Population dynamics of splitnose rockfish (Sebastes diploproa) in the Northeast Pacific Ocean

We developed an age-structured population model of splitnose rockfish, Sebastes diploproa, in the Northeast Pacific Ocean. Splitnose rockfish is a bycatch species that co-occurs with several commercially important species that are currently declared overfished. Bycatch species are typically not the focus of stock assessment efforts because of their limited economic importance, but they may suffer the same population declines as species with which they co-occur. To examine the dynamics of splitnose rockfish for the first time, we analyzed data from three groundfish fisheries and four research surveys conducted in the Northeast Pacific Ocean. To develop a model, we used Stock Synthesis, a statistical framework for the construction of a population dynamics models utilizing both fishery-dependent and fishery-independent data. In the model, we reconstructed the total catch of the species back to 1900, estimated the dynamics of the stock spawning output and recruitment and evaluated biomass depletion relative to the stock's unfished state, as well as sources of uncertainty in model outputs. The results indicate that the splitnose rockfish is currently not overfished even though it has experienced several periods of abrupt decline in its biomass. Revisiting age data from earlier years, monitoring fishery discard, and investigating the spatial dynamics of splitnose rockfish is important to further improve the understanding of this species’ population dynamics, and decrease uncertainty in model results.     

Using a fire propagation model to assess the efficiency of prescribed burning in reducing the fire hazard

We examined how fire hazard was affected by prescribed burning and fuel recovery over the first six years following treatment. Eight common Mediterranean fuel complexes managed by means of prescribed burning in limestone Provence (South-Eastern France) were studied, illustrating forest and woodland, garrigue and grassland situations. The coupled atmosphere-wildfire behaviour model FIRETEC was used to simulate fire behaviour (ROS, intensity) in these complex vegetations. The temporal threshold related to the effectiveness of prescribed burning in reducing the fire hazard was assessed from derivated fuel dynamics after treatment. The study showed that prescribed burning treatment was effective for the first two years in most of the Mediterranean plant communities analysed. Thereafter, all forests and shrublands were highly combustible with a fire line intensity of more than 5000 kW/m except for pine stands with or without oak (medium intensity of 2000 kW m⁻¹ 3 years after treatment). Low fire line intensity (900 kW m⁻¹) was obtained for grassland which was entirely treatment-independent since the resprouter hemicryptophyte, Brachypodium retusum, is highly resilient to fire. Fire behaviour was greatly affected by fuel load accumulation of Quercus ilex in woodland, and by standing necromass of Rosmarinus officinalis in treated garrigue. Pure pine stands with shrub strata similar to garrigue showed a lower fire intensity due to wind speed decrease at ground level under tree canopy, underlining the advantage of maintaining a proportion of canopy cover in strategic fuel-break zones.     

基于空间马尔科夫链的关中地区生态安全时空演变分析

生态系统内部和生态系统之间都不是封闭的,各要素间均存在着相互作用。利用已获得的陕西关中地区生态安全格网化评价结果数据,运用空间马尔科夫链对该区域的生态安全时空演变进行了分析,得出以下四个结论：①区域背景在关中地区生态安全趋同时空演变过程中起着相当重要作用;②不同区域背景在区域生态安全等级转移中所起的作用也各不相同;③一个区域生态安全等级向上或向下转移的概率与该区域和周围邻居之间的差异程度不成比例;④空间马尔可夫转移概率矩阵为＂区域趋同的时空演变＂现象提供了空间上的解释。实践表明,空间马尔可夫链方法为定量分析地理环境对区域生态安全变化的空间效应提供了方法依据,值得进一步研究和讨论。     

Stabilised Coal Ash Studies in Italy

The ENEL Ash Research Centre - (Brindisi, Italy) - has started a research programme on the use of coal ash derived from its thermoelectric power plants as a component of blocks for artificial habitats. After preliminary laboratory tests, systematic physical, chemical, and biological tests were carried out in an experimental installation constructed in the area of the Torrevaldaliga power plant (80 km NW of Rome).

Two reef models - each made by assembling pyramids of 225 20 × 20 × 20 cm blocks - were submerged in two tanks (10 × 2 × 1.5 m) with running sea water (water flow: 3-5 cm s-1). the ash blocks were composed of fly ash (52.1%), bottom ash (26.1%), hydrated lime (5.2%) and water 16.6%, while concrete blocks were made of pozzolanic cement, sand and gravel. After two years, ash based blocks showed no weathering, volume variation or swelling; marked compressive strength and sonic velocity increases have, on the contrary, been recorded. No significant leaching of chemical elements of environmental concern was found. the biotic settlement on the ash blocks proved greater in quantity and better in quality than that on the concrete blocks; on ash blocks 62 species were found, compared to 54 on concrete. Ash-based materials seem to be more suitable for the settlement of the macrobenthos.     

Individual based model of slug population and spatial dynamics

The slug, Deroceras reticulatum, is one of the most important pests of agricultural and horticultural crops in UK and Europe. In this paper, a spatially explicit individual based model (IbM) is developed to study the dynamics of a population of D. reticulatum. The IbM establishes a virtual field within which slug spatial dynamics and changes in abundance were simulated. The strong dependence of slug behaviour on environmental conditions is built into the model, which is based upon previous work on the environmental dependence of slug population dynamics. The simulation results show that the IbM described well changes in the slug population. The IbM proved capable of describing slug populations over 3.5 years, including the presence, magnitude and duration of D. reticulatum population crashes within this period. Moreover, the model was capable of reproducing slug population dynamics at two sites, with distinct weather and some 100 km apart, with minor changes in initialisation values but no change in model structure and parameter values. A study of field heterogeneity, which might simulate various field designs, indicated the importance of spatial structuring to slug population dynamics and the utility of the IbM for simulating a range of potential spatial management treatments for slug control to maximise crop yield. This IbM system performs well and is currently being used as part of an integrated approach to predict slug population dynamics and control in the UK.     

Long-term dynamics of technogenic radionuclide concentrations in moss-lichen cover

Ample factual data has been used to analyze the long-term dynamics of ⁹⁰Sr and ¹³⁷Cs concentrations in moss-lichen cover. The stocks of radionuclides in lichens, mosses, and the moss-lichen cover of northern regions of the Urals and Siberia has been estimated for the first time. The data on recent ranges of ⁹⁰Sr and ¹³⁷Cs concentrations in lichens and mosses can serve as a basis for determining the background levels of radionuclide contamination for long-term monitoring and prognostic radioecological studies.     

A Systems Based Framework to Examine The Multi-contextural Application of the Sustainability Concept

A conceptual framework is generated through systems principles to explain sustainability’s wide diversity of interpretation and contextual application. Sustainability is reduced to a literal interpretation as the ability to sustain, and then expressed in simple systems as the ability of one system to sustain another system over time. This reinforces the importance of time in the sustainability debate, and suggests the concept can be legitimately applied to timeframes that have absolute limits. The framework is expanded to complex systems as the changing ability of one or many systems to sustain the changing requirements of one or many systems, over time. This accommodates multiple relations and system dynamics, and hints at the extraordinary complexity encompassed by the sustainability concept. Practical implications relate to the evolving meaning of sustainability, the need for continual change to remain sustainable, and that the sustainability concept can be validly applied to virtually any context or situation that exhibits a dimension of continuity. Derived criteria useful for clarifying contextual applications of sustainability include stating the how, what, why, who and for how long of sustainability, along with indicating the most appropriate hierarchical tier at which the concept is being applied.     

Analyzing the carbon dynamics of central European forests: comparison of Biome-BGC simulations with measurements

Biogeochemical models are often used for making projections of future carbon dynamics under scenarios of global change. The aim of this study was to assess the accuracy of the process-based biogeochemical model Biome-BGC for application in central European forests from the lowlands to upper treeline as a pre-requisite for environmental impact assessments. We analyzed model behavior along an altitudinal gradient across the alpine treeline, which provided insights on the sensitivity of simulated average carbon pools to changes in environmental factors. A second set of tests included medium-term (30 years) simulations of carbon fluxes, and a third set of tests focused on daily carbon and water fluxes. Model results were compared to aboveground biomass measurements, leaf area index recordings as well as net ecosystem exchange (NEE) and actual evapotranspiration (AET) measurements. The simulated medium-term forest growth agreed well with measured data. Also daily NEE fluxes were simulated adequately in most cases. Problems were detected when simulating ecosystems close to the upper timberline (overestimation of measured growth and pool sizes), and when simulating daily AET fluxes (overestimation of measured fluxes). The results showed that future applications of Biome-BGC could benefit much from an improvement of model algorithms (e.g., the Q₁₀ model for respiration) as well as from a detailed analysis of the ecological significance of crucial parameters (e.g., the canopy water interception coefficient).     

煤矿区域可持续发展的动力学模型

本文从系统论的观点出发 ,结合当前煤矿区域的实际情况 ,给出了煤矿区域系统所具备的动力学性质和特征 ,通过所建的一个数学模型 ,探讨了煤矿区域煤炭资源持续利用与地方经济可持续发展之间的非线性关系及其调控措施     

Daily Activity and Mobility of the Common Shrew (Sorex araneus L.)

Data on the daily activity and mobility of the common shrew (Sorex araneusL.) were obtained by the method of animal marking and recapturing in test plots. Sex- and age-related differences in the locomotor activity of animals were revealed, which depended on population size and the phase of the population cycle. Under natural conditions, animal activity in the daytime proved to decrease to a lesser extent than in captivity. The mobility (locomotor activity) of shrews was shown to depend on population density, reproductive rate, and weather.