Land Use (land + use)

Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Land Use

  • agricultural land use
  • catchment land use
  • current land use
  • different land use
  • human land use
  • past land use
  • previous land use
  • sustainable land use
  • urban land use

  • Terms modified by Land Use

  • land use change
  • land use data
  • land use history
  • land use management
  • land use pattern
  • land use planning
  • land use policy
  • land use practice
  • land use system
  • land use type

  • Selected Abstracts


    Alex Anas
    ABSTRACT RELU is a dynamic general equilibrium model of a metropolitan economy and its land use, derived by unifying in a theoretically valid way, models developed by one of the authors [Anas (1982), Anas,Arnott (1991, 1997), Anas,Kim (1996), Anas,Xu (1999)]. RELU equilibrates floor space, land and labor markets, and the market for the products of industries, treating development (construction and demolition), spatial interindustry linkages, commuting, and discretionary travel. Mode choices and equilibrium congestion on the highway network are treated by unifying RELU with the TRAN algorithm of stochastic user equilibrium [Anas,Kim (1990)]. The RELU-TRAN algorithm's performance for a stationary state is demonstrated for a prototype consisting of 4-building, 4-industry, 4-labor-type, 15-land-use-zone, 68-link-highway-network version of the Chicago MSA. The algorithm solves 656 equations in a special block-recursive convergent procedure by iterations nested within loops and loops within cycles. Runs show excellent and smooth convergence from different starting points, so that the number of loops within successive cycles continually decreases. The tests also imply a numerically ascertained unique stationary equilibrium solution of the unified model for the calibrated parameters. [source]


    Daren Harmel
    ABSTRACT: Measured field scale data are increasingly used to guide policy and management decisions based on comparative pollutant load information from various land management alternatives. The primary objective of this study was to compile measured annual nitrogen (N) and phosphorus (P) load data representing field scale transport from agricultural land uses. This effort expanded previous work that established an initial nutrient export coefficient dataset. Only measured annual N and P load data published in scientific peer-reviewed studies were included in the present compilation. Additional criteria for inclusion were: spatial scale (field scale or farm scale, minimum 0.009 ha); land use (homogeneous, either cultivated agriculture or pasture/rangeland/hay); natural rainfall (not rainfall simulation); and temporal scale (minimum one year). Annual N and P load data were obtained from 40 publications, resulting in a 163-record database with more than 1,100 watershed years of data. Basic descriptive statistics in relation to N and P loads were tabulated for tillage management, conservation practices, fertilizer application, soil texture, watershed size, and land use (crop type). The resulting Measured Annual Nutrient loads from A Circumlittoral Environments (MANAGE) database provides readily accessible, easily queried watershed characteristic and nutrient load data and establishes a platform suitable for input of additional project specific data. [source]

    Time-Dependent Discrete Network Design Frameworks Considering Land Use

    W. Y. Szeto
    Unlike existing models, the optimization frameworks can determine the optimal designs automatically without trial-and-error once the objective(s) is/are clearly defined. Moreover, these frameworks allow the evaluation of the impacts of the optimal designs on the related parties including landowners, toll road operators, transit operators, and road users, and help network planners and profit-makers with decision making by eliminating many alternative designs. A numerical study is set up to examine road network design's effects on these related parties under three road construction schemes: exact cost recovery, build-operate-transfer, and cross-subsidization. The results show that the changes in landowner profits are not the same after implementing any scheme. These unequal changes raise the issue of the landowner equity. This implies that the government has to consider trade-offs between parties' objectives carefully. [source]

    Death Rides the Forest: Perceptions of Fire, Land Use, and Ecological Restoration of Western Forests

    fuego prescrito; incendios catastróficos; incendios en áreas silvestres; incendios no controlados; reducción de riesgo de combustible; restauración de bosques; tala de bosques Abstract:,Large wild fires occurring in forests, grasslands, and chaparral in the last few years have aroused much public concern. Many have described these events as "catastrophes" that must be prevented through aggressive increases in forest thinning. Yet the real catastrophes are not the fires themselves but those land uses, in concert with fire-suppression policies that have resulted in dramatic alterations to ecosystem structure and composition. The first step in the restoration of biological diversity (forest health) of western landscapes must be to implement changes in those factors that have caused degradation or are preventing recovery. This includes changes in policies and practices that have resulted in the current state of wildland ecosystems. Restoration entails much more than simple structural modifications achieved though mechanical means. Restoration should be undertaken at landscape scales and must allow for the occurrence of dominant ecosystem processes, such as the natural fire regimes achieved through natural and/or prescribed fires at appropriate temporal and spatial scales. Resumen:,En años recientes, grandes incendios en bosques, pastizales y chaparrales han causado bastante preocupación en la opinión pública. Muchos han descrito estos eventos como "catástrofes" que deben ser prevenidas mediante incrementos agresivos en la tala de bosques. Pero los incendios mismos no son las verdaderas catástrofes, sino los usos del suelo en conjunto con políticas de supresión de fuego que han resultado en alteraciones dramáticas de la estructura y composición de ecosistemas. El primer paso en la restauración de la diversidad biológica (salud del bosque) en paisajes occidentales debe ser la implementación de cambios en los factores que causaron la degradación o que están impidiendo la recuperación. Esto incluye cambios en políticas y prácticas que han resultado en el estado actual de ecosistemas en áreas silvestres. La restauración implica mucho más que simples modificaciones estructurales obtenidas mediante medios mecánicos. La restauración debe llevarse a cabo a nivel de paisaje y debe permitir que ocurrencia de procesos ecológicos dominantes (por ejemplo, regímenes de incendios naturales logrados mediante incendios naturales y/o prescritos en escalas temporales y espaciales apropiadas). [source]

    Diversified Agriculture, Land Use, and Agrofood Networks in Hawaii,

    ECONOMIC GEOGRAPHY, Issue 1 2002
    Krisnawati Suryanata
    Abstract: Agriculture dominated the culture and economy of Hawaii until the mid-twentieth century, but has since been in a prolonged state of decline. This article examines strategies in Hawaii's diversified agriculture that seek to revitalize its agrarian sector and the difficult challenges these efforts face within the globalized agrofood systems. Drawing from the actor-network perspective, this article suggests an alternative approach to developing Hawaii's diversified agriculture. Networks of social actors that include growers, processors, gourmet chefs, retailers, and consumers have been able to create viable diversified agriculture in spite of the globalized agrofood systems. The article then discusses how the politics of land use and land development could condition Hawaii's ability to build networks that are critical to the maintenance of a diversified agricultural sector. [source]

    Drivers of Unsustainable Land Use in the Semi-Arid Khabur River Basin, Syria

    Abstract The semi-arid zone of Southwest Asia, known as the Fertile Crescent, is under unprecedented stress because of agricultural development. Where rain-fed agriculture and transhumant herding had prevailed over ten millennia, today intensive cultivation with irrigation threatens future sustainability. A number of interconnected, but uncoordinated drivers of change combine to shape the landscape and its future, and their changes make it hard to anticipate future requirements and opportunities, as well as to implement policies, whether by local stakeholders or at the national level. Among the factors that comprise the socio-natural systems are (1) climate, (2) water and soil resources, (3) history of land use, (4) social, economic and political factors, (5) infrastructural developments (6) interstate impacts, and (7) legacies of the past. The example of the Khabur River drainage in northeastern Syria shows the dynamic interplay among these factors over the past 70 years, with implications for the way future policies and practices are developed. [source]

    Effects of Land Use on Ground Water Quality in the Anoka Sand Plain Aquifer of Minnesota

    GROUND WATER, Issue 4 2003
    Michael D. Trojan
    We began a study, in 1996, to compare ground water quality under irrigated and nonirrigated agriculture, sewered and nonsewered residential developments, industrial, and nondeveloped land uses. Twenty-three monitoring wells were completed in the upper meter of an unconfined sand aquifer. Between 1997 and 2000, sampling occurred quarterly for major ions, trace inorganic chemicals, volatile organic compounds (VOCs), herbicides, and herbicide degradates. On single occasions, we collected samples for polynuclear aromatic hydrocarbons (PAHs), perchlorate, and coliform bacteria. We observed significant differences in water chemistry beneath different land uses. Concentrations of several trace inorganic chemicals were greatest under sewered urban areas. VOC detection frequencies were 100% in commercial areas, 52% in sewered residential areas, and <10% for other land uses. Median nitrate concentrations were greatest under irrigated agriculture (15,350 ,g/L) and nonsewered residential areas (6080 ,g/L). Herbicides and degradates of acetanilide and triazine herbicides were detected in 86% of samples from irrigated agricultural areas, 68% of samples from nonirrigated areas, and <10% of samples from other land uses. Degradates accounted for 96% of the reported herbicide mass. We did not observe seasonal differences in water chemistry, but observed trends in water chemistry when land use changes occurred. Our results show land use is the dominant factor affecting shallow ground water quality. Trend monitoring programs should focus on areas where land use is changing, while resource managers and planners must consider potential impacts of land use changes on ground water quality. [source]

    The Spatial Segregation of Zooplankton Communities with Reference to Land Use and Macrophytes in Shallow Lake Wielkowiejskie (Poland)

    Natalia Kuczy, ska-Kippen
    Abstract The spatial distribution of zooplankton in relation to two types of land-use (forested and pastoral-arable) of a lake's surroundings and to various habitats (helophytes, elodeids, nymphaeids and open water) was examined along 16 parallel transects on a macrophyte-dominated lake (area , 13.3 ha; mean depth , 1.4 m). The type of habitat was the main determinant of zooplankton community structure. Dissected-leaved elodeids harboured the richest and most abundant community with typically littoral (e.g., Colurella uncinata) and pelagic species (e.g., Keratella cochlearis). Two species (Polyarthra major and P. vulgaris) selectively chose the open water and one (Lecane quadridentata) the Typha stand. No spatial differentiation in zooplankton abundance was recorded between the two types of the catchment area. One possible explanation may be the shallowness and small area of this lake which may support full mixing and no difference in physical-chemical gradients. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Reflexive Interdisciplinary Research: The Making of a Research Programme on the Rural Economy and Land Use

    Philip Lowe
    Abstract This paper provides an account of the origins and formation of the UK Research Councils' Rural Economy and Land Use (RELU) programme and its approach to promoting interdisciplinary working between social and natural scientists. The programme is set in the context of broader developments in science policy, including a policy discourse centred upon sustainable development and the knowledge economy and associated demands for greater accountability in science. Interdisciplinarity promises research that will be more relevant and responsive to public needs and concerns. In describing the provenance of the RELU programme, therefore, the paper seeks to lay out the different stages in its initiation and design to show how, to varying degrees, these were open to external scrutiny and influence. The process of developing the programme illustrates that it is not straightforward to make research agendas and funding more transparent and accountable. It also provides insights into the challenges that interdisciplinarity and accountability present to established science institutions. [source]

    Working to Make Interdisciplinarity Work: Investing in Communication and Interpersonal Relationships

    Mariella Marzano
    Abstract In this paper, we apply qualitative methodologies to explore the practice of interdisciplinary research. The UK's Rural Economy and Land Use (RELU) Programme aims to advance understanding of the challenges faced by rural areas through funding interdisciplinary research to inform future policy and practice on management choices for the countryside and rural economies. Addressing the challenges faced by rural areas often requires a combination of different perspectives, involving research to address subjects that may lie beyond the skills of individual researchers. An interdisciplinary approach requires the integration of both data/information and the experiences and perspectives of different people (natural/social scientists, local people and policy-makers). We focus here on the processes involved in making interdisciplinarity work, documenting the experiences, perceptions, ideas and concerns of researchers working in interdisciplinary projects (specifically two EU-funded projects but also the first wave of RELU projects). A key finding from this research is that interdisciplinarity requires conscious effort, time and resources for the development of interpersonal relationships to enhance effective communication and thus successful collaboration. [source]

    A Spatial Economic Analysis of Urban Land Use and Obesity,

    Andrew J. Plantinga
    Households maximize utility defined over housing, weight, and food subject to a fixed time budget allocated to commuting, calorie expenditure, and work. Our model explains the observed correspondence between high obesity rates and low development densities, but implies that these are determined endogenously in a spatial market equilibrium. We study the sorting of residents by attributes such as income, initial weight, and weight preferences, and examine the impacts on weight and density of urban design modifications that lower the costs of calorie expenditure. [source]

    Verifying the Multi-Dimensional Nature of Metropolitan Land Use: Advancing the Understanding and Measurement of Sprawl

    Jackie Cutsinger
    Common patterns of variation in these indices across metropolitan areas are discerned using correlation and factor analyses. We find that: (1) seven principal components best summarize the dimensions of housing and employment land uses, (2) metro areas often exhibit both high and low levels of sprawl-like patterns across the seven components, and (3) housing and employment aspects of sprawl-like patterns differ in nature. Thus, land use patterns prove multi-dimensional in both theory and practice. Exploratory analyses indicate: (1) little regional variation in land use patterns, (2) metro areas with larger populations are more dense/continuous with greater housing centrality and concentration of employment in the core, (3) older areas have higher degrees of housing concentration and employment in the core, (4) constrained areas evince greater density/continuity, and (5) inter-metropolitan variations in several dimensions of land use patterns are not well explained by population, age, growth patterns, or topographical constraints on development. Results imply that policymakers must carefully unravel which land use dimension is causing undesirable outcomes, and then devise precise policy instruments to change only this dimension. [source]

    Mapping sensitivity to land degradation in Extremadura.

    SW Spain
    Abstract An assessment of sensitivity to land degradation has been carried out in the Extremadura region, SW Spain, by means of a modelling approach developed by the European Commission funded MEDALUS project (Mediterranean Desertification and Land Use) which identifies such areas on the basis of an index (Environmentally Sensitive Area index, ESA index) that incorporates data on environmental quality (climate, vegetation, soil) as well as anthropogenic factors (management). Two maps of environmental sensitivity (ES) to degradation with different legend resolution (four and eight classes of sensitivity) have been made and tested by comparing classes of the legends with an extensive number (2690) of true field data gathered from plots distributed all over the study region. Independent variables of validation consisted of nine degradation-related types of data and the method tested the performance of the whole model and the statistical separability among classes of sensitivity, as well as the capability of the variables in delimiting the classes. Results showed a good performance of the whole model to both, the map of four and eighth classes of sensitivity. Separation among classes of sensitivity showed a slightly different behaviour of both maps, identifying transitional classes in the map of eight classes where classification could be improved in terms of the ranges of ESA index values assigned to the different classes. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Local land use strategies in a globalizing world,managing social and environmental dynamics

    R. L. Wadley
    Abstract This special issue deals with local rural people's economic, social and cultural responses to external and internal pressures generated by processes of global and regional change. The contributions deal with issues of resource-base degradation and stable land management, with special emphases on market integration and increased vulnerability of natural resources and local livelihoods in Lao DPR; land-use change in a Malaysian swidden system under varied patterns of migration and off-farm labour; occupational multiplicity and agricultural specialization in the Philippines; land degradation and environmental perceptions in peri-urban Nigeria; food security, gendered labour and shifting cultural-economic values in Uganda; and the rehabilitation of environment and social institutions through neo-localism in Thailand. All of the articles were originally presented at an International Conference in Copenhagen, Denmark in 2003, under the auspices of the Danish University Consortium on Environment and Development,Sustainable Land Use and Natural Resource Management (DUCED SLUSE). Copyright © 2006 John Wiley & Sons, Ltd. [source]

    The Influence of Historical Land Use and Water Availability on Grassland Restoration

    Zhuwen Xu
    The ecological role of historical land use has rarely been explored in the context of grassland restoration. We conducted a 4-year field experiment in a steppe and an old field in Inner Mongolia in northern China to examine the influence of historical land use and water availability on ecosystem restoration. Species richness, evenness, and plant cover were higher in the steppe than in the old field. The steppe was more temporally stable compared with the old field in terms of species richness, evenness, plant density, and cover. Water addition increased peak aboveground biomass, belowground net primary productivity, species richness, plant density, and cover in both the steppe and the old field. Water addition also enhanced the stability of ecosystems and the restoration of grassland. Our findings suggested that historical land use determines community structure and influences the process of grassland restoration. Converting grasslands to farmland in semiarid areas can cause the long-term loss of biodiversity and instability of ecosystem with consequent impacts on ecosystem services. The amendment of limited resources is an effective practice to increase the success of ecosystem restoration. [source]

    Border Landscapes: The Politics of Akha Land Use in China and Thailand by Janet C. Sturgeon

    No abstract is available for this article. [source]

    Evaluating the Effect of Conservation Policies on Agricultural Land Use: A Site-specific Modeling Approach

    Katsuya Tanaka
    This study evaluates quantitatively the effect of three policies (payments for cropland retirement, fertilizer use taxes and payments for crop rotations) on agricultural land use in the upper Mississippi River basin. This is done by estimating two logit models of land use decisions using data from the 1982, 1987,1992 and 1997 Natural Resource Inventories. The models predict farmers' crop choice, crop rotation and participation in the Conservation Reserve Program (CRP) at more than 48,000 Natural Resource Inventories sites under each of the three policies. Results suggest that an increase in the CRP rental rates would significantly increase the CRP acreage, but most of the acreage increase would come initially from less fertilizer-intensive crops. In contrast, a fertilizer use tax would significantly reduce acreage planted to more fertilizer-intensive crops, and thus would likely be cost effective for reducing agricultural chemical use and pollution. Although an incentive payment for a corn-soybean rotation would raise acreage of this rotation and reduce the acreage of continuous corn, the acreage response is in general quite inelastic. Cette étude évalue quantitativement les effets rovoqués par les trois politiques (paiements pour le retrait des terres cultivables, taxes sur l'utilisation d'engrais et paiements pour l'alternance des cultures) sur les terres agricoles du bassin supérieur du Mississipi. Ceci est obtenu en évaluant deux modéles logit des décisions sur l'utilisation des terres provenant des données des «Natural Resource Inventories» de 1982, 1987, 1992 et 1997. Les modéles prédisent le choix des cultures des agriculteurs, l'alternance des cultures et la participation du «Conservation Reserve Program (CRP)» dans plus de 48 000 Natural Resource Inventories dans le cadre de chacune des trois politiques. Les résultats suggérent qu'une augmentation des taux de location du CRP accroisse de maniére significative la surface de CRP, mais la majeure partie de cet accroissement de surface provenaient initialement de cultures moins intensives sans engrais. Cependant, l'utilisation d'une taxe sur l'utilisation d'engrais pouvait réduire de maniére significative la surface plantée avec des récoltes intensives utilisant plus d'engrais, et ainsi ce serait sans doute plus économique pour réduire la pollution et l'utilisation de produits chimiques en agriculture. Bien que des paiements incitatifs à l'alternance maïs-soja réduisent la surface d'une culture continue de maïs et augmentaient la surface de l'alternance maïs-soja, les résultats aux transformations des surfaces des terres seraient tout à fait rigides. [source]

    Forest Restoration in Urbanizing Landscapes: Interactions Between Land Uses and Exotic Shrubs

    Kathi L. Borgmann
    Abstract Preventing and controlling exotic plants remains a key challenge in any ecological restoration, and most efforts are currently aimed at local scales. We combined local- and landscape-scale approaches to identify factors that were most closely associated with invasion of riparian forests by exotic shrubs (Amur honeysuckle [Lonicera maackii] and Tatarian honeysuckle [L. tatarica]) in Ohio, U.S.A. Twenty sites were selected in mature riparian forests along a rural,urban gradient (<1,47% urban land cover). Within each site, we measured percent cover of Lonicera spp. and native trees and shrubs, percent canopy cover, and facing edge aspect. We then developed 10 a priori models based on local- and landscape-level variables that we hypothesized would influence percent cover of Lonicera spp. within 25 m of the forest edge. To determine which of these models best fit the data, we used an information-theoretic approach and Akaike's information criterion. Percent cover of Lonicera was best explained by the proportion of urban land cover within 1 km of riparian forests. In particular, percent cover of Lonicera was greater in forests within more urban landscapes than in forests within rural landscapes. Results suggest that surrounding land uses influence invasion by exotic shrubs, and explicit consideration of land uses may improve our ability to predict or limit invasion. Moreover, identifying land uses that increase the risk of invasion may inform restoration efforts. [source]

    Recovery of a Subtropical Dry Forest After Abandonment of Different Land Uses,

    BIOTROPICA, Issue 3 2006
    Sandra Molina Colón
    ABSTRACT We studied the ecological characteristics of 45,50-yr-old subtropical dry forest stands in Puerto Rico that were growing on sites that had been deforested and used intensively for up to 128 yr. The study took place in the Guánica Commonwealth Forest. Our objective was to assess the long-term effects of previous land use on this forest,i.e., its species composition, structure, and functioning. Previous land-use types included houses, farmlands, and charcoal pits. Stands with these land uses were compared with a nearby mature forest stand. The speed and path of forest recovery after deforestation and land-use abandonment depended on the conditions of the land. Study areas where land uses had removed the forest canopy and altered soil conditions (houses and farmlands) required a longer time to recover and had a different species composition than study areas where land uses retained a forest canopy (charcoal pits). Different forest attributes recovered at different rates. Crown area index, stem density, and litterfall rate recovered faster than stemwood and root, biomass, tree height, and basal area. Where previous land uses removed the canopy, Leucaena leucocephala, a naturalized alien pioneer species, dominated the regrowth. Native species dominated abandoned charcoal pits and mature forest. The change in species composition, including the invasion of alien species, appears to be the most significant long-term effect of human use and modification of the landscape. RESUMEN Estudiamos las características ecológicas de rodales de un bosque seco subtropical en Puerto Rico que tenían 45-50 años de recuperación después de haber sido usados intensamente durante 128 años. El estudio se realizó en el Bosque Estatal de Guánica. Nuestro objetivo fue el de evaluar los efectos a largo plazo de los distintos tipos de usos del terreno en la composición de especies, la estructura y el funcionamiento. Los usos de terreno en el pasado incluyeron viviendas, terrenos agrícolas y carboneras. Estos rodales fueron comparados con un rodal de bosque maduro en un área cercana. La rápidez de recuperación y la manera en cómo sucede depende de las condiciones del terreno después de ser abandonado. Las áreas de estudio en las que se había removido el dosel y alterado las condiciones del suelo (casas y terrenos agrícolas) necesitaron más tiempo para recuperarse y reflejaron una composición de suelo diferente a las áreas de estudio donde el dosel se mantuvo (carboneras). Los diferentes atributos forestales se recuperaban a ritmos diferentes. El índice del área foliar de la copa, la densidad de tallos y la caída de hojarasca se recuperaron más rápido que la biomasa de tallos y raíces, la altura de los árboles y el área basal. La especie pionera naturalizada, Leucaena leucocephala (Lam.) de Wit-Fabaceae, fue la especie dominante en los bosques donde se habia removido el dosel. Las especies nativas dominaban las carboneras abandonadas y el bosque maduro. El cambio en la composición de especies e incluso la invasión de especies foráneas, parece ser el efecto a largo plazo más significativo del uso humano y de la modificación del paisaje. [source]

    Neophyte species richness at the landscape scale under urban sprawl and climate warming

    Michael P. Nobis
    Abstract Aim, Land use and climate are two major components of global environmental change but our understanding of their simultaneous and interactive effects upon biodiversity is still limited. Here, we investigated the relationship between the species richness of neophytes, i.e. non-native vascular plants introduced after 1500 AD, and environmental covariates to draw implications for future dynamics under land-use and climate change. Location, Switzerland, Central Europe. Methods, The distribution of vascular plants was derived from a systematic national grid of 1 km2 quadrates (n = 456; Swiss Biodiversity Monitoring programme) including 1761 species, 122 of which were neophytes. Generalized linear models (GLMs) were used to correlate neophyte species richness with environmental covariates. The impact of land-use and climate change was thereafter evaluated by projections for the years 2020 and 2050 using scenarios of moderate and strong changes for climate warming (IPCC) and urban sprawl (NRP 54). Results, Mean annual temperature and the amount of urban areas explained neophyte species richness best, with a high predictive power of the corresponding model (cross-validated D2 = 0.816). Climate warming had a stronger impact on the potential increase in the mean neophyte species richness (up to 191% increase by 2050) than ongoing urban sprawl (up to 10% increase) independently from variable interactions and model extrapolations to non-analogue environments. Main conclusions, In contrast to other vascular plants, the prediction of neophyte species richness at the landscape scale in Switzerland requires few variables only, and regions of highest species richness of the two groups do not coincide. The neophyte species richness is basically driven by climatic (temperature) conditions, and urban areas additionally modulate small-scale differences upon this coarse-scale pattern. According to the projections climate warming will contribute to the future increase in neophyte species richness much more than ongoing urbanization, but the gain in new neophyte species will be highest in urban regions. [source]

    Where do Swainson's hawks winter?

    Satellite images used to identify potential habitat
    ABSTRACT During recent years, predictive modelling techniques have been increasingly used to identify regional patterns of species spatial occurrence, to explore species,habitat relationships and to aid in biodiversity conservation. In the case of birds, predictive modelling has been mainly applied to the study of species with little variable interannual patterns of spatial occurrence (e.g. year-round resident species or migratory species in their breeding grounds showing territorial behaviour). We used predictive models to analyse the factors that determine broad-scale patterns of occurrence and abundance of wintering Swainson's hawks (Buteo swainsoni). This species has been the focus of field monitoring in its wintering ground in Argentina due to massive pesticide poisoning of thousands of individuals during the 1990s, but its unpredictable pattern of spatial distribution and the uncertainty about the current wintering area occupied by hawks led to discontinuing such field monitoring. Data on the presence and abundance of hawks were recorded in 30 × 30 km squares (n = 115) surveyed during three austral summers (2001,03). Sixteen land-use/land-cover, topography, and Normalized Difference Vegetation Index (NDVI) variables were used as predictors to build generalized additive models (GAMs). Both occurrence and abundance models showed a good predictive ability. Land use, altitude, and NDVI during spring previous to the arrival of hawks to wintering areas were good predictors of the distribution of Swainson's hawks in the Argentine pampas, but only land use and NDVI were entered into the model of abundance of the species in the region. The predictive cartography developed from the models allowed us to identify the current wintering area of Swainson's hawks in the Argentine pampas. The highest occurrence probability and relative abundances for the species were predicted for a broad area of south-eastern pampas that has been overlooked so far and where neither field research nor conservation efforts aiming to prevent massive mortalities has been established. [source]

    Managerial failure in late Victorian Britain?: Land use and English agriculture

    E.H. Hunt
    This article focuses upon the neglected role of agriculture in Britain's relative economic decline. Landlords and farmers stand accused of responding inadequately to the flood of American cereal imports. Land-use changes are analysed by soil type and access to urban markets, revealing a range of opportunities and restraints, and an appropriate variety of responses. Other aspects of agriculturalists' responses to depression remain to be examined, but this exercise finds no evidence of significant managerial shortcomings. Rather, the interim verdict is similar to that on the performance of those British industrialists whose once-savaged reputations have been partly redeemed by the researches of McCloskey, Sandberg, et al. [source]

    Agrichemicals in nebraska, USA, watersheds: Occurrence and endocrine effects

    Marlo K. Sellin
    Abstract The objective of the present study was to determine the occurrence and endocrine effects of agrichemicals in four Nebraska, USA, watersheds,the Elkhorn, Platte, Niobrara, and Dismal rivers. Land use in the Elkhorn River and Platte River watersheds is characterized by intense agriculture, including row crop and beef cattle production. In contrast, land within the Niobrara River and Dismal River watersheds consists primarily of grasslands. Polar organic chemical integrative samplers (POCIS) and caged fathead minnows were deployed at a site within each watershed for 7 d. The POCIS were analyzed for pesticides and hormones, while the caged minnows were analyzed for the expression of estrogen- and androgen-responsive genes. Amounts of pesticides recovered in POCIS extracts from the Elkhorn and Platte rivers were higher than those recovered from the Niobrara and Dismal rivers. Furthermore, female minnows deployed in the Elkhorn River experienced significant reductions in expression of two estrogen-responsive genes (vitellogenin and estrogen receptor ,) relative to females deployed at the other sites, indicating alterations in endocrine function. However, the defeminization of these females could not be definitely linked to any of the agrichemicals detected in the POCIS recovered from the Elkhorn River. [source]

    Variable carbon recovery of Walkley-Black analysis and implications for national soil organic carbon accounting

    S. Lettens
    Summary There is considerable interest in the computation of national and regional soil carbon stocks, largely as the result of the provisions of the Kyoto Protocol. Such stocks are often calculated and compared without proper reference to the uncertainties induced by different analytical methodologies. We illustrate the nature and magnitude of these uncertainties with the present soil organic carbon (SOC) study in Belgium. The SOC recovery of the Walkley-Black method was investigated based on a database of 475 samples of silt loam and sandy soils, which cover different soil depths and vegetation types in northern Belgium. The organic carbon content of the soil samples was measured by the original Walkley-Black method and by a total organic carbon analyser. The recovery was computed as the ratio of these two results per soil sample. Land use, texture and soil sampling depth had a significant influence on the recovery as well as their three-way interaction term (land use × texture × sampling depth). The impact of a land use, texture and sampling depth dependent Walkley-Black correction on the year 2000 SOC inventory of Belgium was determined by regression analysis. Based on new correction factors, the national SOC stocks increased by 22% for the whole country, ranging from 18% for cropland to 31% for mixed forest relative to the standard corrected SOC inventory. The new recovery values influenced therefore not only C stocks in the year 2000, but also the expected SOC change following land use change. Adequate correction of Walkley-Black measurements is therefore crucial for the absolute and comparative SOC assessments that are required for Kyoto reporting and must be computed to take into account the regional status of soil and land use. ,Universal' corrections are probably an unrealistic expectation. [source]

    Local Knowledge and Economic Realities Affecting Soil Erosion in the Rach Rat Catchment, Vietnam

    Abstract Several parts of Binh Phuóc Province, southern Vietnam, suffer from degraded soils and vegetation as a result of both natural erosion of weak mud rocks and sandstones and intensive human activity, especially through land clearing for agriculture on unstable slopes, deforestation, and abandonment of poor farmland. The underlying cause of this land degradation has been the farming habits of migrants of varying ethnic groups who have settled in the area since 1980. The indigenous farming knowledge of these people and the role of that knowledge in soil erosion were examined by a series of household surveys. They enabled farming practices to be related to ground cover established from a 2002 Landsat 7 ETM (Enhanced Thematic Mapper), and erosion data from a series of erosion bridge measurements. A GIS (Geographical Information System) approach was piloted as a means of identifying areas vulnerable to erosion. This could then be combined with the understanding of farming practices to reveal the relative roles of farmer behaviour, crop cover, and slope and soil characteristics in the erosion process. Land use, local people's knowledge and economic realities are the main factors, as well as natural conditions, that drive this land degradation. [source]

    Land-use impact on ecosystem functioning in eastern Colorado, USA

    J. M. Paruelo
    Abstract Land-cover change associated with agriculture has had an enormous effect on the structure and functioning of temperate ecosystems. However, the empirical evidence for the impact of land use on ecosystem functioning at the regional scale is scarce. Most of our knowledge on land-use impact has been derived from simulation studies or from small plot experiments. In this article we studied the effects of land use on (i) the seasonal dynamics and (ii) the interannual variability of the Normalized Difference Vegetation Index (NDVI), a variable linearly related to the fraction of the photosynthetically active radiation (PAR) intercepted by the canopy. We also analysed the relative importance of environmental factors and land use on the spatial patterns of NDVI. We compared three cultivated land-cover types against native grasslands. The seasonal dynamics of NDVI was used as a descriptor of ecosystem functioning. In order to reduce the dimensionality of our data we analysed the annual integral (NDVI-I), the date of maximum NDVI (DMAX) and the quarterly average NDVI. These attributes were studied for 7 years and for 346 sites distributed across eastern Colorado (USA). Land use did modify ecosystem functioning at the regional level in eastern Colorado. The seasonal dynamics of NDVI, a surrogate for the fraction of PAR intercepted by the canopy, were significantly altered by agricultural practices. Land use modified both the NDVI integral and the seasonal dynamics of this spectral index. Despite the variability within land-cover categories, land use was the most important factor in explaining regional differences of the NDVI attributes analysed. Within the range of environmental conditions found in eastern Colorado, land use was more important than mean annual precipitation, mean annual temperature and soil texture in determining the seasonal dynamics of NDVI. [source]

    Ecological gradients, subdivisions and terminology of north-west European mires

    JOURNAL OF ECOLOGY, Issue 2 2000
    B. D. Wheeler
    Summary 1,The historical development of mire ecology and terminology is reviewed in relation to evolving concepts and perceptions, and the diverse schools and traditions of vegetation and habitat description and research. 2,Most ecological and floristic variation within north-west European mire vegetation is accounted for by three ecological gradients: the acid base-poor vs. neutral, base- and bicarbonate-rich gradient; the gradient in fertility related to availability of the limiting nutrient elements N and P; and the water level gradient. Effects of salinity and the spring,flush,fen gradients are of more local significance, usually easily recognized. Land use is an important additional factor. 3,The mineral-soil-water limit between ombrotrophic and minerotrophically influenced sites is not sharp, and cannot be related to consistent differences in either vegetation or water chemistry. It should be abandoned as a general main division within mires. 4,The most important natural division is between ,bog', with pH generally < 5.0, low Ca2+, and Cl, and SO42, as the main inorganic anions, typically dominated by sphagna, ericoids and calcifuge Cyperaceae, and ,fen', with pH generally > 6.0, high Ca2+ and HCO3,, vegetation rich in dicotyledonous herbs and ,brown mosses'. This division is reflected in a bimodal distribution of pH. 5,The terms oligotrophic, mesotrophic and eutrophic should refer only to nutrient richness (fertility, mainly N and P), not to base richness (metallic cations and pH). 6,It is recommended that ,mire' should embrace both wetlands on peat and related communities on mineral soils, that ,bog' (unqualified) should encompass both ombrotrophic and weakly minerotrophic mires, including ,bog woodland', and that ,fen' should be restricted to base-rich mires but include both herbaceous and wooded vegetation (,fen carr'). 7,Definitions are given for a range of broadly defined categories that should cover most vegetation types commonly encountered. The relation of these to British national vegetation classification types and to major units in European phytosociology is outlined. [source]

    Soils and land use in the Tigray highlands (Northern Ethiopia)

    J. Nyssen
    Abstract Land use in a 208,ha representative catchment in the Tigray Highlands, Dogu'a Tembien district in Northern Ethiopia was studied in relation to soil geography. Typical soils are Vertisols, Vertic Cambisols, Cumulic Regosols, Calcaric Regosols and Phaeozems. Patterns of land use vary greatly within the catchment and results from ,2 -tests showed strong associations (p,<,0·001) between soil type and land use and crop production system. There is a strong association between cropland and colluvium high in basaltic content because the most fertile soils, such as Vertisols and Vertic Cambisols, have developed on this material. Preference is for autochthonous soils on in situ parent material, irrespective of the rock type, to be put under rangeland. Land use by smallholders in Dogu'a Tembien appears to be the result primarily of the interaction between environmental and social factors. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Land use and soil erosion in the upper reaches of the Yangtze River: some socio-economic considerations on China's Grain-for-Green Programme

    H. L. Long
    Abstract Soil erosion in the upper reaches of the Yangtze River in China is a major concern and the Central Government has initiated the Grain-for-Green Programme to convert farmland to forests and grassland to improve the environment. This paper analyses the relationship between land use and soil erosion in Zhongjiang, a typical agricultural county of Sichuan Province located in areas with severe soil erosion in the upper reaches of the Yangtze River. In our analysis, we use the ArcGIS spatial analysis module with detailed land-use data as well as data on slope conditions and soil erosion. Our research shows that the most serious soil erosion is occurring on agricultural land with a slope of 10,25 degrees. Both farmland and permanent crops are affected by soil erosion, with almost the same percentage of soil erosion for corresponding slope conditions. Farmland with soil erosion accounts for 86·2,per,cent of the total eroded agricultural land. In the farmland with soil erosion, 22·5,per,cent have a slope of,<,5 degrees, 20·3,per,cent have a slope of 5,10 degrees, and 57·1,per,cent have a slope of,>,10 degrees. On gentle slopes with less than 5 degrees inclination, some 6,per,cent of the farmland had strong (5000,8000,t,km,2,y,1) or very strong (8000,15000,t,km,2,y,1) erosion. However, on steep slopes of more than 25 degrees, strong or very strong erosion was reported for more than 42,per,cent of the farmland. These numbers explain why the task of soil and water conservation should be focused on the prevention of soil erosion on farmland with steep or very steep slopes. A Feasibility Index is developed and integrated socio-economic assessment on the feasibility of improving sloping farmland in 56 townships and towns is carried out. Finally, to ensure the success of the Grain-for-Green Programme, countermeasures to improve sloping farmland and control soil erosion are proposed according to the values of the Feasibility Index in the townships and towns. These include: (1) to terrace sloping farmland on a large scale and to convert farmland with a slope of over 25 degrees to forests or grassland; (2) to develop ecological agriculture combined with improving the sloping farmland and constructing prime farmland and to pay more attention to improving the technology for irrigation and cultivation techniques; and (3) to carry out soil conservation on steep-sloping farmland using suggested techniques. In addition, improving ecosystems and the inhabited environment through yard and garden construction for households is also an effective way to prevent soil erosion. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Land use in prehistoric malta.

    A re-examination of the maltese, cart ruts'
    Summary. This paper explores the manufacture and function of the so-called ,cart ruts' within the harsh environment of Malta and proposes that they were deliberately constructed in order to push the boundaries of available arable land and are better identified as field furrows. Using comparative ethnographic evidence as well as archaeological data from European contexts, it is argued that the driving force, which necessitated their manufacture in Malta, lay in socio-economic pressures. It is argued that the ruts are of high antiquity, products of Temple Period intensification and marginalism in land use. [source]