Is plant biodiversity loss and recovery in N polluted ecosystems regulated by phosphorus acquisition?

化石燃料燃烧和农业向大气中排放的氮（N）增加了氮在生态系统中的沉积速率。氮沉降速率的增加是全球生态系统生物多样性丧失的最重要原因之一。例如，在北方，许多首先接受这些高氮输入的生态系统（如物种丰富的草原）已经失去了许多生物多样性，包括稀有或受保护物种的损失。因此，最重要的是，我们要了解驱动这种物种变化的机制，这既可以让我们预测对生态系统的影响，也可以更好地管理和恢复已经污染的系统。在生态系统中，磷（P）通常是决定植物生长的最重要或第二重要的营养元素。因此，氮污染对植物磷吸收的影响可能会显着影响植物生长，因此也改变了植物群落的生物多样性。最近的证据表明，这种情况可能正在发生。特别是，物种丰富的石灰质草原的主要植物类型显示出相当大的变化，丰富的N污染下（莎草和草增加丰富，减少了草本植物的多样性，包括许多有吸引力的花，使这些草原的保护重要性）。重要的是，这些主要的植物群体有不同的磷吸收方法。莎草（草在较小程度上）有特殊的根适应，而杂类草是依赖于菌根共生获得P.因此，很明显，N污染对这些对比P吸收机制的影响可能会推动物种的变化。使用丰富的石灰质草原（峰区国家公园，德比郡，英国），这项研究计划将是第一项研究，以确定和比较的影响，氮沉降的独特机制，磷收购内的主要植物类型。它将确定氮沉降对植物磷供应的影响，并确定这些影响是否可以驱动物种变化。这也将确定是否植被可以恢复这些影响磷供应时，氮沉降下降，由于有效的控制措施。这项工作对那些关心生态系统养护和生物多样性保护的人来说相当重要。它将告知政策制定者污染物氮负荷的影响，使我们能够更好地预测污染物氮对生态系统的影响，更好地建立“临界负荷”。机械的理解也将提供重要的洞察力，如何在地球仪周围的其他相关系统可能会对污染物的N负荷，特别是其他系统中的P供应是最重要的因素，在确定植物生长。

Increased emissions of nitrogen (N) to the atmosphere from fossil fuel burning and agriculture are increasing the rates of deposition of this N to ecosystems. These increased rates of N deposition are one of the most important causes of biodiversity loss in ecosystems at a global scale. Within northern Europe, for example, many ecosystems first to receive these high N inputs (such as species rich grasslands), have lost much biodiversity, including loss of rare or protected species. It is most important, therefore, that we understand the mechanisms that drive this species change, both to allow us to predict impacts on ecosystems, and better manage and restore already polluted systems. In ecosystems, phosphorus (P) is generally the most or second most important nutrient for determining the growth of plants. An impact of N pollution on plant P uptake could therefore significantly impact on plant growth and therefore also alter the biodiversity of plant communities. Recent evidence suggests that this may be happening. In particular, the major plant types of species rich calcareous grasslands show considerable change in abundance under N pollution (sedges and grasses increase in abundance which reduces the diversity of herbaceous plants, including many attractive flowers that give these grasslands their conservation importance). Importantly, these major plant groups have contrasting methods of P uptake. Sedges (and to a lesser extent grasses) have special root adaptations while forbs are reliant on mycorrhizal symbioses to acquire P. It is therefore apparent that N pollution impacts on these contrasting P uptake mechanisms could drive species change. Using a floristically rich calcareous grassland (Peak District National Park, Derbyshire, UK), this programme of research will be the first study to determine and compare the impacts of N deposition on the distinctive mechanisms of P acquisition within the major plant types. It will determine the impacts of N deposition on plant P supply and determine whether these impacts can drive species change. It will also determine whether vegetation can recover from these impacts on P supply when N deposition declines as a result of effective control measures. The work is of considerable importance to those concerned with the conservation of ecosystems and preservation of biodiversity. It will inform policy makers of the impacts of pollutant N loading and allow us to better predict pollutant N impact on ecosystems and better establish 'critical loads'. The mechanistic understanding will also provide important insight into how other related systems around the globe may respond to pollutant N loading, particularly other systems where P supply is the most important factor in determining plant growth.