Nutrient release from coniferous woodland stimulated by changes in forest management: A new nitrate time bomb?

森林管理变化刺激针叶林释放养分：新的硝酸盐定时炸弹？

• 批准号: 2284192
• 金额: --
• 依托单位: University of Reading
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2284192
• 关键词: Nutrient; release; coniferous; woodland; stimulated

Despite large UK reductions in nitrogen (N) emissions since 1970, recent total N deposition was unchanged. Nutrient models indicate that N loads in most broadleaf and conifer systems in the UK exceed critical limits. Forest ecosystems are efficient atmospheric nitrogen scavengers and can accumulate more nitrogen than other land uses, particularly near woodland edges and where habitat fragmentation has occurred. Data collected by Forest Research suggest that large amounts of nitrogen and carbon (C) have accumulated in forest soils and in particular in the upper organic soil horizons. Increased leaching of N and C species has been detected at a number of sites. Nitrogen stored in forest soils presents a risk to water quality if N stores are mineralized and released as a result of changes in forest management. Nitrogen losses to aquatic systems cost billions of pounds per year globally in water treatment and environmental damage from eutrophication. Despite this risk, the potential impact of changes in forest management on N leaching from forests to aquatic systems is poorly understood. Current government policy proposes more afforestation, but also changes to tree species which are more suitable for future climates, and converting some conifer systems to native broadleaves. In addition, productive forests are associated with intensive forest management processes which all can disturb the soils before tree planting, during forest development and harvest. Changes in forest due to pests and diseases could also have profound impact on nitrate inputs and leaching in forest ecosystems. In summary, we are expecting significant change of forest cover which is likely to alter established N leaching regimes which we know little about, thus creating a major research need.ApproachThis PhD will quantify the impacts of changes in forest management practices on nitrogen fate and transport beneath forested areas in the UK. The PhD will use monitoring and modelling approaches to quantify N fluxes to aquatic systems at a range of scales. The PhD will achieve this through the following tasks:1. Detailed quantitative analysis of long term (>15 years) monitoring data of soil and soil solution nitrogen (total, nitrate, ammonium, dissolved organic nitrogen) measured at 10 Forest Research monitoring sites across the UK. Additional monitoring data collection and lab analysis will be carried out (soil N leaching, groundwater nitrate concentrations, pore water profiles).2. Development of conceptual and process-based models of N leaching to aquatic systems parameterised at each site, and a number of generalised scenarios describing N leaching from forests, to be used in large scale modelling.3. Upscaling of site-specific models to national scale by exploiting national scale datasets from Forest Research and CEH, e.g. BioSoil (220 sites) and soil survey and hydrogeological data.4. Application of developed models (site and national scales) to predict impacts of changes in forest management on N fluxes from forests, and resultant impacts on aquatic system N concentrations.

尽管自1970年以来英国氮（N）排放量大幅减少，但最近的氮沉降总量没有变化。营养模型表明，在英国的大部分阔叶树和针叶树系统中的氮负荷超过临界限值。森林生态系统是有效的大气氮清除剂，可以积累比其他土地利用更多的氮，特别是在林地边缘和栖息地破碎化发生的地方。森林研究所收集的数据表明，大量的氮和碳（C）积累在森林土壤中，特别是在有机土壤的上层。在一些地点已发现氮和碳的淋失增加。森林土壤中储存的氮，提出了一个风险，水质，如果氮存储被矿化和释放的结果，在森林管理的变化。氮损失到水生系统每年在全球水处理和富营养化造成的环境破坏中花费数十亿英镑。尽管有这种风险，森林管理的变化对氮从森林淋溶到水生系统的潜在影响知之甚少。目前的政府政策建议更多的植树造林，但也改变树种，更适合未来的气候，并转换一些针叶林系统，以本地阔叶。此外，生产性森林与密集的森林管理过程有关，这些过程在植树之前、森林发展和收获期间都会破坏土壤。病虫害造成的森林变化也可能对森林生态系统中的硝酸盐投入和沥滤产生深远影响。总之，我们期待着显着的变化，森林覆盖，这是可能改变既定的N淋溶制度，我们所知甚少，从而创造一个重大的研究need.ApproachThis博士将量化的影响，在森林管理实践中的氮的命运和运输下的森林地区在英国。博士将使用监测和建模方法来量化N通量的水生系统在一系列尺度。博士将通过以下任务来实现这一目标：1。详细的定量分析长期（>15年）监测数据的土壤和土壤溶解氮（总，硝酸盐，铵，溶解有机氮）测量在10个森林研究监测点在英国。将进行额外的监测数据收集和实验室分析（土壤氮淋溶、地下水硝酸盐浓度、孔隙水剖面）。在每个站点参数化的水生系统氮淋溶的概念和基于过程的模型的开发，以及描述森林氮淋溶的一些通用情景，用于大规模建模。通过利用森林研究和CEH的国家尺度数据集，如BioSoil（220个地点）和土壤调查及水文地质数据，将特定地点的模型升级到国家尺度。应用已开发的模型（站点和国家尺度）预测森林管理变化对森林氮通量的影响，以及对水生系统氮浓度的影响。