Study

Fire, mowing, and hand-removal of woody species in restoring a native wetland prairie in the Willamette Valley of Oregon

  • Published source details Clark D.L. & Wilson M.V. (2001) Fire, mowing, and hand-removal of woody species in restoring a native wetland prairie in the Willamette Valley of Oregon. Wetlands, 21, 135-144.

Actions

This study is summarised as evidence for the following.

Action Category

Cut large trees/shrubs to maintain or restore disturbance: freshwater marshes

Action Link
Marsh and Swamp Conservation

Use prescribed fire to maintain or restore disturbance: freshwater marshes

Action Link
Marsh and Swamp Conservation

Cut/mow herbaceous plants to maintain or restore disturbance: freshwater marshes

Action Link
Marsh and Swamp Conservation
  1. Cut large trees/shrubs to maintain or restore disturbance: freshwater marshes

    A replicated, randomized, paired, controlled, before-and-after study in 1994–1997 in an ephemeral wet prairie in Oregon, USA (Clark & Wilson 2001) found that cutting woody plants reduced their cover (but not their short-term survival) and affected cover of forbs – but not the dominant herb species or vegetation overall. Over three years, woody plant cover declined in plots where they were cut (by 79%), but increased in plots where they were not cut (by 20%). This is despite no significant effect on woody plant survival in the first year after cutting (cut: 60%; uncut: 83%). Changes in forb cover also significantly differed between cut and uncut plots, although the precise effect depended on whether forbs were native (cut: 167% increase; uncut: 77% decrease) or non-native (cut: 45% decrease; uncut: 28% increase). Plots under each treatment experienced statistically similar increases in overall vegetation cover (cut: 42%; uncut: 31%) and cover of the dominant herb species, tussock grass Deschampsia cespitosa (cut: 8%; uncut: 31%; see original paper for data on other individual plant species). Methods: In 1994, five pairs of plots (each 56–140 m2) were established in a degraded, seasonally flooded prairie. Woody plants had grown over 200 years of fire suppression. In autumn 1994 and 1996, all woody vegetation was cut with pruners or loppers, then removed, from one plot/pair. Vegetation was surveyed before (summer 1994) and after cutting. Survival of six tagged woody plants/plot was recorded in summer 1995. Cover of selected herb species was recorded in three 0.5-m2 quadrats/plot in summer 1997.

    (Summarised by: Nigel Taylor)

  2. Use prescribed fire to maintain or restore disturbance: freshwater marshes

    A replicated, randomized, paired, controlled, before-and-after study in 1994–1997 in an ephemeral wet prairie in Oregon, USA (Clark & Wilson 2001) found that burning woody plants reduced their survival and cover and increased native forb abundance, but had no significant effect on overall vegetation or herb cover. After one year, the survival rate of woody plants was lower in burned (33%) than unburned plots (83%). Over three years, woody plant cover decreased in burned plots (by 63%) but increased in unburned plots (by 20%). Native forb cover increased in burned plots at the expense of non-native forbs (natives: 8% increase; non-natives: 77% decrease). The opposite was true in unburned plots (natives: 30% decrease; non-natives: 28% increase). However, burned and unburned plots experienced statistically similar changes in overall vegetation cover (increase; burned: 41%; unburned: 31%) and cover of the dominant herb species, tussock grass Deschampsia cespitosa (increase; burned: 31%; unburned: 31%; see original paper for data on other individual plant species). Methods: In 1994, five pairs of plots (each 64–160 m2) were established in a degraded, seasonally flooded prairie. Woody plants had grown over 200 years of fire suppression. In each pair, one random plot was burned in autumn 1994 and 1996. Vegetation was surveyed before (summer 1994) and after burning. Survival of six tagged woody plants/plot was recorded in summer 1995. Cover of selected herb species was recorded in three 0.5-m2 quadrats/plot in summer 1997.

    (Summarised by: Nigel Taylor)

  3. Cut/mow herbaceous plants to maintain or restore disturbance: freshwater marshes

    A replicated, randomized, paired, controlled, before-and-after study in 1994–1997 in an ephemeral wet prairie in Oregon, USA (Clark & Wilson 2001) found that mowing did not significantly affect the overall vegetation cover, forb cover, cover of the dominant herb species, and woody plant cover or survival. Over three years, mown and unmown plots experienced similar proportional changes in overall vegetation cover (increase; mown: 60%; unmown: 31%), native forb cover (decrease; mown: 14%; unmown: 77%), non-native forb cover (increase; mown: 43%; unmown: 28%), cover of the dominant herb species, tussock grass Deschampsia cespitosa (mown: 1% decrease; unmown: 30% increase; see original paper for data on other individual plant species) and woody plant cover (increase; mown: 25%; unmown: 20%). Furthermore, woody plants had similar survival rates over one year in mown plots (88%) and unmown plots (83%). Methods: In 1994, five pairs of plots (each 56–140 m2) were established in a degraded, seasonally flooded prairie. Woody plants had grown over 200 years of fire suppression. One plot/pair was mown (herbs and woody vegetation; cuttings removed) in autumn 1994 and 1996. Vegetation was surveyed before (summer 1994) and after mowing. Survival of six tagged woody plants/plot was recorded in summer 1995. Cover of selected herb species was recorded in three 0.5-m2 quadrats/plot in summer 1997.

    (Summarised by: Nigel Taylor)

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