What happens after a grassland fire: how do grasslands and firebreaks recover?
In our recently published paper, we investigated grassland recovery following wildfire and firebreak establishment.
Deák B., Süveges K., Gőri Sz., Kapocsi I., Gál L. and Valkó O. (2026): Trade-offs between fire suppression and biodiversity: vegetation recovery in burnt grasslands and firebreaks under different restoration treatments. Fire Ecology, 22: 128.
The study is freely available to read and download here.
Fire has been part of grassland ecosystems in the Carpathian Basin since historical times. Together with flooding and grazing animals, it has shaped the landscape and contributed substantially to maintaining open habitats. Today, however, climate change, frequent droughts and the accumulation of dry plant biomass are increasing the risk of larger and less predictable fires. Such fires may threaten not only natural values but also human safety, as they can spread to farmland, farms and other infrastructure.
Fire has been part of grassland ecosystems in the Carpathian Basin since historical times. Together with flooding and grazing animals, it has shaped the landscape and contributed substantially to maintaining open habitats. Today, however, climate change, frequent droughts and the accumulation of dry plant biomass are increasing the risk of larger and less predictable fires. Such fires may threaten not only natural values but also human safety, as they can spread to farmland, farms and other infrastructure.
To suppress rapidly spreading fires, it may be necessary to establish firebreaks that interrupt the continuity of combustible plant material and can thus slow or stop the advancing flames. Firebreaks can therefore play an important role in fire suppression. In grasslands, however, their establishment usually involves soil disturbance, often by disk-harrowing. In protected areas, their location and method of establishment should consequently be selected with care. It is also important to understand how vegetation recovers on firebreaks and which treatments can support the restoration of the original vegetation.
In collaboration with the Hortobágy National Park Directorate, we investigated how vegetation recovered after an extensive but low-intensity grassland fire in the summer of 2022. Our study included both pristine and restored loess grasslands. For three years, we monitored vegetation changes in the burnt areas and in disk-harrowed firebreaks, comparing them with adjacent unburnt reference areas.
Some sections of the firebreaks were left to recover without further intervention after disk-harrowing. Elsewhere, we used a ring roller to level and compact the rough soil surface. In a third treatment, rolling was followed by sowing seeds of locally sourced Festuca rupicola. This allowed us to compare spontaneous recovery, the effects of soil-surface levelling and active grassland restoration.
Our results showed that the low-intensity fire caused only moderate and temporary changes in grassland vegetation. Grassland species recovered well during the first year, and no substantial weed encroachment occurred in the burnt areas over the longer term. One reason is that many perennial dry-grassland plants are adapted to occasional fires: although their above-ground shoots may burn, they can resprout from below-ground organs and stored reserves.
Recovery also began quickly on the firebreaks. Vegetation cover increased rapidly, and grassland species appeared from the first year onwards. Nevertheless, their cover had still not reached the levels observed in the surrounding grasslands after three years. Disk-harrowing removed the original vegetation, while soil disturbance promoted the germination of weed and disturbance-tolerant species present in the soil seed bank. Consequently, weeds and disturbance-tolerant species still accounted for a considerable proportion of the vegetation on spontaneously recovering and rolled firebreaks after three years. These findings show that, although recovery begins quickly, the development of vegetation resembling the surrounding grasslands may take considerably longer.
Rolling alone had only a moderate effect on the rate of recovery, whereas sowing Festuca rupicola substantially suppressed weeds. This vigorous perennial grass rapidly formed a continuous grass matrix that left progressively less space for weed species. At the same time, a dense Festuca stand may also slow the establishment of other valuable grassland species. The most appropriate method for restoring firebreaks should therefore be selected according to the condition of the surrounding grassland, the abundance of weeds and the potential for natural colonisation by grassland species.
Our research highlights the importance of considering fire-safety and biodiversity-conservation objectives together. Firebreaks can play an important role in suppressing wildfires, but in grasslands they should be planned and established with care. After their creation, vegetation recovery should also be monitored over the longer term. Regular monitoring makes it possible to identify persistent weed encroachment or stalled recovery at an early stage and, where necessary, support the development of grassland vegetation through targeted management, such as removing weeds before seed set or applying appropriate mowing, grazing or seed sowing.
It is important to emphasise that our results concern a single summer fire of relatively low intensity. Grassland species may not be able to withstand frequent or high-intensity fires without damage. As the climate becomes drier, uncontrolled fires therefore require increasing attention because they can rapidly cause both conservation and safety problems. Our study focused on vegetation, but extensive fires may affect some groups of animals, such as arthropods and ground-nesting birds, much more severely than plants.
The abstract of the paper is provided below.
Abstract
Background: Wildfire is an important component of many grassland ecosystems, but it is often suppressed in modern landscapes to protect infrastructure and human safety. Disk-harrowed firebreaks are frequently used to stop wildfire spread; however, this method represents a severe soil disturbance that may alter grassland species composition and structure. We studied the effects of a low-intensity growing-season wildfire on the vegetation of pristine and restored Central European dry grasslands, and evaluated vegetation recovery on firebreaks for three years post-fire. Firebreaks were subjected to passive restoration (disk-harrowing), assisted natural regeneration (rolling) or active restoration (rolling combined with grass seed sowing). In total, 180 permanent vegetation plots were surveyed for three years.
Results: Several grassland specialist species were associated with burnt grasslands during the first two post-fire years, but these patterns disappeared by the third year and did not affect overall specialist richness or cover. Fire did not promote disturbance-tolerant or weed species in the long run. Grassland specialists were able to re-establish in disk-harrowed and rolled firebreaks from the seed bank and seed rain; however, their cover remained substantially lower than in reference grasslands. Sowing seeds of the competitive perennial grass Festuca rupicola accelerated the development of a continuous grass cover and substantially reduced the proportion of weeds. Even in the third year after disturbance, firebreak vegetation remained dominated by disturbance-tolerant and weed species. Recovery of specialists was faster in restored grasslands, characterised by species typical of mid-successional stages, than in pristine grasslands.
Conclusion: Low-intensity growing-season wildfire had moderate and temporary effects on dry grasslands, indicating that fire represents an endogenous disturbance to which these communities respond with a short-term internal reorganisation. In contrast, mechanical soil disturbance associated with firebreak establishment represented an exogenous disturbance with longer-lasting effects on vegetation composition and structure. Although species richness of target grassland species recovered quickly, their cover remained lower than in reference grasslands even for the third year. Sowing a dominant perennial grass effectively suppressed weeds, but increased competition may limit the establishment of other grassland species. Our results highlight a trade-off between short-term fire safety and long-term biodiversity conservation, suggesting that firebreak establishment should be cautiously applied and accompanied by appropriate monitoring and targeted management.