Showing papers in "Frontiers in Ecology and the Environment in 2009"

Modeling multiple ecosystem services, biodiversity conservation, commodity production, and tradeoffs at landscape scales

Abstract: Nature provides a wide range of benefits to people. There is increasing consensus about the importance of incorporating these “ecosystem services” into resource management decisions, but quantifying the levels and values of these services has proven difficult. We use a spatially explicit modeling tool, Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST), to predict changes in ecosystem services, biodiversity conservation, and commodity production levels. We apply InVEST to stakeholder-defined scenarios of land-use/land-cover change in the Willamette Basin, Oregon. We found that scenarios that received high scores for a variety of ecosystem services also had high scores for biodiversity, suggesting there is little tradeoff between biodiversity conservation and ecosystem services. Scenarios involving more development had higher commodity production values, but lower levels of biodiversity conservation and ecosystem services. However, including payments for carbon sequestration alleviates this tradeoff. Quantifying ecosystem services in a spatially explicit manner, and analyzing tradeoffs between them, can help to make natural resource decisions more effective, efficient, and defensible.

Ecosystem services in decision making: time to deliver

Abstract: Over the past decade, efforts to value and protect ecosystem services have been promoted by many as the last, best hope for making conservation mainstream – attractive and commonplace worldwide. In theory, if we can help individuals and institutions to recognize the value of nature, then this should greatly increase investments in conservation, while at the same time fostering human well-being. In practice, however, we have not yet developed the scientific basis, nor the policy and finance mechanisms, for incorporating natural capital into resource- and land-use decisions on a large scale. Here, we propose a conceptual framework and sketch out a strategic plan for delivering on the promise of ecosystem services, drawing on emerging examples from Hawai‘i. We describe key advances in the science and practice of accounting for natural capital in the decisions of individuals, communities, corporations, and governments.

Adaptive co-management for social–ecological complexity

Abstract: Building trust through collaboration, institutional development, and social learning enhances efforts to foster ecosystem management and resolve multi-scale society–environment dilemmas One emerging approach aimed at addressing these dilemmas is adaptive co-management This method draws explicit attention to the learning (experiential and experimental) and collaboration (vertical and horizontal) functions necessary to improve our understanding of, and ability to respond to, complex social–ecological systems Here, we identify and outline the core features of adaptive co-management, which include innovative institutional arrangements and incentives across spatiotemporal scales and levels, learning through complexity and change, monitoring and assessment of interventions, the role of power, and opportunities to link science with policy

Non‐linearity in ecosystem services: temporal and spatial variability in coastal protection

Abstract: Natural processes tend to vary over time and space, as well as between species. The ecosystem services these natural processes provide are therefore also highly variable. It is often assumed that ecosystem services are provided linearly (unvaryingly, at a steady rate), but natural processes are characterized by thresholds and limiting functions. In this paper, we describe the variability observed in wave attenuation provided by marshes, mangroves, seagrasses, and coral reefs and therefore also in coastal protection. We calculate the economic consequences of assuming coastal protection to be linear. We suggest that, in order to refine ecosystem-based management practices, it is essential that natural variability and cumulative effects be considered in the valuation of ecosystem services.

Forecasting the effects of accelerated sea‐level rise on tidal marsh ecosystem services

Abstract: We used field and laboratory measurements, geographic information systems, and simulation modeling to investigate the potential effects of accelerated sea-level rise on tidal marsh area and delivery of ecosystem ser- vices along the Georgia coast. Model simulations using the Intergovernmental Panel on Climate Change (IPCC) mean and maximum estimates of sea-level rise for the year 2100 suggest that salt marshes will decline in area by 20% and 45%, respectively. The area of tidal freshwater marshes will increase by 2% under the IPCC mean scenario, but will decline by 39% under the maximum scenario. Delivery of ecosystem services associated with productivity (macrophyte biomass) and waste treatment (nitrogen accumulation in soil, potential denitrification) will also decline. Our findings suggest that tidal marshes at the lower and upper salinity ranges, and their attendant delivery of ecosystem services, will be most affected by accelerated sea- level rise, unless geomorphic conditions (ie gradual increase in elevation) enable tidal freshwater marshes to migrate inland, or vertical accretion of salt marshes to increase, to compensate for accelerated sea-level rise.

Tree die-off in response to global change-type drought: mortality insights from a decade of plant water potential measurements.

Abstract: Global climate change is projected to produce warmer, longer, and more frequent droughts, referred to here as “global change-type droughts”, which have the potential to trigger widespread tree die-off. However, drought-induced tree mortality cannot be predicted with confidence, because long-term field observations of plant water stress prior to, and culminating in, mortality are rare, precluding the development and testing of mechanisms. Here, we document plant water stress in two widely distributed, co-occurring species, pinon pine (Pinus edulis) and juniper (Juniperus monosperma), over more than a decade, leading up to regional-scale die-off of pinon pine trees in response to global change-related drought. Pinon leaf water potentials remained substantially below their zero carbon assimilation point for at least 10 months prior to dying, in contrast to those of juniper, which rarely dropped below their zero-assimilation point. These data suggest that pinon mortality was driven by protracted water stress,...

Tracking the rhythm of the seasons in the face of global change: phenological research in the 21st century.

Abstract: Phenology is the study of recurring life-cycle events, classic examples being the flowering of plants and animal migration. Phenological responses are increasingly relevant for addressing applied environmental issues. Yet, challenges remain with respect to spanning scales of observation, integrating observations across taxa, and modeling phenological sequences to enable ecological forecasts in light of future climate change. Recent advances that are helping to address these questions include refined landscape-scale phenology estimates from satellite data, advanced, instrument-based approaches for field measurements, and new cyberinfrastructure for archiving and distribution of products. These breakthroughs are improving our understanding in diverse areas, including modeling land-surface exchange, evaluating climate–phenology relationships, and making land-management decisions.

Why biodiversity is important to the functioning of real‐world ecosystems

Abstract: Controlled experiments have substantially advanced our understanding of the links between changing biodiversity and ecosystem functioning (BEF) in recent years. However, controversy continues regarding the relevance of BEF experiments to the complex ecosystems and large spatial and temporal scales of interest in conservation and management. Here, I address some of the persistent criticisms regarding experimental BEF research and argue that these have been overstated. Contrary to some suggestions, many putative artifacts attributed to experiments render their conclusions about BEF links stronger, rather than weaker. Like other broad ecological concepts, BEF focuses on general patterns, rather than looking at species-level, applied conservation problems. Nevertheless, insights from BEF experiments conducted to date are likely to underestimate, rather than overestimate, the importance of biodiversity to ecosystem functioning and the provision of ecosystem services in the real world. These experiments suggest...

Maximizing arthropod‐mediated ecosystem services in agricultural landscapes: the role of native plants

Abstract: Beneficial arthropods, including native bees, predators, and parasitoids, provide valuable ecosystem services worth $8 billion to US agriculture each year. These arthropod-mediated ecosystem services (AMES) include crop pollination and pest control, which help to maintain agricultural productivity and reduce the need for pesticide inputs. Maximizing survival and reproduction of beneficial arthropods requires provision of pollen and nectar resources that are often scarce in modern agricultural landscapes. Increasingly, native plants are being evaluated for this purpose. Native plants can outperform recommended non-natives and also provide local adaptation, habitat permanency, and support of native biodiversity. We predict that the success of insect conservation programs using flowering plants to increase AMES on farmland will depend on landscape context, with the greatest success in landscapes of moderate complexity. Reintegration of native plants into agricultural landscapes has the potential to support m...

Tropical turmoil: a biodiversity tragedy in progress

Abstract: All is not well for biodiversity in the tropics. Despite recent debate over the extent of future tropical extinctions and the effectiveness of reserve systems, the continued disappearance of habitat, soaring human population, and loss of vital ecosystem services demand immediate action. This crisis is worrying, given that tropical regions support over two-thirds of all known species and are populated by some of the world's poorest people, who have little recourse to lower environmental-impact lifestyles. Recent evidence has shown that – in addition to unabated rates of forest loss – coastal development, overexploitation of wildlife, catchment modification, and habitat conversion are threatening human well-being. We argue that the recent technical debate about likely extinctions masks the real issue – that, to prevent further loss of irreplaceable tropical biodiversity, we must err on the side of caution. We need to avoid inadvertently supporting political agendas that assume low future extinction rates, because this will result in further destruction of tropical biodiversity.

Designing marine protected area networks to address the impacts of climate change

Abstract: Principles for designing marine protected area (MPA) networks that address social, economic, and biological criteria are well established in the scientific literature. Climate change represents a new and serious threat to marine ecosystems, but, to date, few studies have specifically considered how to design MPA networks to be resilient to this emerging threat. Here, we compile the best available information on MPA network design and supplement it with specific recommendations for building resilience into these networks. We provide guidance on size, spacing, shape, risk spreading (representation and replication), critical areas, connectivity, and maintaining ecosystem function to help MPA planners and managers design MPA networks that are more robust in the face of climate-change impacts.

Why forests appear resistant to exotic plant invasions: intentional introductions, stand dynamics, and the role of shade tolerance

Abstract: Invasion ecology has traditionally focused on exotic plant species with early successional life-history traits, adapted to colonize areas following disturbance. However, the ecological importance of these traits may be overstated, in part because most invasive plants originate from intentional introductions. Furthermore, this focus neglects the types of plants most likely to invade established communities, particularly forests – namely shade-tolerant, late-successional species. In invasion ecology, it is generally assumed that undisturbed forests are highly resistant to plant invasions. Our review reveals that this assumption is not justified: in temperate and tropical regions around the world, at least 139 exotic plant species are known to have invaded deeply shaded forest understories that have not undergone substantial disturbance. These exotics present a particular management challenge, as they often increase in abundance during succession. While forest invasions may develop comparatively slowly under natural disturbance regimes, anthropogenic processes, including the spread of exotic pests and pathogens, can be expected to accelerate the rate of invasion.

Ain't no mountain high enough: plant invasions reaching new elevations

Abstract: Most studies of invasive species have been in highly modified, lowland environments, with comparatively little attention directed to less disturbed, high-elevation environments. However, increasing evidence indicates that plant invasions do occur in these environments, which often have high conservation value and provide important ecosystem services. Over a thousand non-native species have become established in natural areas at high elevations worldwide, and although many of these are not invasive, some may pose a considerable threat to native mountain ecosystems. Here, we discuss four main drivers that shape plant invasions into high-elevation habitats: (1) the (pre-)adaptation of non-native species to abiotic conditions, (2) natural and anthropogenic disturbances, (3) biotic resistance of the established communities, and (4) propagule pressure. We propose a comprehensive research agenda for tackling the problem of plant invasions into mountain ecosystems, including documentation of mountain invasion patterns at multiple scales, experimental studies, and an assessment of the impacts of non-native species in these systems. The threat posed to high-elevation biodiversity by invasive plant species is likely to increase because of globalization and climate change. However, the higher mountains harbor ecosystems where invasion by non-native species has scarcely begun, and where science and management have the opportunity to respond in time.

Airborne spectranomics: mapping canopy chemical and taxonomic diversity in tropical forests

Abstract: Tree canopies play an enormous role in the maintenance of tropical forest diversity and ecosystem function, and are therefore central to conservation, management, and resource policy development in tropical regions. However, high-resolution mapping of tropical forest canopies is very difficult, because traditional field, airborne, and satellite measurements cannot resolve the number of canopy species, or particular species of interest, over the large regional scales commensurate with conservation goals and strategies. Newer technologies, such as imaging spectroscopy and light detection and ranging (lidar), are just now reaching performance levels that will allow monitoring of tropical forest diversity from the air, but the methods for applying these technologies are not yet ready. Here, we present concepts that combine chemical and spectral remote sensing perspectives to facilitate canopy diversity mapping. Using examples from our ongoing work in the Hawaiian Islands, we demonstrate how a new “airborne sp...

Assessing benefit transfer for the valuation of ecosystem services

Abstract: The valuation of ecosystem services can play an important role in conservation planning and ecosystem-based management. Unfortunately, gathering primary, site-specific data is costly. As a result, a popular alternate method is to conduct a “benefit transfer” (applying economic value estimates from one location to a similar site in another location). Among the potential pitfalls of such an approach, the correspondence (or lack thereof) between the locations is probably the most important for evaluating the probable validity of the benefit transfer. A common type of benefit transfer in ecosystem service valuation applies an estimate of value per hectare to all areas having the same land-cover or habitat type, and is particularly susceptible to errors resulting from lack of correspondence. Enhancing the use of benefit transfers in this and other ecosystem service applications requires paying closer attention to simple guidelines, developed by economists, for improving validity and accuracy.

Nested and teleconnected vulnerabilities to environmental change

Abstract: The vulnerability of distant peoples and places to global change in environment and society is nested and teleconnected. Here, we argue that such vulnerabilities are linked through environmental change process feedbacks, economic market linkages, and flows of resources, people, and information. We illustrate these linkages through the examples of the global transmission of severe acute respiratory syndrome (SARS) and the interdependent vulnerabilities and adaptations of coffee farmers in Vietnam and Mexico. These cases demonstrate that the vulnerability of specific individuals and communities is not geographically bounded but, rather, is connected at different scales, so that the drivers of their exposure and sensitivity are inseparable from large-scale processes of sociocultural change and market integration. Aggregate outcomes of government policies, trends in global commodity markets, and even decisions by individuals to improve livelihood security can have negative repercussions, not only locally, through transformations of ecological systems and social relations, but also at larger scales.

Associations of concern: Declining seagrasses and threatened dependent species

Abstract: Seagrasses are important marine foundation species that are reported to be declining worldwide, with almost 15% of species considered threatened. Seagrasses are highly productive plants that reconfigure water flow and influence nutrient cycling, as well as provide critical habitat for a wide array of fish and invertebrate species. Yet, many of these seagrass-dependent species, including economically important fishes and invertebrates, are themselves in danger of overexploitation or extinction. In fact, there is on average more than one threatened associated species for every seagrass species across the globe. Links between threatened seagrasses and their dependent communities illustrate the importance of an ecosystem-based management approach that incorporates interdependencies and facilitation among species.

Forest management is driving the eastern North American boreal forest outside its natural range of variability

Abstract: Fire is fundamental to the natural dynamics of the North American boreal forest. It is therefore often suggested that the impacts of anthropogenic disturbances (eg logging) on a managed landscape are attenuated if the patterns and processes created by these events resemble those of natural disturbances (eg fire). To provide forest management guidelines, we investigate the long-term variability in the mean fire interval (MFI) of a boreal landscape in eastern North America, as reconstructed from lacustrine (lake-associated) sedimentary charcoal. We translate the natural variability in MFI into a range of landscape age structures, using a simple modeling approach. Although using the array of possible forest age structures provides managers with some flexibility, an assessment of the current state of the landscape suggests that logging has already caused a shift in the age-class distribution toward a stronger representation of young stands with a concurrent decrease in old-growth stands. Logging is indeed quickly forcing the studied landscape outside of its long-term natural range of variability, implying that substantial changes in management practices are required, if we collectively decide to maintain these fundamental attributes of the boreal forest.

Managing for ocean biodiversity to sustain marine ecosystem services

Abstract: Managing a complex ecosystem to balance delivery of all of its services is at the heart of ecosystem-based management. But how can this balance be accomplished amidst the conflicting demands of stakeholders, managers, and policy makers? In marine ecosystems, several common ecological mechanisms link biodiversity to ecosystem functioning and to a complex of essential services. As a result, the effects of preserving diversity can be broadly beneficial to a wide spectrum of important ecosystem processes and services, including fisheries, water quality, recreation, and shoreline protection. A management system that conserves diversity will help to accrue more “ecoservice capital” for human use and will maintain a hedge against unanticipated ecosystem changes from natural or anthropogenic causes. Although maintenance of biodiversity cannot be the only goal for ecosystem-based management, it could provide a common currency for evaluating the impacts of different human activities on ecosystem functioning and can...

Twenty years of zebra mussels: lessons from the mollusk that made headlines

Abstract: In the 20 years since zebra mussels (Dreissena polymorpha) first appeared in North America, they have become one of our most widespread and abundant freshwater animals, and have fundamentally transformed freshwater food webs and biogeochemistry. Indeed, few human impacts on North American fresh waters have been greater or more far-reaching than the arrival of this single species. Nevertheless, ecological research has been uneven, and important research questions remain unanswered, especially concerning the long-term, large-scale effects of the invasion. Economic impacts have also been incompletely estimated, although they already exceed $100 million. We know little about the extent to which large outreach programs about zebra mussels have changed public knowledge, attitudes, or behaviors, and there are still substantial gaps in policies to curb the establishment, spread, and impacts of species like zebra mussels. Scientific, educational, and policy responses to the zebra mussel invasion highlight our successes and limitations concerning alien species in general.

Native predators and exotic prey –an acquired taste?

Abstract: Only a small proportion of exotic species invasions give rise to hyper-successful nuisance species, but those that do have dramatic negative impacts on ecosystems, such as the displacement of native species and disruption of native food webs. For a native predator, such changes may mean a major transformation in its resource base and a decline in its fitness. However, native predators may adapt to become more effective at feeding on exotic prey, either rapidly, via existing phenotypic plasticity, or more slowly, via natural selection. Despite a rapidly growing number of publications on the importance of species invasions as a driver of contemporary evolution in both invading and native species, we know little about how the arrival of exotic prey affects native predators. We propose that native predators could be important in regulating the long-term dynamics of invading species and, consequently, that the overexploitation of predators could facilitate biological invasions.

A New Biology for the 21st Century

Abstract: An editorial on A New Biology for the 21st Century: A Critical Role for Ecologists for Frontiers Magazine

Polarized light pollution: a new kind of ecological photopollution

Abstract: The alteration of natural cycles of light and dark by artificial light sources has deleterious impacts on animals and ecosystems. Many animals can also exploit a unique characteristic of light – its direction of polarization –as a source of information. We introduce the term “polarized light pollution” (PLP) to focus attention on the ecological consequences of light that has been polarized through interaction with human-made objects. Unnatural polarized light sources can trigger maladaptive behaviors in polarization-sensitive taxa and alter ecological interactions. PLP is an increasingly common byproduct of human technology, and mitigating its effects through selective use of building materials is a realistic solution. Our understanding of how most species use polarization vision is limited, but the capacity of PLP to drastically increase mortality and reproductive failure in animal populations suggests that PLP should become a focus for conservation biologists and resource managers alike.

Potential habitat distribution for the freshwater diatom Didymosphenia geminata in the continental US

Abstract: The diatom Didymosphenia geminata is a single-celled alga found in lakes, streams, and rivers. Nuisance blooms of D geminata affect the diversity, abundance, and productivity of other aquatic organisms. Because D geminata can be transported by humans on waders and other gear, accurate spatial prediction of habitat suitability is urgently needed for early detection and rapid response, as well as for evaluation of monitoring and control programs. We compared four modeling methods to predict D geminata's habitat distribution; two methods use presence–absence data (logistic regression and classification and regression tree [CART]), and two involve presence data (maximum entropy model [Maxent] and genetic algorithm for rule-set production [GARP]). Using these methods, we evaluated spatially explicit, bioclimatic and environmental variables as predictors of diatom distribution. The Maxent model provided the most accurate predictions, followed by logistic regression, CART, and GARP. The most suitable habitats we...

Fuel treatment effects on tree‐based forest carbon storage and emissions under modeled wildfire scenarios

Abstract: Forests are viewed as a potential sink for carbon (C) that might otherwise contribute to climate change. It is unclear, however, how to manage forests with frequent fire regimes to maximize C storage while reducing C emissions from prescribed burns or wildfire. We modeled the effects of eight different fuel treatments on tree-based C storage and release over a century, with and without wildfire. Model runs show that, after a century of growth without wildfire, the control stored the most C. However, when wildfire was included in the model, the control had the largest total C emission and largest reduction in live-tree-based C stocks. In model runs including wildfire, the final amount of tree-based C sequestered was most affected by the stand structure initially produced by the different fuel treatments. In wildfire-prone forests, tree-based C stocks were best protected by fuel treatments that produced a low-density stand structure dominated by large, fire-resistant pines.

Silica: an essential nutrient in wetland biogeochemistry

Abstract: Recent research has emphasized the importance of terrestrial ecosystems in the global biogeochemical cycle of silica (Si). The production, retention, and dissolution of amorphous silica of biological origin in soils and vegetation effectively control terrestrial Si fluxes. However, surprisingly little is known about the role of wetlands in these processes. Wetlands are known hotspots for both nitrogen and phosphorus cycling, and there have been countless studies and numerous reviews on these nutrients worldwide. By bringing together previously scattered results, we show that wetland ecosystems may be as important for Si transport and processing as they are for other important biogeochemical cycles. Yet, the range of studied systems is small and incomplete. This constitutes a serious gap in our understanding of both coastal eutrophication and climate change, issues that are strongly linked to Si biogeochemistry. Ecosystem scientists and wetland biogeochemists around the world need to begin addressing these issues.

Creating multifunctional landscapes: how can the field of ecology inform the design of the landscape?

Abstract: The opportunity exists to improve intensively managed landscapes (urban and agricultural areas dominated by human activities) through greater engagement of ecologists in the process of ecological landscape design. This approach encourages exploration of multifunctional solutions to meet the needs of growing populations in many areas around the world, while minimizing the negative impacts of human activities on the environment. This is achieved by incorporating theoretical and applied principles from the fields of landscape ecology, agroecology, and ecological design. Multifunctional landscapes can be designed to provide a range of environmental, social, and economic functions, while considering the interests of landowners and users. Here, we propose a process for designing multifunctional landscapes, guided by ecological principles in the following steps: (1) defining the project site and landscape context, (2) analyzing landscape structure and function, (3) master planning using an ecosystem approach, (4...

Paleoecology meets genetics: deciphering past vegetational dynamics

Abstract: Genetic analysis adds a novel dimension to paleoecology that is becoming increasingly important for elucidating vegetational dynamics in relation to climate change Because past vegetational changes have often left distinct genetic imprints on current plant populations, genetic analysis can add detail to fossil-based reconstructions Recent surveys of DNA polymorphisms yield new insights into past vegetational changes and address long-standing paleoecological questions These studies reveal that small tree populations survived in mid- to high-latitude refugia throughout the Quaternary glacial episodes They further reveal migration pathways and demographic processes during postglacial range expansion These results challenge previous notions regarding tree species responses to climate change and help to identify genetic conservation targets Here, we review these recent advances and outline research prospects at the interface between paleoecology and genetics

A century of changing land-use and water-quality relationships in the continental US

Abstract: We quantify the relationships between riverine nitrate–nitrogen (NN) concentration and agricultural land use in the continental United States – from the early 1900s through the end of the last century – on spatial scales ranging from the entire Mississippi River Basin to 1000-km2 watersheds. Cropland cover is linearly related to the NN concentration that exits a watershed at both the beginning and end of the 20th century. In addition, the slope of the relationship is higher at the end of the century, and the intercept of the regression analysis is not different from zero. These findings imply that agriculture was already affecting NN export by the early 1900s, that intensive management practices in modern agriculture have significantly increased the NN export per hectare of cropland, and that the baseline of exported NN has not shifted. We identify agricultural practices, principally associated with corn cultivation, that contribute substantially to NN concentrations and suggest that increasing cropland d...

Monitoring and evaluating the ecological integrity of forest ecosystems

Abstract: “Ecological integrity” provides a useful framework for ecologically based monitoring and can provide valuable information for assessing ecosystem condition and management effectiveness. Building on the related concepts of biological integrity and ecological health, ecological integrity is a measure of the composition, structure, and function of an ecosystem in relation to the system’s natural or historical range of variation, as well as perturbations caused by natural or anthropogenic agents of change. We have developed a protocol to evaluate the ecological integrity of temperate zone, forested ecosystems, based on long-term monitoring data. To do so, we identified metrics of status and trend in structure, composition, and function of forests impacted by multiple agents of change. We used data, models, and the scientific literature to interpret and report integrity using “stoplight” symbology, ie “Good” (green), “Caution” (yellow), or “Significant Concern” (red). Preliminary data indicate that forested ecosystems in Acadia National Park have retained ecological integrity across a variety of metrics, but that some aspects of soil chemistry and stand structure indicate potential problems. This protocol was developed for the National Park Service Vital Signs Monitoring Program and holds promise for application in the temperate zone, forested ecosystems of eastern North America.