Soil carbon (C) is a dynamic and integral part of the global C cycle. It has been a source of atmospheric carbon dioxide (CO2) since the dawn of settled agriculture, depleting more than 320 billion ...metric tons (Pg) from the terrestrial pool, 78±12 Pg of which comes from soil. In comparison, approximately 292 Pg C have been emitted through fossil-fuel combustion since about 1750. However, terrestrial pools can act as a sink for as much as 50 parts per million of atmospheric CO2 for 100 to 150 years. The technical sink capacity of US soils is 0.288 Pg C per year; Earth's terrestrial biosphere can act as a sink for up to 3.8 Pg C per year. The economic potential of C storage depends on its costs and cobenefits, such as global food security, water quality, and soil biodiversity. Therefore, optimally managing the soil C pool must be the bash of any strategy to improve and sustain agronomic production, especially in developing countries.
Pest risk maps are powerful visual communication tools to describe where invasive alien species might arrive, establish, spread, or cause harmful impacts. These maps inform strategic and tactical ...pest management decisions, such as potential restrictions on international trade or the design of pest surveys and domestic quarantines. Diverse methods are available to create pest risk maps, and can potentially yield different depictions of risk for the same species. Inherent uncertainties about the biology of the invader, future climate conditions, and species interactions further complicate map interpretation. If multiple maps are available, risk managers must choose how to incorporate the various representations of risk into their decisionmaking process, and may make significant errors if they misunderstand what each map portrays. This article describes the need for pest risk maps, compares pest risk mapping methods, and recommends future research to improve such important decision-support tools.
Marine ecosystems provide essential services to humans, yet these services have been diminished, and their future sustainability endangered, by human patterns of exploitation that threaten system ...robustness and resilience. Marine ecosystems are complex adaptive systems composed of individual agents that interact with one another to produce collective effects, integrating scales from individual behaviors to the dynamics of whole systems. In such systems, small changes can be magnified through nonlinear interactions, facilitating regime shifts and collapses. Protection of the services these ecosystems provide must therefore maintain the adaptive capacities of these systems by preserving a balance among heterogeneity, modularity, and redundancy, tightening feedback loops to provide incentives for sound stewardship. The challenge for management is to increase incentives to individuals, and tighten reward loops, in ways that will strengthen the robustness and resilience of these systems and preserve their ability to provide ecosystem services for generations to come.
Until recently, continuous monitoring of global vegetation productivity has not been possible because of technological limitations. This article introduces a new satellite-driven monitor of the ...global biosphere that regularly computes daily gross primary production (GPP) and annual net primary production (NPP) at 1-kilometer (km) resolution over 109,782,756 km2 of vegetated land surface. We summarize the history of global NPP science, as well as the derivation of this calculation, and current data production activity. The first data on NPP from the EOS (Earth Observing System) MODIS (Moderate Resolution Imaging Spectroradiometer) sensor are presented with different types of validation. We offer examples of how this new type of data set can serve ecological science, land management, and environmental policy. To enhance the use of these data by nonspecialists, we are now producing monthly anomaly maps for GPP and annual NPP that compare the current value with an 18-year average value for each pixel, clearly identifying regions where vegetation growth is higher or lower than normal.
Concern is resurfacing in the United States over the long-term effects of excess nitrogen (N) deposition and mobility in the environment. We present here a new synthesis of existing data sets for the ...northeastern United States, intended to answer a single question: Is N deposition altering the N status of forest ecosystems in this region? Surface water data suggest a significant increase in nitrate losses with N deposition. Soil data show an increase in nitrification with decreasing ratio of soil carbon to nitrogen (C:N) but weaker relationships between N deposition and soil C:N ratio or nitrification. Relationships between foliar chemistry and N deposition are no stronger than with gradients of climate and elevation. The differences in patterns for these three groups of indicators are explained by the degree of spatial and temporal integration represented by each sample type. The surface water data integrate more effectively over space than the foliar or soil data and therefore allow a more comprehensive view of N saturation. We conclude from these data that N deposition is altering N status in northeastern forests.
Marine predators attract significant attention in ocean conservation planning and are therefore often used politically to promote reserve designation. We discuss whether their ecology and life ...history can help provide a rigorous ecological foundation for marine reserve design. In general, we find that reserves can benefit marine megafauna, and that megafauna can help establish target areas and boundaries for ecosystem reserves. However, the spatial nature of the interplay between potential threats and predator life histories requires careful consideration for the establishment of effective reserves. Modeling tools such as demographic sensitivity analysis will aid in establishing protection for different life stages and distributional ranges. The need for pelagic marine reserves is becoming increasingly apparent, and it is in this venue that marine predators may be most effectively used as indicator species of underlying prey distribution and ecosystem processes.
Wildlife species have been recognized as sentinels of environmental health for decades. In fact, ecological data on various wildlife populations provided the impetus for banning some organochlorine ...pesticides over the last few decades. Alligators are important sentinels of ecosystem health in the wetlands of the southeastern United States. Over the last 15 years, a series of studies have demonstrated that environmental exposure to a complex mixture of contaminants from agricultural and municipal activities alters the development and functioning of alligators' reproductive and endocrine systems. Further studies of basic developmental and reproductive endocrinology in alligators and exposure studies performed under controlled laboratory conditions support the role of contaminants as causal agents of abnormalities in gonadal steroidogenesis and in reproductive tract development. These studies offer potential insight into environmentally induced defects reported in other wildlife and human populations exposed to a wide array of endocrine-disruptive contaminants.
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