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Ecological Understanding (ecological + understanding)
Selected AbstractsAnthropogenic disturbance and the formation of oak savanna in central Kentucky, USAJOURNAL OF BIOGEOGRAPHY, Issue 5 2008Ryan W. McEwan Abstract Aim, To deepen understanding of the factors that influenced the formation of oak savanna in central Kentucky, USA. Particular attention was focused on the link between historical disturbance and the formation of savanna ecosystem structure. Location, Central Kentucky, USA. Methods, We used dendrochronological analysis of tree-ring samples to understand the historical growth environment of remnant savanna stems. We used release detection and branch-establishment dates to evaluate changes in tree growth and the establishment of savanna physiognomy. We contrasted our growth chronology with reference chronologies for regional tree growth, climate and human population dynamics. Results, Trees growing in Kentucky Inner Bluegrass Region (IBR) savanna remnants exhibited a period of suppression, extending from the establishment date of the tree to release events that occurred c. 1800. This release resulted in a tripling of the annual radial growth rate from levels typical of oaks suppressed under a forest canopy (< 1 mm year,1) to levels typical of open-grown stems (3 mm year,1). The growth releases in savanna trees coincided with low branch establishment. Over the release period, climatic conditions remained relatively constant and growth in regional forest trees was even; however, the growth increase in savanna stems was strongly correlated with a marked increase in Euro-American population density in the region. Main conclusions, Our data suggest that trees growing in savanna remnants originated in the understorey of a closed canopy forest. We hypothesize that Euro-American land clearing to create pasturelands released these trees from light competition and resulted in the savanna physiognomy that is apparent in remnant stands in the IBR. Although our data suggest that savanna trees originated in a forest understorey, this system structure itself may have been a result of an unprecedented lack of Native American activity in the region due to population loss associated with pandemics brought to North America by Euro-Americans. We present a hypothetical model that links human population dynamics, land-use activities and ecosystem structure. Our model focuses on the following three land-use eras: Native American habitation/utilization; land abandonment; and Euro-American land clearance. Ecological understanding of historical dynamics in other ecosystems of eastern North America may be enhanced through recognition of these eras. [source] New York's nature: a review of the status and trends in species richness across the metropolitan regionDIVERSITY AND DISTRIBUTIONS, Issue 1 2009Linda M. Puth ABSTRACT Aim, The world's population is urbanizing, yet relatively little is known about the ecology of urban areas. As the largest metropolitan area in the USA, New York City is an ideal location to study the effects of urbanization. Here, we aim to produce a better understanding of the state of the research for species richness of flora and fauna across the New York metropolitan region. Location, New York metropolitan region, USA. Methods, We conducted a review of the published and grey literature, in which we targeted studies of species richness, and categorized each study by habitat, location and taxonomic group. Results, We found 79 studies reporting location-specific species richness data, resulting in 261 location-taxonomic group records. Of these, 26 records had data from multiple time periods; 17 showed decreases in species richness, six reported increases and three showed stable species richness. Of these 26 records, most declines were attributed to anthropogenic causes, such as habitat loss/degradation and invasive species, while most increases reflected recovery from major habitat loss or increases in exotic species. Overall, most records (84) were terrestrial, followed by those in freshwater (72) and mixed habitats (61). When parsed by taxonomic group, the most commonly studied groups were plants (76) and mammals (48). Main conclusions, In general, we discovered fewer studies than expected reporting species richness, especially studies reporting species richness for more than one point in time. Most studies that did contain data over time reported declines in species richness, while several studies reporting increasing or stable species richness reflected increases in exotic species. This survey provides a crucial first step in establishing baseline ecological knowledge for the New York metropolitan region that should help prioritize areas for protection, research and development. Furthermore, this research provides insights into the impacts of urbanization across the USA and beyond and should help establish similar frameworks for ecological understanding for other metropolitan regions throughout the world. [source] The ecology of restoration: historical links, emerging issues and unexplored realmsECOLOGY LETTERS, Issue 6 2005T. P. Young Abstract Restoration ecology is a young academic field, but one with enough history to judge it against past and current expectations of the science's potential. The practice of ecological restoration has been identified as providing ideal experimental settings for tests of ecological theory; restoration was to be the ,acid test' of our ecological understanding. Over the past decade, restoration science has gained a strong academic foothold, addressing problems faced by restoration practitioners, bringing new focus to existing ecological theory and fostering a handful of novel ecological ideas. In particular, recent advances in plant community ecology have been strongly linked with issues in ecological restoration. Evolving models of succession, assembly and state-transition are at the heart of both community ecology and ecological restoration. Recent research on seed and recruitment limitation, soil processes, and diversity,function relationships also share strong links to restoration. Further opportunities may lie ahead in the ecology of plant ontogeny, and on the effects of contingency, such as year effects and priority effects. Ecology may inform current restoration practice, but there is considerable room for greater integration between academic scientists and restoration practitioners. [source] Managing ecosystem services: what do we need to know about their ecology?ECOLOGY LETTERS, Issue 5 2005Claire Kremen Abstract Human domination of the biosphere has greatly altered ecosystems, often overwhelming their capacity to provide ecosystem services critical to our survival. Yet ecological understanding of ecosystem services is quite limited. Previous work maps the supply and demand for services, assesses threats to them, and estimates economic values, but does not measure the underlying role of biodiversity in providing services. In contrast, experimental studies of biodiversity,function examine communities whose structures often differ markedly from those providing services in real landscapes. A bridge is needed between these two approaches. To develop this research agenda, I discuss critical questions and key approaches in four areas: (1) identifying the important ,ecosystem service providers'; (2) determining the various aspects of community structure that influence function in real landscapes, especially compensatory community responses that stabilize function, or non-random extinction sequences that rapidly erode it; (3) assessing key environmental factors influencing provision of services, and (4) measuring the spatio-temporal scale over which providers and services operate. I show how this research agenda can assist in developing environmental policy and natural resource management plans. [source] Current issues with fish and fisheries: editor's overview and introductionJOURNAL OF APPLIED ECOLOGY, Issue 2 2003S. J. Ormerod Summary 1.,By any measure, fishes are among the world's most important natural resources. Annual exploitation from wild populations exceeds 90 million tonnes, and fish supply over 15% of global protein needs as part of total annual trade exceeding $US 55 billion. Additionally, with over 25 000 known species, the biodiversity and ecological roles of fishes are being increasingly recognised in aquatic conservation, ecosystem management, restoration and aquatic environmental regulation. 2.,At the same time, substantial management problems now affect the production, exploitable stocks, global diversity, trophic structure, habitat quality and local composition of fish communities. 3.,In marine systems, key issues include the direct effects of exploitation on fish, habitats and other organisms, while habitat or water quality problems arise also from the atmospheric, terrestrial and coastal environments to which marine systems are linked. In freshwaters, flow regulation and obstruction by dams, fragmentation, catchment management, pollution, habitat alterations, exotic fish introductions and nursery-reared fish are widespread issues. 4.,Management responses to the problems of fish and fisheries include aquatic reserves in both marine and freshwater habitats, and their effectiveness is now being evaluated. Policies on marine exploitation increasingly emphasise fishes as integral components of aquatic ecosystems rather than individually exploitable stocks, but the rationalisation of fishing pressures presents many challenges. In Europe, North America and elsewhere, policies on freshwaters encourage habitat protection, integrated watershed management and restoration, but pressures on water resources will cause continued change. All these management approaches require development and evaluation, and will benefit from a perspective of ecological understanding with ecologists fully involved. 5.,Synthesis and applications. Although making a small contribution to the Journal of Applied Ecology in the past, leading work on aquatic problems and fish-related themes appear increasingly in this and other mainstream ecology journals. As this special profile of five papers shows, significant contributions arise on diverse issues that here include the benefit of aquatic reserves, river restoration for fish, the accumulation of contaminants, interactions with predators, and the fitness of salmonids from nurseries. This overview outlines the current context in which papers on the applied ecology of fish and fisheries are emerging, and it identifies scope for further contributions. [source] Applied issues with predators and predation: editor's introductionJOURNAL OF APPLIED ECOLOGY, Issue 2 2002S. J. Ormerod Summary 1,The effects of predation are among the most pervasive in ecology. As parasitoids, parasites, grazers or top carnivores, predators have large influences on the distribution, density, dynamics and evolved traits of other organisms. Effects scale-up to influence community attributes such as species coexistence and ecosystems processes such as production or trophic cascades. 2,Increasingly, however, some of the largest predation issues fall clearly within the scope of applied ecology. They include instances where, due to their ecological attributes and trophic position: (i) predators are valuable to nature conservation, as biocontrol agents, as natural enemies, or as grazers used in rangeland or ecosystem management; (ii) natural or introduced predators are viewed negatively due to effects on conservation, agriculture, forestry, hunting or disease transmission; (iii) predators are affected by human activities such as resource exploitation, or from exposure to factors such as biomagnified pollutants and disturbance; (iv) predators are controversial because different groups view them as either desirable or undesirable. 3,In all these cases, ecologists have a pivotal rôle in facilitating appropriate management. For valued predators, this involves developing sufficient ecological understanding to optimize habitat, increase prey abundance or to reinforce, establish or reintroduce desirable species. For predators considered undesirable, management can involve direct control. In other cases, predation and its consequences can be mitigated by deterrent, exclusion, supplementary feeding, habitat management to favour prey, predator swamping, or by compensating losses financially. These latter strategies are often used where predators are themselves considered too valuable to remove or control. 4,This collection of seven papers illustrates many of these themes by examining contrasting aspects of the applied ecology of Eurasian lynx; by further probing the interaction between predatory birds and red grouse; by exploring the effects of weather on biocontrol; and by illustrating effects on plant species where grazing or seed predation play a dominant rôle. 5,A key lesson from these and other recent papers in the Journal of Applied Ecology is that the successful management of predators depends invariably on understanding adequately the exact ecological context in which predator,prey interactions take place and in which problems arise. With predator-related issues growing rather than diminishing, ecologists will need sufficient resources to maintain current research if they are to provide the understanding required to offer and evaluate sound management. [source] Facilitation in the conceptual melting potJOURNAL OF ECOLOGY, Issue 6 2009Rob W. Brooker Summary 1. Here we present an introduction to this issue's Special Feature arising from the British Ecological Society Symposium: Facilitation in Plant Communities (20,22 April 2009). 2. Papers in the Special Feature demonstrate the benefits that arise from cross-system application of general concepts, for example, the well-known stress gradient hypothesis. Such comparisons challenge our definition of facilitation, as well as our pre-conceptions on the nature of intermediary organisms. 3. We suggest that under some circumstances a clear definition of the two-way nature of interactions is essential, e.g. when considering the evolutionary implications of facilitation. In other cases, however, we can perhaps be more relaxed, e.g. when facilitation is a component of conservation ecology. 4.Synthesis. Overall we believe that establishing facilitation as an independent concept has driven substantial progress towards a clearer understanding of how ecological systems work. Through the links established by work such as that presented in this Special Feature, we believe this field will continue to make rapid progress and aid ecological understanding in general. [source] Advancing urban ecological studies: Frameworks, concepts, and results from the Baltimore Ecosystem StudyAUSTRAL ECOLOGY, Issue 2 2006S. T. A. PICKETT Abstract Urban ecological studies have had a long history, but they have not been a component of mainstream ecology until recently. The growing interest of ecologists in urban systems provides an opportunity to articulate integrative frameworks, and identify research tools and approaches that can help achieve a broader ecological understanding of urban systems. Based on our experience in the Baltimore Ecosystem Study (BES), Long-term Ecological Research project, located in metropolitan Baltimore, Maryland, USA, we identify several frameworks that may be useful in comparative urban studies, and may be worthy of consideration in other integrative urban ecosystem studies: (i) spatial patch dynamics of biophysical and social factors; (ii) the watershed as an integrative tool; and (iii) the human ecosystem framework. These frameworks build on empirical research investigating urban biota, nutrient and energy budgets, ecological footprints of cities, as well as biotic classifications aimed at urban planning. These frameworks bring together perspectives, measurements, and models from biophysical and social sciences. We illustrate their application in the BES, which is designed to investigate (i) the structure and change of the urban ecosystem; (ii) the fluxes of matter, energy, capital, and population in the metropolis; and (iii) how ecological information affects the quality of the local and regional environments. Exemplary results concerning urban stream nutrient flux, the ability of riparian zones to process nitrate pollution, and the lags in the relationships between vegetation structure and socio-economic factors in specific neighbourhoods are presented. The current advances in urban ecological studies have profited greatly from the variety of integrative frameworks and tools that have been tested and applied in urban areas over the last decade. The field is poised to make significant progress as a result of ongoing conceptual and empirical consolidation. [source] | ||||||||||