Chair of Soil Science, Center of Life and Food Sciences Weihenstephan, Technical University München, Freising, Germany.
Bavarian State Institute of Forestry, Freising, Germany.
Glob Chang Biol. 2020 Oct;26(10):5796-5815. doi: 10.1111/gcb.15265. Epub 2020 Aug 9.
At two forest sites in Germany (Pfaffenwinkel, Pustert) stocked with mature Scots pine (Pinus sylvestris L.), we investigated changes of topsoil chemistry during the recent 40 years by soil inventories conducted on replicated control plots of fertilization experiments, allowing a statistical analysis. Additionally, we monitored the nutritional status of both stands from 1964 until 2019 and quantified stand growth during the monitoring period by repeated stand inventories. Moreover, we monitored climate variables (air temperature and precipitation) and calculated annual climatic water balances from 1991 to 2019. Atmospheric nitrogen (N) and sulfur (S) deposition between 1964 and 2019 was estimated for the period 1969-2019 by combining annual deposition measurements conducted in 1985-1987 and 2004 with long-term deposition records from long-term forest monitoring stations. We investigated interrelations between topsoil chemistry, stand nutrition, stand growth, deposition, and climate trends. At both sites, the onset of the new millennium was a turning point of important biogeochemical processes. Topsoil acidification turned into re-alkalinization, soil organic matter (SOM) accumulation stopped, and likely turned into SOM depletion. In the new millennium, topsoil stocks of S and plant-available phosphorus (P) as well as S and P concentrations in Scots pine foliage decreased substantially; yet, age-referenced stand growth remained at levels far above those expected from yield table data. Tree P and S nutrition as well as climate change (increased temperature and drought stress) have replaced soil acidification as major future challenges for both forests. Understanding of P and S cycling and water fluxes in forest ecosystems, and consideration of these issues in forest management is important for successfully tackling the new challenges. Our study illustrates the importance of long-term forest monitoring to identify slow, but substantial changes of forest biogeochemistry driven by natural and anthropogenic global change.
在德国的两个森林地点（Pfaffenwinkel、Pustert），我们对成熟的欧洲赤松（Pinus sylvestris L.）进行了研究，通过对施肥实验的对照控制地块进行土壤清查，调查了最近 40 年来表土化学性质的变化，这使得我们可以进行统计分析。此外，我们从 1964 年到 2019 年监测了两个林分的营养状况，并通过重复的林分清查来量化监测期间的林分生长。此外，我们还监测了气候变量（气温和降水），并根据 1991 年至 2019 年的气候数据计算了年气候水量平衡。1964 年至 2019 年期间的大气氮（N）和硫（S）沉降量，是通过结合 1985-1987 年和 2004 年的年度沉降测量值以及长期森林监测站的长期沉降记录来估算的。我们调查了表土化学、林分营养、林分生长、沉积和气候趋势之间的相互关系。在这两个地点，新千年的开始是重要生物地球化学过程的转折点。表土酸化转为再碱化，土壤有机质（SOM）积累停止，可能转为 SOM 耗竭。在新千年，表土 S 和植物有效磷（P）储量以及欧洲赤松叶片中的 S 和 P 浓度大幅下降；然而，参考年龄的林分生长仍保持在远高于从产量表数据中预期的水平。树木 P 和 S 营养以及气候变化（温度升高和干旱胁迫）已取代土壤酸化，成为两个林分的主要未来挑战。了解森林生态系统中的 P 和 S 循环以及水通量，并在森林管理中考虑这些问题，对于成功应对新挑战非常重要。我们的研究说明了长期森林监测的重要性，因为它可以识别由自然和人为全球变化驱动的森林生物地球化学的缓慢但实质性变化。
