A comparative study of the growth and morphology of eight grass species from habitats with different nutrient availabilities.

1. To find out which properties enable plant species to dominate in nutrient-poor habitats and which properties benefit species in nutrient-rich habitats, we studied the growth and morphology of eight perennial grass species from habitats with contrasting soil fertilities in a pot experiment under controlled conditions in a glasshouse. 2. The species were grown under nutrient-poor and nutrient-rich conditions. Ranked from the least responsive to the most responsive to the supply of nutrients they were: Festuca ovina, F. rubra, Anthoxanthum odoratum, F. arundinacea, Alopecurus pratensis, F. pratensis, Arrhenatherum elatius, Lolium perenne. 3. The response correlated positively with the Ellenberg nitrogen number of the species. No differences in initial relative growth rate were found between the species, but after 4 weeks the plant dry weight increased with increasing nitrogen number as a result of variation in embryo plus endosperm weight. 4. Species characteristic of nutrient-rich hayfields are taller and show a more homogeneous vertical distribution of photosynthetic area than the species from nutrient-poor habitats, which have most of their leaf area below 15 cm. Species from the nutrient-poor habitats allocated less dry matter to the roots and consequently more to the shoot, than species from nutrient-rich conditions. However, leaf and root morphology seem to be most clearly adapted to the habitat. 5. Species from nutrient-rich habitats have a higher specific leaf area (SLA) than species from nutrient-poor habitats, while species from nutrient-poor habitats had more root length per unit root weight (SRL) than species from nutrient-rich habitats

Experiments on the restoration of species-rich meadows in The Netherlands

Three long-term experiments were carried out in meadows that were mown twice a year on three different soils: heavy clay, sand and clay-on-peat. The experiment on heavy clay studied the effect of an increase in nutrient supply on dry matter production and species diversity in a species-rich meadow. Here the increased productivity due to fertilizers reduced species diversity to only 25% of the original number of species after 30 years. In the two other experiments an attempt was made to reverse this process: to reduce annual productivity and increase species diversity by exporting nutrients through hay or sod removal. In the experimental on sandy soil, nutrient removal led to a sharp decline in production from 12 to c. 5 tonnes/ha, but nevertheless species diversity declined significantly. In the experiment on clay-on-peat the productivity declined more slowly from 12 to 7–8 tonnes/ha. The number of plant species in the plots from which the sod layer had been removed was greater than in the plots that were only mown. It is concluded that low productivity levels are essential, but cannot guarantee successful restoration of species-rich meadows

Restoration of species-rich grassland communities

An experiment was carried out at the Veenkampen, the application of fertilizers being stopped. Two possible tools were studies for the restoration of species rich grassland communities: removing nutrients through hay or sod removal and raising the groundwater leve