The influence of deciduous tree species on soil carbon dynamics and sequestration in temperate forests

温带森林储存了3000亿吨有机碳（C）。在欧洲，每年有8亿吨碳固定在森林中，约40%在土壤中，约60%在生物量中。可持续林业的目标之一是保证和提高森林生态系统的碳汇功能。然而，控制这一过程的因素尚未完全了解。本研究的主要目的是分析重要树种（Fagus sylvatica L.，栎属，白蜡，拟悬铃木，紫椴和欧洲云杉Picea abies L.喀斯特。）关于森林碳固存本研究将针对以下具体目标：（1） 虽然树种对土壤碳储量的影响有据可查，但土壤碳储量随时间的变化，即碳固存，在很大程度上仍然未知。在本研究中，森林土壤将重新采样的土壤碳在不同的树种在丹麦共同花园实验，分析了C 10年前在2004/2005年。因此，土壤碳储量的可能变化可以直接量化。（二） 目前还不清楚是什么机制负责的树种对森林土壤碳储量和储量变化的影响。因此，将在两年期间测量土壤呼吸，并将其分为两个来源：异养呼吸（有机物质的分解）和自养呼吸（根呼吸）。将核查这些来源在土壤呼吸总量中的相对比例是否取决于树种，从而促成森林地表不同的碳储存。（三） 在以前的研究树种的影响，碳股票的差异，观察无论是在土壤中或在生物量。然而，物种之间在土壤和生物量碳储量方面的差异可能并不呈正相关，即现有的研究无法得出关于森林碳平衡取决于总树种的结论。此外，痕量气体一氧化二氮（N2 O）和甲烷（CH 4）也是相关的温室气体，因为它们的变暖潜力分别是CO2的28倍（CH 4）和264倍（N2 O）。树种对N_2O排放和CH_4吸收的影响可能不同于CO_2排放。在本研究中，将在两年内在树种水平上对包括CH 4吸收和N2 O排放在内的土壤（生物量和土壤）进行量化。将分析其他土壤特性，例如养分含量，以便能够校准和验证现有的生物地球化学模型（例如Biome-BGC，Zalf版）在本供资期之后的一个后续项目中进行。

Temperate forests store 300 billion tons of organic carbon (C). In Europe, 800 million tons of C are fixed annually in the forest, ~40% in the soil and ~60% in the living biomass. One goal of sustainable forestry is to ensure and increase the C sink function of the forest ecosystem. However, the factors controlling this process are not yet fully understood. The main objective of the proposed study is to analyze the effect of important tree species (Fagus sylvatica L., Quercus spec., Fraxinus excelsior L., Acer pseudoplatanus L., Tilia cordata Mill. and Picea abies L. Karst.) on forest C-sequestration. The study will address the following specific objectives:(1) While the tree species effect on soil C stocks is well documented, the change in soil C stocks over time, i.e. the C sequestration, remains largely unknown. In the present study, the forest soil will be resampled for soil C under different tree species in Danish common garden experiments which were analyzed for C 10 years ago in 2004/2005. Thus, possible changes in soil C stocks can be directly quantified. (2) It remains unclear which mechanisms are responsible for the tree species effect on forest soil C stocks and stock changes. Thus, soil respiration will be measured over two years and partitioned into its sources, the heterotrophic respiration (decomposition of organic substances) and the autotrophic respiration (root respiration). It will be checked whether the relative proportions of these sources to the total soil respiration are dependent on tree species and thus contribute to different carbon stocks in the forest floor.(3) In previous studies of tree species effects, differences in C stocks were observed either in the soil or in the biomass. However, it is possible that differences between species in soil and biomass C stocks are not positively related to each other, i.e. the available studies do not allow drawing conclusions concerning a total tree species dependent C-balance of the forests. Furthermore, the trace gases nitrous oxide (N2O) and methane (CH4) are relevant greenhouse gases, too, as their warming potentials are 28 times (CH4) and 264 times (N2O) higher than that of CO2, respectively. Tree species may influence the N2O emission and CH4 uptake in a different way than the CO2 emission. In the present study the total greenhouse gas balance (biomass and soil) including the CH4 uptake and N2O emissions will be quantified at the tree species level over a period of two years.Additional soil properties, e.g. nutrient content, will be analyzed in order to enable calibration and validation of existing biogeochemical models (e.g. Biome-BGC, Version Zalf) in a follow-up project to be pursued subsequent to this funding period.