Extensive physiological integration in intact clonal systems of Carex arenaria

1. Carex arenaria forms large clonal fragments (up to 12 m long) in environments in which soil-bound resources limit growth. 2. We hypothesized that extensive integration of C. arenaria would facilitate the exploitation of scarce and patchily distributed soil resources and that the continued functioning of old roots would enable exploitation of resources that are temporally variable. 3. We used labelling with ¹⁴C and acid fuchsin to study the degree and extent of physiological integration and root function of intact clonal systems of C. arenaria in a sand dune area in south Sweden. 4. The uptake and translocation of dye suggests that old roots remain capable of taking up water and nutrients, in contrast with negative reports from previous studies. Water was translocated both acropetally and basipetally. 5. Thirty per cent of the assimilated carbon was found to be translocated towards the growing apex. Smaller, but significant, amounts of carbon were translocated basipetally throughout the fragments (17-74 ramet generations). 6. The results are discussed in terms of the source-sink relations of large clonal systems in the field. The translocation patterns are considered in relation to soil moisture and nutrient availability.