Abstract and background

Widespread changes in forest structure and distribution have been documented in northern Patagonia over the past century. We employed LPJ-GUESS, a dynamic global vegetation model (DGVM) to investigate the role of climate, atmospheric carbon dioxide (CO₂), and fire on simulated forest cover during the twentieth century. Our objective was to assess the drivers responsible for forest change to temperature, precipitation, radiation, fire and atmospheric CO₂

Results

Simulations using observed changes in climate and CO₂ from 1930 to 2010, showed an increase in forest cover under changing climate and CO₂, because of higher carbon assimilation and net primary production. The model results were compared with a remote-sensing-derived biomass map and ‘greening’ indices from the normalized difference vegetation index. Model simulations and satellite data both show increased greening at high and low elevations. In contrast, simulations using pre-industrial climate and CO₂ conditions resulted in a decrease in fire frequency and lower simulated biomass than is reflected by present-day vegetation.

Conclusion

Our simulations shows that climate is the primary driver and CO₂ fertilization is the secondary driver of forest expansion in northern Patagonia. We suggest that rising CO₂ mitigates climate-induced drought stress due to increases in water-use efficiency.

中文翻译：

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南美洲南部近期森林覆盖变化的驱动因素与气候和二氧化碳有关

摘要和背景

在过去的一个世纪里，巴塔哥尼亚北部的森林结构和分布发生了广泛的变化。我们采用 LPJ-GUESS，一种动态全球植被模型 (DGVM) 来研究20 世纪气候、大气二氧化碳 (CO ₂ ) 和火灾对模拟森林覆盖的作用。我们的目标是评估导致森林温度、降水、辐射、火灾和大气 CO ₂变化的驱动因素

结果

使用1930 年至 2010 年观测到的气候和 CO ₂变化进行的模拟显示，由于更高的碳同化和净初级生产，在气候和 CO ₂变化的情况下森林覆盖率增加。将模型结果与遥感衍生的生物量图和归一化差异植被指数中的“绿化”指数进行比较。模型模拟和卫星数据均显示高海拔和低海拔的绿化增加。相比之下，使用工业化前气候和 CO ₂条件的模拟导致火灾频率降低，模拟生物量低于当今植被所反映的情况。

结论

我们的模拟表明，气候是巴塔哥尼亚北部森林扩张的主要驱动因素，而 CO ₂施肥是其次要驱动因素。我们认为，由于水资源利用效率的提高，CO ₂上升可以减轻气候引起的干旱压力。