Utility of Landsat 7 satellite data for continued monitoring of forest cover change in protected areas in Southeast Asia

Satellite instruments, particularly the Landsat TM (Thematic Mapper) and ETM+ (Enhanced Thematic Mapper Plus) series of sensors, are important tools in the interdisciplinary study of tropical forests that are increasingly integrated into studies that monitor changes in vegetation cover within tropical forests and tropical protected areas, and also applied with other types of data to investigate the drivers of land cover change. However, further advances in the use of Landsat to study and monitor tropical forests and protected areas are threatened by the scan line corrector failure on the ETM+ sensor, as well as uncertainty about the continuity of the Landsat mission. Given these problems, this paper illustrates how ETM+ data were used in an interdisciplinary study that effectively monitored forest cover change in Gunung Palung National Park in West Kalimantan, Indonesian Borneo. Following 31 May 2003, when the ETM+ sensor's scan line corrector failed, we analysed how this failure impedes our ability to perform a similar study from this date onwards. This analysis uses six simulated post-scan line corrector failure (SLC-off) images and reveals that data gaps caused by SLC-off introduce maximum errors of 1.47 per cent and 4.04 per cent in estimates of forest cover and rates of forest loss, respectively. The analysis also demonstrates how SLC-off has transformed ETM+ data from a complete inventory dataset to a statistical sample with variable sample fraction, and notes how this data loss will confound the use of Landsat data to model land cover change in a spatially explicit manner. We discuss potential limited uses of SLC-off data and suggest alternative sensors that may provide essential remotely sensed data for monitoring tropical forests in Southeast Asia.     

Anaerobic biodegradation of TCE in laboratory columns of fractured saprolite

An experiment was conducted to determine if biodegradation of trichloroethylene (TCE) can occur in previously uncontaminated ground water in saturated fractured saprolite (highly weathered material derived from sedimentary rocks). Two undisturbed columns (0.23 m diameter by 0.25 m long) of fractured saprolite were collected from approximately 2 m depth at an uncontaminated site on the Oak Ridge Reservation, Oak Ridge, Tennessee. Natural, uncontaminated ground water from the site, which was degassed and spiked with dissolved phase TCE, was continuously pumped through one column containing the natural microbial communities (the biotic column). In a second column, the microorganisms were inhibited and the dissolved phase TCE was added under aerobic conditions (dissolved oxygen conditions > 2 ppm). In effluent from the biotic column, reducing conditions rapidly developed and evidence of anaerobic biodegradation of TCE, by the production of cDCE, first appeared approximately 31 days after addition of TCE. Reductive dechlorination of TCE occurred after iron-reducing conditions were established and about the same time that sulfate reduction began. There was no evidence of methanogenesis. Analyses using polymerase chain reaction with specific primers sets detected the bacteria Geothrix, Geobacter, and Desulfococcus-Desulfonema-Desulfosarcina in the effluent of the biotic column, but no methanogens. The presence of these bacteria is consistent with iron- and sulfate-reducing conditions. In the inhibited column, there were no indicators of TCE degradation. Natural organic matter that occurs in the saprolite and ground water at the site is the most likely primary electron donor for supporting reductive dechlorination of TCE. The relatively rapid appearance of indicators of TCE dechlorination suggests that these processes may occur even in settings where low oxygen conditions occur seasonally due to changes in the water table.     

Topographic locations and size of earthquake‐ and typhoon‐generated landslides,Tachia River,Taiwan

Analysis of mapped landslide locations using a high‐resolution (5‐m grid) digital elevation model (DEM) in the Tachia River basin, Taiwan, finds distinct differences in the topographic locations and size of landslides during the 1999 Chi‐Chi earthquake and the 2001 Toraji typhoon. Our analysis supports Densmore and Hovius' hypothesis that earthquake‐induced landslides cluster near ridgetops due to topographic amplification of ground shaking, and that typhoon‐induced landslides occur with greater frequency lower on slopes. In addition, the differing topographic locations of seismically‐induced and subsequent typhoon‐induced landslides shows no evidence of residual post‐earthquake influences on landslides during typhoon Toraji previously hypothesized for drainage basins closer to the earthquake epicenter. Our results support the interpretation that in this tectonically active landscape, seismically‐induced landslides help shatter and erode ridgetops but typhoon‐triggered landslides concentrate erosion farther downslope, with the combination acting to more uniformly lower upland terrain than either process does individually. Copyright © 2013 John Wiley & Sons, Ltd.     

Estuaries of the South Atlantic coast of North America: Their geographical signatures

Estuaries of the southeastern Atlantic coastal plain are dominated by shallow meso-tidal bar-built systems interspersed with shallow sounds and both low flow coastal plain and high flow piedmont riverine systems. Three general geographical areas can be discriminated: the sounds of North Carolina; the alternating series of riverine and ocean dominated bar-built systems of South Carolina, Georgia, and northeast Florida, and the subtropical bar-built estuaries of the Florida southeast coast. The regional climate ranges from temperate to subtropical with sea level rise and hurricanes having a major impact on the region's estuaries because of its low and relatively flat geomorphology. Primary production is highest in the central region. Seagrasses are common in the northern and southern most systems, while intertidal salt marshes composed ofSpartina alterniflora reach their greatest extent and productivity in South Carolina and Georgia. Nuisance blooms (cyanobacteria, dinoflagellates, and cryptomonads) occur more frequently in the northern and extreme southern parts of the region. Fishery catches are highest in the North Carolina and Florida areas. Human population growth with its associated urbanization reaches a maximum in Florida and it is thought that the long-term sustainability of the Florida coast for human habitation will be lost within the next 25 years. Tidal flushing appears to play an important role in mitigating anthropogenic inputs in systems of moderate to high tidal range, i.e., the South Carolina and Georgia coasts. The most pressing environmental problems for the estuaries of the southeastern Atlantic coast seem to be nutrient loading and poor land use in North Carolina and high human population density and growth in Florida. The future utilization of these estuarine systems and their services will depend on the development of improved management strategies based on improved data quality.     

Interactive effects of hypoxia and PBDE on larval settlement of a marine benthic polychaete

Marine benthic polychaete Capitella sp. I is widely known to adapt to polluted habitats; however, its response to xenobiotics under hypoxic conditions has been rarely studied. This research aimed to test the hypothesis that interactive effects of hypoxia and congener BDE-47 of polybrominated diphenyl ethers (PBDE), which is ubiquitous in marine sediments, may alter the settlement of Capitella sp. I. Our results revealed that under hypoxic condition, settlement success and growth in body length of Capitella larvae were significantly reduced compared to those under normoxia of similar BDE-47 concentration. While no significant changes in morphology of settled larvae were noted in both exposure conditions, the presence of BDE-47 could enhance polychaete growth. The present findings demonstrated that the interactive effects of hypoxia and environmentally realistic concentrations of BDE-47 in sediments could affect polychaete settlement, which, in turn, reduce its recruitment and subsequent population size in the marine benthic ecosystem.     

Relationships between cut-off lows and the semiannual and southern oscillations

The characteristics of Southern Cut-off Lows (CoLs) are studied for the period 1979–2008. The systematic identification of CoLs is realized by applying an original automated scheme using mean daily geopotential height and air temperature at 500?hPa NCEP-DOE II Reanalysis data. From closed lows’ trajectories established from the Equator to the polar jet stream, extratropical lows are analyzed and the stage of cut-off is defined as a secluded low presenting a cold core. From 4,843 cases the general CoL features are presented and confirm several previous results such as the geographic distribution which shows that they are more frequent in the latitudinal band contained between 20°S and 45°S and in close proximity to the continents. On a seasonal time scale, CoLs are more numerous from late summer to autumn, with a maximum of frequency in March/April. In winter (June–July–August), they are fewer but deeper than during the rest of the year. In the median domain (~32.5°S), the annual cycle of the frequency is bimodal and present two peaks during transitional seasons. In this zone, the seasonal cycle varies in accordance with the Semiannual Oscillation. Thereby, when the meridional gradient of temperature/pressure is reinforced between mid and high latitudes, CoLs are more frequent in the median domain. Over the period 1979–2008, the annual CoLs’ frequency exhibits a positive trend of about 25%. This increase is associated with a widening of the latitudinal domain of occurrence equatorward as well as poleward. The trend is linked with an abrupt positive shift in the number of CoLs’ generation between 1998 and 1999. The geographical distribution of CoLs frequency varies significantly in accordance with El Ni?o Southern Oscillation with more CoL’s at lower (higher) latitudes during La Ni?a (El Ni?o) events, principally in the Southern Pacific.     

Determinants of poverty: lessons from Kenya

Poverty and food security are twin concerns of Kenya in a manner similar to many affected developing countries. It is characterized by the inability of the affected households in the country to acquire and retain sustainable livelihoods. The picture in Kenya is bound to be complicated by the projected changes in climate, as well as by population increase and environmental degradation, all which will put pressure on the natural resource base and militate against the achievement of sustainable development. The poverty picture in Kenya has hardly changed since independence over four decades ago despite the enormous resources and efforts which have been directed at tackling it. The current national poverty level remains high at well over 70% in some pockets which remain particularly vulnerable. Following the recent post-election violence, there is now a fear that the situation could degenerate into famine conditions and further hopelessness for a sizeable proportion of the rural population. Government efforts to eradicate poverty and food insecurity spelled out in a thirty year development plan are unlikely to succeed unless underlying causes of inequality are properly addressed. The paper contains suggestions for new approaches to addressing the twin problems.     

Eutrophication and some European waters of restricted exchange

Regions of Restricted Exchange (RREs) are an important feature of the European coastline. They are historically preferred sites for human settlement and aquaculture and their ecosystems, and consequent human use, may be at risk from eutrophication. The OAERRE project (EVK3-CT1999-0002) concerns ‘Oceanographic Applications to Eutrophication in Regions of Restricted Exchange’. It began in July 2000, and studies six sites. Four of these sites are fjords: Kongsfjorden (west coast of Spitzbergen); Gullmaren (Skagerrak coast of Sweden); Himmerfjärden (Baltic coast of Sweden); and the Firth of Clyde (west coast of Scotland). Two are bays sheltered by sand bars: Golfe de Fos (French Mediterranean); and Ria Formosa (Portuguese Algarve). Together they exemplify a range of hydrographic and enrichment conditions. The project aims to understand the physical, biogeochemical and biological processes, and their interactions, that determine the trophic status of these coastal marine RRE through the development of simple screening models to define, predict and assess eutrophication. This paper introduces the sites and describes the component parts of a basic screening model and its application to each site using historical data. The model forms the starting point for the OAERRE project and views an RRE as a well-mixed box, exchanging with the sea at a daily rate E determined by physical processes, and converting nutrient to phytoplankton chlorophyll at a fixed yield q. It thus uses nutrient levels to estimate maximum biomass; these preliminary results are discussed in relation to objective criteria used to assess trophic status. The influence of factors such as grazing and vertical mixing on key parameters in the screening model are further studied using simulations of a complex ‘research’ model for the Firth of Clyde. The future development of screening models in general and within OAERRE in particular is discussed. In addition, the paper looks ahead with a broad discussion of progress in the scientific understanding of eutrophication and the legal and socio-economic issues that need to be taken into account in managing the trophic status of RREs.