Patch dynamics of the stream macrophyte, Callitriche cophocarpa

SUMMARY 1. We examined changes in position and growth of Callitriche cophocarpa patches in a shallow section of a small Danish stream during the main expansion of plant cover between April and June. Mean upstream growth of patches was only 7.5% of downstream growth. The mean growth rate was 1,02cm day−1 in length and 0.55 cm day−1 in width and the growth rates were not significantly dependent on patch size. For patches with an area (A) above 100cm2, the growth rates in patch area (dA/dt) was proportional to patch circumference and thus √Aand the relative growth rate (dA/dt A−1) was inversely proportional to √A.The smallest patches (