No abstract

We studied how the dominant factor affecting stem volume growth changes during stand development in a monoclonal stand of Cryptomeria japonica D. Don. Stem analysis was used to compare growth history of trees in an unthinned plot (closed canopy) and a thinned plot (open canopy). In the unthinned plot, the dominant factor affecting stem volume growth was basal area (BA) before canopy closure, whereas neighborhood competition index (CI) was the dominant factor after canopy closure. In contrast, the dominant factor affecting stem volume in the thinned plot was BA throughout stand development. Spearman's rank correlation coefficient between BA and CI continued to increase after canopy closure and size rank among individuals became increasingly fixed. Our results indicated that stem volume growth shifts from size-dependent to competitiondependent growth at canopy closure. The apparent correlation between tree size and growth rate observed in many previous studies may be the result of competitionmediated positive feedback between size and growth.

No abstract

We compared acclimation potential of three native, evergreen tree species to wind-exposure in an 6 urban green-roof environment. One year after planting on the green roof, Machilus thumbergii 7 retained all leaves and produced new leaves. In contrast, Fraxinus griffithii, and Quercus 8 myrsinifolia shed all leaves but produced more new leaves than the previous year. After two years, 9 current-year leaves of all three species had acclimated hydraulically (lower osmotic potentials at 10 saturation and turgor loss) to wind-induced water stress and leaf number increased to four to eight 11 times the initial amount. When trees were exposed to simulated winds in a greenhouse experiment, 12 osmotic adjustment was observed for current-year leaves of M. thumbergii, whereas leaves of F.13 griffithii and Q. myrsinifolia had hydraulic traits more vulnerable to wind-induced water stress 14 (higher osmotic potential and relative water content at turgor loss). We inferred that, M.15 thumbergii invests in hydraulic acclimation to retain current-year leaves in response to increased 16 wind, whereas F. griffithii and Q. myrsinifolia allocate resources to new leaf production. Our 17 results suggest both strategies achieve tree-level acclimation to wind exposure.

No abstract