The change in forest productivity was simulated in six stands in Wallonia (Belgium) following different climate scenarios using a process-based and spatially explicit tree growth model. Simulations revealed a strong and positive impact of the CO2fertilization while the negative effect of the transpiration deficit was compensated by longer vegetation periods. The site modulated significantly the forest productivity, mainly through the stand and soil characteristics. Forest net primary production (NPP) reflects forest vitality and is likely to be affected by climate change. Simulating the impact of changing environmental conditions on NPP and two of its main drivers (transpiration deficit and vegetation period) in six Belgian stands and decomposing the site effect. Based on the tree growth model HETEROFOR, simulations were performed for each stand between 2011 and 2100 using three climate scenarios and two CO2 modalities (constant vs time dependent). Then, the climate conditions, soils and stands were interchanged to decompose the site effect in these three components. In a changing climate with constant atmospheric CO2, NPP values remained constant due to a compensation of the negative effect of increased transpiration deficit by a positive impact of longer vegetation periods. With time-dependent atmospheric CO2, NPP substantially increased, especially for the scenarios with higher greenhouse gas (GHG) emissions. For both atmospheric CO2 modalities, the site characteristics modulated the temporal trends and accounted in total for 56 to 73% of the variability. Long-term changes in NPP were primarily driven by CO2 fertilization, reinforced transpiration deficit, longer vegetation periods and the site characteristics.

中文翻译：

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CO2 施肥、蒸腾亏缺和植被期驱动混合阔叶林对瓦隆地区气候变化的响应

使用基于过程和空间明确的树木生长模型，根据不同的气候情景，在瓦隆（比利时）的六个林分中模拟森林生产力的变化。模拟显示了二氧化碳施肥的强大而积极的影响，而蒸腾不足的负面影响被更长的植被周期所补偿。该场地主要通过林分和土壤特征显着调节森林生产力。森林净初级生产力（NPP）反映了森林的活力，很可能受到气候变化的影响。在六个比利时林分模拟环境条件变化对 NPP 及其两个主要驱动因素（蒸腾赤字和植被期）的影响并分解场地效应。基于树木生长模型 HETEROFOR，使用三种气候情景和两种 CO2 模式（恒定与时间相关）对 2011 年至 2100 年之间的每个展位进行了模拟。然后，交换气候条件、土壤和林分，以分解这三个分量中的立地效应。在大气 CO2 不变的气候变化中，NPP 值保持不变，这是由于较长植被期的积极影响补偿了蒸腾不足增加的负面影响。随着时间依赖的大气 CO2，NPP 大幅增加，特别是对于温室气体 (GHG) 排放量较高的情景。对于这两种大气 CO2 模式，场地特征调节了时间趋势，总共占了 56% 到 73% 的变异性。NPP 的长期变化主要由 CO2 施肥驱动，