Differential impacts of fire and inundation on a wetland plant community after wildfire

Abstract

<p><b>Context.</b> Understanding fire and inundation impacts on wetland vegetation communities is crucial for effective post-fire wetland management. <b>Aims.</b> We aimed to determine the impact of post-fire inundation on plant community structure and seedling germination and establishment after a large wildfire. We asked two questions, namely (1) did fire, drought or inundation affect plant communities the most; and (2) did fire or inundation affect seedling germination and establishment? <b>Methods.</b> Using a before–after–control–impact (BACI) design, we monitored vegetation changes in water-couch wetland communities before and after a wildfire. Also, soil samples were collected from burnt and unburnt sites and assessed for impacts of fire and post-fire inundation regimes on seed germination and seedling establishment. <b>Key results.</b> Inundation variables had more pronounced and more consistent impacts on vegetation measures than did fire or drought variables. Fire impacts were mainly short-term, with impact thresholds at 72 and 143 days after fire. Low germination levels and zero seedling survival were observed without inundation. <b>Conclusions.</b> Fire was a major but short-term contributor to wetland vegetation change, whereas drought had longer-term impacts, and inundation regimes had the greatest impacts. <b>Implications.</b> Providing a range of inundation conditions post-fire may enhance wetland vegetation recovery and have modifying effects on invasive species.</p>