Data Sheet 1_Short-term impacts of wildfire on vegetation recovery, soil chemical properties and community-level physiological profiling in a savanna ecosystem of Botswana.pdf

IntroductionSavanna ecosystems, an important contributor to Botswana’s economy and occupy up to 86 percent of the land mass of Botswana serving as habitat for wildlife and livestock that are being affected by frequent wildfire which are attributed in part to climate change. While the impact of wildfires on the environment has been extensively studied, there are some uncertainties as to their short-term effects on vegetation dynamics as well as the ability for vegetation to recover from fires. In addition, the impact on soil biogeochemical properties, soil microbial community dynamics, and their interaction within the savanna ecosystem in Botswana, needs to be understood to effectively manage the increasing occurrence of wildfires.
Methodology A comparative study was conducted on a burned area and unburned adjacent area within a period after 6 months after wildfire occurrence.
Results and discussionOur findings reveal that the ecological impacts of fire on vegetation, soil chemical properties, and microbial community dynamics were not uniform but were strongly mediated by site-specific conditions and the soil type of the associated plant species. Wildfire consistently reduced vegetation cover, plant biomass, and net primary productivity. In contrast, wildfire increased plant species diversity and evenness by disrupting competitive dominance. The impact of wildfire significant increases in soil pH and exchangeable cations (P, K, and Mg) only occurred at the nutrient-rich Mmashoro site and were further localized to the soils under Combretum apiculatum. Conversely, total organic matter increased post-fire at both sites, likely due to ash deposition. The effects of the wildfire on soil microbial community was also site-specific. In Palapye, fire significantly suppressed metabolic activity and functional evenness, leading to a less balanced community but was poorer in key mineral nutrients (K and Mg). Conversely, in Mmashoro, the microbial community associated with the fire-adapted tree C. apiculatum exhibited significant functional resilience, which retained high metabolic activity post-fire. We conclude that certain keystone plant species can mitigate the impacts of fire on belowground processes, creating resilient patches within the landscape. These findings underscore that effective fire management and conservation strategies in savanna ecosystems must be context-specific, accounting for the unique vegetation and soil characteristics of the area.

引言 稀树草原（Savanna）生态系统是博茨瓦纳经济的重要贡献者，其占地范围可达博茨瓦纳陆地总面积的86%，同时作为野生动物与家畜的栖息地，但频繁发生的野火正威胁这一生态系统，而野火频发在一定程度上归因于气候变化。尽管野火对环境的影响已被广泛研究，但目前仍存在诸多不确定性：野火对植被动态的短期效应，以及植被从野火扰动中恢复的能力，尚未明确。此外，为有效管控日益频发的野火事件，需进一步明确野火对博茨瓦纳稀树草原生态系统中土壤生物地球化学特性、土壤微生物群落动态及其相互作用的影响。
研究方法 本研究针对野火发生后的6个月周期内的火烧区域与相邻未火烧区域开展对比研究。
结果与讨论 本研究结果显示，野火对植被、土壤化学特性及微生物群落动态的生态影响并非统一，而是强烈受样地特异性条件与伴生植物物种的土壤类型所调控。野火普遍降低了植被覆盖度、植物生物量与净初级生产力。与之相对，野火通过破坏物种间的竞争优势地位，提升了植物物种多样性与均匀度。野火仅在养分富集的Mmashoro样地显著提升了土壤pH值与交换性阳离子（磷P、钾K、镁Mg）含量，且该效应仅局限于尖叶风车子（Combretum apiculatum）林下的土壤。与之相反，两处样地的土壤总有机质含量均在野火后有所提升，这大概率源于灰烬沉积。野火对土壤微生物群落的效应同样具有样地特异性。在Palapye样地，野火显著抑制了微生物代谢活性与功能均匀度，导致群落平衡性下降，且该样地土壤的关键矿质养分（钾K、镁Mg）含量也有所降低。与之相对，在Mmashoro样地，与适应野火的乔木尖叶风车子（C. apiculatum）共生的微生物群落展现出显著的功能恢复力，野火后仍维持了较高的代谢活性。本研究得出结论：部分关键植物物种可缓解野火对地下生态过程的影响，在景观中形成具有恢复力的生态斑块。上述研究结果表明，稀树草原生态系统的高效野火管理与保护策略必须具备情境特异性，需充分考量区域独特的植被与土壤特性。