Dirnböck T, Kraus D, Grote R, Klatt S, Kobler J, Schindlbacher A, Seidl R, Thom D, Kiese R
1Department for Ecosystem Research and Environmental Information Management, Environment Agency Austria, Spittelauer Lände 5, 1090 Vienna, Austria.
2Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Kreuzeckbahnstraße 19, 82467 Garmisch-Partenkirchen, Germany.
Landsc Ecol. 2020;35(2):483-499. doi: 10.1007/s10980-019-00960-2. Epub 2020 Feb 3.
The contribution of forest understory to the temperate forest carbon sink is not well known, increasing the uncertainty in C cycling feedbacks on global climate as estimated by Earth System Models.
We aimed at quantifying the effect of woody and non-woody understory vegetation on net ecosystem production (NEP) for a forested area of 158 km in the European Alps.
We simulated C dynamics for the period 2000-2014, characterized by above-average temperatures, windstorms and a subsequent bark beetle outbreak for the area, using the regional ecosystem model LandscapeDNDC.
In the entire study area, woody and non-woody understory vegetation caused between 16 and 37% higher regional NEP as compared to a bare soil scenario over the 15-year period. The mean annual contribution of the understory to NEP was in the same order of magnitude as the average annual European (EU-25) forest C sink. After wind and bark beetle disturbances, the understory effect was more pronounced, leading to an increase in NEP between 35 and 67% compared to simulations not taking into account these components.
Our findings strongly support the importance of processes related to the understory in the context of the climate change mitigation potential of temperate forest ecosystems. The expected increases in stand replacing disturbances due to climate change call for a better representation of understory vegetation dynamics and its effect on the ecosystem C balance in regional assessments and Earth System Models.
森林林下植被对温带森林碳汇的贡献尚不明确，这增加了地球系统模型估算的全球气候碳循环反馈的不确定性。
我们旨在量化欧洲阿尔卑斯山158平方千米森林区域内木本和非木本林下植被对净生态系统生产力（NEP）的影响。
我们使用区域生态系统模型LandscapeDNDC，模拟了2000 - 2014年期间该区域的碳动态，该时期的特点是气温高于平均水平、有风暴以及随后发生了树皮甲虫爆发。
在整个研究区域，在15年期间，与裸土情景相比，木本和非木本林下植被使区域NEP提高了16%至37%。林下植被对NEP的年平均贡献与欧洲（欧盟25国）森林碳汇的年均值处于同一数量级。在风灾和树皮甲虫干扰之后，林下植被的影响更为显著，与未考虑这些因素的模拟相比导致NEP增加了35%至67%。
我们的研究结果有力地支持了在温带森林生态系统缓解气候变化潜力的背景下，与林下植被相关过程的重要性。气候变化导致的林分更替干扰预计会增加，这就要求在区域评估和地球系统模型中更好地体现林下植被动态及其对生态系统碳平衡的影响。
