Donovan Victoria M, Ludwig Alison K, Fogarty Dillon T, Roberts Caleb P, Twidwell Dirac
West Florida Research and Education Center, School of Forest, Fisheries, and Geomatics Sciences, Institute of Food and Agricultural Sciences, University of Florida, Milton, FL, USA.
Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
J Environ Manage. 2025 Sep;391:126469. doi: 10.1016/j.jenvman.2025.126469. Epub 2025 Jul 15.
Woody encroachment has driven drastic declines in grassland biodiversity and productivity. In the U.S. Great Plains, high-intensity prescribed fire is increasingly being used to shift encroaching redcedar woodlands to a grassland state. High-intensity fire treatments drive redcedar mortality and increase herbaceous biomass. However, it is unclear how grassland community composition recovers following stand-consuming fire. We contrast herbaceous community composition, basal cover, and species richness in woodlands treated with stand-consuming high-intensity fire to reference grassland and woodland sites to examine whether high-intensity fires facilitate restoration of grassland communities. To determine the long-term outcomes of high-intensity fire treatments, we use a space-for-time substitute to measure changes to herbaceous community and species richness over a time-since-fire gradient of 17 years. We found that herbaceous cover and species richness increased substantially in woodlands treated with stand-consuming high-intensity fire compared to unburned woodlands, and that these values were similar to those observed in both burned and unburned grasslands. Herbaceous community composition in woodlands treated with high-intensity fire also shifted towards grasslands, though some legacies of woodland communities persisted. Time-since-fire generally did not have a large influence on total herbaceous cover or species richness through time, though grass cover decreased in woodlands treated with high-intensity fire a decade post-treatment. Our findings suggest that a single high-intensity fire can support the restoration of herbaceous plant species richness and cover, and shift community composition to a grassland regime, though additional low-intensity fire treatments may be necessary to erode legacies from the encroached state.
木本植物入侵导致了草原生物多样性和生产力的急剧下降。在美国大平原地区，高强度的规定火烧正越来越多地被用于将入侵的红雪松林地转变为草原状态。高强度火烧处理会导致红雪松死亡，并增加草本生物量。然而，尚不清楚在消耗性火烧之后草原群落组成是如何恢复的。我们对比了经过消耗性高强度火烧处理的林地与参考草原和林地的草本群落组成、基部覆盖度和物种丰富度，以研究高强度火烧是否有助于草原群落的恢复。为了确定高强度火烧处理的长期效果，我们使用空间换时间的替代方法，来测量在17年的火烧后时间梯度上草本群落和物种丰富度的变化。我们发现，与未火烧的林地相比，经过消耗性高强度火烧处理的林地中草本覆盖度和物种丰富度大幅增加，而且这些数值与在火烧和未火烧草原中观察到的数值相似。经过高强度火烧处理的林地中的草本群落组成也向草原方向转变，不过林地群落的一些遗留特征仍然存在。随着时间推移，火烧后时间一般对总草本覆盖度或物种丰富度没有太大影响，尽管在处理后十年，经过高强度火烧处理的林地中草覆盖度有所下降。我们的研究结果表明，单次高强度火烧能够促进草本植物物种丰富度和覆盖度的恢复，并使群落组成转变为草原状态，不过可能需要额外的低强度火烧处理来消除入侵状态带来的遗留影响。
