Overcoming an 'irreversible' threshold: A 15-year fire experiment
| Autor: | Victoria M. Donovan, Dirac Twidwell, Craig R. Allen, Christine H. Bielski, Rheinhardt Scholtz |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Environmental Engineering
0208 environmental biotechnology Biodiversity 02 engineering and technology Woodland 010501 environmental sciences Management Monitoring Policy and Law Forests 01 natural sciences Grassland Fires Dominance (ecology) Regime shift Biomass Waste Management and Disposal Ecosystem 0105 earth and related environmental sciences geography geography.geographical_feature_category biology Ecology General Medicine Herbaceous plant biology.organism_classification 020801 environmental engineering Disturbance (ecology) Environmental science Juniper |
| Zdroj: | Journal of environmental management. 291 |
| ISSN: | 1095-8630 |
| Popis: | A key pursuit in contemporary ecology is to differentiate regime shifts that are truly irreversible from those that are hysteretic. Many ecological regime shifts have been labeled as irreversible without exploring the full range of variability in stabilizing feedbacks that have the potential to drive an ecological regime shift back towards a desirable ecological regime. Removing fire from grasslands can drive a regime shift to juniper woodlands that cannot be reversed using typical fire frequency and intensity thresholds, and has thus been considered irreversible. This study uses a unique, long-term experimental fire landscape co-dominated by grassland and closed-canopy juniper woodland to determine whether extreme fire can shift a juniper woodland regime back to grassland dominance using aboveground herbaceous biomass as an indicator of regime identity. We use a space-for-time substitute to quantify herbaceous biomass following extreme fire in juniper woodland up to 15 years post-fire and compare these with (i) 15 years of adjacent grassland recovery post-fire, (ii) unburned closed-canopy juniper woodland reference sites and (iii) unburned grassland reference sites. Our results show grassland dominance rapidly emerges following fires that operate above typical fire intensity thresholds, indicating that grassland-juniper woodlands regimes are hysteretic rather than irreversible. One year following fire, total herbaceous biomass in burned juniper stands was comparable to grasslands sites, having increased from 5 ± 3 g m−2 to 142 ± 42 g m−2 (+2785 ± 812 percent). Herbaceous dominance in juniper stands continued to persist 15-years after initial treatment, reaching a maximum of 337 ± 42 g m−2 eight years post-fire. In juniper encroached grasslands, fires that operate above typical fire intensity thresholds can provide an effective method to reverse juniper woodland regime shifts. This has major implications for regions where juniper encroachment threatens rancher-based economies and grassland biodiversity and provides an example of how to operationalize resilience theory to disentangle irreversible thresholds from hysteretic system behavior. |
| Databáze: | OpenAIRE |
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