Frequency and severity of wildfires have intensified in many regions in the world. High severity fires often initiate vegetation regrowth and succession, and thus alter ecosystem processes and functioning. Understanding how high severity fire-induced variations in gross primary production (GPP) respond to climate variability is critically important. This study aimed to quantify fire-induced changes in the response of GPP to concurrent and antecedent precipitation and air temperature in a semi-arid woodland in South Australia, using MODIS derived near-infrared reflectance of vegetation (NIRv) time series data (2000–2021) and associated climate data. Additionally, the magnitude and time course of climate legacies on GPP of unburnt and severely burnt sites were determined. The results showed that fire severity increased the variability in post-fire vegetation recovery. Prior to fire disturbance, NIRv as a proxy of GPP, was predominately affected by both concurrent and antecedent precipitation. Pre-fire precipitation legacy was about 9 months. Post-fire precipitation legacy duration was shorter in the unburnt patches within fire scar (ca. 9 months) than outside the fire scar (ca. 15 months), suggesting that the unburnt patches remaining within fire scar were more vulnerable to climate change than the adjacent intact woodland. In addition, the temperature legacies varied over time, likely mediated by water availability in this woodland. Post-fire regrowth from lignotubers was not significantly affected by concurrent and antecedent climate variables, but dependent upon endogenous growth which depends on previous growth conditions. This may be due to the smaller root system which reduced the capacity for taking up rain water after the fire event when annual precipitation was relatively low. We suggest that higher temperature together with reduced and more variable precipitation in the future could induce greater uncertainty in recovery of trees post-fire.

中文翻译：

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严重的野火增加了南澳大利亚以桉树为主的半干旱林地总初级生产对气候响应的变异性


世界许多地区野火的发生频率和严重程度都在加剧。高强度火灾通常会引发植被再生和演替，从而改变生态系统过程和功能。了解严重火灾引起的初级生产总值 (GPP) 变化如何应对气候变化至关重要。本研究旨在利用 MODIS 导出的植被近红外反射率 (NIRv) 时间序列数据（2000 年 - 2021）和相关气候数据。此外，还确定了未燃烧和严重燃烧地点的气候遗产对 GPP 的影响程度和时间进程。结果表明，火灾严重程度增加了火灾后植被恢复的可变性。在火灾发生之前，NIRv 作为 GPP 的代表，主要受到同期和前期降水的影响。火前降水遗留时间约为9个月。火痕内未烧毁斑块的火后降水遗留持续时间（约 9 个月）比火疤外未烧毁斑块（约 15 个月）短，这表明火痕内未烧毁斑块比火痕内未烧毁斑块更容易受到气候变化的影响。毗邻完整的林地。此外，温度遗留随时间变化，可能是由这片林地的可用水量调节的。木薯的火灾后再生并不受当时和先前气候变量的显着影响，而是依赖于内源生长，而内源生长又取决于先前的生长条件。 这可能是由于根系较小，导致火灾后年降水量相对较低时吸收雨水的能力降低。我们认为，未来气温升高，加上降水减少且变化更大，可能会给火灾后树木的恢复带来更大的不确定性。