Nitrogen budgets for Scots pine and Norway spruce ecosystems 12 and 7 years after the end of long-term fertilisation |
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| Institution: | 1. Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, PR China;2. College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, PR China;3. Geography, CLES, Amory Building, University of Exeter, Rennes Drive, Exeter EX4 4RJ UK;4. School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK;5. College of Resources and Environment, Zunyi Normal College, Zunyi, Guizhou, PR China;1. Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, Hunan, China;2. Huanjiang Observation and Research Station for Karst Ecosystems, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Huanjiang 547100, Guangxi, China;3. College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China;1. College of Forest Resources and Environment, Nanjing Forestry University, 159 Longpan Road, Nanjing 210037, China;2. Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan;3. Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, Alberta T6G 2E3, Canada;1. School of Geography and Earth Sciences, McMaster University, Hamilton, Ontario L8S 4L8, Canada;2. Department of Marine Sciences, Texas A&M at Galveston, Galveston, TX 77553, USA;3. Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA;4. National Museum of The Bahamas/Antiquities, Monuments and Museums Corporation, PO Box AB20755, Marsh Harbour, Abaco, Bahamas |
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| Abstract: | The magnitude of nitrogen storage and its temporal change in forest ecosystems are important when analysing global change. For example, the accelerated growth of European forests has been linked to increased nitrogen deposition, but the changes in the N inputs that cause long-term changes in ecosystems have not yet been identified. We used two Swedish forest optimum nutrition experiments with Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) to study the long-term fate of N applied to these forest ecosystems. In the pine experiment, in addition to fertiliser (NPK) application, soil acidity was manipulated by application of lime and dilute sulphuric acid. From the spruce experiment, we selected treatments with similar fertiliser doses as in the pine experiment and with and without lime addition.We quantified various terms in the N budget 12 years (pine) and 7 years (spruce) after the last N addition. In the pine stand the NPK-treatment was the only treatment to produce a significant increase in N in the tree biomass (97% above control), whereas in the spruce stand the N additions increased tree N in all treatment combinations (207% above control). In the pine stand the relative distribution of nitrogen between trees and soil did not vary across treatments, with trees containing around 12% of ecosystem N and humus containing around 44% of soil N. The increases in N stocks in the pine stands were mainly in the soil. In contrast, in the spruce ecosystem trees accumulated most of the added N and the increase in the soil was restricted to the humus layer.In the pine ecosystem, large losses of added N (between 254 and 738 kg ha?1 out of 1040 kg ha?1 added as fertiliser) occurred, whereas in the spruce ecosystem we recovered more N than could be accounted for by inputs (between 250 and 591 kg ha?1). There was no clear pattern in the interaction between acidification/liming and N additions. |
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