Abstract The effects of selective logging in Argentinean native subtropical forests or its replacement by pine plantations on carbon and hydrological cycles is of importance for developing strategies for a sustainable use of water resources and climate mitigation in subtropical humid regions. Ecosystem-level gross primary productivity (GPP), evapotranspiration (ET) and water use efficiency (WUE) were assessed using multi-temporal MODIS remote sensing data and its response to climatic variables were analyzed in well-preserved native forests, degraded native forests by selective harvesting and pine plantations. Field measurements of leaf area index (LAI), tree density, basal area, tree high, diameter at breast height and understory cover was implemented. The GPP was high throughout the year across all three-land use types. Selective harvesting of commercial trees resulted in a significant decrease in tree density and in basal area compared to well-preserved native forests but did not have a negative impact on GPP. Mean annual ET was similar between both native forests because although the degraded forest had a lower tree density they had a greater maximun DBH per tree than the well-preserved forests and therefore high transpiration. The WUE was similar across the ecosystem types. Removal of 5.5 m2 of canopy trees produced a compensatory change in ecosystem structure and function resulting in the maintenance of GPP and ET. Replacement of native forests by pine plantations for wood production did not change annual GPP compared to native forests, but the final carbon assimilation should be lower due to the CO2 released before canopy closure and after harvesting. All climatic variables were linearly and significantly related to monthly GPP, ET and WUE with the exception of precipitation with monthly GPP. Finding forest management techniques for increasing carbon assimilation is of importance for limiting the rise of global CO2 emissions and for regulation of the water cycle.

中文翻译：

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亚热带生态系统不同土地利用类型下的碳同化、耗水量和用水效率：从原始森林到松林

摘要 阿根廷本土亚热带森林的选择性采伐或被松树人工林替代对碳和水文循环的影响对于制定可持续利用水资源和减缓亚热带湿润地区气候的战略具有重要意义。使用多时相 MODIS 遥感数据评估了生态系统一级的总初级生产力 (GPP)、蒸散量 (ET) 和用水效率 (WUE)，并在保存完好的原始森林、退化的原始森林中分析了其对气候变量的响应选择性收获和松树种植园。实施了叶面积指数 (LAI)、树密度、基面积、树高、胸高直径和林下覆盖率的实地测量。所有三种土地利用类型的 GPP 全年都很高。与保存完好的原生林相比，选择性采伐商业树木导致树木密度和基底面积显着下降，但并未对 GPP 产生负面影响。两种原始森林的年平均 ET 相似，因为尽管退化森林的树木密度较低，但与保存完好的森林相比，它们每棵树的最大胸径更大，因此蒸腾作用较高。不同生态系统类型的 WUE 相似。移除 5.5 m2 的树冠导致生态系统结构和功能的补偿性变化，从而维持 GPP 和 ET。与原生林相比，用松树人工林替代原生林用于木材生产并没有改变年度 GPP，但由于冠层关闭前和采伐后释放的二氧化碳，最终的碳同化应该较低。除降水与月 GPP 外，所有气候变量均与月 GPP、ET 和 WUE 呈线性显着相关。寻找增加碳同化的森林管理技术对于限制全球二氧化碳排放量的增加和调节水循环具有重要意义。