bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of Domestic Sewage Waste Treatment by the Polychaetes, Neanthes japonica and Perinereis nuntia var. vallata, on an Artificial Tidal Flat
Authors: Kurihara Yasushi 
Published: February 2007

AbstractIn order to establish a new biological method of treating sewage waste, mass cultures of the polychaete annelids, Neanthes japonica and Perinereis nuntia var. vallata, were employed. These species are known to ingest a large quantity of sewage sludge extracted from domestic sewage treatment plants. During this study, laboratory experiments were carried out to determine the effects of changes in various environmental factors on sludge consumption and growth. A pilot plant with an artificial tidal flat simulating natural estuarine tidal flat conditions was constructed and operated as a habitat for the polychaetes. The suitability of this artificial tidal flat for the treatment of sewage waste was discussed.
Theory of the Upper Limit to Phytoplankton Production per Unit Area in Natural Waters
Authors: Baumert Helmut , Uhlmann Dietrich 
Published: February 2007

AbstractUsing the maximum quantum yield of photosynthesis, the maximum daily integral of photosynthetically active radiation (PAR) and the euphotic zone depth as a basis, general formulae for the upper limits to gross and net carbon fixation in natural waters are derived by theoretical considerations. The results are compared with a set of extremely high production data published by independently working authors, including data from algal mass cultures, oxidation ponds, freshwater and salt lakes, reservoirs, rivers and canals, coastal and other marine waters, including upwelling areas. The comparison reveals a quite surprising degree of agreement and suggests that the derived formulae represent a new, theoretically sound general approach to phytoplankton production. In particular, it can be shown that the upper limit to phytoplankton production in natural waters is about three times higher than earlier estimates in the literature. The maximum energy efficiency is of the same order of magnitude as in terrestrial plant communities.
Size Structure of Deep‐Sea Meio‐ and Macrobenthos in the Western Pacific
Authors: Shirayama Yoshihisa 
Published: February 2007

AbstractThe size structure of deep‐sea meio‐ and macrobenthos was studied using 12 USNEL box corer samples collected in the Western Pacific. Both macro‐ and meiobenthos decreased in abundance with increasing water depth, as expected, but contrary to previous findings, the rate of decrease did not differ significantly between the two size classes of organisms. The median size index of total meiobenthos decreased with increasing water depth, while when the vertical distribution of organisms in the sediment was considered, such a trend was restricted to the organisms found in the upper 1 cm layer. In contrast, the median size of the nematodes increased with increasing water depth, and a possible cause for this correlation is discussed.
On the Occurrence of “Arctic” Cladocera with Special Reference to those along the Strait of Belle Isle (Quebec, Labrador, Newfoundland)
Authors: Meijering Meertinus P. D. 
Published: February 2007

AbstractIn September, 1978, ten ponds inhabited by Cladocera were sampled along the coasts of the Strait of Belle Isle. Fourteen out of nineteen species that were found there also occur in Greenland. On the other hand, a comparison with faunal lists for the island of Newfoundland and several faunal regions of Western Europe, and the ecological distribution of all European Cladocera reveals that the Arctic is settled exclusively by euryecious species, so that the relatively strong “arctic” element within the cladoceran fauna along the Strait of Belle Isle indicates simply the extreme conditions. Macrothrix hirsuticornis NORMAN & BRADY and Daphnia pulex LEYDIG are new for the island of Newfoundland.
Skeletal morphology and postmetamorphic ontogeny of Acris crepitans (Anura: Hylidae): A case of miniaturization in frogs
Authors: Maglia Anne M. , Pugener L. Analía , Mueller Jessica M. 
Published: February 2007

AbstractAcris crepitans is a small, semiaquatic member of the treefrog family Hylidae. Much recent attention has been paid to this species because of reports of population declines and malformations, yet few works have considered the skeletal anatomy of this common North American frog. Herein, we provide a detailed description of the morphology and adult ontogeny of the skeleton of A. crepitans, and discuss novel morphologies, interesting postmetamorphic developmental patterns, and intraspecific skeletal variation. The reduced amount of adult ossification, as well as several novel morphologies present in this species, are consistent with patterns of miniaturization seen in other anurans. For example, the skull is poorly ossified, but most of the cranial cartilages are heavily mineralized, the nasal bones are fused to endochondral ossification of the tectum nasi, the palatines are reduced, and the prootics and exoccipitals are not fused to one another (although the prootics are well‐developed and ornamented). In addition, several specimens exhibit abnormalities, which might indicate that: (1) the population was under an acute malformation outbreak, (2) a high incidence of small skeletal malformations is normal in this species, (3) the population is under stress because of habitat fragmentation, (4) there is environmental deterioration in the region where the specimens were collected, and/or (5) the species is now showing signs of decline in southern Missouri. Regardless of the cause, it is clear that further examination of skeletal variability in A. crepitans, including ossification patterns and the frequency of abnormalities, is warranted. J. Morphol., 2007. © 2007 Wiley‐Liss, Inc.
Explanation and policy in land degradation and rehabilitation for developing countries
Authors: Blaikie Piers 
Published: February 2007

AbstractThe paper examines why land management practices are not carried out, and what can be done about this. It focuses on the need to obtain an accurate explanation of why degradation has occurred, and highlights the need to examine: whether degradation really is taking place; the identification of those for whom land degradation is, or will be, a problem; the identification of why land degradation is taking place; the need to find solutions and means to reach them (i.e. policy formulation).
Soil degradation: I. Basic processes
Authors: Lal R. , Hall G. F. , Miller F. P. 
Published: February 2007

AbstractThis paper examines soil and land degradation. It describes basic processes and factors responsible for degradation, illustrates the cause‐effect relationships and differentiates between natural and man‐induced regressive effects. The ‘critical limit’ concept is described in terms of properties beyond which the soil will not support an economically‐viable agriculture. This paper is not an exhaustive literature review but emphasizes the scientific principles involved and highlights natural against man‐induced processes. Important natural processes are: laterization, hard‐setting, fragipan and clay pan formation, and geologic erosion. In comparison, man‐induced processes consist of: soil compaction, accelerated erosion, desertification, salt accumulation and leaching and acidification. One of the principal constraints is the problem of data reliability. A reliable database and precise criteria are definitely lacking and hinder the assessment of the extent, type and degree of soil degradation and establishing the cause‐effect scenario. Improving our database is, therefore, of a high priority if we are to adopt land use policy for sustainable soil management and long‐range resource management. Also outlined, are vital research and development strategies. Judicious resource management policy should emphasize managing prime agricultural land to produce to its maximum potential so that there is no need to cultivate marginal and easily‐degraded fragile ecosystems. A strict code of conduct is needed for utilizing marginal/fragile lands. Methods of restoring the productivity of degraded lands must be researched so as to minimize the need to clear and develop new lands.
Soil degradation processes and their control in Hungary
Authors: Várallya György 
Published: February 2007

AbstractSoil degradation is usually a complex process in which several features of soil deterioration can be recognized. Soil degradation may lead to the loss of land or soil; limitations to normal soil functions; decrease of soil fertility and ‘productive capacity’.The main soil degradation process are: (1) soil erosion by water and wind; (2) Development of extreme soil reaction (acidification; salinization/alkalization); (3) physical degradation (structural destruction; compaction; extreme moisture regime); (4) biological degradation; (5) unfavourable changes in the nutrient regime; (6) decrease of buffering capacity (leading to pollution, toxicity).Soil degradation is not an unavoidable consequence of intensive agriculture and social development. Most of the processes and their unfavourable consequences can be controlled, prevented, eliminated, or at least moderated.A rational strategy of efficient soil degradation control should be based on a system involving the following (consecutive) steps: (a) registration of facts and consequences; (b) analysis of reasons, processes, influencing factors and their mechanisms; (c) determination of the theoretical, real, rational and economic possibilities for control; (d) prediction of the potential impacts of these control alternatives; (e) elaboration and extension of technologies for the optimum alternatives.The present status of soil degradation processes in Hungary is briefly summarized in this paper and the possibilities for control are reviewed, with special regard to soil erosion, salinization/alkalization, acidification and physical degradation (compaction, structure destruction). Based on detailed and comprehensive information on soils (thematic maps of various scales; computerized geographical soil information system) the potential future development of various soil degradation processes is forecast and technologies are elaborated and recommended for use in Hungarian agriculture to prevent soil degradation.
Land use, deforestation and reforestation in the Zambian Copperbelt
Authors: Chidumayo E. N. 
Published: February 2007

AbstractTemporal and spatial changes in land use, vegetation cover, deforestation and reforestation in the Zambian Copperbelt were studied using a combination of aerial photograph analysis, literature review and inquiries among relevant government institutions.The study showed that between 1937 and 1984 loss of natural woodlands in the Copperbelt of Zambia (total area of Copperbelt: 9,615 km2) amounted to 41 per cent woodland area (8,419 km2). The major causes of this deforestation are woodfuel collection (for firewood and charcoal), cultivation and replacement of natural woodland with forest plantations. These accounted for 38 per cent, 37 per cent and 15 per cent of the total deforestation, respectively. Before 1962 the copper mining industry used large quantities of firewood to generate electricity and this resulted in the loss of 150,413 ha of woodland between 1937 and 1961. When the mining industry switched to hydroelectricity, urban households became the major users of woodfuel. The urban population in the Copperbelt increased from 0.412 million in 1960 to 1.400 million in 1984 and its consumption of woodfuel led to the deforestation of at least 89,436 ha between 1962 and 1984.Deforested areas are left to regenerate naturally. However, due to poor management about 34 per cent of the area deforested before 1962 has failed to regenerate. Although 50,200 ha have been reforested with exotic trees, only 5,020 ha of this is on land previously deforested. Thus only about 10 per cent of reforestation efforts have contributed to the rehabilitation of damaged land. Ninety per cent of the reforestation has actually replaced standing indigenous woodland.Uncontrolled bushfires have destroyed forest plantations and have also caused the failure of woodland regeneration in deforested areas. These observations indicate that if forest resources in the Copperbelt of Zambia are to be properly managed it will be necessary:

to effectively regulate land use changes and;
to control bushfires.
Assessing the sustainability of agricultural land in Botswana and Sierra Leone
Authors: Biot Y. , Sessay M. , Stocking M. 
Published: February 2007

AbstractLand degradation processes, such as soil erosion, which threaten the sustainability of agricultural production have been studied for many years. While research progresses on the processes, little advance has been ade on translating results into terms which can be used directly in the design of appropriate and economically justified forms of soil conservation and land husbandry.Research by the authors has shown how soil erosion affects the potential of land to produce crops. Simple models have been developed which provide a first approximation of the impact of soil erosion on future production, to be used as a baseline against which the benefits of soil conservation can be compared. The concepts of soil life and residual suitability have been developed as a measure of the sustainability of the production system considered. In this paper a simple experimental technique to derive the future production and the residual suitability of land is proposed.The method is based on the principle of sequential testing and uses a simple graphical technique to translate information on production and erosion into a crop production forecast. The soil life or residual suitability of land is derived from the minimum allowable crop production which depends on socio‐economic criteria. In case the minimum allowable production level cannot be reliably estimated, the concept of production ‘half‐life’ is introduced as a relative measure of sustainability. The method and its applications are illustrated using examples from Botswana and Sierra Leone.
African soil erosion — nature undone and the limitations of technology
Authors: Millington A. C. , Mutiso S. K. , Kirby J. , O'keefe P. 
Published: February 2007

AbstractA wide range of mechanical soil conservation techniques commonly used in Africa are reviewed in a politico‐economic framework. Three factors within this framework play a significant role in the adoption of mechanical soil conservation techniques. These are: (a) land considerations, such as land availability and tenure, and farm size; (b) capital and labour constraints; and (c) access to, and functioning of, institutions.Hypotheses which are concerned with the relationships between these factors and the likelihood of farmers adopting soil conservation techniques are introduced. Case studies drawn from Kenya, Lesotho, Malawi, Swaziland and Sierra Leone, as well as from Jamaica, are used to test these hypotheses in relationship to such techniques as terracing, grass strip cultivation, bunding, and contour cultivation. Greater reliance on local knowledge and indigenous soil conservation techniques seems to provide the best solution to the introduction of mechanical soil conservation techniques.
Impacts of environmental change on sustainable food production in Southwest Ontario, Canada
Authors: Brklacich M. , Smit B. , Bryant C. , Dumanski J. 
Published: February 2007

AbstractA sustainable food production system may be defined as an agri‐food sector which over the long term can simultaneously maintain environmental quality, produce a sufficient food supply and provide adequate rewards to primary producers. This paper investigates the implications of two forms of environmental change for sustainable food production in Southwest Ontario, a major agricultural region in Canada. A modified version of the Universal Soil Loss Equation was employed to estimate long‐term erosion, whereas an altered climate was derived from a general circulation model. Crop productivity models were used to estimate the impacts of modified environmental conditions on yields. Mathematical programming models were used to estimate economic viability and food production capacity given these changed conditions. Soil erosion combined with a climatic warming induced by a doubling of atmospheric concentrations of CO2 or its equivalent would contribute to severe declines in resource quality, and result in declines of 18 per cent to 35 per cent in average yields for major grains and oilseeds. On lands with a relatively high natural risk to erosion, the yield‐reducing impacts of erosion and a climatic warming would reduce profits from cash grain farming by 26 per cent, and increase concern about the economic viability of these enterprises. Environmental change would reduce the region's food production potential to 86 per cent of current production levels, and possibly endanger the security of its food supplies. These findings suggest the need to explore strategies which would either prevent future environmental change or mitigate its adverse impacts.
Desert: A prototype expert system to advise on land degradation control
Authors: Balachandran C. S. , Fisher P. F. 
Published: February 2007

AbstractLand degradation is a collection of processes causing the removal of land from agricultural productivity. Four major processes can be identified: soil erosion by water and wind, soil salinization, and vegetation degradation. Much knowledge exists on how these processes may be combated and ameliorated; however, it is in the minds of a relatively few, widely dispersed experts. The authors have developed a prototype computer‐based expert system (DESERT) which provides advice on strategies for control of land degradation. The knowledge was acquired from experts by interviews. The knowledge was then formulated into two components. The first component enables identification of possible technical solutions, while the other imposes socio‐economic and physical constraints on these technical solutions. Thus, a set of acceptable solutions is formulated. The results are presented here as a proof of concept in an attempt to stimulate further development. Later versions of the program will include problem diagnosis components, as well as a mechanism for prioritizing recommendations.
Field measurement of the sheltering effect of vegetation on erodible land surfaces
Authors: Stockton P. H. , Gillette D. A. 
Published: February 2007

AbstractNatural vegetation on erodible land surfaces, such as the loose sandy soils found in the southwestern United States and in Soviet Central Asia, absorbs part of the wind momentum flux (stress) and thus protects the erodible soil to a degree that depends on the geometry of plant distribution and profile. The sheltering effect of natural plants may be expressed as the ratio, R, of threshold friction velocity for the bare soil (determined in the laboratory or in specially prepared areas of bare soil in the field) to that for the naturally vegetated surface. We used new automated instrumentation to detect erosion thresholds in locations where erosion events are widely separated in time. Measured values of R were low for our most vegetated sites and nearer unity for the sparsely vegetated site.
Climate change and soil erosion on agricultural land in england and wales
Authors: Boardman J. , Evans R. , Favis‐Mortlock D. T. , Harris T. M. 
Published: February 2007

AbstractTo assess the effects of climate change on soil erosion we need to model changes in rate, frequency and extent of erosion. Present day rates of soil erosion for agricultural land in England and Wales are known from a national monitoring scheme and also from a local one. The latter, for the South Downs, covers a seven‐year period and includes climatic data. This shows a strong correlation between total erosion and a Rainfall Index. The availability of these databases allows us to use existing models such as EPIC and an Expert System to predict erosion rates for postulated warmer and wetter (winter) conditions. EPIC is particularly suitable for specific sites where detailed data exists and crop yield implications can also be modelled. A rule‐based Expert System approach allows us to examine erosion rates at a different scale across the landscape. We postulate that water erosion rates on arable land in the lowlands will increase markedly in severity, frequency and extent especially if land use changes. In the uplands predicted climatic warming suggests a longer growing season and fewer frosts: these may lead to a decrease in erosion of overgrazed eroding slopes. Increases in erosion rates are not inevitable if policy decisions are taken and implemented in good time.
The effect of simulated runoff on the erosion of gypsiferous soils
Authors: Navas A. 
Published: February 2007

AbstractThe effect of runoff generation on the erosion of gypsiferous soils under different experimental conditions was investigated by applying simulated rainfalls of 48 and 58 mm h−1 to experimental plots exhibiting representative characteristics of these soils. The 45 experiments indicate differing erosive behaviour as test conditions varied. Suspended gypsum yields ranged from 0‐3.9 gm−2 h−1 the higher values occurring with the steeper slopes and dry soil conditions. The differences among the soils tested were mainly due to variations in underlying rock outcrop, whilst within each soil type, slope was the most important variable. Transport of suspended gypsum by runoff is inversely related to rock outcrop, and positively related to slope. The highest erosion rates are registered in Gypsic Calcisols, followed by Gypsic Calcisols (lithic phase), while production of suspended gypsum is not verified for Dystric Leptosols. By transporting gypsum particles down‐slope, runoff is probably responsible for the dynamic evolution of gypsiferous hillslopes as well as the genetic evolution of the studied soils.
Grass mixtures for afforested opencast spoils in South Wales
Authors: Moffat A. J. , Roberts C. J. 
Published: February 2007

AbstractAn experiment that investigated the establishment of seven grass and legume seed mixes on opencast coal mining spoil in South Wales is described. After three years, mixtures containing Poa pratensis and Festuca rubra var. rubra were the most successful in covering the spoil; the ‘Johnson JR33’ seed mix proved the best of those commercially available that was tested. Tree growth was not detrimentally affected by the establishment of a grass ground cover. Erosion was not an important process at the experimental site, though slumping occurred locally from plough ridge to plough furrow.
Calibration of caesium‐137 measurements to provide quantitative erosion rate data
Authors: Walling D. E. , Quine T. A. 
Published: February 2007

AbstractThe caesium‐137 technique for investigating rates and patterns of soil loss has now been successfully applied in a wide range of environments. However, some uncertainty still surrounds the ability of the technique to provide quantitative estimates of rates of erosion. The wide range of calibration relationships that have been employed by individual workers to derive erosion rates from estimates of the amount of 137Cs (caesium‐137) lost from the soil profile, emphasize the uncertainty involved. Existing calibration procedures, involving both empirical relationships and theoretical models and accounting procedures are reviewed and their limitations and inconsistencies are identified. Further research is required in this important area, if the clear potential of the caesium‐137 technique is to be fully realized.