Progress in Physical Geography recent issues

Progress in Physical Geography: retrospect and prospect 2009--10

Clifford, N. J. — Fri, 20 Nov 2009 04:03:15 PST

Synchronization of transport and supply in beach-dune interaction

Houser, C. — Fri, 20 Nov 2009 04:03:15 PST

This review considers the role of nearshore processes and morphological change as a flexible and dynamic constraint on the supply and transport of sediment between beach and dune. It is argued that the lack of information in this regard remains a central barrier to the development of a theory of beach-dune interaction that can be translated across scales and between field sites. Existing beach-dune models do not consider how and when sediment gets transferred to the backshore where it becomes available for transport by wind. Rather, existing models largely ascribe regional variations in dune morphology to fixed constraints on beach slope and sediment budget, without explicit recognition of processes involved. Recent (process-scale) transport studies have shown that the transfer of sediment is both spatially variable and temporally intermittent as a result of transport limitations across the beachface. While these studies have identified varied controls on sediment transport and exchange, there remains a limited capacity to predict the evolution of beach-dune systems, largely because the beachface tends to be viewed as a static transport surface without regard to supply or to the changing limits to transport. Following storm erosion, dune recovery first requires that the beach recovers through the onshore migration and welding of nearshore bars, followed by accretion in the backshore to create a supply of sediment for transport by the wind. The dependence of dune recovery on the synchronization of transport events with the recovery of sediment supply in the backshore creates a strong asymmetry in dune recovery that makes barrier island susceptible to widespread erosion and breaching if a change in the frequency or grouping of storm events is capable of resetting the bar system (offshore) before the next extreme storm.

Problems in remote sensing of landscapes and habitats

Wang, K., Franklin, S. E., Guo, X., He, Y., McDermid, G. J. — Fri, 20 Nov 2009 04:03:15 PST

Wildlife habitat mapping strongly supports applications in natural resource management, environmental conservation, impacts of anthropogenic activity, perturbed ecosystem restoration, species-at-risk recovery and species inventory. Remote sensing has long been identified as a feasible and effective technology for large-area habitat mapping. However, existing and future uncertainties in remote sensing will definitely have a significant effect on the relevant scientific research. This article attempts to identify the current challenges and opportunities in remote sensing for large-area wildlife habitat mapping, and accordingly provide possible solutions and directions for further research.

Advances in interferometric synthetic aperture radar (InSAR) in earth system science

Rott, H. — Fri, 20 Nov 2009 04:03:16 PST

During recent years, synthetic aperture radar (SAR) interferometry (InSAR) has become an important tool for precise measurements of the earth’s surface topography and deformation. This paper presents an overview on recent developments in InSAR applications, with emphasis on the use of satellite-borne sensors for applications in geoscience, topographic mapping, natural hazard monitoring and environmental research. InSAR measurement principles are briefly introduced. Recent results on the use of repeat-pass interferometry for mapping seismic and volcanic deformation, monitoring landslides and subsidence, and mapping glacier motion are described. Other InSAR applications introduced in the paper are: topographic mapping, retrieval of biogeophysical parameters on land surfaces, and measurements of water currents. Examples of interferometric products are shown for satellite-borne SAR systems operating at X-band, C-band and L-band radar frequencies. An outlook is provided on upcoming SAR systems which will spur further advances in InSAR techniques and applications.

The effects of land-use combinations on soil erosion: a case study in the Loess Plateau of China

Fu, B.-J., Wang, Y.-F., Lu, Y.-H., He, C.-S., Chen, L.-D., Song, C.-J. — Fri, 20 Nov 2009 04:03:16 PST

Land use is one of the key factors affecting soil erosion in the Loess Plateau of China. This paper examines soil erosion under different land uses and land-use combinations using ¹³⁷ Cs tracing in the Yangjuangou Catchment, a tributary of the Yan River in the Loess Plateau of Northern Shaanxi Province. The results show that the order of ¹³⁷Cs activity in different land uses decreases sequentially from mature forest to grass to young forest to orchard to terrace crop, indicating that the mature forests had the lowest erosion rates while the terraced cropland produced the highest erosion amount. The majority of ¹³⁷Cs is distributed in the top 0—10 cm of the soil layer. The ¹³⁷Cs activity in mature forest and grass soil is significantly higher than in other land uses. Three land-use combinations on the hillslope were selected to study the relationship between land-use combination and soil erosion. The mixtures of ‘grass (6 years old) + mature forest (25 years old) + grass (25 years old)’ and ‘grass (6 years old) + young forest (6 years old) + mature forest (25 years old) + grass (25 years old)’ are better for soil erosion control, lowering soil erosion amount by 42% compared with a land-use combination of ‘grass (6 years old) and shrub (6 years old)’. The results provide an important basis for optimizing land-use combinations to control soil erosion on slopes and may also result in important ecological benefits.

The endokarstic erosion of marble in cold climates: Corbel revisited

Faulkner, T. L. — Fri, 20 Nov 2009 04:03:16 PST

After the work of Jean Corbel in the 1950s, who compared karstification in the Scandinavian Caledonide marbles with that in sedimentary limestones in temperate and tropical regions, the understanding of underground limestone dissolution has developed considerably. Corbel concluded that ‘karstification proceeds much faster in a cold than in a warm climate’, based on the knowledge that the solubilities of both CO₂ and CaCO₃ increase with lower temperature, without realizing that because cave streams in Scandinavia rarely reach saturation this fact is not directly relevant. We now know that the dissolutional enlargement of inception channels in limestones proceeds commonly via a slow initial ‘pre-breakthrough’ laminar flow stage before conduits can enlarge chemically at maximum rates under turbulent flow conditions. Recent research has shown that the pre-breakthrough stage is speeded up at low temperatures, as occurs in cold climates now, and as occurred during the deglaciation of the Weichselian ice sheet in Scandinavia, especially under steep hydraulic gradients and, in many cases, despite the lower partial pressure of CO₂. Additionally, this whole stage might be bypassed if fractures created by deglacial seismicity were wide enough and short enough. After breakthrough, although limestone dissolution is slower in cold rather than warm climates, conduit enlargement still proceeds at a significant rate, provided the water remains unsaturated, and especially if high flow rates promote mechanical erosion. The exploration of large numbers of (short) caves in central Scandinavia shows that Corbel’s conclusion is partly true for the more recent geological past, because of the special conditions that apply during the Quaternary glacial cycles.

Topographic normalization of satellite imagery for image classification in northeast India

Reddy, M. B., Blah, B. — Fri, 20 Nov 2009 04:03:17 PST

IRS-LISS-III satellite imagery covering Nongkhyllem Wildlife Sanctuary area located within the Ri-Bhoi District of Meghalaya State, northeast India, was used for analysis of the landcover pattern and vegetation types occurring there. A maximum likelihood classifier was used to generate a supervised classification into land-cover types and the vegetation types within the forested area. The preparation of training data sets used thematic maps of the area, and knowledge accruing from extensive personal field visits. Sample field plots were located at 30 different places in the Sanctuary for classification accuracy assessment. The Normalized Difference Vegetation Index (NDVI) was also computed from LISS-III satellite imagery. A digital elevation model (DEM) of the Sanctuary was generated using a GIS. The DEM was used to test the hypothesis that its joint use with the satellite data would increase classification accuracy. This proved to be the case. Bivariate correlation analysis was performed between spectral and DEM variables to cross-check the results. In the example used, that of the rugged terrain in mountainous parts of northeast India, such integration of satellite land-cover data and DEM information appears to be a necessity in improved land-cover mapping for resource planning and utilization.

Hydrology: catchment vegetation and runoff

Peel, M. C. — Fri, 20 Nov 2009 04:03:17 PST

The interactions between catchment vegetation and runoff continue to be a staple area of hydrological research. Drawing mainly upon material published since 2002, this report briefly reviews progress in this area with specific reference to: (1) paired and single catchment studies; (2) top-down models; and (3) the likely impact of climate change. Results from a wider range of paired and single catchments studies are revealing the complex relationship between catchment vegetation and runoff and prompting a reassessment of the methodologies used to generalize this relationship. Vegetation appears to have a significant influence on runoff at small scales, which reduces to a second-order influence, relative to aridity, at larger scales. Top-down models of catchment behaviour generally reflect this second-order influence at the large scale. As vegetation responds to CO₂ enrichment under climate change, the magnitude and direction of associated changes in runoff remains uncertain. A key element in quantifying the hydrological impact of climate change is the relationship between catchment vegetation and runoff, which continues to be a productive area of research within hydrology.

Research resource review: Burek, C.V. and Prosser, C.D., editors 2008: The history of geoconservation. Bath: The Geological Society Publishing House. 320 pp. {pound}60 cloth. ISBN: 978 1 86239 254 0

Page, K. — Fri, 20 Nov 2009 04:03:17 PST

Research resource review: Pelletier, J.D. 2008: Quantitative modeling of Earth surface processes. Cambridge: Cambridge University Press. 304 pp. {pound}40 cloth. ISBN: 978 0 521 85597 6

Wainwright, J. — Fri, 20 Nov 2009 04:03:17 PST

Approaches to modelling land erodibility by wind

Webb, N. P., McGowan, H. A. — Fri, 23 Oct 2009 04:16:50 PDT

Land susceptibility to wind erosion is governed by complex multiscale interactions between soil erodibility and non-erodible roughness elements populating the land surface. Numerous wind erosion modelling systems have been developed to quantify soil loss and dust emissions at the field, regional and global scales. All of these models require some component that defines the susceptibility of the land surface to erosion, ie, land erodibility. The approaches taken to characterizing land erodibility have advanced through time, following developments in empirical and process-based research into erosion mechanics, and the growing availability of moderate to high-resolution spatial data that can be used as model inputs. Most importantly, the performance of individual models is highly dependent on the means by which soil erodibility and surface roughness effects are represented in their land erodibility characterizations. This paper presents a systematic review of a selection of wind erosion models developed over the last 50 years. The review evaluates how land erodibility has been modelled at different spatial and temporal scales, and in doing this the paper identifies concepts behind parameterizations of land erodibility, trends in model development, and recent progress in the representation of soil, vegetation and land management effects on the susceptibility of landscapes to wind erosion. The paper provides a synthesis of the capabilities of the models in assessing dynamic patterns of land erodibility change, and concludes by identifying key areas that require research attention to enhance our capacity to achieve this task.

Modelling impacts of climate change on snowmelt runoff generation and streamflow across western US mountain basins: a review of techniques and applications for water resource management

Day, C. A. — Fri, 23 Oct 2009 04:16:50 PDT

The western US region is heavily reliant on spring snowmelt for much of its annual water supply. However, rising temperatures across the region over the latter half of the twentieth century have reduced snowpack accumulation, snowmelt timing and magnitude, especially at lower elevations. Water resource planners must be prepared to understand and counter the possible consequences resulting from a continuation in rising air temperatures on snowmelt and streamflow into the twenty-first century. This review aims to thoroughly analyse what tools and techniques are available to monitor and plan for such changes. A historical analysis of snowmelt trends in response to increasing air temperatures is followed by a review of methods used to forecast the effects of future changes in air temperature on snowmelt processes along with both general approaches to snowmelt modelling and different snowmelt models themselves. The techniques and methods to be ultimately employed will depend greatly upon data availability and on the scale at which they are to be applied.

Response of karst springs to climate change and anthropogenic activities: the Niangziguan Springs, China

Hao, Y., Wang, Y., Zhu, Y., Lin, Y., Wen, J.-C., Yeh, T.-C. J. — Fri, 23 Oct 2009 04:16:51 PDT

Discharge from the largest karst spring in north China, the Niangziguan Springs, has been declining since the 1950s. This paper examines the response of these springs to climatic change and anthropogenic influence by attempting a model-based discrimination between phases in the stream discharge record. In Niangziguan Springs Basin, the exploitation of karst groundwater began in 1979. Accordingly, the spring discharge data were divided into two phases: pre-1979 and post-1979. In the first phase (1957—78) the spring discharge was believed to be affected solely by climate change, and in the second phase (1979—2007) the spring discharge was influenced by both climate change and human activities. Using grey system theory, a discharge model was estimated for the first phase. Extrapolating the model, we obtained a projection of the spring discharge during the second phase. Using a water balance calculation, we discerned the respective effects of climate change and human activities on depletion of spring discharge for the second phase. The results show that the contribution of climate change to depletion of Niangziguan Springs is 2.30m³/s and the contribution of anthropogenic activities ranges from 1.89 to 2.90 m³/s, although this assumes a constant for the climate change effect. Accordingly, the anthropogenic effects have been approaching and surpassing the effects of climate change during the second phase. With respect to the impact of human activities on spring discharge, groundwater abstraction accounts for only about 34—52% of the declines; 48—66% of the declines are related to other human activities, such as dewatering from coal mining, dam building and deforestation.

A review of hydrological modelling of basin-scale climate change and urban development impacts

Praskievicz, S., Chang, H. — Fri, 23 Oct 2009 04:16:51 PDT

Hydrological modelling is a valuable tool for researchers in geography and other disciplines for studying the processes governing impacts of climate change and urban development on water resources and for projecting potential ranges of impacts from scenarios of future change. Modelling is an inherently probabilistic exercise, with uncertainty amplified at each stage of the process, from scenario generation to issues of scale, to simulation of hydrological processes, to management impacts. At the basin scale, significant factors affecting hydrological impacts of climate change include latitude, topography, geology, and land use. Under scenarios of future climate change, many basins are likely to experience changes not only in their mean hydrology, but also in the frequency and magnitude of extreme hydrological events. Impacts of climate change on water quality are largely determined by hydrological changes and by the nature of pollutants as flushingor dilution-controlled. The most significant impact of urban development on water resources is an increase in overall surface runoff and the flashiness of the storm hydrograph. The increase in impervious surface area associated with urban development also contributes to degradation of water quality as a result of non-point source pollution. Modelling studies on the combined impacts of climate change and urban development have found that either change may be more significant, depending on scenario assumptions and basin characteristics, and that each type of change may amplify or ameliorate the effects of the other. Hydrological impacts of climate change and urban development are likely to significantly affect future water resource management.

Glacier mapping: a review with special reference to the Indian Himalayas

Bhambri, R., Bolch, T. — Fri, 23 Oct 2009 04:16:51 PDT

This paper deals with the development of glacier mapping and glacier fluctuations since the mid-nineteenth century, with special reference to the Indian Himalayas, and the contributions of the Survey of India and the Geological Survey of India. In addition, it presents a review of the limitations and challenges relating to: the mapping of clean-ice and debris-covered glaciers; the comparison of different data sets; and the measurement of glacier volume changes based on multitemporal digital elevation models. Possible solutions are discussed, and the emerging areas of glacier mapping research and applications for the Indian Himalayas are highlighted.

Glaciohydraulic supercooling

Cook, S. J., Knight, P. G. — Fri, 23 Oct 2009 04:16:52 PDT

In this progress report we review recent work which has investigated the process of glaciohydraulic supercooling and its significance for a range of glaciological and geological phenomena. Since our last report (Knight and Cook, 2008), glaciohydraulic supercooling has been identified in new locations and under hitherto unrecognized conditions, both for modern and formerly glaciated environments. Recent work has examined the record of supercooling preserved in the landform and sediment record, within tunnel valleys and in sequences of melt-out till. We suggest that supercooling may also have important implications for glacier dynamics because of the role it may play in controlling the geometry of subglacial overdeepenings, which in turn acts as a control on the dynamics of tidewater glaciers. Despite these numerous recent scientific advances, there remains a need to critically evaluate the importance of supercooling for the various aspects of sediment entrainment and flux, glacial geomorphology and ice dynamics with which it has become associated. We illustrate how collaboration with researchers in other branches of cryospheric science, such as sea-ice scientists, might shed new light on the significance of supercooling within these various aspects of glacier science.

Micro- and mesoclimatology

Mills, G. — Fri, 23 Oct 2009 04:16:52 PDT

This report focuses on research in this area published during 2007. It reflects the broad themes that emerged in the literature during this period, with an emphasis on urban-based work. Urban-based climatology is assuming increased importance in the literature for a number of reasons, including the inherent complexity of urban environments, which makes their study difficult, and the potential for purposeful use of micrometeorology to improve the environment experienced by most of the population. Moreover, 2007 provided a rich vein of work in this area. The report is divided into two main sections, associated with the surface energy budget and its application to ‘natural’ settings and the study of urban climates.

Charney, J.G. 1947: The dynamics of long waves in a baroclinic westerly current. Journal of Meteorology 4, 135--62

James, I. N. — Fri, 23 Oct 2009 04:16:52 PDT

Research resource review: Billy, Y. 2008: Strait through the ice. New York: Icarus Films. 52 minutes. US$390. DVD

Russell, A. — Fri, 23 Oct 2009 04:16:52 PDT

Research resource review: Polunin, N.V.C., editor 2008: Aquatic ecosystems: trends and global prospects. Cambridge: Cambridge University Press. 512 pp. {pound}80 cloth. ISBN: 978 0 521 83327 1

Hughes, F. — Fri, 23 Oct 2009 04:16:52 PDT

Remote sensing in physical geography: a twenty-first-century perspective

Boyd, D. S. — Tue, 06 Oct 2009 09:20:06 PDT

Remote sensing of soil surface properties

Anderson, K., Croft, H. — Tue, 06 Oct 2009 09:20:06 PDT

Remote sensing is now in a strong position to provide meaningful spatial data for use in soil science investigations. In the last 10 years, advancements in remote sensing techniques and technologies have given rise to a wealth of exciting new research findings in soil-related disciplines. This paper provides a critical insight into the role played by remote sensing in this field, with a specific focus on soil surface monitoring. Two key soil properties are considered in this review, soil surface roughness and moisture, because these two variables have benefited most from recent cutting-edge advances in remote sensing. Of note is the fact that the major recent advancements in spatial assessment of soil structure have emerged from optical remote sensing, while the soil moisture community has benefited from advancements in microwave systems, justifying the focus of this paper in these specific directions. The paper considers the newest techniques within active, passive, optical and microwave remote sensing and concludes by considering future challenges, multisensor approaches and the issue of scale — which is a key cross-disciplinary research question of relevance to soil scientists and remote sensing scientists alike.

A review of satellite meteorology and climatology at the start of the twenty-first century

Kidd, C., Levizzani, V., Bauer, P. — Tue, 06 Oct 2009 09:20:06 PDT

The observation of the atmosphere by satellite instrumentation was one of the first uses of remotely sensed data nearly 50 years ago. Since then a range of satellites have carried many different meteorological sensors capable of monitoring the dynamics of the atmosphere and the capture and retrieval of information about atmospheric parameters for use in meteorological and climatological applications. The utilization of satellite observations for meteorology and climatology is essential since the atmosphere is a global feature, and conventional observations of it are primarily land-based. Satellites, with their synoptic view, provide much information benefiting numerical weather prediction models to improve weather forecasting and the ability to monitor weather systems, in particular those that pose a threat to humankind, over the entire Earth. Development of new observational capabilities has led to new insights into atmospheric processes and their interaction, allowing the consequences of anthropogenic activities, such as climate change, to be monitored.

Remote sensing: hydrology

Tang, Q., Gao, H., Lu, H., Lettenmaier, D. P. — Tue, 06 Oct 2009 09:20:06 PDT

Satellite remote sensing is a viable source of observations of land surface hydrologic fluxes and state variables, particularly in regions where in situ networks are sparse. Over the last 10 years, the study of land surface hydrology using remote sensing techniques has advanced greatly with the launch of NASA’s Earth Observing System (EOS) and other research satellite platforms, and with the development of more sophisticated retrieval algorithms. Most of the constituent variables in the land surface water balance (eg, precipitation, evapotranspiration, snow and ice, soil moisture, and terrestrial water storage variations) are now observable at varying spatial and temporal resolutions and accuracy via remote sensing. We evaluate the current status of estimates of each of these variables, as well as river discharge, the direct estimation of which is not yet possible. Although most of the constituent variables are observable by remote sensing, attempts to close the surface water budget from remote sensing alone have generally been unsuccessful, suggesting that current generation sensors and platforms are not yet able to provide hydrologically consistent observations of the land surface water budget at any spatial scale.

Paving the planet: impervious surface as proxy measure of the human ecological footprint

Sutton, P. C., Anderson, S. J., Elvidge, C. D., Tuttle, B. T., Ghosh, T. — Tue, 06 Oct 2009 09:20:06 PDT

Fundamental questions regarding the human-environment-sustainability problematic remain contested. What are the relative roles of population, consumption, and technology with respect to sustainability? How can sustainability be measured? Numerous metrics have been developed to address these controversial questions including ideas of carrying capacity, environmental sustainability indices, and ecological footprints. This work explores the question: is pavement a proxy measure of human impact on the environment? We explore and evaluate the use of satellite derived density grids of constructed area (aka ‘pavement’ or ‘impervious surface’) in the calculation of national and subnational ‘ecological footprints’. We generated a global constructed area density grid for the 2000—2001 period using satellite observed nighttime lights and a population count grid from the US Department of Energy. Satellite data inputs to the population product include MODIS landcover, SRTM topography and high-resolution imagery. Calibration of the global constructed area density product was derived from high-resolution aerial photographs. We demonstrate that a satellite derived constructed area per person index can serve as a proxy measure of ecological footprints at both the national and subnational level. This relatively simple and globally uniform measure of human impact on the environment correlates strongly with other more difficult to obtain measures.

Remote sensing and the future of landscape ecology

Tue, 06 Oct 2009 09:20:06 PDT

Landscape ecology focuses on the analysis of spatial pattern and its relationship to ecological processes. As a scientific discipline, landscape ecology has grown rapidly in recent years, supported by developments in GIS and spatial analysis techniques. Although remote sensing data are widely employed in landscape ecology research, their current and potential roles have not been evaluated critically. To provide an overview of current practice, 438 research papers published in the journal Landscape Ecology for the years 2004—2008 were examined for information about use of remote sensing. Results indicated that only 36% of studies explicitly mentioned remote sensing. Of those that did so, aerial photographs and Landsat satellite sensor images were most commonly used, accounting for 46% and 42% of studies, respectively. The predominant application of remote sensing data across these studies was for thematic mapping purposes. This suggests that landscape ecologists have been relatively slow to recognize the potential value of recent developments in remote sensing technologies and methods. The review also provided evidence of a frequent lack of key detail in studies recently published in Landscape Ecology , with 75% failing to provide any assessment of uncertainty or error relating to image classification and mapping. It is suggested that the role of remote sensing in landscape ecology might be strengthened by closer collaboration between researchers in the two disciplines, by greater integration of diverse remote sensing data with ecological data, and by increased recognition of the value of remote sensing beyond land-cover mapping and pattern description. This is illustrated by case studies drawn from Latin America (focusing on forest loss and fragmentation) and the UK (focusing on habitat quality for woodland birds). Such approaches might improve the analytical and theoretical rigour of landscape ecology, and be applied usefully to issues of outstanding societal interest, such as the impacts of environmental change on biodiversity and ecosystem services.

Progress in satellite remote sensing of ice sheets

Quincey, D.J., Luckman, A. — Tue, 06 Oct 2009 09:20:06 PDT

Understanding the changing mass balance and surface dynamics of the Earth’s major ice sheets in Greenland and Antarctica is of fundamental importance for accurate predictions of future sea-level rise. In this review, the remote sensing data sources available to ice-sheet studies are considered and the range of information that can be gained from remote sensing is examined. The review demonstrates that the integration of a range of remote sensing data sets can provide information on ice-sheet dynamics and volume changes, melt patterns and formation and drainage of supra- and subglacial lakes. Such data are highly complementary to field investigations by providing a regional-scale, synoptic perspective. The review concludes that emerging remote sensing techniques such as SAR interferometry, feature tracking, scatterometry, altimetry and gravimetry provide vital information without which an understanding of ice sheets would be far less advanced. It also concludes that there remain several key challenges for remote sensing, in particular relating to the observation of rapid dynamical changes that are characteristic of contemporary ice-sheet response to continued climatic warming.

Applications of remote sensing in geomorphology

Smith, M.J., Pain, C.F. — Tue, 06 Oct 2009 09:20:06 PDT

Remotely sensed imagery has been used extensively in geomorphology since the availability of early Landsat data, with its value measurable by the extent to which it can meet the investigative requirements of geomorphologists. Geomorphology focuses upon landform description/classification, process characterization and the association between landforms and processes, while remote sensing is able to provide information on the location/distribution of landforms, surface/subsurface composition and surface elevation. The current context for the application of remote sensing in geomorphology is presented with a particular focus upon the impact of new technologies, in particular: (1) the wide availability of digital elevation models; and (2) the introduction of hyperspectral imaging, radiometrics and electromagnetics. Remote sensing is also beginning to offer capacity in terms of close-range (<200 m) techniques for very high-resolution imaging. This paper reviews the primary sources for DEMs from satellite and airborne platforms, as well as briefly reviewing more traditional multispectral scanners, and radiometric and electromagnetic systems. Examples of the applications of these techniques are summarized and presented within the context of geomorphometric analysis and spectral modelling. Finally, the wider issues of access to geographic information and data distribution are discussed.

Effects of rainfall change on water erosion processes in terrestrial ecosystems: a review

Wei Wei, , Liding Chen, , Bojie Fu, — Thu, 27 Aug 2009 07:47:37 PDT

Water erosion is the most destructive erosion type worldwide, causing serious land degradation and environmental deterioration. Against a background of climate change and accelerated human activities, changes in natural rainfall regimes have taken place and will be expected to become more pronounced in future decades. Long-term shifts may challenge the existing cultivation systems worldwide and eventually alter the spatiotemporal patterns of land use and topography. Meanwhile, specific features of soil crusting/sealing, plant litter and its decomposition, and antecedent soil moisture content (ASMC) will accompany rainfall variability. All these changes will increase pressures on soil erosion and hydrological processes, making accurate erosion prediction and control more difficult. An improved knowledge and understanding of this issue, therefore, is essential for dealing with the forthcoming challenges regarding soil and water conservation practices. In this paper, the characteristics of changes in natural rainfall, its role on terrestrial ecosystems, the challenges, and its effect on surface water erosion dynamics are elaborated and discussed. The major priorities for future research are also highlighted, and it is hoped that this will promote a better understanding of water erosion processes and related hydrological issues.

Impacts of alien plant invasions on species richness in Mediterranean-type ecosystems: a meta-analysis

Gaertner, M., Den Breeyen, A., Cang Hui, , Richardson, D. M. — Thu, 27 Aug 2009 07:47:37 PDT

Besides a general consensus regarding the negative impact of invasive alien species in the literature, only recently has the decline of native species attributable to biological invasions begun to be quantified in many parts of the world. The cause-effect relationship between the establishment and proliferation of alien species and the extinction of native species is, however, seldom demonstrated. We conducted a meta-analysis of studies in Mediterranean-type ecosystems (MTEs) to examine: (1) whether invasion of alien plant species indeed causes a reduction in the number of native plant species at different spatial and temporal scales; (2) which growth forms, habitat types and areas are most affected by invasions; and (3) which taxa are most responsible for native species richness declines. Our results confirm a significant decline in native species richness attributable to alien invasions. Studies conducted at small scales or sampled over long periods reveal stronger impacts of alien invasion than those at large spatial scales and over short periods. Alien species from regions with similar climates have much stronger impacts, with the native species richness in South Africa and Australia declining significantly more post-invasion than for European sites. Australian Acacia species in South Africa accounted for the most significant declines in native species richness. Among the different growth forms of alien plants, annual herbs, trees and creepers had the greatest impact, whereas graminoids generally caused insignificant changes to the native community. Native species richness of shrublands, old fields and dune vegetation showed significant declines, in contrast to insignificant declines for forest habitats.

Sustaining river ecosystems: balancing use and protection

O'Keeffe, J. — Thu, 27 Aug 2009 07:47:37 PDT

Sustainable management of natural resources is a well-accepted concept, but there are few practical guidelines for its application. This paper suggests methods for the sustainable operation of water resource use and protection. Environmental flows (EF) for rivers are used to illustrate some of the opportunities and problems inherent in managing rivers sustainably. In particular, there is a requirement for agreeing on clear and measurable environmental objectives for which a modified flow regime can be set. Knowledge from a number of different disciplines, including hydrology, ecology, hydraulics, geomorphology, water quality and socio-economics has to be integrated to provide holistic levels of understanding if sustainable management is to be achieved. Methods for EF assessment have been developed to provide an effective framework for integration leading to a clear end-point. The implementation of EF has been hampered in the past by a concentration on the ecohydrological technicalities of the process. More recently, it has been realized that achieving a consensus in the socio-economic and political context is of overriding importance for successful implementation. Case studies from South African river research over the past 20 years are used to illustrate the policies, methods, impediments and successes of sustainable river management. In particular, a recognition of complexity and change, both in ecosystems and in human thinking and behaviour, is emphasized. Timeframes of decades are required for both types of change, but there is evidence that patience is being rewarded by gradual success.

Scale appropriate modelling of diffuse microbial pollution from agriculture

Thu, 27 Aug 2009 07:47:37 PDT

The prediction of microbial concentrations and loads in receiving waters is a key requirement for informing policy decisions in order to safeguard human health. However, modelling the fate and transfer dynamics of faecally derived microorganisms at different spatial scales poses a considerable challenge to the research and policy community. The objective of this paper is to critically evaluate the complexities and associated uncertainties attributed to the development of models for assessing agriculturally derived microbial pollution of watercourses. A series of key issues with respect to scale appropriate modelling of diffuse microbial pollution from agriculture is presented, and these include: (1) appreciating inadequacies in baseline sampling to underpin model development; (2) uncertainty in the magnitudes of microbial pollutants attributed to different faecal sources; (3) continued development of the empirical evidence base in line with other agricultural pollutants; (4) acknowledging the value of interdisciplinary working; and (5) beginning to account for economics in model development. It is argued that uncertainty in model predictions produces a space for meaningful scrutiny of the nature of evidence and assumptions underpinning model applications around which pathways towards more effective model development may ultimately emerge.

Mapping and monitoring intertidal benthic habitats: a review of techniques and a proposal for a new visual methodology for the European coasts

Godet, L., Fournier, J., Toupoint, N., Olivier, F. — Thu, 27 Aug 2009 07:47:37 PDT

Mapping seafloors is a fundamental step for managing and preserving coastal zones. Moreover, in a context of current global environmental changes, new methods allowing long-term monitoring are increasingly required. Various methods have been used to map seafloors, primarily benthic macrofauna and sediment sampling along regular grids or transects, and remote sensing methods. These methods map very different things, do not have the same accuracy levels, and have different costs in time and money. Furthermore, such methods often require the competencies of highly skilled scientists and exclude non-specialists otherwise best placed to perform them. In this paper, we test a method based on Direct Field Observations (‘DFO method’), which can be used by non-specialists, and assess if it is sufficient for mapping and monitoring intertidal habitats. We further compare this method with other conventional ones. The results show that such a simple method is relatively rapid and inexpensive given the results obtained. Moreover, it is particularly suitable for highly fragmented intertidal landscapes where other methods are often very limited. In consequence, in areas such as the European coasts, it can be used by non-specialists, such as protected-area managers, and because it is an inexpensive and quick method long-term monitoring is also possible.

Supporting large-area, sample-based forest inventories with very high spatial resolution satellite imagery

Falkowski, M. J., Wulder, M. A., White, J. C., Gillis, M. D. — Thu, 27 Aug 2009 07:47:37 PDT

Information needs associated with forest management and reporting requires data with a steadily increasing level of detail and temporal frequency. Remote sensing satellites commonly used for forest monitoring (eg, Landsat, SPOT) typically collect imagery with sufficient temporal frequency, but lack the requisite spatial and categorical detail for some forest inventory information needs. Aerial photography remains a principal data source for forest inventory; however, information extraction is primarily accomplished through manual processes. The spatial, categorical, and temporal information requirements of large-area forest inventories can be met through sample-based data collection. Opportunities exist for very high spatial resolution (VHSR; ie, <1 m) remotely sensed imagery to augment traditional data sources for large-area, sample-based forest inventories, especially for inventory update. In this paper, we synthesize the state-of-the-art in the use of VHSR remotely sensed imagery for forest inventory and monitoring. Based upon this review, we develop a framework for updating a sample-based, large-area forest inventory that incorporates VHSR imagery. Using the information needs of the Canadian National Forest Inventory (NFI) for context, we demonstrate the potential capabilities of VHSR imagery in four phases of the forest inventory update process: stand delineation, automated attribution, manual interpretation, and indirect attribute modelling. Although designed to support the information needs of the Canadian NFI, the framework presented herein could be adapted to support other sample-based, large-area forest monitoring initiatives.

Biogeography and landscape ecology: the way forward -- gradients and graph theory

Kent, M. — Thu, 27 Aug 2009 07:47:37 PDT

Following the previous report on this subject, published in 2007, there has been a very substantial increase in publications relevant to landscape ecology and this is illustrated by the growth in citations for articles in the core journal Landscape Ecology over the period 2000—2007. The continuing ‘identity crisis’ of landscape ecology is described and recent literature in the field is then summarized under the following headings: ‘Landscape ecology and climate change research’; ‘Alternatives to fragmentation and the patch-based model — the links between pattern and process’; ‘Fragmentation research’; ‘Methodology and techniques in landscape ecology’; and ‘Connectivity and graph theoretical approaches’. The review concludes that landscape ecology now represents one important focus within biogeography, linked to ecological biogeography, and takes its place alongside other key foci, including macroecology, palaeoecology and soil science/pedology. Nevertheless, both physical and human geographers still need to embrace landscape ecology even more enthusiastically than they have up until now.

Chandler, T.J. 1965: The climate of London. London: Hutchinson, 292 pp

Oke, T.R. — Thu, 27 Aug 2009 07:47:37 PDT

Research resource reviews: Bridge, J.S. and Demicco, R.V. 2008: Earth surface processes, landforms and sediment deposits. Cambridge: Cambridge University Press. 830 pp. {pound}45 cloth. ISBN: 978 0 5218 5780 2

Decaulne, A. — Thu, 27 Aug 2009 07:47:38 PDT

Book Review: Castree, N., Demeritt, D., Liverman, D. and Rhoads, B., editors 2009: A companion to environmental geography. Chichester: Wiley-Blackwell. 608 pp. {pound}95 cloth. ISBN: 978 1 4051 5622 6

Millington, J. D.A. — Thu, 27 Aug 2009 07:47:38 PDT