Showing papers in "Frontiers in Ecology and the Environment in 2007"

Bio-energy in the black

Abstract: At best, common renewable energy strategies can only offset fossil fuel emissions of CO2 – they cannot reverse climate change. One promising approach to lowering CO2 in the atmosphere while producing energy is biochar bio-energy, based on low-temperature pyrolysis. This technology relies on capturing the off-gases from thermal decomposition of wood or grasses to produce heat, electricity, or biofuels. Biochar is a major by-product of this pyrolysis, and has remarkable environmental properties. In soil, biochar was shown to persist longer and to retain cations better than other forms of soil organic matter. The precise half-life of biochar is still disputed, however, and this will have important implications for the value of the technology, particularly in carbon trading. Furthermore, the cation retention of fresh biochar is relatively low compared to aged biochar in soil, and it is not clear under what conditions, and over what period of time, biochar develops its adsorbing properties. Research is still n...

Novel climates, no‐analog communities, and ecological surprises

Abstract: No-analog communities (communities that are compositionally unlike any found today) occurred frequently in the past and will develop in the greenhouse world of the future. The well documented no-analog plant communities of late-glacial North America are closely linked to “novel” climates also lacking modern analogs, characterized by high seasonality of temperature. In climate simulations for the Intergovernmental Panel on Climate Change A2 and B1 emission scenarios, novel climates arise by 2100 AD, primarily in tropical and subtropical regions. These future novel climates are warmer than any present climates globally, with spatially variable shifts in precipitation, and increase the risk of species reshuffling into future no-analog communities and other ecological surprises. Most ecological models are at least partially parameterized from modern observations and so may fail to accurately predict ecological responses to these novel climates. There is an urgent need to test the robustness of ecological mode...

A niche for isotopic ecology

Abstract: Fifty years ago, GE Hutchinson defined the ecological niche as a hypervolume in n-dimensional space with environmental variables as axes. Ecologists have recently developed renewed interest in the concept, and technological advances now allow us to use stable isotope analyses to quantify these niche dimensions. Analogously, we define the isotopic niche as an area (in δ-space) with isotopic values (δ-values) as coordinates. To make isotopic measurements comparable to other niche formulations, we propose transforming δ-space to p-space, where axes represent relative proportions of isotopically distinct resources incorporated into an animal's tissues. We illustrate the isotopic niche with two examples: the application of historic ecology to conservation biology and ontogenetic niche shifts. Sustaining renewed interest in the niche requires novel methods to measure the variables that define it. Stable isotope analyses are a natural, perhaps crucial, tool in contemporary studies of the ecological niche.

A new generation of climate-change experiments: events, not trends

Abstract: Intensification of weather extremes is currently emerging as one of the most important facets of climate change. Research on extreme events (“event-focused” in contrast to “trend-focused”) has increased in recent years and, in 2004, accounted for one-fifth of the experimental climate-change studies published. Numerous examples, ranging from microbiology and soil science to biogeography, demonstrate how extreme weather events can accelerate shifts in species composition and distribution, thereby facilitating changes in ecosystem functioning. However, assessing the importance of extreme events for ecological processes poses a major challenge because of the very nature of such events: their effects are out of proportion to their short duration. We propose that extreme events can be characterized by statistical extremity, timing, and abruptness relative to the life cycles of the organisms affected. To test system response to changing magnitude and frequency of weather events, controlled experiments are useful tools. These experiments provide essential insights for science and for societies that must develop coping strategies for such events. Here, we discuss future research needs for climate-change experiments in ecology. For illustration, we describe an experimental plan showing how to meet the challenge posed by changes in the frequency or magnitude of extreme events.

Have we overemphasized the role of denitrification in aquatic ecosystems? A review of nitrate removal pathways

Abstract: The removal of nitrogen (N) in aquatic ecosystems is of great interest because excessive nitrate in groundwater and surface water is a growing problem. High nitrate loading degrades water quality and is linked to eutrophication and harmful algal blooms, especially in coastal marine waters. Past research on nitrate removal processes has emphasized plant or microbial uptake (assimilation) or respiratory denitrification by bacteria. The increasing application of stable isotopes and other tracer techniques to the study of nitrate removal has yielded a growing body of evidence for alternative, microbially mediated processes of nitrate transformation. These include dissimilatory (the reduction of nitrogen into other inorganic compounds, coupled to energy producing processes) reduction of nitrate to ammonium (DNRA), chemoautotrophic denitrification via sulfur or iron oxidation, and anaerobic ammonium oxidation (anammox), as well as abiotic nitrate removal processes. Here, we review evidence for the importance of...

Protected area needs in a changing climate

Abstract: Range shifts due to climate change may cause species to move out of protected areas. Climate change could therefore result in species range dynamics that reduce the relevance of current fixed protected areas in future conservation strategies. Here, we apply species distribution modeling and conservation planning tools in three regions (Mexico, the Cape Floristic Region of South Africa, and Western Europe) to examine the need for additional protected areas in light of anticipated species range shifts caused by climate change. We set species representation targets and assessed the area required to meet those targets in the present and in the future, under a moderate climate change scenario. Our findings indicate that protected areas can be an important conservation strategy in such a scenario, and that early action may be both more effective and less costly than inaction or delayed action. According to our projections, costs may vary among regions and none of the three areas studied will fully meet all conservation targets, even under a moderate climate change scenario. This suggests that limiting climate change is an essential complement to adding protected areas for conservation of biodiversity.

Amazonia revealed: forest degradation and loss of ecosystem goods and services in the Amazon Basin

Abstract: The Amazon Basin is one of the world's most important bioregions, harboring a rich array of plant and animal species and offering a wealth of goods and services to society. For years, ecological science has shown how large-scale forest clearings cause declines in biodiversity and the availability of forest products. Yet some important changes in the rainforests, and in the ecosystem services they provide, have been underappreciated until recently. Emerging research indicates that land use in the Amazon goes far beyond clearing large areas of forest; selective logging and other canopy damage is much more pervasive than once believed. Deforestation causes collateral damage to the surrounding forests – through enhanced drying of the forest floor, increased frequency of fires, and lowered productivity. The loss of healthy forests can degrade key ecosystem services, such as carbon storage in biomass and soils, the regulation of water balance and river flow, the modulation of regional climate patterns, and the ...

Ecological Impacts of Wind Energy Development on Bats: Questions, Research Needs, and Hypotheses

Abstract: At a time of growing concern over the rising costs and long-term environmental impacts of the use of fossil fuels and nuclear energy, wind energy has become an increasingly important sector of the electrical power industry, largely because it has been promoted as being emission-free and is supported by government subsidies and tax credits. However, large numbers of bats are killed at utility-scale wind energy facilities, especially along forested ridgetops in the eastern United States. These fatalities raise important concerns about cumulative impacts of proposed wind energy development on bat populations. This paper summarizes evidence of bat fatalities at wind energy facilities in the US, makes projections of cumulative fatalities of bats in the Mid-Atlantic Highlands, identifies research needs, and proposes hypotheses to better inform researchers, developers, decision makers, and other stakeholders, and to help minimize adverse effects of wind energy development.

Invasive Alien Species in an Era of Globalization

Abstract: Globalization facilitates the spread of invasive alien species (IAS) as international commerce develops new trade routes, markets, and products. New technologies increase the pace at which humans and commodities can move around the world. Recent research on IAS at the global scale has examined commerce and travel in order to inform predictions, risk analyses, and policy. Due to limited data, regional-scale studies have primarily focused on invasion patterns rather than impacts. Local-scale experimental research can identify mechanisms and impacts of biological invasions, but the results may not be applicable at larger spatial scales. However, the number of information networks devoted to IAS is increasing globally and may help integrate IAS research at all scales, particularly if data sharing and compatibility can be improved. Integrating ecological and economic factors with trade analysis to explore the effectiveness of different approaches for preventing invasions is a promising approach at the global s...

Spatial heterogeneity in urban ecosystems: reconceptualizing land cover and a framework for classification

Abstract: Urban areas are heterogeneous. Transitions in architecture and building density, vegetation, economic activity, and culture can occur at the scale of city blocks. Ecologists have been criticized for treating the city as homogeneous and urbanization as one-dimensional. To develop ecological understanding of integrated human–natural systems, the fine-scale heterogeneity of their built and natural components must be quantified. There have been calls for the integration of the biophysical and human components of systems, but here we provide a new tool to quantify this integrated heterogeneity by reconceptualizing urban land-use and land-cover classification approaches. This new tool, High Ecological Resolution Classification for Urban Landscapes and Environmental Systems (HERCULES), balances detail and efficiency and is flexible, allowing it to be used for interdisciplinary research, with ancillary datasets, and across urban systems.

Filling key gaps in population and community ecology

Abstract: We propose research to fill key gaps in the areas of population and community ecology, based on a National Science Foundation workshop identifying funding priorities for the next 5-10 years. Our vision for the near future of ecology focuses on three core areas: predicting the strength and context-dependence of species interactions across multiple scales; identifying the importance of feedbacks from individual interactions to ecosystem dynam- ics; and linking pattern with process to understand species coexistence. We outline a combination of theory devel- opment and explicit, realistic tests of hypotheses needed to advance population and community ecology.

Who needs environmental monitoring

Abstract: Environmental monitoring is often criticized as being unscientific, too expensive, and wasteful. While some monitoring studies do suffer from these problems, there are also many highly successful long-term monitoring programs that have provided important scientific advances and crucial information for environmental policy. Here, we discuss the characteristics of effective monitoring programs, and contend that monitoring should be considered a fundamental component of environmental science and policy. We urge scientists who develop monitoring programs to plan in advance to ensure high data quality, accessibility, and cost-effectiveness, and we urge government agencies and other funding institutions to make greater commitments to increasing the amount and long-term stability of funding for environmental monitoring programs.

Driving the human ecological footprint

Abstract: This comparative analysis shows that population size and affluence are the principal drivers of anthropogenic environmental stressors, while other widely postulated drivers (eg urbanization, economic structure, age distribution) have little effect. Similarly, increased education and life expectancy do not increase environmental stressors, suggesting that some aspects of human well-being can be improved with minimal environmental impact. Projecting to 2015, we suggest that increases in population and affluence will likely expand human impact on the environment by over one-third. Countering these driving forces would require increases in the efficiency of resource use of about 2% per year.

Confronting the challenges of implementing marine ecosystem-based management

Abstract: Many services provided by coastal and marine ecosystems are in decline. Awareness of these declines and the need to improve existing management has led to a shift toward ecosystem-based approaches to marine management and conservation, both in the US and elsewhere. Marine ecosystem-based management (EBM) involves recognizing and addressing interactions among different spatial and temporal scales, within and among ecological and social systems, and among stakeholder groups and communities interested in the health and stewardship of coastal and marine areas. We discuss some overarching principles of marine EBM and highlight key challenges facing implementation. We then recommend ways in which natural and social scientists can advance implementation of ecosystem-based approaches in the oceans by addressing key research needs, building interdisciplinary scientific capacity, and synthesizing and communicating scientific knowledge to policy makers, managers, and other stakeholders.

Unexpected impacts of climate change on alpine vegetation

Abstract: The vegetation in a high alpine site of the European Alps experienced changes in area between 1953 and 2003 as a result of climate change. Shrubs showed rapid expansion rates of 5.6% per decade at altitudes between 2400 m and 2500 m. Above 2500 m, vegetation coverage exhibited unexpected patterns of regression associated with increased precipitation and permafrost degradation. As these changes follow a sharp increase in both summer and annual temperatures after 1980, we suggest that vegetation of the alpine (2400–2800 m) and nival (above 2800 m) belts respond in a fast and flexible way, contradicting previous hypotheses that alpine and nival species appear to have a natural inertia and are able to tolerate an increase of 1–2°C in mean air temperature.

From controversy to consensus: making the case for recent climate change in the Arctic using lake sediments

Abstract: We live in a constantly changing environment, yet tracking ecological change is often very difficult. Long-term monitoring data are frequently lacking and are especially sparse from Arctic ecosystems, where logistical difficulties limit most monitoring programs. Fortunately, lake and pond sediments contain important archives of past limnological communities that can be used to reconstruct environmental change. Here, we summarize some of the paleolimnological studies that have documented recent climate warming in Arctic lakes and ponds. Several hypotheses have been evaluated to determine if warming, resulting in changes in ice cover and related variables (eg increased habitat availability), was the factor most strongly influencing recent diatom and other biotic changes. Striking and often unprecedented community changes were evident in post-1850 sediments, and could be linked to ecological shifts consistent with warming. Because future temperature increases are predicted to be greatly amplified in polar re...

Trans-equatorial migration and mixing in the wintering areas of a pelagic seabird

Abstract: Despite increasing interest in long-distance migration, the wintering areas, migration corridors, and population mix in winter quarters of most pelagic marine predators are unknown. Here, we present the first study tracking migration movements of shearwaters through the non-breeding period. We used geolocators (global location sensing [GLS] units based on ambient light levels) to track 22 Cory's shearwaters (Calonectris diomedea) breeding in three different areas. Most birds wintered in one or more of three relatively small areas, all clearly associated with major coastal upwelling systems of the tropical and south Atlantic. Trans-equatorial movements were dominated by prevailing trade winds and westerlies, while calm, oligotrophic areas were avoided. Breeding populations clearly differed in their preference amongst the three major wintering areas, but showed substantial mixing. This illustrates the exceptional value of GLS, not only for determining and describing the influence of oceanographic features o...

Incorporating positive interactions in aquatic restoration and conservation

Abstract: The role of positive interactions in structuring biological communities is recognized throughout the field of ecology, but has yet to be well integrated into the restoration and conservation of aquatic systems. Here, we use examples of success in terrestrial restoration to (1) describe how a broader perspective on the scale and nature of positive interactions is necessary if we are to take full advantage of their conservation potential and (2) explain why and when positive interactions should be considered in restoration and conservation of marine, estuarine, and freshwater habitats. Such goals can be accomplished without considering positive interactions, and situations certainly exist in which positive interactions should play a minor role in restoration plans. However, a more explicit recognition of these interactions will make restoration and conservation more successful. In some cases, restoration activities may fail if these interactions are not included.

Adaptive capacity and learning to learn as leverage for social–ecological resilience

Abstract: Adaptive capacity is increasingly recognized as essential for maintaining the resilience of social–ecological systems and for coping with environmental change Four main requirements enable societies to successfully adapt to change: (1) the will and intention to maintain social–ecological resilience, (2) knowledge about current problems and the desired direction of change, (3) proactive behavior, and (4) the capacity to change existing patterns of behavior The adaptive capacity of societies can be greatly enhanced by fostering the adaptive capacity of their individual members Considerable knowledge about how to foster the adaptability of individuals exists in the science of education and in cognitive and social psychology Developing the ability to learn flexibly in a variety of ways, contexts, and circumstances is an important element of developing adaptive capacity The widespread implementation of modern teaching approaches in the education sector could make a substantial contribution to building and

The future of production systems in a globalized world

Abstract: Human life is ultimately dependent on ecosystem services supplied by the biosphere. These include food, disease regulation, and recreational opportunities. Over the past 50 years, humans have changed ecosystems more rapidly and extensively than at any other time in human history, primarily to meet our growing demands for provisioning ecosystem services (eg food, freshwater, and timber). These changes have impacted other ecosystem services (eg climate regulation and erosion control). Current demand for ecosystem services is growing rapidly. How these demands are met will play a major role in determining the ecological, economic, and cultural future of the planet. While much is known about improving management of production systems to be more sustainable, research gaps remain. Challenges for ecologists include understanding the connection between management regimes, ecosystem structures and provision of multiple types of ecosystem services, understanding interactions among ecosystem services, and exploring ...

Forest fire and climate change in western North America: insights from sediment charcoal records

Abstract: Millennial-scale records of forest fire provide important baseline information for ecosystem management, especially in regions with too few recent fires to describe the historical range of variability. Charcoal records from lake sediments and soil profiles are well suited for reconstructing the incidence of past fire and its relationship to changing climate and vegetation. We highlight several records from western North America and their relevance in reconstructing historical forest dynamics, fire-climate relationships, and feedbacks between vegetation and fire under climate change. Climatic effects on fire regimes are evident in many regions, but comparisons of paleo-fire records sometimes show a lack of synchrony, indicating that local factors substantially affect fire occurrence, even over long periods. Furthermore, the specific impacts of vegetation change on fire regimes differ among regions with different vegetation histories. By documenting the effects on fire patterns of major changes in climate and vegetation, paleo-fire records can be used to test the mechanistic models required for the prediction of future variations in fire.

Freshwater biomonitoring with macroinvertebrates in East Asia

Abstract: This paper summarizes the history and current status of efforts to implement macroinvertebrate biomonitoring protocols for surface water pollution in China, Japan, South Korea, Malaysia, Mongolia, Russia (Far East), and Thailand. Impediments to biomonitoring in some of these countries include: (1) lack of knowledge about macroinvertebrate fauna and their tolerance values, especially during the aquatic, immature stages; (2) the scarcity of research programs and formal training opportunities for biomonitoring offered in universities; (3) the shortage of high-quality microscopes and other necessary equipment; and (4) limited government understanding and support for biomonitoring, few skilled regulatory staff, and the persistence of old and unusable biomonitoring protocols. A recently established regional network, the Aquatic Entomological Society of East Asia (AESEA), and several major recent publications are helping to coordinate and promote science and technology in East Asia.

Be careful what you wish for: the legacy of Smokey Bear

Abstract: A century of wildfire suppression in the United States has led to increased fuel loading and large-scale ecological change across some of the nation's forests. Land management agencies have responded by increasing the use of prescribed fire and thinning. However, given the continued emphasis on fire suppression, current levels of funding for such fuel management practices are unlikely to maintain the status quo, let alone reverse the effects of fire exclusion. We suggest an alternative approach to wildfire management, one that places less emphasis on suppression and instead encourages managers to balance short-term wildfire damages against the long-term consequences of fire exclusion. However, any major change in wildfire management, such as the one proposed here, will shift the costs and benefits of wildfire management, inevitably raising opposition.

Infectious diseases in wildlife: the community ecology context

Abstract: Species diversity can have important effects on disease dynamics. While these effects are often considered with respect to alternate hosts and predators, the influence of diversity may also be seen at the level of the parasite or pathogen. Pathogenic microbes face an array of abiotic and biotic challenges, both within their host and, often, in the external environment. Here, we examine the role of microbial ecology in maintaining health and in contributing to disease. As suggested by some medical scientists and others, we argue that placing pathogens in an ecological context can contribute to our understanding of emerging infectious diseases in natural systems. In addition, we suggest that this view could provide important insights for the conservation of species, including many amphibians, that are threatened by disease outbreaks.

Amazonian exploitation revisited: ecological asymmetry and the policy pendulum

Abstract: The influence of pre-Columbian human populations on Amazonian ecosystems is being actively debated. The longstanding view that Amazonia was only minimally impacted by human actions has been challenged, and a new paradigm of Amazonia as a “manufactured landscape” is emerging. If such disturbance was the norm until just 500 years ago, Amazonian ecosystems could be far more ecologically resilient to disturbance than previously supposed. Alternatively, if the “manufactured landscape” label is an overstatement, then policy that assumes such resilience may cause substantial and long-lasting ecological damage. We present paleoecological data suggesting a middle path, in which some areas were heavily modified, but most of Amazonia was minimally impacted. Bluffs adjacent to main river channels and highly seasonal areas appear to have been the most extensively settled locations. Away from areas where humans lived, their influence on ecosystems was very local. Consequently, we see no evidence suggesting that large a...

Managing natural wildfires in Sierra Nevada wilderness areas

Abstract: Past policies of excluding all wildfires from forests throughout the US are giving way to new strategies that incorporate naturally ignited fires into forest and fire management. In this paper, we evaluate the effects of long-standing natural fire programs (now referred to as wildland fire use or WFU) in two Sierra Nevada wilderness areas. We present reconstructions of historical fire occurrence using tree ring proxies, along with chronologies of tree recruitment, to infer the effects of WFU programs on forest structure. Historically, fires burned every 6 to 9 years, which moderated tree recruitment. Fire suppression policies established in the early 1900s successfully excluded fire and allowed for unprecedented tree recruitment. Despite the substantial changes in forest structure and composition, the frequency and extent of fires during the current WFU period (1972–present) approach historical levels. This information can provide some necessary insight in implementing WFU policy and developing management...

Conservation easements in context: a quantitative analysis of their use by The Nature Conservancy

Abstract: Conservation easements have become the principal tool used by land trusts to preserve habitat and open space. However, anecdotal evidence has led some to question whether easements actually deliver conservation value. Our analysis of data from 119 easements held by The Nature Conservancy (TNC), spanning eight states and 20 years (1984–2004), is the first study to examine temporal patterns in the stated goals of, and activities allowed under, conservation easements. We found that these easements operate in accordance with conservation principles: 96% of sampled easements have identified biological targets, 84% are within TNC priority sites, and 79% are adjacent to protected areas. Easement usage has also become more strategic; recently established easements are more likely than older easements to be large and to include a management plan that focuses on biological targets. The one shortcoming we uncovered is a lack of biological monitoring. Although 92% of sampled easements have been monitored for legal co...

Compensatory mitigation as a solution to fisheries bycatch–biodiversity conservation conflicts

Abstract: Globally, fisheries catch of non-target species has major environmental impacts, resulting in social conflict, litigation, and fisheries closures. We use a bio-economic approach to demonstrate that compensatory mitigation – an innovative, market-influenced approach to fishery–conservation conflicts – can facilitate high-value uses of biological resources and cost-effective conservation gains for species of concern. We illustrate the strategy with a seabird example: levying fishers for their bycatch and using the funds to remove invasive mammals from breeding islands. Removal of invasive predators is 23 times more effective from a return-on-investment perspective (ie percent increase in population growth per dollar invested) in comparison to fisheries closures, and is more socio-politically feasible. A bycatch levy, which would increase with endangerment, provides an individual incentive for avoiding bycatch, the most effective mechanism for sustainable management of fisheries. Compensatory mitigation provides an opportunity to address a global concern, optimize conservation interventions, and forge an alliance between conservation and fisheries organizations.

Managing coastal resources in the 21st century

Abstract: Coastal ecosystems are increasingly dominated by humans. Consequently, the human dimensions of sustainability science have become an integral part of emerging coastal governance and management practices. But if we are to avoid the harsh lessons of land management, coastal decision makers must recognize that humans are one of the more coastally dependent species in the biosphere. Management responses must therefore confront both the temporal urgency and the very real compromises and sacrifices that will be necessary to achieve a sustainable coastal ecosystem, one that is economically feasible, socially just, and ecologically sound.

Linking ecosystem services and water resources: landscape‐scale hydrology of the Little Karoo

Abstract: There is growing acknowledgement of the dependence of human society on ecosystem services and of the fact that service delivery is being compromised by human impacts on ecosystems. This paper describes the linkage between landscape-scale hydrology and ecosystem services, and how degradation of the landscape is believed to have altered the delivery of those services. The Little Karoo, an arid environment in South Africa that encompasses a remarkable diversity of plant species, has been degraded by inappropriate agricultural practices, mainly overgrazing, cultivation, and irrigation. Landscape linkages, such as hydrological flows and the recycling of organic matter and nutrients, have been disrupted, resulting in net losses at all scales, from the shrub patch to the river basin. Land rehabilitation, while in most cases too expensive at the farm scale, may be economically feasible at the river basin scale, provided that some of the economic benefits are used to rehabilitate and manage areas as socioecological systems.