS ALPES group, made up of French, Swiss and Italian research organizations, has achieved the first large-scale
GPS surveys of the Western Alps. More than 60 sites were surveyed in 1993 and 1998 with a minimum observation of 3 days at
each site. GPS data processing has been done by three independent teams using different software. The different solutions
have horizontal repeatabilities (N–E) of 4–7 mm in 1993 and 2–3 mm in 1998 and compare at the 3–5-mm level in position and
2-mm/yr level in velocity. A comparison of 1993 and 1998 coordinates shows that residual velocities of the GPS marks are generally
smaller than 2 mm/yr, precluding a detailed tectonic interpretation of the differential motions. However, these data seem
to suggest that the N–S compression of the Western Alps is quite mild (less than 2 mm/yr) compared to the global convergence
between the African and Eurasian plate (6 mm/yr). This implies that the shortening must be accomodated elsewhere by the deformation
of the Maghrebids and/or by rotations of Mediterranean microplates. Also, E–W velocity components analysis supports the idea
that E–W extension exists, as already suggested by recent structural and seismotectonic data interpretation.
Received: 27 November 2000 / Accepted: 17 September 2001 相似文献
149.
150.