Liu Yijun, Zhang Li, Yan Wende, Peng Yuanying, Sun Hua, Chen Xiaoyong
College of Life Science and Technology, Central South University of Forestry and Technology, Changsha 410004, China.
National Engineering Laboratory for Applied Forest Ecological Technology in Southern China, Changsha 410004, China.
Plants (Basel). 2024 Oct 20;13(20):2937. doi: 10.3390/plants13202937.
Over the past three decades, China has implemented extensive reforestation programs, primarily utilizing Chinese fir ( (Lamb.) Hook) in southern China, to mitigate greenhouse gas emissions and counter extreme climate events. However, the effects of drought on the carbon sequestration capacity of these forests, particularly during the trunk wood stage, remain unclear. This study, conducted in Huitong, Hunan, China, from 2008 to 2013, employed the eddy covariance method to measure carbon dioxide (CO) and water fluxes in Chinese fir forests, covering a severe drought year in 2011. The purpose was to elucidate the dynamics of carbon and water fluxes during a drought year and across multi-normal year averages. The results showed that changes in soil water content (-8.00%), precipitation (-18.45%), and relative humidity (-5.10%), decreases in air temperature (-0.09 °C) and soil temperature (-0.79 °C), and increases in vapor pressure deficit (19.18%) and net radiation (8.39%) were found in the drought year compared to the normal years. These changes in environmental factors led to considerable decreases in net ecosystem exchange (-40.00%), ecosystem respiration (-13.09%), and gross ecosystem productivity (-18.52%), evapotranspiration (-12.50%), and water use efficiency (-5.83%) in the studied forests in the drought year. In this study, the occurrence of seasonal drought due to uneven precipitation distribution led to a decrease in gross ecosystem productivity (GEP) and evapotranspiration (ET). However, the impact of drought on GEP was greater than its effect on ET, resulting in a reduced water use efficiency (WUE). This study emphasized the crucial role of water availability in determining forest productivity and suggested the need for adjusting vegetation management strategies under severe drought conditions. Our results contributed to improving management practices for Chinese fir plantations in response to changing climate conditions.
在过去三十年里，中国实施了大规模的植树造林计划，主要在中国南方种植杉木（Cunninghamia lanceolata (Lamb.) Hook），以减少温室气体排放并应对极端气候事件。然而，干旱对这些森林碳固存能力的影响，尤其是在树干木质阶段，仍不明确。本研究于2008年至2013年在中国湖南会同进行，采用涡度相关法测量了杉木林的二氧化碳（CO₂）和水分通量，涵盖了2011年的一个严重干旱年份。目的是阐明干旱年份以及多个正常年份平均值期间碳和水分通量的动态变化。结果表明，与正常年份相比，干旱年份土壤含水量下降了8.00%、降水量下降了18.45%、相对湿度下降了5.10%，气温下降了0.09℃、土壤温度下降了0.79℃，水汽压差上升了19.18%、净辐射上升了8.39%。这些环境因素的变化导致研究森林在干旱年份的净生态系统交换量下降了40.00%、生态系统呼吸下降了13.09%、总生态系统生产力下降了18.52%、蒸散量下降了12.50%以及水分利用效率下降了5.83%。在本研究中，降水分布不均导致的季节性干旱使总生态系统生产力（GEP）和蒸散量（ET）下降。然而，干旱对GEP的影响大于对ET的影响，导致水分利用效率（WUE）降低。本研究强调了水分有效性在决定森林生产力方面的关键作用，并建议在严重干旱条件下需要调整植被管理策略。我们的结果有助于改进杉木人工林应对气候变化条件的管理实践。
