Study

Effects of habitat management treatments on plant community composition and biomass in a montane wetland

  • Published source details Austin J.E., Keough J.R. & Pyle W.H. (2007) Effects of habitat management treatments on plant community composition and biomass in a montane wetland. Wetlands, 27, 570-587.

Actions

This study is summarised as evidence for the following.

Action Category

Change season/timing of livestock grazing: brackish/salt marshes

Action Link
Marsh and Swamp Conservation

Change season/timing of livestock grazing: freshwater marshes

Action Link
Marsh and Swamp Conservation

Use grazing to maintain or restore disturbance: brackish/salt marshes

Action Link
Marsh and Swamp Conservation

Use grazing to maintain or restore disturbance: freshwater marshes

Action Link
Marsh and Swamp Conservation

Use prescribed fire to maintain or restore disturbance: brackish/salt marshes

Action Link
Marsh and Swamp Conservation

Use prescribed fire to maintain or restore disturbance: freshwater marshes

Action Link
Marsh and Swamp Conservation
  1. Change season/timing of livestock grazing: brackish/salt marshes

    A replicated, randomized, paired, controlled, before-and-after study in 1998–1999 in six fields containing ephemeral alkali marshes in Idaho, USA (Austin et al. 2007) found that summer and autumn grazing had similar effects on vegetation biomass. Over one year including a period of grazing, changes in live above-ground plant biomass were statistically similar in summer-grazed alkali marshes (non-significant decrease of 30 g/m2) and autumn-grazed alkali marshes (non-significant increase of 30 g/m2). Methods: The study used three pairs of fields around a lake. Each field contained a range of wetland habitats, including alkali flats (seasonally flooded; developed salt crust in summer). All fields had been historically grazed and cut, but were undisturbed from 1996. In each pair, one random field was grazed July–August 1998 and the other was grazed September–October 1998 (both by cattle, at 2.3–2.5 animal unit months/ha; one AUM is the amount of feed required to sustain a 1,000-lb cow and her calf for one month). Vegetation was surveyed in June–July before (1998) and after (1999) one season of grazing.

    (Summarised by: Nigel Taylor)

  2. Change season/timing of livestock grazing: freshwater marshes

    A replicated, randomized, paired, controlled, before-and-after study in 1998–1999 in six fields containing a range of freshwater marsh and wet meadow habitats in Idaho, USA (Austin et al. 2007) found that summer and autumn grazing typically had similar effects on plant communities and on vegetation biomass. Over one year including a period of grazing, summer- and autumn-grazed plots experienced similar changes plant community composition (if any) in all four freshwater habitat types (data presented as graphical analyses; statistical significance of differences not assessed). In three of four freshwater habitat types, summer- and autumn-grazed plots experienced similar changes in live above-ground biomass (summer-grazed: decrease of 290 g/m2 to increase of 60 g/m2; autumn-grazed: decrease, but not always significant, of 5–140 g/m2). For the other vegetation type, plant biomass declined in summer-grazed plots (by 350 g/m2) but did not change in autumn-grazed plots (non-significant increase of 20 g/m2). Methods: The study used three pairs of fields around a lake. Each field contained a range of freshwater habitats, from permanently flooded marshes to ephemeral wet meadows. All fields had been historically grazed and cut, but were undisturbed from 1996. In each pair, one random field was grazed July–August 1998 and the other was grazed September–October 1998 (both by cattle, at 2.3–2.5 animal unit months/ha; one AUM is the amount of feed required to sustain a 1,000-lb cow and her calf for one month). Vegetation was surveyed in June–July before (1998) and after (1999) one season of grazing.

    (Summarised by: Nigel Taylor)

  3. Use grazing to maintain or restore disturbance: brackish/salt marshes

    A replicated, randomized, paired, controlled, before-and-after study in 1998–2000 in ephemeral alkali marshes around one lake in Idaho, USA (Austin et al. 2007) found that grazing had no significant effect on vegetation biomass. After both one and two years, changes in live above-ground plant biomass were statistically similar in grazed plots (non-significant change of <40 g/m2 from before to after intervention) and ungrazed plots (non-significant change of <100 g/m2 from before to after intervention). Methods: Three sets of three fields with similar neighbouring vegetation were studied. Each field contained a range of wetland habitats, including alkali flats (seasonally flooded; developed salt crust in summer). All fields had been historically grazed and cut, but were undisturbed from 1996. Three fields (one random field/set) received each treatment: annual autumn grazing (September–October 1998 and 1999), one-off summer grazing (July–August 1998) or no grazing. Grazing intensity was 2.3–2.5 animal unit months/ha (one AUM is the amount of feed required to sustain a 1,000-lb cow and her calf for one month). Vegetation was surveyed in June–July before intervention (1998) and for two years after (1999, 2000).

    (Summarised by: Nigel Taylor)

  4. Use grazing to maintain or restore disturbance: freshwater marshes

    A replicated, randomized, paired, controlled, before-and-after study in 1998–2000 of a range of freshwater marsh and wet meadow habitats around one lake in Idaho, USA (Austin et al. 2007) found that grazing typically had no clear effect on plant community composition, but that summer grazing affected vegetation biomass in some vegetation types. Over two years, the overall plant community composition within freshwater habitats remained similar in autumn-grazed, summer-grazed and ungrazed plots (data presented as graphical analyses; statistical significance of differences not assessed). In 12 of 16 comparisons, changes in live, above-ground plant biomass (from before to after grazing) were not significantly different in grazed and ungrazed plots. This was true for all eight comparisons involving autumn grazing and four of eight comparisons involving summer grazing (see original paper for data). In the other four comparisons, all in the wettest habitats, vegetation biomass declined in summer-grazed plots (by 200–350 g/m2) but did not significantly change in ungrazed plots (non-significant increases of 20–230 g/m2). Methods: Three sets of three fields with similar neighbouring vegetation were studied. Each field contained a range of freshwater habitats, from permanently flooded marshes to ephemeral wet meadows. All fields had been historically grazed and cut, but were undisturbed from 1996. Three fields (one random field/set) received each treatment: annual autumn grazing (September–October 1998 and 1999), one-off summer grazing (July–August 1998) or no grazing. Grazing intensity was 2.3–2.5 animal unit months/ha (one AUM is the amount of feed required to sustain a 1,000-lb cow and her calf for one month). Vegetation was surveyed in June–July before intervention (1998) and for two years after (1999, 2000).

    (Summarised by: Nigel Taylor)

  5. Use prescribed fire to maintain or restore disturbance: brackish/salt marshes

    A replicated, randomized, paired, controlled, before-and-after study in 1998–2000 in ephemeral alkali marshes around one lake in Idaho, USA (Austin et al. 2007) found that a single prescribed burn had no significant effect on vegetation biomass. After both one and two years, changes in live above-ground plant biomass were statistically similar in burned plots (non-significant change of <40 g/m2 from before to after intervention) and unburned plots (non-significant change of <100 g/m2 from before to after intervention). Methods: Three pairs of fields with similar neighbouring vegetation were studied. Each field contained a range of wetland habitats, including alkali flats (seasonally flooded; developed a salt crust each summer). All fields had been historically grazed and cut, but were undisturbed from 1996. In October 1998 (when vegetation was dormant) one random field per pair was burned. Vegetation was surveyed in June–July before intervention (1998) and for two years after (1999, 2000).

    (Summarised by: Nigel Taylor)

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

    A replicated, randomized, paired, controlled, before-and-after study in 1998–2000 of a range of marsh and wet meadow habitats around one lake in Idaho, USA (Austin et al. 2007) found that prescribed burning typically had no clear or significant effect on plant community composition or biomass. Over two years, the overall plant community composition within freshwater habitats remained similar in burned and unburned plots (data presented as graphical analyses; statistical significance of differences not assessed). In six of eight comparisons, changes in live, above-ground plant biomass (from before to after grazing) were not significantly different in burned plots (decrease of 200 g/m2 to non-significant increase of 20 g/m2) and unburned plots (decrease of 170 g/m2 to non-significant increase of 130 g/m2). Methods: Three pairs of fields with similar neighbouring vegetation were studied. Each field contained a range of freshwater habitats, from permanently flooded marshes to ephemeral wet meadows. All fields had been historically grazed and cut, but were undisturbed from 1996. In October 1998 (when vegetation was dormant) one random field in each pair was burned. Vegetation was surveyed in June–July before intervention (1998) and for two years after (1999, 2000).

    (Summarised by: Nigel Taylor)

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