A Bayesian strategy for combining predictions from empirical and process-based models

We present a strategy for using an empirical forest growth model to reduce uncertainty in predictions made with a physiological process-based forest ecosystem model. The uncertainty reduction is carried out via Bayesian melding, in which information from prior knowledge and a deterministic computer model is conditioned on a likelihood function. We used predictions from an empirical forest growth model G-HAT in place of field observations of aboveground net primary productivity (ANPP) in a deciduous temperate forest ecosystem. Using Bayesian melding, priors for the inputs of the process-based forest ecosystem PnET-II were propagated through the model, and likelihoods for the PnET-II output ANPP were calculated using the G-HAT predictions. Posterior distributions for ANPP and many PnET-II inputs obtained using the G-HAT predictions largely matched posteriors obtained using field data. Since empirical growth models are often more readily available than extensive field data sets, the method represents a potential gain in efficiency for reducing the uncertainty of process-based model predictions when reliable empirical models are available but high-quality data are not.     

Organoiodine formation during humification in peatlands

Although two billion people in the world are suffering from iodine deficiency there is little information on the chemical fate of iodine in the terrestrial environment. Here we show that peatlands play a major role in terrestrial iodine cycling. Chemical data from two peat profiles from Patagonia, Chile imply that transformation of iodine from its inorganic form to organoiodine compounds during early humification in peatlands is a key process in storage of iodine in the terrestrial environment. Once bound in peat, iodine remains stable for thousands of years. In the earths peatlands, net accumulation of iodine since the last glacial period is estimated to be 12–36 teragrams (1 Tg=10¹² g). These data suggest that peatlands are a major reservoir of iodine in terrestrial ecosystems. Our novel model of iodine distribution in the terrestrial environment demonstrates the key role of peatlands in burial and reemission of organically bound iodine.     

Application of a coupled ecosystem-chemical equilibrium model, DayCent-Chem, to stream and soil chemistry in a Rocky Mountain watershed

Atmospheric deposition of sulfur and nitrogen species have the potential to acidify terrestrial and aquatic ecosystems, but nitrate and ammonium are also critical nutrients for plant and microbial productivity. Both the ecological response and the hydrochemical response to atmospheric deposition are of interest to regulatory and land management agencies. We developed a non-spatial biogeochemical model to simulate soil and surface water chemistry by linking the daily version of the CENTURY ecosystem model (DayCent) with a low temperature aqueous geochemical model, PHREEQC. The coupled model, DayCent-Chem, simulates the daily dynamics of plant production, soil organic matter, cation exchange, mineral weathering, elution, stream discharge, and solute concentrations in soil water and stream flow. By aerially weighting the contributions of separate bedrock/talus and tundra simulations, the model was able to replicate the measured seasonal and annual stream chemistry for most solutes for Andrews Creek in Loch Vale watershed, Rocky Mountain National Park. Simulated soil chemistry, net primary production, live biomass, and soil organic matter for forest and tundra matched well with measurements. This model is appropriate for accurately describing ecosystem and surface water chemical response to atmospheric deposition and climate change.     

四川升钟水库经济和环境协调发展研究

大型水库以灌溉为主兼有防洪、发电、饮用、游览、航运、水产养殖、降低局部地域的气温.净化环境、土壤持留等综合效益.文章以我国西南地区库容最大的四川升钟水库为例,概要的介绍了该库区建造前后环境与经济发展的情况,分析了水库建成后库区环境污染的原因,评估了库区的服务功能与经济价值,给出了实现库区经济与环境发展的措施.     

浅谈我国环境标准在环境管理中的作用

简述了我国环境标准的现状,体系和分类,分析了环境标准在环境管理中的作用。指出环境标准是制定环境规划的重要依据;是各级环保部门行使管理职能的基本依据;是企业污染治理是否达标的限定值;是推动环保科技进步的动力;是环境评价的准绳;是开展环境保护工作的基础;是环境保护法规的重要组成部分;具有投资导向作用。     

Simulated dynamics of carbon stocks driven by changes in land use, management and climate in a tropical moist ecosystem of Ghana

Sub-Saharan Africa is large and diverse with regions of food insecurity and high vulnerability to climate change. This project quantifies carbon stocks and fluxes in the humid forest zone of Ghana, as a part of an assessment in West Africa. The General Ensemble biogeochemical Modeling System (GEMS) was used to simulate the responses of natural and managed systems to projected scenarios of changes in climate, land use and cover, and nitrogen fertilization in the Assin district of Ghana. Model inputs included historical land use and cover data, historical climate records and projected climate changes, and national management inventories. Our results show that deforestation for crop production led to a loss of soil organic carbon (SOC) by 33% from 1900 to 2000. The results also show that the trend of carbon emissions from cropland in the 20th century will continue through the 21st century and will be increased under the projected warming and drying scenarios. Nitrogen (N) fertilization in agricultural systems could offset SOC loss by 6% with 30 kg N ha⁻¹ year⁻¹ and by 11% with 60 kg N ha⁻¹ year⁻¹. To increase N fertilizer input would be one of the vital adaptive measures to ensure food security and maintain agricultural sustainability through the 21st century.     

Optimizing the biodiversity gain from agri-environment schemes

How best to optimize the biodiversity gain from agri-environment schemes (AES) has recently been identified as a key policy-relevant question. Here, the effects of two features of lowland agricultural landscapes on the abundance and diversity of larger moths are contrasted. Although both features bring about positive effects, hedgerow trees have a larger impact than 6 m wide grassy field margins. Whilst AES payments are given to create and maintain grass margins, no financial reward is currently offered for the retention of hedgerow trees. Furthermore, it was only in areas where the amount of land under AES was experimentally increased, by targeting farmers, that the presence of hedgerow trees resulted in a substantially higher abundance (+60%) and diversity (+38%) of moths. Thus, by using larger moths as bio-indicators of landscape-scale quality, it is demonstrated that improvements to the cost-effectiveness of AES could be achieved, firstly, by providing more appropriate financial rewards to farmers for different landscape features, and secondly, through landscape-scale targeting of farmers to encourage participation in AES.     

Establishing a Regional Monitoring Strategy: The Pacific Northwest Forest Plan

adaptive monitoring design. Adaptive monitoring design is an iterative process that refines the specifications for monitoring over time as a result of experience in implementing a monitoring program, assessing results, and interacting with users. An adaptive design therefore facilitates ecosystem management. We also discuss lessons of temporal and spatial scales raised by the consideration of a design for ecosystem management. Three additional issues—integration of information from different sources, institutional infrastructure, and the roles of individuals working in an interagency setting—are also identified, but not developed in detail.     

Change in Fish Fauna as Indication of Aquatic Ecosystem Condition in Río Grande de Morelia–Lago de Cuitzeo Basin, Mexico

Chirostoma charari and C. compressum, and they are presumed extinct. Twelve (63%) of the remaining species had declines in distribution. Sixteen (80%) of the 20 localities sampled had lost species. The greatest declines occurred in Lago de Cuitzeo proper and in the lower portion of the Río Grande de Morelia watershed. Species losses from the lake were attributable to drying and hypereutrophication of the lake because of substantial reductions in the amount and quality of tributary inputs, whereas losses from the Río Grande de Morelia watershed were the result of pollution from agricultural, municipal, and industrial sources, especially in the region around the city of Morelia. Three localities in the upper portion of the Río Grande de Morelia watershed—Cointzio reservoir, La Mintzita spring, and Insurgente Morelos stream—contained most of the remaining fish species diversity in the basin and deserve additional protection. Fish faunal changes indicated major declines in the health of aquatic ecosystems in the Morelia–Cuitzeo basin.