How accurately may we project tropical forest-cover change? A validation of a forward-looking baseline for REDD

The Reduced Emissions from Deforestation and forest Degradation (REDD+) mechanism of a future post-2012 global climate-change treaty would aim to give incentive to tropical countries to reduce deforestation and thus forest-carbon emissions. It would do so by crediting tropical countries for reducing deforestation relative to a baseline scenario describing carbon emissions and removals from forest-cover change expected in the absence of REDD+. Defining a credible and accurate baseline is both critical and challenging. One approach considered promising is spatial modelling to project forest-cover change on the basis of historical trends; yet few such projections have been validated at a national scale. We develop and validate a novel GEOMOD projection of forest-cover change in Panama over 2000–2008, based on trends over 1990–2000 and 25 drivers of forest-cover change. Compared with the actual landscape of 2008, our projection is 85.2% accurate at a 100-m pixel resolution. More error is attributable to the location of projected forest (8.6%) than to its area (6.2%). Accuracy was least where forest regeneration predominated (80%), and greatest where deforestation predominated (90%). Despite the sophistication of our projection, it is slightly less accurate than if we had assumed no forest-cover change over 2000–2008. We identify factors limiting projection accuracy, including the complexity of forest-cover change, the spatial variability of forest-carbon density, and the relatively small area of change at the national scale. We conclude that, with the exception of contexts where forest-cover change is significant and straightforward and where forest-carbon density relatively uniform (e.g., agricultural frontiers), spatially projected baselines are of limited value for REDD+ – their accuracy is too limited given their relative lack of transparency. Simpler, relatively coarse scale, retrospective baselines are recommended instead.     

Constitutive approach for rate‐sensitive anisotropic structured clays

This paper describes a constitutive approach to model the behavior of rate‐dependent anisotropic structured clay. Rate‐sensitivity is modeled using overstress viscoplasticity. Clay structure is treated as a viscous phenomenon whereby the viscosity of the undisturbed structured clay is initially very high and the viscosity degrades or decreases with plastic straining until the intrinsic or residual viscosity is reached. A microstructure tensor approach is used to make the structured viscosity anisotropic; whereas, the intrinsic viscosity is assumed to be isotropic. The behavior of the constitutive model is compared with the measured response of two clays (Gloucester and St. Vallier clay) from Eastern Canada during triaxial compression tests on specimens trimmed at different orientations to the vertical. The comparisons show that the constitutive framework is able to describe the anisotropic and rate‐sensitive response of both clays. The response of the model is also examined for the more general case of anisotropic consolidated triaxial compression and extension. Copyright © 2010 John Wiley & Sons, Ltd.     

A User-Oriented Perspective of Error-sensitive GIS Development

The current lack of error-sensitive functionality found in commercial GIS is at odds with the research focus error-sensitive GIS development has enjoyed over recent years. In an attempt to address this undesirable situation, this paper explores the development of error handling capabilities within GIS from the perspective of GIS users. Increasingly, GIS users need to fulfil a variety of different roles, from database designers and data capture personnel through to decision makers, each of which may require an awareness of data quality issues. The user-oriented approach taken here contrasts with the predominately developer-oriented perspective in the literature. The paper concludes that from a user's perspective it is possible to identify a number of simple reformulations of current research that would help bring about the desired increase in availability and use of error-sensitive functionality within commercial GIS technology and applications.     

Contracts and member checks in qualitative research in human geography: reason for caution?

Contracts with, and member checks by, research participants are increasingly recommended in qualitative research in human geography. However, differences in qualitatively researching 'the powerful', as opposed to researching 'down' mean that contracts and member checks may need to be approached with caution regarding the former. The possibility of the censorship of critique by powerful research participants is exemplified in this article, and a number of more general dilemmas in qualitatively researching 'up' are also discussed. Finally, some choices which might help address possible difficulties in qualitatively researching the powerful are outlined.     

Complexity in astroplasmas

Ideas of complexity theory – including self-organized criticality – are being applied to the study of turbulence and astroplasmas in the solar system. An RAS MIST meeting in London brought together researchers from different disciplines to compare established paradigms with more recent ideas. Sandra Chapman , Mervyn Freeman and Sean Oughton report.     

Distorted Froude‐scaled flume analysis of large woody debris

This paper presents the results of a movable‐boundary, distorted, Froude‐scaled hydraulic model based on Abiaca Creek, a sand‐bedded channel in northern Mississippi. The model was used to examine the geomorphic and hydraulic impact of simplified large woody debris (LWD) elements. The theory of physical scale models is discussed and the method used to construct the LWD test channel is developed. The channel model had bed and banks moulded from 0·8 mm sand, and flow conditions were just below the threshold of motion so that any sediment transport and channel adjustment were the result of the debris element. Dimensions and positions of LWD elements were determined using a debris jam classification model. Elements were attached to a dynamometer to measure element drag forces, and channel adjustment was determined through detailed topographic surveys. The fluid drag force on the elements decreased asymptotically over time as the channel boundary eroded around the elements due to locally increased boundary shear stress. Total time for geomorphic adjustment computed for the prototype channel at the Q₂ discharge (discharge occurring once every two years on average) was as short as 45 hours. The size, depth and position of scour holes, bank erosion and bars created by flow acceleration past the elements were found to be related to element length and position within the channel cross‐section. Morphologies created by each debris element in the model channel were comparable with similar jams observed in the prototype channel. Published in 2001 John Wiley & Sons, Ltd.     

Global climatic change,hurricanes, and a tropical forest

Most, if not all forests in the Caribbean are subject to occasional disturbances from hurricanes. If current general circulation model (GCM) predictions are correct, with doubled atmospheric CO₂ (2 × CO₂), the tropical Atlantic will be between 1 °C and 4 °C warmer than it is today. With such a warming, more than twice as many hurricanes per year could be expected in the Caribbean. Furthermore, Emanuael (1987) indicates that in a warmed world the destructive potential of Atlantic hurricanes could be increased by 40% to 60%. While speculative, these increases would dramatically change the disturbance regimes affecting tropical forests in the region and might alter forest structure and composition. Global warming impacts through increased hurricane damage on Caribbean forests are presented.An individual tree, gap dynamics forest ecosystem model was used to simulate the range of possible hurricane disturbance regimes which could affect the Luquillo Experimental Forest in Puerto Rico. Model storm frequency ranged from no storms at all up to one storm per year; model storm intensity varied from no damage up to 100% mortality of trees. The model does not consider the effects of changing temperature and rainfall patterns on the forest. Simulation results indicate that with the different hurricane regimes a range of forest types are possible, ranging from mature forest with large trees, to an area in which forest trees are never allowed to reach maturity.     

Evolution of late pleistocene and holocene climates in the circum-south pacific land areas

Paleovegetation maps were reconstructed based on a network of pollen records from Australia, New Zealand, and southern South America for 18 000, 12000, 9000, 6000, and 3000 BP and interpreted in terms of paleoclimatic patterns. These patterns permitted us to speculate on past atmospheric circulation in the South Pacific and the underlying forcing missing line mechanisms. During full glacial times, with vastly extended Australasian land area and circum-Antarctic ice-shelves, arid and cold conditions characterized all circum-South Pacific land areas, except for a narrow band in southern South America (43° to 45°S) that might have been even wetter and moister than today. This implies that ridging at subtropical and mid-latitudes must have been greatly increased and that the storm tracks were located farther south than today. At 12000 BP when precipitation had increased in southern Australia, New Zealand, and the mid-latitudes of South America, ridging was probably still as strong as before but had shifted into the eastern Pacific, leading to weaker westerlies in the western Pacific and more southerly located westerlies in the eastern Pacific. At 9000 BP when, except for northernmost Australia, precipitation reached near modern levels, the south Pacific ridges and the westerlies must have weakened. Because of the continuing land connection between New Guinea and Australia, and reduced seasonality, the monsoon pattern had still not developed. By 6000 BP, moisture levels in Australia and New Zealand reached their maximum, indicating that the monsoon pattern had become established. Ridging in the South Pacific was probably weaker than today, and the seasonal shift of the westerlies was stronger than before. By 3000 BP essentially modern conditions had been achieved, characterized by patterns of high seasonal variability.Contribution to Clima Locarno — Past and Present Climate Dynamics; Conference September 1990, Swiss Academy of Sciences — National Climate Program     

Contaminant concentrations in sport fish from San Francisco Bay, 1997

In 1997, seven sport fish species were sampled from seven popular fishing areas in San Francisco Bay. Mercury exceeded a human health screening value in 44 of 84 (52%) samples. All collected samples of leopard shark and striped bass exceeded the mercury screening value of 0.23 microg/g wet weight. PCBs exceeded the screening value in 51 of 72 (71%) samples. DDT, chlordane, and dieldrin, had lower numbers of samples above screening values: 16 of 72 (22%) for DDT, 11 of 72 (15%) for chlordanes, and 27 of 72 (37%) for dieldrin. Concentrations of PCBs and other trace organics were highest in white croaker and shiner surfperch, the two species with the highest fat content in their muscle tissue. Fish from one location, Oakland Harbor, had significantly elevated wet weight concentrations of mercury, PCBs, DDTs, and chlordanes compared to other locations. Removal of skin from white croaker fillets reduced lipid concentrations by 27-49% and concentrations of trace organics by 33-40%.