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    早春低温对千烟洲人工林总初级生产力的影响评估

    Assessment of the impact of early spring low temperatures on the gross primary productivity in Qianyanzhou plantations

    • 摘要: 气候变化背景下,极端气象事件频发,但早春低温对亚热带人工针叶林的影响尚未得到充分关注。本研究基于2003-2019年千烟洲站气象数据与生态系统总初级生产力(Gross Primary Productivity, GPP)数据,选取1-3月日平均温度低于5℃的天数(≥32天)和1-3月积温≤750℃作为早春低温气候致灾风险指标,并利用主成分分析量化两个低温因子的相对贡献,构建综合早春低温危险性模型,评估早春低温对GPP的影响。结果显示,千烟洲早春低温频发,出现概率高达23.2%,综合低温指数小于0.38可判定人工针叶林出现早春低温风险,能准确识别低温年份。早春低温对人工林GPP的影响评估模型表明,早春累计GPP与综合低温指数密切相关(R2=0.64,P<0.01);全年GPP与综合低温指数显著相关(R2=0.43,P<0.01)。综合早春低温指数每降低0.1单位,早春累计GPP和全年GPP分别平均减少12.5 g C·m?2、18.3 g C·m?2。这一研究结果可为定量评估人工林生态系统早春低温受害程度提供科学参考。

       

      Abstract: Under the background of climate change, extreme meteorological events have become increasingly frequent, yet the impacts of early spring low temperatures on subtropical artificial coniferous forests have received limited attention. Based on meteorological and gross primary productivity (GPP) data from the Qianyanzhou station during 2003–2019, this study selected days with daily mean temperatures below 5?°C (≥32 days) and cumulative temperatures ≤750?°C during January–March as early spring low-temperature hazard indicators. Principal component analysis was applied to quantify the relative contributions of these two low-temperature factors, and a comprehensive early spring low-temperature risk model was constructed to assess the impact of early spring low temperatures on GPP. The results indicate that early spring low temperatures are frequent at Qianyanzhou, with an occurrence probability of up to 23.2%. A comprehensive low-temperature index below 0.38 can be used to identify early spring low-temperature risk in artificial coniferous forests, effectively distinguishing low-temperature years. The assessment model of early spring low-temperature effects on artificial forest GPP shows that cumulative GPP in early spring is closely related to the comprehensive low-temperature index (R2=0.64, P<0.01), and annual GPP is significantly correlated with the index (R2=0.43, P<0.01). For every 0.1-unit decrease in the comprehensive early spring low-temperature index, cumulative GPP in early spring and annual GPP decrease on average by 12.5 g C·m?2 and 18.3 g C·m?2, respectively. These findings provide a scientific basis for quantitatively evaluating early spring low-temperature damage in artificial forest ecosystems.

       

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