CERES — A model of forest stand biomass dynamics for predicting trace contaminant,nutrient, and water effects. I. Model description

CERES is a forest stand growth model which incorporates sugar transport in order to predict both short-term effects and long-term accumulation of trace contaminants and/or nutrients when coupled with the soil chemistry model (SCHEM), and models of solute uptake (DIFMAS and DRYADS) of the Unified Transport Model, UTM. An important feature of CERES is its ability to interface with the soil-plant-atmosphere water model (PROSPER) as a means of both predicting and studying the effects of plant water status on growth and solute transport.CERES considers the biomass dynamics of plants, standing dead and litter with plants divided into leaves, stems, roots, and fruits. The plant parts are divided further into sugar substrate, storage, and in the case of stems and roots, heartwood components.Each ecosystem component is described by a mass balance equation written as a first-order ordinary differential equation.     

Modelling solute uptake and incorporation into vegetation and litter

The concepts and algorithms of the Baldwin, Nye and Tinker model describing solute movement from bulk soil solution to roots (DIFMAS) and a model of solute dynamics and accumulation in plant tissues and litter (DRYADS) are presented. Foliar uptake of solutes and gases are included in the DRYADS code. These models form components in a coupled system of models having hourly resolution of carbon, water, and solute dynamics in terrestrial ecosystems. Applications showing successive hourly, monthly, and annual results illustrate the utility of the models. The DRYADS model sensitivity to both leaf solute conductivity and root solute conductivity parameters suggest the importance of careful experimental determination of these plant properties. The tissues of solute entry (leaves, roots) initially accumulate solutes in a fixed form in preference to the more remote tissues (stems, fruits). Model application results show that root sapwood is the first major site of trace contaminant accumulation from soil-borne pollutants. The algorithms describing solute movement along a concentration gradient in phloem and as mass flow in the xylem transpiration stream result in high mobility of solutes in vegetation. The simulated diurnal pattern of root solute uptake showed that more than 85% of solutes were taken up during the daylight hours. The simulations further showed that contaminants had the greatest effect on the litter system. Toxic effects of contaminants on decomposition resulted in lower mineralization losses and accumulation of contaminant in litter with continuing deposition.     

Shifting cultivation, forest fallow, and externalities in ecosystem services: Evidence from the Eastern Amazon

This study examines the value of fallow ecosystem services in shifting cultivation, including hydrological externalities that may affect other farms. Using farm-level survey data from the Brazilian Amazon, I estimate a production function to assess the value of forest fallow and test whether it provides local externalities to agricultural production. Soil quality controls, instrumental variables, and spatial econometric approaches help address endogeneity issues. I use GIS data on external forest cover at the farm level and model the hydrological externality as an upstream-to-downstream process. The estimated parameters indicate that fallow contributes significantly to productivity both on farm and downstream. In addition, most farms allocate sufficient land to fallow, accounting for both the value of hydrological spillovers and the opportunity cost of land left out of cultivation. These results suggest that farming communities may have some self-interest in preserving forest cover locally—a finding that may bolster policy efforts aimed at conserving tropical forests for their global public goods.     

Translating effects of inbreeding depression on component vital rates to overall population growth in endangered bighorn sheep

Evidence of inbreeding depression is commonly detected from the fitness traits of animals, yet its effects on population growth rates of endangered species are rarely assessed. We examined whether inbreeding depression was affecting Sierra Nevada bighorn sheep (Ovis canadensis sierrae), a subspecies listed as endangered under the U.S. Endangered Species Act. Our objectives were to characterize genetic variation in this subspecies; test whether inbreeding depression affects bighorn sheep vital rates (adult survival and female fecundity); evaluate whether inbreeding depression may limit subspecies recovery; and examine the potential for genetic management to increase population growth rates. Genetic variation in 4 populations of Sierra Nevada bighorn sheep was among the lowest reported for any wild bighorn sheep population, and our results suggest that inbreeding depression has reduced adult female fecundity. Despite this population sizes and growth rates predicted from matrix-based projection models demonstrated that inbreeding depression would not substantially inhibit the recovery of Sierra Nevada bighorn sheep populations in the next approximately 8 bighorn sheep generations (48 years). Furthermore, simulations of genetic rescue within the subspecies did not suggest that such activities would appreciably increase population sizes or growth rates during the period we modeled (10 bighorn sheep generations, 60 years). Only simulations that augmented the Mono Basin population with genetic variation from other subspecies, which is not currently a management option, predicted significant increases in population size. Although we recommend that recovery activities should minimize future losses of genetic variation, genetic effects within these endangered populations-either negative (inbreeding depression) or positive (within subspecies genetic rescue)-appear unlikely to dramatically compromise or stimulate short-term conservation efforts. The distinction between detecting the effects of inbreeding depression on a component vital rate (e.g., fecundity) and the effects of inbreeding depression on population growth underscores the importance of quantifying inbreeding costs relative to population dynamics to effectively manage endangered populations.     

Should I stay or should I go? An experimental study of health and economic government policies following a severe biological agent release

Extensive research has explored policy challenges associated with preparing and responding to a large-scale biological release. A key component in recovery strategy development that has received less attention is the understanding of government policy influence on the impacted populations’ migratory decisions. This study experimentally manipulates health and economic government policies during response and recovery to assess the extent to which public migration is contingent on the level of government intervention. Set immediately following a large-scale anthrax release in San Francisco, we use a five episode video scenario to describe details about the environmental impacts of the disaster, emergency response procedures, and clean-up operations. Within these video segments, the extent of government involvement in economic and health risk policies is manipulated. Using these manipulations as predictors, we track how varying levels of government risk signals influence migration behavior at three distinct decision points during disaster recovery. In addition, two belief scales and two scales of emotion (affect) are included as predictors to explore the potential for their mediating role in explaining intentions to migrate. We find that the decision to migrate is highly context-sensitive, with each decision point showing a unique combination of significant predictors influencing decision making. At 19 days following the anthrax release, the health risk policy manipulation has both a direct and indirect effect on migration behavior. At 3 months, the influence of the health risk policy manipulation is mediated by beliefs, and at 1 year, only indirect effects associated with affect and beliefs influence migration.     

Planning under a Co-operative Mandate: New Plans for New Zealand

The Resource Management Act 1991 provides a new mandate for effectsbased planning with its goal of sustainable management. Regional, city and district councils are responsible for administering the Act, including preparation of regional policy statements, regional and district plans. The paper reports on a collaborative research programme,funded by the New Zealand Foundation for Research, Science and Technology. The three-year programme has two objectives: (1) to determine the quality of policy statements and plans; and (2) to identify the extent and means by which councils co-ordinate policy statements and plans. Preliminary findings on implementation of the Act are presented.     

Development and demonstration of fuel cell vehicles and supporting infrastructure in China

The demand for urban transportation in China, including cars, motorbikes, buses, and trains, is growing substantially. China’s transportation fleet is projected to expand from 16 to 94 million vehicles between 2000 and 2020, with liquid and electricity transport fuel demand growing from about 5 Quadrillion British Thermal Units (Quads) to over 20 Quads in 2035. In response to energy security, economic growth and environmental protection needs, Chinese government agencies, academia and the private sector have organized their programs and investments to advance development and demonstration of sustainable alternative transportation systems. This analysis surveys historic development of fuel cell vehicle (FCV) including fuel cell buses (FCB) technology in China, summarizes recent efforts to scale-up FCV development and associated infrastructure in major Chinese cities, and briefly addresses future directions in Chinese fuel cell and hydrogen energy technology development. Since the late 1990’s, Chinese universities, government institutions and the private sector have implemented research, development, demonstration and deployment programs for electric (EV), fuel cell (FCV), and hybrid electric vehicles (HEV). These efforts have advanced the feasibility of FCVs to be a part of sustainable urban transportation system, including technical performance, infrastructure, and customer acceptance. Three generations of FCVs, START I, START II and START III have been developed, demonstrated and deployed. Similarly, several generations of FCBs have been developed and demonstrated. Collectively, these efforts have demonstrated and deployed over 1,000 FCBs and FCVs in several Chinese cities. Large-scale, intensive-use FCV and FCB demonstration trials, including those during the 2008 Beijing Olympics and the 2010 Shanghai World Exposition (EXPO), have been successfully built and operated. Infrastructure, such as hydrogen production facilities, fuelling stations, and maintenance stations have been constructed and operated to support the fleets of FCBs and FCVs. Experiences learned from these FCV research, development, and demonstration activities are the foundation for scaling up infrastructure and fleet trials in a growing number of cities in eastern and western China. An aggressive research and development vision and 2020 technology performance targets provide a foundation for the next generation of EVs, FCVs and HEVs, and, options for China’s efforts to develop a portfolio of sustainable transportation systems.     

Featured Collection Introduction: Connectivity of Streams and Wetlands to Downstream Waters

Connectivity is a fundamental but highly dynamic property of watersheds. Variability in the types and degrees of aquatic ecosystem connectivity presents challenges for researchers and managers seeking to accurately quantify its effects on critical hydrologic, biogeochemical, and biological processes. However, protecting natural gradients of connectivity is key to protecting the range of ecosystem services that aquatic ecosystems provide. In this featured collection, we review the available evidence on connections and functions by which streams and wetlands affect the integrity of downstream waters such as large rivers, lakes, reservoirs, and estuaries. The reviews in this collection focus on the types of waters whose protections under the U.S. Clean Water Act have been called into question by U.S. Supreme Court cases. We synthesize 40+ years of research on longitudinal, lateral, and vertical fluxes of energy, material, and biota between aquatic ecosystems included within the Act's frame of reference. Many questions about the roles of streams and wetlands in sustaining downstream water integrity can be answered from currently available literature, and emerging research is rapidly closing data gaps with exciting new insights into aquatic connectivity and function at local, watershed, and regional scales. Synthesis of foundational and emerging research is needed to support science‐based efforts to provide safe, reliable sources of fresh water for present and future generations.