Study

Effects of harvesting dates and frequencies on above and below-ground dynamics in Belgian wet grasslands

  • Published source details Dumortier M., Verlinden A., Beeckman H. & Van D.M.K. (1996) Effects of harvesting dates and frequencies on above and below-ground dynamics in Belgian wet grasslands. Écoscience, 3, 190-198

Actions

This study is summarised as evidence for the following.

Action Category

Reduce frequency of vegetation harvest: freshwater marshes

Action Link
Marsh and Swamp Conservation

Change season/timing of vegetation harvest: freshwater marshes

Action Link
Marsh and Swamp Conservation

Reduce frequency of cutting/mowing: freshwater marshes

Action Link
Marsh and Swamp Conservation

Change season/timing of cutting/mowing: 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. Reduce frequency of vegetation harvest: freshwater marshes

    A replicated, paired, controlled, before-and-after study in 1986–1988 in five wet grasslands in Belgium (Dumortier et al. 1996) reported that harvesting plots once per year increased plant species richness and sometimes increased plant biomass, whilst harvesting twice per year increased plant species richness and reduced plant biomass. Statistical significance was not assessed. Over two years, plant species richness increased whether plots were harvested once per year (July: from 15 to 18 species/6 m2; October: from 19 to 20 species/6 m2) or twice per year (July and October: from 17 to 19 species/6 m2). Total above-ground biomass (including litter) increased in plots harvested in July (from 460 to 490 g/m2), but declined in plots harvested in October (from 730 to 480 g/m2) or July and October (from 660 to 630 g/m2). The study also included some data on the abundance of individual plant species under each harvesting regime (see original paper). Methods: In spring 1986, three 7 x 7 m plots were established in each of five adjacent wet grasslands (mown annually for the previous 10 years). From 1986, five plots (one plot/grassland) were mown in July, five were mown in October, and five were mown in July and October. Cuttings were removed. Plant species were recorded each summer between 1986 and 1988. Biomass was cut and collected from five 30 x 30 cm quadrats/plot/year, immediately before the first harvest (so not at the same time in all plots), then dried and weighed.

    (Summarised by: Nigel Taylor)

  2. Change season/timing of vegetation harvest: freshwater marshes

    A replicated, paired, before-and-after study in 1986–1988 in five wet grasslands in Belgium (Dumortier et al. 1996) reported mixed effects of single annual harvests, between June and November, on plant species richness and biomass. Statistical significance was not assessed. Over two years, plant species richness increased in plots harvested between July and October (from 15–19 to 18–20 species/6 m2). It declined in plots harvested in November (from 19 to 18 species/6 m2) and was stable in plots harvested in June (17 species/6 m2). Total above-ground biomass (including litter) declined in plots harvested between August and October (from 550–730 g/m2 to 480–560 g/m2). It increased in plots harvested in June, July or November (from 310–660 g/m2 to 410–780 g/m2). The study also reported data on the cover of some example individual plant species (see original paper). Methods: In spring 1986, six 7 x 7 m plots were established in each of five adjacent wet grasslands (mown annually for the previous 10 years). From 1986, one plot/grassland was mown in each month between June and November. Cuttings were removed. Plant species were recorded each summer between 1986 and 1988. Biomass was cut and collected from five 30 x 30 cm quadrats/plot/year, immediately before mowing (so not at the same time in all plots), then dried and weighed.

    (Summarised by: Nigel Taylor)

  3. Reduce frequency of cutting/mowing: freshwater marshes

    A replicated, paired, controlled, before-and-after study in 1986–1988 in five wet grasslands in Belgium (Dumortier et al. 1996) reported that mowing plots once per year increased plant species richness and sometimes increased plant biomass, whilst mowing twice per year increased plant species richness and reduced plant biomass. Statistical significance was not assessed. Over two years, plant species richness increased whether plots were mown once per year (July: from 15 to 18 species/6 m2; October: from 19 to 20 species/6 m2) or twice per year (July and October: from 17 to 19 species/6 m2). Total above-ground biomass (including litter) increased in plots mown in July (from 460 to 490 g/m2), but declined in plots mown in October (from 730 to 480 g/m2) or July and October (from 660 to 630 g/m2). The study also included some data on the abundance of individual plant species under each mowing regime (see original paper). Methods: In spring 1986, three 7 x 7 m plots were established in each of five adjacent wet grasslands (mown annually for the previous 10 years). From 1986, five plots (one plot/grassland) were mown in July, five were mown in October, and five were mown in July and October. Cuttings were removed. Plant species were recorded each summer between 1986 and 1988. Biomass was cut and collected from five 30 x 30 cm quadrats/plot/year, immediately before the first mow (so not at the same time in all plots), then dried and weighed.

    (Summarised by: Nigel Taylor)

  4. Change season/timing of cutting/mowing: freshwater marshes

    A replicated, paired, controlled, before-and-after study in 1986–1988 in five wet grasslands in Belgium (Dumortier et al. 1996) reported mixed effects of single annual mows, between June and November, on plant species richness and biomass. Statistical significance was not assessed. Over two years, plant species richness increased in plots mown between July and October (from 15–19 to 18–20 species/6 m2). It declined in plots mown in November (from 19 to 18 species/6 m2) and was stable in plots mown in June (17 species/6 m2). Total above-ground biomass (including litter) declined in plots mown between August and October (from 550–730 g/m2 to 480–560 g/m2). It increased in plots mown in June, July or November (from 310–660 g/m2 to 410–780 g/m2). The study also reported data on the cover of some example individual plant species (see original paper). Methods: In spring 1986, six 7 x 7 m plots were established in each of five adjacent wet grasslands (mown annually for the previous 10 years). From 1986, one plot/grassland was mown in each month between June and November. Cuttings were removed. Plant species were recorded each summer between 1986 and 1988. Biomass was cut and collected from five 30 x 30 cm quadrats/plot/year, immediately before mowing (so not at the same time in all plots), then dried and weighed.

    (Summarised by: Nigel Taylor)

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

    A replicated, paired, controlled study in 1986–1988 in five wet grasslands in Belgium (Dumortier et al. 1996) reported that plots in which annual mowing continued contained less plant biomass than unmown plots after two years, and were more dominated by a single species but contained more plant species. Statistical significance was not assessed. After two years, mown plots contained less above-ground plant biomass (550 g/m2 standing vegetation; 710 g/m2 including litter) than unmown plots (770 g/m2 standing vegetation; 1,120 g/m2 including litter). Acute sedge Carex acuta comprised 92% of the standing vegetation biomass in mown plots, compared to only 65% in unmown plots. However, mown plots contained more plant species (17–20 species/6 m2) than unmown plots (16 species/6 m2). The exact nature of changes in biomass and species richness over time depended on the month in which mowing was carried out (see Action: Change season/timing of cutting/mowing). The study also reported data on the cover of some example individual plant species (see original paper). Methods: In spring 1986, seven 7 x 7 m plots were established in each of five adjacent wet grasslands (mown annually for the previous 10 years). From 1986, one plot/grassland was mown in each month between June and November. Cuttings were removed. In the other plot in each grassland, mowing was stopped. Vegetation was surveyed each summer between 1986 and 1988. Biomass was cut and collected from five 30 x 30 cm quadrats/plot/year, before any mowing in that year, then dried and weighed.

    (Summarised by: Nigel Taylor)

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