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）排放量的减少幅度很大，但最近的n个总沉积仍未变化。营养模型表明，在英国大多数Broadeaf和针叶树系统中，N负载超过了关键限制。森林生态系统是有效的大气氮清道夫，并且比其他土地用途（尤其是在林地边缘和发生栖息地发生碎片的地方）可以积累更多的氮。森林研究收集的数据表明，大量的氮和碳（C）积累在森林土壤中，尤其是在上部有机土壤中。在多个地点发现了N和C种的浸出增加。如果n商店被矿化并因森林管理的变化而释放，则存储在森林土壤中的氮将面临水质的风险。水生系统损失每年在全球范围内耗资数十亿英镑，从而在富营养化的水处理和环境损失方面损失。尽管有这种风险，但森林管理变化对从森林到水生系统的N浸出的潜在影响知之甚少。当前的政府政策提出了更多的造林，但也会改变树种，这些物种更适合将来的气候，并将某些针叶树系统转化为本地阔叶。此外，生产森林与密集的森林管理过程有关，这些过程都会在植树前，森林开发和收获期间干扰土壤。由于害虫和疾病引起的森林变化也可能对森林生态系统中的硝酸盐投入和浸出产生深远的影响。总而言之，我们预计森林覆盖范围可能会发生重大变化，这可能会改变既定的n浸出制度，因此我们对此一无所知。博士将使用监视和建模方法在一系列尺度上量化为水生系统的N通量。博士将通过以下任务实现这一目标：1。长期（> 15年）监测土壤和土壤溶液的数据的详细定量分析（总，硝酸盐，硝酸盐，铵，溶解有机氮），在英国的10个森林研究监测地点进行了测量。将进行其他监测数据收集和实验室分析（土壤N浸出，地下水硝酸盐浓度，毛孔水剖面）。2。开发了在每个站点参数化的水生系统的概念和基于过程的模型，以及许多广义场景描述了N森林中的n浸出，用于大规模模型3。通过从森林研究和CEH（例如Biosoil（220个地点）以及土壤调查以及水文地质数据4。发达的模型（现场和国家尺度）的应用来预测森林管理变化对森林N通量的影响，以及对水生系统N浓度的影响。