Targeted grazing and mechanical thinning enhance forest stand resilience under a narrow range of wildfire scenarios
Abstract Increasing wildfire activity has spurred ecological resilience‐based management that aims to reduce the vulnerability of forest stands to wildfire by reducing the probability of crown fire. Targeted grazing is increasingly being used to build forest resilience to wildfire, either on its own...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2022-05-01
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| Series: | Ecosphere |
| Subjects: | |
| Online Access: | https://doi.org/10.1002/ecs2.4061 |
| _version_ | 1818236209631068160 |
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| author | Victoria M. Donovan Caleb P. Roberts Dillon T. Fogarty David A. Wedin Dirac Twidwell |
| author_facet | Victoria M. Donovan Caleb P. Roberts Dillon T. Fogarty David A. Wedin Dirac Twidwell |
| author_sort | Victoria M. Donovan |
| collection | DOAJ |
| description | Abstract Increasing wildfire activity has spurred ecological resilience‐based management that aims to reduce the vulnerability of forest stands to wildfire by reducing the probability of crown fire. Targeted grazing is increasingly being used to build forest resilience to wildfire, either on its own or in combination with treatments such as mechanical thinning; however, it is unclear how effective this method is at altering the probability of crown fire in forest stands. We use crown fire simulation models to quantify to what extent targeted grazing, mechanical thinning targeting the vertical fuel stratum, and a combination of both treatments alter eastern ponderosa pine savanna stand resilience to wildfire by modeling their relative impacts on the fuel stratum gap and subsequent crown fire occurrence under six different wildfire risk scenarios generated by altering wind and fuel moisture conditions. We then model changes in the probability of crown fire occurrence resulting from treatments across 75 field‐sampled sites in the Pine Ridge region of Nebraska relative to predicted crown fire occurrence when sites are left untreated. We find that mechanical (vertical) thinning has the potential to alter the probability of crown fire in ponderosa pine stands to a much greater extent than targeted grazing. Combining both approaches had a slightly higher probability of reducing crown fire risk across the greatest range of wildfire risk scenarios. Across 75 sample sites, targeted grazing was only predicted to prevent crown fire occurrence at two sites expected to experience crown fire under observed stand conditions across all six of our wildfire risk scenarios. In contrast, targeted grazing combined with mechanical thinning was predicted to prevent crown fire at approximately half of the sites expected to experience crown fire under observed conditions for mild and moderate wildfire risk scenarios. Thus, targeted grazing should be combined with mechanical thinning to best enhance forest resilience to wildfire. No combination of targeted grazing or mechanical thinning was able to alter the probability of crown fire under wildfire risk scenarios most conducive to wildfire, confirming that relying solely on vertical thinning and targeted grazing is unlikely to sufficiently enhance resilience of forest stands to future wildfire conditions. |
| first_indexed | 2024-12-12T12:06:14Z |
| format | Article |
| id | doaj.art-78a325b36abe4e7587c496a450e4acd9 |
| institution | Directory Open Access Journal |
| issn | 2150-8925 |
| language | English |
| last_indexed | 2024-12-12T12:06:14Z |
| publishDate | 2022-05-01 |
| publisher | Wiley |
| record_format | Article |
| series | Ecosphere |
| spelling | doaj.art-78a325b36abe4e7587c496a450e4acd92022-12-22T00:25:00ZengWileyEcosphere2150-89252022-05-01135n/an/a10.1002/ecs2.4061Targeted grazing and mechanical thinning enhance forest stand resilience under a narrow range of wildfire scenariosVictoria M. Donovan0Caleb P. Roberts1Dillon T. Fogarty2David A. Wedin3Dirac Twidwell4Department of Agronomy and Horticulture University of Nebraska‐Lincoln Lincoln Nebraska USADepartment of Agronomy and Horticulture University of Nebraska‐Lincoln Lincoln Nebraska USADepartment of Agronomy and Horticulture University of Nebraska‐Lincoln Lincoln Nebraska USASchool of Natural Resources University of Nebraska‐Lincoln Lincoln Nebraska USADepartment of Agronomy and Horticulture University of Nebraska‐Lincoln Lincoln Nebraska USAAbstract Increasing wildfire activity has spurred ecological resilience‐based management that aims to reduce the vulnerability of forest stands to wildfire by reducing the probability of crown fire. Targeted grazing is increasingly being used to build forest resilience to wildfire, either on its own or in combination with treatments such as mechanical thinning; however, it is unclear how effective this method is at altering the probability of crown fire in forest stands. We use crown fire simulation models to quantify to what extent targeted grazing, mechanical thinning targeting the vertical fuel stratum, and a combination of both treatments alter eastern ponderosa pine savanna stand resilience to wildfire by modeling their relative impacts on the fuel stratum gap and subsequent crown fire occurrence under six different wildfire risk scenarios generated by altering wind and fuel moisture conditions. We then model changes in the probability of crown fire occurrence resulting from treatments across 75 field‐sampled sites in the Pine Ridge region of Nebraska relative to predicted crown fire occurrence when sites are left untreated. We find that mechanical (vertical) thinning has the potential to alter the probability of crown fire in ponderosa pine stands to a much greater extent than targeted grazing. Combining both approaches had a slightly higher probability of reducing crown fire risk across the greatest range of wildfire risk scenarios. Across 75 sample sites, targeted grazing was only predicted to prevent crown fire occurrence at two sites expected to experience crown fire under observed stand conditions across all six of our wildfire risk scenarios. In contrast, targeted grazing combined with mechanical thinning was predicted to prevent crown fire at approximately half of the sites expected to experience crown fire under observed conditions for mild and moderate wildfire risk scenarios. Thus, targeted grazing should be combined with mechanical thinning to best enhance forest resilience to wildfire. No combination of targeted grazing or mechanical thinning was able to alter the probability of crown fire under wildfire risk scenarios most conducive to wildfire, confirming that relying solely on vertical thinning and targeted grazing is unlikely to sufficiently enhance resilience of forest stands to future wildfire conditions.https://doi.org/10.1002/ecs2.4061agroforestryfuel managementfuel stratum gapmechanical thinningprescribed firepruning |
| spellingShingle | Victoria M. Donovan Caleb P. Roberts Dillon T. Fogarty David A. Wedin Dirac Twidwell Targeted grazing and mechanical thinning enhance forest stand resilience under a narrow range of wildfire scenarios Ecosphere agroforestry fuel management fuel stratum gap mechanical thinning prescribed fire pruning |
| title | Targeted grazing and mechanical thinning enhance forest stand resilience under a narrow range of wildfire scenarios |
| title_full | Targeted grazing and mechanical thinning enhance forest stand resilience under a narrow range of wildfire scenarios |
| title_fullStr | Targeted grazing and mechanical thinning enhance forest stand resilience under a narrow range of wildfire scenarios |
| title_full_unstemmed | Targeted grazing and mechanical thinning enhance forest stand resilience under a narrow range of wildfire scenarios |
| title_short | Targeted grazing and mechanical thinning enhance forest stand resilience under a narrow range of wildfire scenarios |
| title_sort | targeted grazing and mechanical thinning enhance forest stand resilience under a narrow range of wildfire scenarios |
| topic | agroforestry fuel management fuel stratum gap mechanical thinning prescribed fire pruning |
| url | https://doi.org/10.1002/ecs2.4061 |
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