Leaf phenology,photosynthesis, and the persistence of saplings and shrubs in a mature northern hardwood forest

We quantified leaf phenologies of saplings and overstory trees of sugar maple (Acer saccharum Marsh.) and American beech (Fagus grandifolia Ehrh.), and the shrub hobblebush viburnum (Viburnum alnifolium Marsh.) in a 72-year-old northern hardwood forest. Seasonal changes in irradiance in the shrub layer, and in the leaf CO(2) exchange of viburnum, and sugar maple and beech saplings were also measured. Leaf expansion occurred earlier in the spring and green leaves were retained later in the autumn in saplings and shrubs than in overstory trees. During the spring light phase (before overstory closure), large CO(2) gains by all three shrub-layer species occurred as a result of a combination of relatively large leaf area, high photosynthetic capacity, and high irradiance. Throughout the summer shade phase, photosynthetic capacity at a given irradiance remained relatively constant, but CO(2) gain was typically limited by low irradiances. Even though irradiance in the shrub layer increased during the autumn light phase as the overstory opened, CO(2) gains were modest compared to springtime values because of declining leaf area and photosynthetic capacity in all three species. The CO(2) gains during the spring light phase, and to a lesser extent during the autumn light phase, may be important to the carbon balance and long-term persistence of saplings and shrubs in the usually light-limited shrub layer of a northern hardwood forest. Therefore, for some late-successional species, leaf phenology may be an important characteristic that permits their long-term persistence in the shrub layer of mature northern hardwood forests.     

Farm-SAFE: the process of developing a plot- and farm-scale model of arable,forestry, and silvoarable economics

Financial feasibility and financial return are two key issues that farmers and land owners consider when deciding between alternative land uses such as arable farming, forestry and agroforestry. Moreover regional variations in yields, prices and government grants mean that the relative revenue and cost of such systems can vary substantially within Europe. To aid our understanding of these variations, the European Commission sponsored a research project called “Silvoarable Agroforestry For Europe” (SAFE). This paper describes the process of developing a new economic model within that project. The initial stages included establishing criteria for the model with end-users and reviewing the literature and existing models. This indicated that the economic model needed to allow comparison of arable farming, forestry and agroforestry systems at a plot- and a farm-scale. The form of comparisons included net margins, net present values, infinite net present values, equivalent annual values, and labour requirements. It was decided that the model would operate in a spreadsheet format, and the effect of phased planting patterns would be included at a farm-scale. Following initial development, additional user feedback led to a final choice on a model name, a final method of collating input data, and the inclusion of field-based operations such as varying the cropped area, replacing dead trees, and pruning. In addition options in terms of improved graphical outputs and the ability to undertake sensitivity analysis were developed. Some of the key lessons learnt include the need to establish clear model criteria and the benefits of developing a working prototype at an early stage to gain user-feedback.     

Towards a donut regime? Domestic actors,climatization, and the hollowing-out of the international forests regime in the Anthropocene

Political responses to global deforestation, as a defining characteristic of the so-called Anthropocene, are a key field for scholarship and policy analysis. In the past decade, research has proliferated on global forest governance and the international forest regime (IFR), yet the academic literature on the IFR is just as dispersed and fragmented as the IFR itself. An emerging body of literature now suggests the key role of domestic actors in international forest governance, questioning an implicit top-down logic of global arrangements. In spite of all the resources at its disposal, the IFR is characterised by complexity, fragmentation and ineffectiveness regarding its main objective of reducing global deforestation.Based on an extensive literature review, the authors’ long-standing observations and selected own empirical findings, this review article aims to provide an updated historical account of the IFR and proposes a from-below approach for analysing the IFR from the viewpoint of domestic actors. In this bottom-up perspective the IFR is conceptualised as a set of resources that key domestic actors can pick and choose from according to their interests and in the light of domestic politics.Using illustrative empirical examples from recent research and own observations, the article finds that the IFR is being hollowed-out by (i) the growing policy links between forests and climate change - a process referred to as “climatization”- and (ii) domestic influences. We conclude that our from-below approach is instrumental in further explaining why deforestation has largely continued, despite the emergence of the IFR some three decades ago. Our findings about the importance of domestic actors illustrate that global governance arrangements cannot operate effectively, relative to their ambitious mandate and for tackling policy issues relating to the Anthropocene, unless they are granted adequate resources and support by key domestic actors.     

Porewater dynamics and the formation of iron sulfides in a mangrove ecosystem,Sepetiba Bay,Brazil

Porewater dynamics and the formation of iron sulfides were studied in the Brazilian mangrove. Porewater samples were collected during tidal cycles using in situ equipment and physical–chemical and chemical data were obtained. The advective transport of porewater by tidal currents was found to be more effective between 0 and 5cm depth than below 15cm. The diffusive input of atmospheric oxygen during low tides resulted in oxidation of porewater dissolved sulfides. Thermodynamic considerations identified pyrite as the main iron sulfide forming at this depth, and the amorphous iron hydroxides are probably the main iron source. Below 15cm depth, irregular root distribution underground and benthic faunal bioturbation caused considerable spatial variation in a small scale (20cm). The correlation between alkalinity and total dissolved sulfide suggests that the main pathway for organic matter decomposition is sulfate reduction. Formed in the highly sulfidic diagenetic zone, the dissolved iron went through iron sulfide formation process. Crystalline iron oxides like hematite and magnetite may constitute an important iron source below 15cm, whereas pyrite is still the most probably occurring iron sulfide, according to thermodynamic considerations.     

肩负使命、把握机遇,开创学会工作新局面

领导、来宾、各位代表们:在举世瞩目的党的十八大胜利闭幕的喜庆日子里,广东园林学会成立50周年纪念大会今天在这里隆重举行,首先,我代表广东省科协对大会的胜利召开表示热烈的祝贺!向出席会议的各位领导、各位来宾、各位代     

认清形势强化管理为林业跨越式发展提供基础保障--在2003年局直属单位计划会议上的讲话

同志们 :这次会议是经过国家林业局党组批准召开的 ,局党组专门召开会议听取了汇报。会议的主要任务是 ,贯彻落实中央经济工作会议、全国计划会议、全国财政工作会议和全国林业计划财务会议精神 ,总结和交流 2 0 0 2年局直属单位计划与资金管理工作的经验和做法 ,按照国家林业局 2 0 0 3年重点工作的部署 ,衔接 2 0 0 3年基本建设投资计划 ,布置局直属单位重点基本建设工作。在前不久结束的全国林业计划财务会议上 ,李育材副局长代表国家林业局党组做了重要讲话 ,强调要深刻认识新世纪林业承担的重大历史使命 ,按照”围绕一个中心 ,坚持三个…     

Changes in the Ground Flora of a Broadleaved Wood within a Clear Fell, Group Fells and a Coppiced Block

Changes in the ground flora, relative to undisturbed woodland,were measured in permanent (100 m² quadrats in a clear fell,group fells and a coppice area in Sheephouse Wood (Buckinghamshire)from 1984 to 1988. Species numbers rose rapidly in the clearand group fells to about twice that in the undisturbed woodland.Species indicative of higher light, moisture and nutrient conditionsappeared after felling or coppicing and the flora shifted fromone dominated by stress-tolerant species to a flora with morecompetitive and ruderal species. After two years, in both clearand group fells, the ground flora covered 90–100 per centof the quadrats (compared with 30–75 per cent in the undisturbedwoodland), but species richness started to decline. This wasprobably because of increased competition associated with thespread of grasses and rushes (Agrostis stolonifera, Deschampsiacespitosa, Holcus mollis and Juncus spp.). Species richnessdid not increase as much in the coppice area, and bramble (Rubusfruticosus), rather than grasses, became dominant. The subsequentdecline in species richness was more gradual in the coppicearea than in the clear fells. During this period there wereno significant changes in the species richness, total coveror species composition within the undisturbed woodland.