3,530 research outputs found

    Spatio-temporal analysis of vegetation dynamics of selected successional stages of dry acidic grasslands : experimental studies and model simulations

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    Austenfeld M. Spatio-temporal analysis of vegetation dynamics of selected successional stages of dry acidic grasslands : experimental studies and model simulations. Bielefeld (Germany): Bielefeld University; 2009.Eine allgemeine Entwicklungsumgebung wurde für die Analyse und Simulation von räumlich-zeitlichen Phänomenen in ökologischen Systemen entwickelt. Die gesamte Plattform basiert auf einer "Rich-Client-Platform" (RCP), die neue Konzepte der Modularisierung und allgemeinen Programmarchitektur mitbringt. Damit bietet sie die Grundlage für eine nachhaltige Weiterentwicklung und ist somit eine solide Basis für eine integrierte Entwicklungsumgebung für ökologische Modelle. Die Integration verschiedener statistischer Werkzeuge, Methoden der Bildverarbeitung und spezielle Visualisierungen qualifizieren diese Umgebung besonders für die Analyse der oben genannten räumlich-zeitlichen Prozesse. Aufgrund ihrer vergleichsweise geringen Komplexität wurden Sandlebensräume wiederholt für Studien von Vegetationsmustern und ihrer zugrunde liegenden biotischen Interaktionen genutzt. Für einen integrativen Überblick und weitere integrative Ansätze mit Hilfe von Simulationsmodellen wurde die oben genannte Plattform genutzt, um eine individuenbasierte Modellstruktur für die Analyse von Langzeiteffekten aufgrund von Umweltveränderungen auf die Stabilität von Sandlebensräumen zu entwickeln, die typischerweise von zwei Pionierarten, Corynephorus canescens und Polytrichum piliferum, dominiert werden. Das Modell wurde mit experimentellen Daten verifiziert, und die vom Modell erzeugten räumlich-zeitlichen Muster zeigten eine hohe Übereinstimmung mit natürlich gemessenen Mustern. Das Modell wurde dann genutzt, um Langzeiteffekte von Veränderungen der Temperatur, Nährstoffversorgung und Störungsraten in diesem System zu untersuchen. Die Ergebnisse zeigten eine generell hohe Stabilität des Systems unter veränderten Temperatur- und Nährstoffbedingungen, wobei temporal wiederkehrende, kleinräumige Störungen als Grundlage notwendig waren. Schließlich wurde noch eine Untersuchung über die Auswirkungen von Herbivorie und Konkurrenz auf Corynephorus canescens durchgeführt. In einem kontrollierten Freilandexperiment wurden die Auswirkungen von entfernter Biomasse von Blättern sowie die An- oder Abwesenheit eines intraspezifischen und interspezifischen Konkurrenten (Hieracium pilosella) auf die überirdische und unterirdische Allokation von Biomasse in der folgenden Regenerationsphase analysiert. Die Ergebnisse zeigten, dass Corynephorus canescens die Fähigkeit besitzt, leichte bis mittlere Blattverluste (die typische natürliche Herbivorie von Kaninchen und Paarhufern simulieren sollten) zu kompensieren, ohne dabei an Konkurrenzstärke zu verlieren. Unterirdisch konnten keine Auswirkungen der simulierten Herbivorie bzw. Konkurrenz festgestellt werden. Aufgrund dieser zu vernachlässigenden Effekte wurde Herbivorie nicht in dem Modell berücksichtigt.A generic modeling environment for the analysis and simulation of spatio-temporal phenomena in ecosystems was developed. This framework was built upon a Rich Client Platform (RCP) which uses new concepts of extensibility and software architecture for sustainable development and provides a solid basis for an Integrated Development Environment (IDE) for ecological models. The integration of various statistical tools, imaging routines and several specialized drawing panels makes this environment particularly suitable for the analysis of the above mentioned spatio-temporal ecological processes. Because of their comparatively low complexity, dry acidic grassland ecosystems have been repeatedly used for studying vegetation pattern formation and the underlying biotic interactions. In order to obtain an integrative view of the existing knowledge as well as to provide a possibility for further integrative analysis with the help of model simulations, the above described platform was used to develop an individual based Model structure for the investigation of long term effects of environmental changes on the stability of early successional stages of such dry acidic grasslands which are typically dominated by the two pioneer species Corynephorus canescens and Polytrichum piliferum. The model was validated with experimental data and the spatio-temporal patterns created by the model were in good accordance with the measured natural patterns. The model was then used to analyze the effect of changes in temperature, nutrient supply and disturbance rate on the long term behavior of this ecosystem. The results showed an overall high stability of this system under different temperature and nutrient scenarios as long as an intermediate disturbance frequency is assured. Finally, an experimental study on the effect of herbivory and competition on the Corynephorus canescens was conducted. In a controlled field experiment, the effects of the removal of various amounts of aboveground biomass on the above and belowground biomass allocation during the following regeneration phase was analyzed in the presence or absence of an intraspecific and interspecific competitor (Hieracium pilosella). The results show a rather high ability of C. canescens to compensate low to medium amounts of foliage loss (reflecting the typical natural herbivory induced by grasshoppers and rabbits) without significant changes in its competitive ability. Belowground, no biomass effects of foliage removal and/or competition could be detected. Because of these negligible effects, herbivory was not implemented in the above described model

    Social Evolution: New Horizons

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    Cooperation is a widespread natural phenomenon yet current evolutionary thinking is dominated by the paradigm of selfish competition. Recent advanced in many fronts of Biology and Non-linear Physics are helping to bring cooperation to its proper place. In this contribution, the most important controversies and open research avenues in the field of social evolution are reviewed. It is argued that a novel theory of social evolution must integrate the concepts of the science of Complex Systems with those of the Darwinian tradition. Current gene-centric approaches should be reviewed and com- plemented with evidence from multilevel phenomena (group selection), the constrains given by the non-linear nature of biological dynamical systems and the emergent nature of dissipative phenomena.Comment: 16 pages 5 figures, chapter in forthcoming open access book "Frontiers in Ecology, Evolution and Complexity" CopIt-arXives 2014, Mexic

    ForestSim model of impacts of smallholder dynamics: forested landscapes of the Upper Peninsula of Michigan

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    Many forested landscapes in the United States contain a large number of small private landowners (smallholders). The individual decisions of these smallholders can collectively have a large impact on the structure, composition, and connectivity of forests. While models have been developed to try to understand this large-scale collective impact, few models have incorporated extensive information from individual decision-making. Here we introduce an agent-based model, infused with sociological data from smallholders, overlaid on a GIS layer to represent individual smallholders, and used to simulate the impact of thousands of harvesting decisions. Our preliminary results suggest that certain smallholder characteristics (such as relative smallholder age and education level as well as whether a smallholder is resident or absentee) and information flow among owners can radically impact forests at the landscape scale. While still in its preliminary stages, this modeling approach is likely to demonstrate in detail the consequences of decision-making due to changing smallholder demographics or new policies and programs. This approach can help estimate the effectiveness of programs based on landscape-scale programmatic goals and the impact of new policy initiatives

    A Climate Change Vulnerability Assessment among Small Farmers: A Case Study in Western Honduras

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    Climate change is now affecting every known society. Small farmers in Low Income Countries (LICs) are especially vulnerable to climate change patterns because they depend heavily on rain, seasonality patterns, and known temperature ranges. To help build climate change resilient communities among rural farmers, the first step is to understand the impact of climate change on the population. This dissertation aims to use information and communication technology (ICT) to assess climate change vulnerabilities among rural farmers. To achieve this overall goal, this dissertation first proposes a comprehensive Climate Change Vulnerability Assessment Framework (CCVAF) that integrates both community level and individual household level indicators. The CCVAF was instantiated into a GIS-based web application named THRIVE for different decision makers to better assess how climate change is affecting rural farmers in Western Honduras. Qualitative evaluation of the THRIVE showed that it is an innovative and useful tool. The CCVAF and its instantiation provides an important initial step towards building climate change resilience among rural farmers. It is the first attempt to provide a comprehensive set of the indicators with related measurements and data sources for climate change vulnerability assessment. The framework thus contributes to the knowledge base of the climate change vulnerability assessment. It also contributes to the design science literature by providing guidelines to design a class of climate change vulnerability assessment solutions. To the best of our knowledge, the CCVAF is the first generalizable artifact that can be used to build a group of ICT-based climate change vulnerability assessment solutions. Another knowledge contribution of this dissertation is its reproducibility by making the input and output data available to the research and practitioner community through a GeoHub. For practical contributions, the framework can be easily used by researchers and practitioners to consistently design a vulnerability assessment tool, starting with the set of indicators organized by the three-level determinants, and following specific spatial data analysis and models. Such an ICT-based tool adds practical values to tackle climate change challenges

    Comparison of Vegetative Community and Soil Organic Matter Depth Among Reference Sites and Two Restored Wetlands in the Coastal Plain of South Carolina

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    Wetland loss and degradation from agriculture, urbanization, forestry, and mining is a global issue. South Carolina alone has lost over 27% of its wetlands. This historical wetland loss and climatic changes and impacts make restoring wetlands critical for the state. In restoration, understanding the difference in restored and reference wetland’s vegetation and soil organic matter depth can be crucial in assessing the recovery rate and determining environmental functions and services. The main objectives for our research were to determine differences in soil organic matter depth and vegetative community between the restored Brosnan Forest wetlands, the headwater flats and headwater slopes, and reference sites at Francis Marion National Forest. Our results indicate no significant differences in soil organic matter depth between the two restored wetlands. However, the reference site’s soil organic matter depth was twice that of the Brosnan wetlands. Additionally, there are differences in vegetative community between the two restored wetlands; different species dominated each wetland. However, compared to the reference sites, the Brosnan wetlands were more similar, with only a few quadrats reaching the reference sites

    Two Decades of Evolutionary Art Using Computational Ecosystems and Its Potential for Virtual Worlds

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    We analyse works of digital art that use a technique from artificial life (ALife) called computational ecosystems (CEs). These are systems running on computers where agents are organized in a hierarchical structure (of a food-chain) and trade token units (of energy and biomass) as a way of promoting community dynamics. We analyse a collection of forty (40) papers communicating works developed in the last two decades. We classify each of these works according to an adapted taxonomy. We then produce a study of cumulative analysis to outline patterns and common features which might define the field. We conclude on the diversity and heterogeneity of the practice, to assert CEs as a multimedia generative tool useful in the construction of bio-mimicking ecosystems as well as in the animation of non-player characters (NPCs) with human-like behaviors in virtual words

    Actors and factors - bridging social science findings and urban land use change modeling

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    Recent uneven land use dynamics in urban areas resulting from demographic change, economic pressure and the cities’ mutual competition in a globalising world challenge both scientists and practitioners, among them social scientists, modellers and spatial planners. Processes of growth and decline specifically affect the urban environment, the requirements of the residents on social and natural resources. Social and environmental research is interested in a better understanding and ways of explaining the interactions between society and landscape in urban areas. And it is also needed for making life in cities attractive, secure and affordable within or despite of uneven dynamics.\ud The position paper upon “Actors and factors – bridging social science findings and urban land use change modeling” presents approaches and ideas on how social science findings on the interaction of the social system (actors) and the land use (factors) are taken up and formalised using modelling and gaming techniques. It should be understood as a first sketch compiling major challenges and proposing exemplary solutions in the field of interest

    From scaling to governance of the land system: bridging ecological and economic perspectives

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    One of the main unresolved problems in policy making is the step from scale issues to effective governance. What is appropriate for a lower level, such as a region or location, might be considered undesirable at a global scale. Linking scaling to governance is an important issue for the improvement of current environmental management and policies. Whereas social–ecological science tends to focus on adaptive behavior and aspects of spatial ecological data, new institutional economics focuses more on levels in institutional scales and temporal dimensions. Consequently, both disciplines perceive different scaling challenges while aiming at a similar improvement of effective governance. We propose that future research needs to focus on four themes: (1) How to combine spatial properties such as extent and grain with the economic units of market and agent; (2) How to combine the different governance instruments proposed by both perspectives; (3) How to communicate the different scaling perspectives (hierarchy vs. no hierarchy) and meanings to policy makers and other stakeholders; and (4) How to deal with the non-equilibrium conditions in the real world and the disciplinary perspectives. Here, we hypothesize that a combined system perspective of both disciplines will improve our understanding of the missing link between scaling and governanc

    Ecological integrity assessment for Colorado wetlands: field manual, version 2.1

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    March 2016.Based on NatureServe's Ecological Integrity Assessment Framework.Includes bibliographical references (pages 59-62).Ecological Integrity Assessment (EIA) for Colorado wetlands is an assessment method that measures overall wetland condition with an emphasis on biological integrity. The method combines quantitative vegetation metrics with qualitative metrics that evaluate landscape context, hydrology, soils, water quality, and size into a multi-metric index. Final EIA scores rank a wetland's condition on a four-tiered scale (excellent/good/ fair/poor), as compared to unaltered wetlands of the same type.Funding provided by U.S. Environmental Protection Agency, Region 8, Wetland Program Development Grants. Matching funds from Colorado Parks and Wildlife

    Multi-biologic group analysis for an ecosystem response to longitudinal river regulation gradients

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    This work assesses the effects of river regulation on the diversity of different instream and riparian biological communities along a relieve gradient of disturbance in regulated rivers. Two case studies in Portugal were used, with different river regulation typology (downstream of run-of-river and reservoir dams), where regulated and free-flowing river stretches were surveyed for riparian vegetation, macrophytes, bryophytes, macroalgae, diatoms and macroinvertebrates. The assessment of the regulation effects on biological communities was approached by both biological and functional diversity analysis. Results of this investigation endorse river regulation as a major factor differentiating fluvial biological communities through an artificial environmental filtering that governs species assemblages by accentuating species traits related to river regulation tolerance. Communities' response to regulation gradient seem to be similar and insensitive to river regulation typology. Biological communities respond to this regulation gradient with different sensibilities and rates of response, with riparian vegetation and macroinvertebrates being the most responsive to river regulation and its gradient. Richness appears to be the best indicator for general fluvial ecological quality facing river regulation. Nevertheless, there are high correlations between the biological and functional diversity indices of different biological groups, which denotes biological connections indicative of a cascade of effects leading to an indirect influence of river regulation even on non-responsive facets of communities' biological and functional diversities. These results highlight the necessary holistic perspective of the fluvial system when assessing the effects of river regulation and the proposal of restoration measures.publishe
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