			Home About us Contact

Intensive Agriculture (intensive + agriculture)

Distribution by Scientific Domains

Life Sciences	25%
Earth and Environmental Science	25%

Selected Abstracts

Spatial patterns of suspended sediment yields in a humid tropical watershed in Costa Rica

HYDROLOGICAL PROCESSES, Issue 12 2001
Jagdish Krishnaswamy
Abstract An Erratum has been published for this article in Hydrological Processes 16(5) 2002, 1130,1131. Humid tropical regions are often characterized by extreme variability of fluvial processes. The Rio Terraba drains the largest river basin, covering 4767 km2, in Costa Rica. Mean annual rainfall is 3139±419sd mm and mean annual discharge is 2168±492sd mm (1971,88). Loss of forest cover, high rainfall erosivity and geomorphologic instability all have led to considerable degradation of soil and water resources at local to basin scales. Parametric and non-parametric statistical methods were used to estimate sediment yields. In the Terraba basin, sediment yields per unit area increase from the headwaters to the basin mouth, and the trend is generally robust towards choice of methods (parametric and LOESS) used. This is in contrast to a general view that deposition typically exceeds sediment delivery with increase in basin size. The specific sediment yield increases from 112±11·4sd t km,2 year,1 (at 317·9 km2 on a major headwater tributary) to 404±141·7sd t km,2 year,1 (at 4766·7 km2) at the basin mouth (1971,92). The analyses of relationships between sediment yields and basin parameters for the Terraba sub-basins and for a total of 29 basins all over Costa Rica indicate a strong land use effect related to intensive agriculture besides hydro-climatology. The best explanation for the observed pattern in the Terraba basin is a combined spatial pattern of land use and rainfall erosivity. These were integrated in a soil erosion index that is related to the observed patterns of sediment yield. Estimated sediment delivery ratios increase with basin area. Intensive agriculture in lower-lying alluvial fans exposed to highly erosive rainfall contributes a large part of the sediment load. The higher elevation regions, although steep in slope, largely remain under forest, pasture, or tree-crops. High rainfall erosivity (>7400 MJ mm ha,1 h,1 year ,1) is associated with land uses that provide inadequate soil protection. It is also associated with steep, unstable slopes near the basin mouth. Improvements in land use and soil management in the lower-lying regions exposed to highly erosive rainfall are recommended, and are especially important to basins in which sediment delivery ratio increases downstream with increasing basin area. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Plant functional group composition and large-scale species richness in European agricultural landscapes

JOURNAL OF VEGETATION SCIENCE, Issue 1 2008
Jaan Liira
Abstract Question: Which are the plant functional groups responding most clearly to agricultural disturbances? Which are the relative roles of habitat availability, landscape configuration and agricultural land use intensity in affecting the functional composition and diversity of vascular plants in agricultural landscapes? Location: 25 agricultural landscape areas in seven European countries. Methods: We examined the plant species richness and abundance in 4 km × 4 km landscape study sites. The plant functional group classification was derived from the BIOLFLOR database. Factorial decomposition of functional groups was applied. Results: Natural habitat availability and low land use intensity supported the abundance and richness of perennials, sedges, pteridophytes and high nature quality indicator species. The abundance of clonal species, C and S strategists was also correlated with habitat area. An increasing density of field edges explained a decrease in richness of high nature quality species and an increase in richness of annual graminoids. Intensive agriculture enhanced the richness of annuals and low nature quality species. Conclusions: Habitat patch availability and habitat quality are the main drivers of functional group composition and plant species richness in European agricultural landscapes. Linear elements do not compensate for the loss of habitats, as they mostly support disturbance tolerant generalist species. In order to conserve vascular plant species diversity in agricultural landscapes, the protection and enlargement of existing patches of (semi-) natural habitats appears to be more effective than relying on the rescue effect of linear elements. This should be done in combination with appropriate agricultural management techniques to limit the effect of agrochemicals to the fields. [source]

The Water Framework Directive and agricultural nitrate pollution: will great expectations in Brussels be dashed in Lower Saxony?

ENVIRONMENTAL POLICY AND GOVERNANCE, Issue 4 2007
Britta Kastens
Abstract This paper discusses the opportunities and constraints regarding the effective implementation of the European Water Framework Directive (WFD) in the area of diffuse nitrate pollution. Owing to the subsidiarity principle and a new procedural mode of governance, the WFD only sets distinct environmental targets, leaving most decisions on how to operationalize and institutionalize the reduction of diffuse nitrate pollution to the member states. This is a particular challenge for Germany, where lower scale regions have become the main implementers of European water policy. Successful implementation of the WFD, i.e. the actual improvement of water quality, depends on a series of key contextual and contingent factors, operating at a regional scale. In a Northwest German region with intensive agriculture and severe nitrate pollution, we analyse the historical and economic context and actor network of the region as well as the influence of environmental groups on public participation, the potential of biogas technology and new financial options. Besides the specific influence of these factors on the implementation process, we explore the uncertainties and difficulties surrounding European legislation and its operationalization in Germany and on a regional scale. Copyright © 2007 John Wiley & Sons, Ltd and ERP Environment. [source]

Wind erosion and intensive prehistoric agriculture: A case study from the Kalaupapa field system, Moloka'i Island, Hawai'i

GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 5 2007
Mark D. McCoy
Wind erosion is a major problem for modern farmers, a key variable affecting nutrient levels in ecosystems, and a potentially major force impacting archaeological site formation; however, it has received scant consideration in geoarchaeological studies of agricultural development compared with more easily quantifiable environmental costs, such as vegetation change or fluvial erosion. In this study, soil nutrient analysis is used in the Kalaupapa field system, Moloka'i Island, Hawai'i, to detect an increase in wind erosion attributable to intensive agriculture following the burning of endemic forest. This practice began on a small scale in the 13th century A.D., expanded around cal A.D. 1450,1550, and continued until the near total abandonment of the fields after European contact in the 18th century. Nutrients that naturally occur in high amounts in coastal windward areas due to the long-term, cumulative effect of sea spray were especially impacted. However, thanks to the unique landform of the Kalaupapa Peninsula, nutrient depletion in windward areas was offset by downwind enrichment and likely contributed to the long-term sustainability of the system as a whole. Future research on tropical and arid agriculture should consider the cumulative environmental cost of increased eolian erosion attributable to anthropogenic landscape modification. © 2007 Wiley Periodicals, Inc. [source]

Water uptake and nutrient concentrations under a floodplain oak savanna during a non-flood period, lower Cedar River, Iowa,

HYDROLOGICAL PROCESSES, Issue 21 2009
Keith E. Schilling
Abstract Floodplains during non-flood periods are less well documented than when flooding occurs, but non-flood periods offer opportunities to investigate vegetation controls on water and nutrient cycling. In this study, we characterized water uptake and nutrient concentration patterns from 2005 to 2007 under an oak savanna located on the floodplain of the Cedar River in Muscatine County, Iowa. The water table ranged from 0·5 to 2·5 m below ground surface and fluctuated in response to stream stage, plant water demand and rainfall inputs. Applying the White method to diurnal water table fluctuations, daily ET from groundwater averaged more than 3·5 mm/day in June and July and approximately 2 mm/day in May and August. Total annual ET averaged 404 mm for a growing season from mid-May to mid-October. Savanna groundwater concentrations of nitrate-N, ammonium-N, and phosphate-P were very low (mean <0·18, <0·14, <0·08 mg/l, respectively), whereas DOC concentrations were high (7·1 mg/l). Low concentrations of N and P were in contrast to high nutrient concentrations in the nearby Cedar River, where N and P averaged 7·5 mg/l and 0·13, respectively. In regions dominated by intensive agriculture, study results document valuable ecosystem services for native floodplain ecosystems in reducing watershed-scale nutrient losses and providing an oasis for biological complexity. Improved understanding of the environmental conditions of regionally significant habitats, including major controls on water table elevations and water quality, offers promise for better management aimed at preserving the ecology of these important habitats. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Spatial patterns of suspended sediment yields in a humid tropical watershed in Costa Rica

Enhancing diversity of species-poor grasslands: an experimental assessment of multiple constraints

JOURNAL OF APPLIED ECOLOGY, Issue 1 2007
RICHARD F. PYWELL
Summary 1Many grasslands in north-west Europe are productive but species-poor communities resulting from intensive agriculture. Reducing the intensity of management under agri-environment schemes has often failed to increase botanical diversity. We investigated biotic and abiotic constraints on diversification by manipulating seed and microsite availability, soil fertility, resource competition, herbivory and deficiencies in the soil microbial community. 2The effectiveness of 13 restoration treatments was investigated over 4 years in a randomized block experiment established in two productive grasslands in central-east and south-west England. 3Severe disturbance involving turf removal followed by seed addition was the most effective and reliable means of increasing grassland diversity. Disturbance by multiple harrowing was moderately effective but was enhanced by molluscicide application to reduce seedling herbivory and by sowing the hemiparasite Rhinanthus to reduce competition from grasses. 4Low-level disturbance by grazing or slot-seeding was ineffective in increasing diversity. Inoculation with soil microbial communities from species-rich grasslands had no effect on botanical diversity. Nitrogen and potassium fertilizer addition accelerated off-take of phosphorus in cut herbage but did not cause a reduction in soil phosphorus or increase botanical diversity. 5Different grazing management regimes had little impact on diversity. This may reflect the constraining effect of the July hay cut on species dispersal and colonization. 6Synthesis and applications. Three alternative approaches to grassland diversification, with different outcomes, are recommended. (i) High intervention deturfing, which would create patches with low competitive conditions for rapid and reliable establishment of the target community. For reasons of cost and practicality this can only be done over small areas but will form source populations for subsequent spread. (ii) Moderate intervention (harrowing or slot-seeding) over large areas, which would establish a limited number of desirable, generalist species that perform well in restoration. This method is low cost and rapid but the increases in biodiversity are less predictable. (iii) Phased restoration, which would complement the above approaches. Productivity and competition are reduced over 3,5 years using Rhinanthus or fertilizers to accelerate phosphorus off-take. After this time harrowing and seeding should allow a wide range of more specialist species to establish. However, further research is required to determine the long-term effectiveness of these approaches. [source]

Releasing genetically modified organisms: will any harm outweigh any advantage?,

JOURNAL OF APPLIED ECOLOGY, Issue 2 2000
John E. Beringer
Summary 1. ,The public debate about genetically modified organisms has concentrated largely on concerns about food safety and potential risks to the environment. In both cases there appears to be an assumption that existing crops and animals are safe. I discuss the experience we have to date from traditional methods and conclude that most concerns about environmental harm are more relevant to existing crops. 2. ,The flow of genes among species, and even within different genera, is discussed with due attention being paid to the need for inherited genes to confer a selective advantage on hosts. 3. ,A reason why so many people are critical of intensive agriculture and biotechnology is that virtually all changes in agricultural practice have an adverse impact on wildlife, particularly when such change leads to increased intensification. The problem of deciding how to manage agriculture to ensure that we maintain or enhance species diversity of wild plants and animals is discussed against the background that most of the UK environment is the result of human intervention. 4. ,Nature and dense human populations cannot coexist without the former suffering. Our objective should be to develop and exploit our understanding of ecology to provide the information required to enable us to develop a far more enlightened future for agriculture and wildlife. [source]

Multivariate analysis of toxicological and environmental properties of soil nematicides

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 1 2009
Sara Sánchez-Moreno
Abstract BACKGROUND: In intensive agriculture, the use of pesticides and soil fumigants is necessary to produce economically viable crops worldwide. However, this practice may involve undesirable effects on human health and the environment. In 1995, methyl bromide was restricted by the Montreal Protocol because of possible ozone depletion. The objective of this study was to compare intrinsic environmental and toxicological properties of 11 active substances with nematicidal properties, some of them recognized as methyl bromide alternatives. RESULTS: Four groups of active substances were discriminated by a series of principal component analyses (PCAs): (a) high toxicity to non-target fauna, humans and animals and medium persistence in the environment (cadusafos, ethoprophos and fenamiphos); (b) high toxicity to humans, animals and non-target fauna and high persistence (carbofuran and fosthiazate); (c) low toxicity to non-target fauna, humans and animals and low persistence (carbosulfan, benfuracarb and oxamyl); (d) low toxicity to humans, animals and non-target fauna and medium persistence in the environment (1,3-dichloropropene, chloropicrin and methyl bromide). CONCLUSION: Evaluating the multiple aspects of toxicological and environmental properties of active substances through PCA is proposed as a helpful tool for initially comparing the complex toxicological behaviour of active substances as plant protection products. Copyright © 2008 Society of Chemical Industry [source]

Multi-scale sampling and statistical linear estimators to assess land use status and change

APPLIED VEGETATION SCIENCE, Issue 2 2009
D. Rocchini
Abstract Question: Multi-temporal analysis of remotely sensed imagery has proven to be a powerful tool for assessment and monitoring of landscape diversity. Here the feasibility of assessing land-use diversity and land-use change was tested at multiple scales and over time by means of statistical linear estimators based on a probabilistic sampling design. Location: The study area (the district of Asciano, Tuscany, Italy) is characterized by erosional forms typical of Pliocene claystone (i.e. calanchi and biancane) that have been subject to the phenomenon of biancane reworking over the past 50 years, mainly owing to the expansion of intensive agriculture. Methods: Cells at two different scales (50 m × 50 m and 10 m × 10 m) were classified by two operators according to a multilevel legend, using 1954 and 2000 aerial photographs. Inter-operator agreement and accuracy were tested by Cohen's K coefficient. Total land cover estimation for each class was carried out using a multistage estimator, while the variance was estimated by means of the Wolter estimator. Field-based information on plant species composition was recorded in order to test for a relationship between land use and plant community composition by anova and indicator species analysis. Results: Agreement between photointerpreters and accuracy were significantly higher than those expected by chance, proving that the approach proposed is reproducible, as long as proper quality assurance methods are used. Our data show that, at the two scales considered (50 m × 50 m and 10 m × 10 m), crops have increased against woodlands and semi-natural areas, the latter showing the highest and significantly different mean species richness. Meanwhile, an increase in the coverage of trees and shrubs was found within the semi-natural areas, probably as a result of secondary succession occurring on typical landscape elements such as biancane. Conclusions: Inferential statistics made it possible to acquire quantitative information on the abundance of land cover classes, allowing formal multi-temporal and multi-scale analysis. Sampling design-based statistical linear estimators were found to be a powerful tool for assessing landscape trends considering both time expenditure and other costs. They make it possible to maintain the same scale of analysis over time series data and to detect both coarse- and fine-grained changes in spatial patterns. [source]

Alien and endemic flora at reference and non-reference sites in Mediterranean-type streams in Portugal

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2007
Francisca C. Aguiar
Abstract 1.A comparison was made between a variety of alien and endemic plant species from 272 aquatic and riparian habitats in Portuguese Mediterranean-type streams in reference condition , i.e. near-natural river corridors , and non-reference condition. The objective was to detect differences in relative proportion and cover between these species groups. The differences in endemic and alien flora from siliceous and calcareous river types were also analysed. Environmental and human disturbance factors were related with the richness and cover of both species groups. 2.A total of 568 species were found, of which 44 were alien and 28 were endemic. Alien species were present at 91% of the surveyed locations, and were consistently more widespread at non-reference sites than at reference ones for both river types, with calcareous sites having a higher invasibility. Endemic species occurred at 45% of the sampling sites and displayed a significantly lower richness and cover than their alien counterparts. 3.Alien richness and cover were positively related to direct human disturbance within the river systems, and with floodplain uses such as urban occupation, intensive agriculture, and nutrient inputs. Endemic species also respond to anthropogenic variables, rather than to climatic and geographical ones, with richness and cover increasing as human impacts on fluvial systems and related floodplains decrease. 4.Comprehensive control of alien invasive species and the protection of endemic plant populations will require attempts at monitoring ecological river integrity, and the achievement of ,good ecological status' , one of the goals of the European Union's Water Framework Directive. Portuguese riparian areas must be managed in such a way as to protect the relatively few preserved riparian habitats by lowering the direct and indirect pressures in fluvial corridors and thus preventing future alien plant invasions. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Ammonia map shows hot spots

ASTRONOMY & GEOPHYSICS, Issue 4 2009
Article first published online: 20 JUL 200
The ESA MetOp satellite has provided the data for researchers to produce the first global map of ammonia emissions. The map shows high production over areas of intensive agriculture, as well as sources not previously known. [source]