Long-Term Effects of Fuels Treatments, Overstory Structure, and Wildfire on Tree Regeneration in Dry Forests of Central Washington
The long-term effectiveness of dry-forest fuels treatments (restoration thinning and prescribed burning) depends, in part, on the pace at which trees regenerate and recruit into the overstory. Knowledge of the factors that shape post-treatment regeneration and growth is limited by the short timefram...
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-08-01
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| Series: | Forests |
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| Online Access: | https://www.mdpi.com/1999-4907/11/8/888 |
| _version_ | 1797557921156956160 |
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| author | Allison K. Rossman Jonathan D. Bakker David W. Peterson Charles B. Halpern |
| author_facet | Allison K. Rossman Jonathan D. Bakker David W. Peterson Charles B. Halpern |
| author_sort | Allison K. Rossman |
| collection | DOAJ |
| description | The long-term effectiveness of dry-forest fuels treatments (restoration thinning and prescribed burning) depends, in part, on the pace at which trees regenerate and recruit into the overstory. Knowledge of the factors that shape post-treatment regeneration and growth is limited by the short timeframes and simple disturbance histories of past research. Here, we present results of a 15-year fuels-reduction experiment in central Washington, including responses to planned and unplanned disturbances. We explore the changing patterns of Douglas-fir regeneration in 72 permanent plots (0.1 ha) varying in overstory abundance (a function of density and basal area) and disturbance history—the latter including thinning, prescribed burning, and/or wildfire. Plots were measured before treatment (2000/2001), soon afterwards (2004/2005), and more than a decade later (2015). Thinning combined with burning enhanced sapling recruitment (ingrowth) into the overstory, although rates of ingrowth were consistently low and greatly exceeded by mortality. Relationships between seedling frequency (proportion of quadrats within a plot) and overstory abundance shifted from weakly negative before treatment to positive after thinning, to neutral in the longer term. However, these relationships were overshadowed by more recent, higher-severity prescribed fire and wildfire that stimulated seedling establishment while killing advanced regeneration and overstory trees. Our results highlight the dependence of regeneration responses on the history of, and time since, fuels treatment and subsequent disturbance. Managers must be aware of this spatial and temporal complexity and plan for future disturbances that are inevitable but unpredictable in timing and severity. |
| first_indexed | 2024-03-10T17:23:05Z |
| format | Article |
| id | doaj.art-13fe38ef0760409e8d831ed10d58c003 |
| institution | Directory Open Access Journal |
| issn | 1999-4907 |
| language | English |
| last_indexed | 2024-03-10T17:23:05Z |
| publishDate | 2020-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Forests |
| spelling | doaj.art-13fe38ef0760409e8d831ed10d58c0032023-11-20T10:15:30ZengMDPI AGForests1999-49072020-08-0111888810.3390/f11080888Long-Term Effects of Fuels Treatments, Overstory Structure, and Wildfire on Tree Regeneration in Dry Forests of Central WashingtonAllison K. Rossman0Jonathan D. Bakker1David W. Peterson2Charles B. Halpern3School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, WA 98195, USASchool of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, WA 98195, USAU.S. Forest Service, Pacific Northwest Research Station, Wenatchee, WA 98801, USASchool of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, WA 98195, USAThe long-term effectiveness of dry-forest fuels treatments (restoration thinning and prescribed burning) depends, in part, on the pace at which trees regenerate and recruit into the overstory. Knowledge of the factors that shape post-treatment regeneration and growth is limited by the short timeframes and simple disturbance histories of past research. Here, we present results of a 15-year fuels-reduction experiment in central Washington, including responses to planned and unplanned disturbances. We explore the changing patterns of Douglas-fir regeneration in 72 permanent plots (0.1 ha) varying in overstory abundance (a function of density and basal area) and disturbance history—the latter including thinning, prescribed burning, and/or wildfire. Plots were measured before treatment (2000/2001), soon afterwards (2004/2005), and more than a decade later (2015). Thinning combined with burning enhanced sapling recruitment (ingrowth) into the overstory, although rates of ingrowth were consistently low and greatly exceeded by mortality. Relationships between seedling frequency (proportion of quadrats within a plot) and overstory abundance shifted from weakly negative before treatment to positive after thinning, to neutral in the longer term. However, these relationships were overshadowed by more recent, higher-severity prescribed fire and wildfire that stimulated seedling establishment while killing advanced regeneration and overstory trees. Our results highlight the dependence of regeneration responses on the history of, and time since, fuels treatment and subsequent disturbance. Managers must be aware of this spatial and temporal complexity and plan for future disturbances that are inevitable but unpredictable in timing and severity.https://www.mdpi.com/1999-4907/11/8/888Douglas-firFire and Fire Surrogatedry forest restorationfuels-reduction treatmentsprescribed firewildfire |
| spellingShingle | Allison K. Rossman Jonathan D. Bakker David W. Peterson Charles B. Halpern Long-Term Effects of Fuels Treatments, Overstory Structure, and Wildfire on Tree Regeneration in Dry Forests of Central Washington Forests Douglas-fir Fire and Fire Surrogate dry forest restoration fuels-reduction treatments prescribed fire wildfire |
| title | Long-Term Effects of Fuels Treatments, Overstory Structure, and Wildfire on Tree Regeneration in Dry Forests of Central Washington |
| title_full | Long-Term Effects of Fuels Treatments, Overstory Structure, and Wildfire on Tree Regeneration in Dry Forests of Central Washington |
| title_fullStr | Long-Term Effects of Fuels Treatments, Overstory Structure, and Wildfire on Tree Regeneration in Dry Forests of Central Washington |
| title_full_unstemmed | Long-Term Effects of Fuels Treatments, Overstory Structure, and Wildfire on Tree Regeneration in Dry Forests of Central Washington |
| title_short | Long-Term Effects of Fuels Treatments, Overstory Structure, and Wildfire on Tree Regeneration in Dry Forests of Central Washington |
| title_sort | long term effects of fuels treatments overstory structure and wildfire on tree regeneration in dry forests of central washington |
| topic | Douglas-fir Fire and Fire Surrogate dry forest restoration fuels-reduction treatments prescribed fire wildfire |
| url | https://www.mdpi.com/1999-4907/11/8/888 |
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