Fig. 7.

Estimated carbon costs of cluster roots in Hakea prostrata (total plant fresh mass was approximately 600 g). While the clusters are active, 52–100 % of daily produced photosynthate is utilized in growth, respiration and carboxylate exudation. On an annual basis, these figures should be divided by 4–6, because the clusters of H. prostrata are only active in the wet season (2–3 months). The calculations are based on primary data presented on growth, respiration and carboxylate exudation in Shane et al. (2004c) and on leaf photosynthesis, total leaf area and total root cluster in Shane and Lambers (2005b), assuming that half of the clusters harvested by Shane and Lambers (2005b) were older than 21 d, and hence dead.