Spatial and Temporal Patterns of Growth and Nutrient Uptake of Five Co- Existing Grasses

(1) Shoot growth and phosphorus and potassium uptake into shoots were measured in a group of five co-existing grass species on an acid, lowland grassland, over 2 years. (2) Extractable P and K concentrations in the soil showed pronounced seasonal variation, with P being high and K low in midsummer. (3) There was evidence of the seasonal order of Poa pratensis-Holcus lanatusAgrostis capillaris for growth and nutrient uptake. Even where dry matter production peaks coincided, peaks of nutrient uptake were separated. (4) Where additional dominant species (Arrhenatherum elatius and Deschampsia cespitosa) were present, the nutrient uptake but not growth of Holcus lanatus was displaced to earlier in the season. Peaks of growth and nutrient uptake of Agrostis capillaris and of Poa pratensis were unaffected and did not overlap those of the dominant species. (5) The responses to temperature and soil moisture in a growth room experiment indicated that the seasonal order (as in (3) above) could be explained by the low temperature resistance of Poa and the drought resistance of Agrostis. (6) Using strontium as a tracer, Poa pratensis was shown to have the shallowest and Agrostis capillaris the deepest root activity. This is more likely to be the explanation for the greater drought resistance of A. capillaris than any physiological attribute.