Digital Ecosystems: Ecosystem-Oriented Architectures

We view Digital Ecosystems to be the digital counterparts of biological ecosystems. Here, we are concerned with the creation of these Digital Ecosystems, exploiting the self-organising properties of biological ecosystems to evolve high-level software applications. Therefore, we created the Digital Ecosystem, a novel optimisation technique inspired by biological ecosystems, where the optimisation works at two levels: a first optimisation, migration of agents which are distributed in a decentralised peer-to-peer network, operating continuously in time; this process feeds a second optimisation based on evolutionary computing that operates locally on single peers and is aimed at finding solutions to satisfy locally relevant constraints. The Digital Ecosystem was then measured experimentally through simulations, with measures originating from theoretical ecology, evaluating its likeness to biological ecosystems. This included its responsiveness to requests for applications from the user base, as a measure of the ecological succession (ecosystem maturity). Overall, we have advanced the understanding of Digital Ecosystems, creating Ecosystem-Oriented Architectures where the word ecosystem is more than just a metaphor.Comment: 39 pages, 26 figures, journa

Impacts of Land Abandonment on Vegetation: Successional Pathways in European Habitats

Changes in traditional agricultural systems in Europe in recent decades have led to widespread abandonment and colonization of various habitats by shrubs and trees. We combined several vegetation databases to test whether patterns of changes in plant diversity after land abandonment in different habitats followed similar pathways. The impacts of land abandonment and subsequent woody colonization on vegetation composition and plant traits were studied in five semi-natural open habitats and two arable habitats in six regions of Europe. For each habitat, vegetation surveys were carried out in different stages of succession using either permanent or non-permanent plots. Consecutive stages of succession were defined on a physiognomic basis from initial open stages to late woody stages. Changes in vegetation composition, species richness, numbers of species on Red Lists, plant strategy types, Ellenberg indicator values of the vegetation, Grime CSR strategy types and seven ecological traits were assessed for each stage of the successional pathway. Abandonment of agro-pastoral land-use and subsequent woody colonization were associated with changes in floristic composition. Plant richness varied according to the different habitats and stages of succession, but semi-natural habitats differed from arable fields in several ecological traits and vegetation responses. Nevertheless, succession occurred along broadly predictable pathways. Vegetation in abandoned arable fields was characterized by a decreasing importance of R-strategists, annuals, seed plants with overwintering green leaves, insect-pollinated plants with hemi-rosette morphology and plants thriving in nutrient-rich conditions, but an increase in species considered as endangered according to the Red Lists. Conversely, changes in plant traits with succession within the initially-open semi-natural habitats showed an increase in plants thriving in nutrient-rich conditions, stress-tolerant plants and plants with sexual and vegetative reproduction, but a sharp decrease in protected species. In conclusion, our study showed a set of similarities in responses of the vegetation in plant traits after land abandonment, but we also highlighted differences between arable fields and semi-natural habitats, emphasizing the importance of land-use legacy

Soil and water bioengineering: practice and research needs for reconciling natural hazard control and ecological restoration

Soil and water bioengineering is a technology that encourages scientists and practitioners to combine their knowledge and skills in the management of ecosystems with a common goal to maximize benefits to both man and the natural environment. It involves techniques that use plants as living building materials, for: (i) natural hazard control (e.g., soil erosion, torrential floods and landslides) and (ii) ecological restoration or nature-based re-introduction of species on degraded lands, river embankments, and disturbed environments. For a bioengineering project to be successful, engineers are required to highlight all the potential benefits and ecosystem services by documenting the technical, ecological, economic and social values. The novel approaches used by bioengineers raise questions for researchers and necessitate innovation from practitioners to design bioengineering concepts and techniques. Our objective in this paper, therefore, is to highlight the practice and research needs in soil and water bioengineering for reconciling natural hazard control and ecological restoration. Firstly, we review the definition and development of bioengineering technology, while stressing issues concerning the design, implementation, and monitoring of bioengineering actions. Secondly, we highlight the need to reconcile natural hazard control and ecological restoration by posing novel practice and research questions

SITE-SPECIFIC AND LANDSCAPE FEATURES ASSOCIATED WITH SHRUBLAND BIRD OCCURENCE IN ANTHROPOGENIC SHRUBLANDS IN THE NORTHEASTERN UNITED STATES

Habitats dominated by low-growing trees and shrubs are becoming increasingly uncommon in the northeastern U.S. Human development, altered natural-disturbance regimes, and forest succession have reduced the quantity and quality of these shrublands. As a result, over half of the shrubland-dependent songbirds in the region have experienced long-term population declines. Anthropogenic shrublands, including regenerating clearcuts, sand and gravel mines, old fields, and transmission line rights-of-way may provide nesting habitat for most shrubland birds; but differences in size, site-specific features, and landscape composition may affect bird use. To assess the features that may influence shrubland bird occurrence in anthropogenic shrublands, I conducted presence/absence surveys of 8 species [alder flycatcher (Empidonax alnorum), brown thrasher (Toxostoma rufum), blue-winged warbler (Vermivora cyanoptera), chestnut-sided warbler (Setophaga pensylvanica), eastern towhee (Pipilo erythrophthalmus), field sparrow (Spizella pusilla), indigo bunting (Passerina cyanea), and prairie warbler (Setophaga discolor)] in 101 sites in southeastern New Hampshire during the 2015 and 2016 nesting seasons. For each shrubland, I measured area, site-specific features (e.g., vegetation height, density, and coverage), and characteristics of surrounding landscape features within different buffer zones. Overall, 67% of the variables in the best models predicting bird occurrence were landscape features and 33% were site-specific features. Bird occurrence at a site was positively associated with the proportion of shrublands in the surrounding landscape, particularly within a 500 m buffer. Occurrence of all species except blue-winged warblers and indigo buntings was negatively associated with the proportion of urban development in the surrounding landscape. Shrubland bird species richness increased with vegetation density until vegetation density became too dense for brown thrashers, field sparrows, and prairie warblers. Occurrence of all species except blue-winged warblers increased with shrubland size. These results provide opportunities to enhance existing anthropogenic habitats to benefit populations of declining shrubland birds

MODELING ECONOMIC AND ECOLOGICAL BENEFITS OF POST-FIRE REVEGETATION IN THE GREAT BASIN

This study employs a Markov chain model of vegetation dynamics to examine the economic and ecological benefits of post-fire revegetation in the Great Basin sagebrush steppe. The analysis is important because synergies between wildland fire and invasive weeds in this ecosystem are likely to result in the loss of native biodiversity, less predictable forage availability for livestock and wildlife, reduced watershed stability and water quality, and increased costs and risk associated with firefighting. The analysis is based on a parameterized state-and-transition model of vegetation change for Wyoming big sagebrush community in the Great Basin sagebrush steppe. This conceptual model was formulated into a quantitative, predictive model by implementing it as a Markov chain process that links vegetation change, management, and costs. Simulation results were used to develop cost curves for achieving ecological goals and to evaluate uncertainty in future vegetation conditions. The Markov chain model shows that post-fire revegetation using either a native seed mix or crested wheatgrass was more effective than no revegetation for achieving ecosystem objectives. Further, post-fire revegetation with either seed mix cost less than no revegetation because of resulting reductions in fire suppression costs. Consequently, post-fire revegetation makes both ecological and economic sense, and the choice of seed mix should depend on the prioritization of management objectives. Identifying the economic and ecological tradeoffs of different management strategies should enable improved management of the sagebrush-steppe, and Markov processes provide a straight-forward method for identifying these trade-offs.Resource /Energy Economics and Policy,

Management recommendations

The acute succession problem justifies an opportunistic use of all suitable methods on the short-term (10 years). The ban on winter burning should be (temporally) lifted. The mown area should be enlarged by activating volunteers, raising budgets and funds for mowing of BNP-owned peatlands and by using peat harvesters. BNP and farmers should co-operate to raise funds and conclude Management Agreements for livestock farming on private and BNP-owned peatland. Agreements should include the use of Biebrza hay and litter. In the longer term (>10 years) extensive grazing seems the most promising tool. It may be implemented as traditional dairy farming, ranching of beef cattle, horses or (semi-) wild herbivores or as Wilderness. Suitability and feasibility may differ between the three basins. The entry of Poland to the EU will affect the feasibility of the strategie

Introduction

The biodiversity of low-productive pastures and hayfields is threatened across Europe by intensified land use and abandonment. The question is whether and how Extensive Farming can be maintained or restored, or whether conservation management should shift to New Wilderness. Suitability and feasibility of both strategies differ and depend on local conditions. The aim of the workshop was to discuss and clarify the strategic management dilemma for peatlands by taking the Biebrza National Park (BNP) in N.E.Poland as a case study. The BNP authorities are facing a tremendous and difficult problem to stop and reverse succession on 20.000 ha abandoned fen peat. Questions addressed during the workshop were 'Which extensive farming methods (grazing, mowing, cutting, and burning) are suitable for BNP-peatlands in view of the management objectives? Which methods are most feasible in view of the actual and future socio-economical environment of the BNP? Which management recommendation and research recommendations can be given to the BNP authorities

Riparian Functional Assessment Phase Two Summary

This report contains data regarding the drainage area, restoration strategy and banks sampled of three Waller Creek locations.In an effort to assess the response of degraded riparian buffers to the cessation of the main disturbance regime (mowing) and the facilitated succession approach to riparian restoration, the City of Austin implemented phase 2 of the Riparian Functional Assessment (RFA) which consisted of sampling degraded buffers after 1 year with no disturbance. Only degraded sites were included in this phase and their functional scores were compared with those of reference sites from the initial sample year representing healthy riparian function. A total of 9 degraded sites were added to the initial 16 degraded sites from phase 1 for this assessment. Results suggest that degraded buffers lacked the necessary time to show a response in riparian function after only one year of recovery. Sampling design changes are recommended to better assess the growing number of buffer site locations tracked in this project, including reinstituting reference site sampling and shifting to a biannual sampling regime. Based on analysis of phase 2 data, changes to the assessment tool include the following: substitute organic soil carbon for direct soil moisture measurements, coalesce the hardwood demography and recruitment parameters into woody community dynamics, and upgrade soil compaction instruments for higher accuracy and reliability.Waller Creek Working Grou

Ocupación urbana de zonas con riesgo de inundación y dinámica territorial: El caso de las aglomeraciones del Gran Nador (Marruecos)

Flooding in the urban environment has long been a major concern for territorial actors as well as for the local population in the Great Nador region. It affects, in a recurring way, the main urban agglomerations and the peripheral zones which surround them. Due to high population growth, a trend towards urbanization and climate change, the causes of floods are changing, and their impacts are intensifying in this area. These phenomena constitute a major obstacle for development and threaten the populations, especially in the peripheral districts which are in rapid urban expansion. This article aims to analyze and inventory the economic, social and environmental consequences of the recent flood events in Nador, while explaining the elements of an integrated approach to flood risk management in urban areas.Las inundaciones en áreas urbanas han sido durante mucho tiempo una gran preocupación para los actores territoriales, así como para la población local en el Gran Nador. Afectan, de manera recurrente, las principales aglomeraciones urbanas y las zonas periféricas que las rodean. Debido al alto crecimiento de la población, una tendencia hacia la urbanización y el cambio climático, las causas de las inundaciones están cambiando y sus impactos se están intensificando. Estos fenómenos constituyen un obstáculo importante para el desarrollo y amenazan a las poblaciones, especialmente en los distritos periféricos que se encuentran en rápida expansión urbana. Este documento tiene como objetivo analizar e inventariar las consecuencias económicas, sociales y ambientales de las recientes inundaciones en Nador, al tiempo que explica los elementos de un enfoque integrado para la gestión del riesgo de inundación en las zonas urbanas