Photosynthesis and growth ofThujopsis dolabratavar.hondaiseedlings in the understory of trees with various phenologies

Abstract

We have studied the photosynthetic production and growth of Thujopsis dolabrata var. hondai (hiba) seedlings under typical light conditions found in mixed forests, including constant shade, phenological gaps under broad-leaved trees with different lengths of foliation period, and in an open plot. Leaves sampled from the open plot had significantly higher rates of light-saturated gross photosynthesis and dark respiration, and a significantly lower specific leaf area than leaves from the other plots. The relative growth rate of whole plant biomass was significantly higher in plots that received larger amounts of light. The variations in these properties under the various light conditions are considered to reflect the ability of hiba seedlings to adapt to available light. In the late autumn, leaves sampled from the open and from the gap under deciduous trees indicated photoinhibition. However, the estimated value of monthly net photosynthesis of hiba seedlings was greater in these plots, indicating that the benefit of a greater light intensity for photosynthesis seems to be larger than the detriment of photoinhibition. The seasonal pattern of photosynthesis by understory hiba seedlings was affected by the phenology of canopy trees. Light availability under the canopy of deciduous trees associated with phenological gaps helped hiba seedlings to tolerate the relatively dark conditions during the subsequent foliation period. These results for reaction to the light regime and for the phenology of hiba seedlings are practicable for hiba forest management.

Ecophysiological responses to different forest patch type of two codominant tree seedlings

“…; Walters and Reich ; Durand and Goldstein ; Hitsuma et al. ). During the gap‐phase dynamics, the light environment varies diurnally and by patch type.…”

“…; Niinemets ; Hitsuma et al. ). Ecophysiological traits are considered to influence where species can appear, which species can coexist, and how species respond to light conditions such as shading and full sun (Yoshimura ; Wyka et al.…”

“…; Niinemets ; Hitsuma et al. ). Vegetation is likely to experience heterogeneous patch habitats throughout the gap‐phase dynamics.…”

“…; Niinemets ; Hitsuma et al. ). Many studies have identified important species‐specific light‐harvesting factors (e.g., Yoshimura ; Wyka et al.…”

“…Tree species have varying leaf life spans, nitrogen concentrations, respiration rates, carboxylation rates, and other traits that are collectively described species' ecophysiological traits (Kitao et al 2000;Walters and Reich 2000;Miller et al 2004;Niinemets 2010;Hitsuma et al 2012). Ecophysiological traits are considered to influence where species can appear, which species can coexist, and how species respond to light conditions such as shading and full sun (Yoshimura 2010;Wyka et al 2012).…”