TY - JOUR
T1 - Spatial and temporal variations in photosynthetic capacity of a temperate deciduous-evergreen forest
AU - Hamada, Shuko
AU - Kumagai, Tomo’omi
AU - Kochi, Kiyotaka
AU - Kobayashi, Nakako
AU - Hiyama, Tetsuya
AU - Miyazawa, Yoshiyuki
N1 - Funding Information:
This work was supported in part by Grants-in-Aid for Scientific Research (Nos. 11213209, 11480130, and 25281005) from the Ministry of Education, Science and Culture, Japan.
Publisher Copyright:
© 2016, Springer-Verlag Berlin Heidelberg.
PY - 2016/8/1
Y1 - 2016/8/1
N2 - Key message: The understory evergreen trees showed maximal photosynthetic capacity in winter, while the overstory deciduous trees showed this capacity in spring. The time lag in productive ecophysiologically active periods between deciduous overstory and evergreen understory trees in a common temperate forest was clearly related to the amount of overstory foliage. Abstract: In temperate forests, where deciduous canopy trees and evergreen understory trees coexist, understory trees experience great variation in incident radiation corresponding to canopy dynamics represented by leaf-fall and leaf-out. It is generally thought that changes in the light environment affect understory plants’ ecophysiological traits. Thus, to project and estimate annual energy, water, and carbon exchange between forests and the atmosphere, it is necessary to investigate seasonal variation in the ecophysiological activities of both evergreen trees in the understory and deciduous trees that make up the canopy/overstory. We conducted leaf-scale gas-exchange measurements and nitrogen content analyses for six tree species along their heights throughout a complete year. Photosynthetic capacity as represented by the maximum carboxylation rate (Vcmax25) and photosynthetic nitrogen use efficiency (PNUE) of deciduous canopy trees peaked immediately after leaf-out in late May, declined and stabilised during the mid-growing season, and drastically decreased just before leaf-fall. On the other hand, the timing of lowest Vcmax25 and PNUE for evergreen understory trees coincided with that of the highest values for canopy trees. Furthermore, understory trees’ highest values appeared just before canopy tree leaf-out, when incident radiation in the understory was highest. This implies that failing to consider seasonal variation in leaf ecophysiological traits for both canopy and understory trees could lead to serious errors in estimating ecosystem productivity and energy balance for temperate forests.
AB - Key message: The understory evergreen trees showed maximal photosynthetic capacity in winter, while the overstory deciduous trees showed this capacity in spring. The time lag in productive ecophysiologically active periods between deciduous overstory and evergreen understory trees in a common temperate forest was clearly related to the amount of overstory foliage. Abstract: In temperate forests, where deciduous canopy trees and evergreen understory trees coexist, understory trees experience great variation in incident radiation corresponding to canopy dynamics represented by leaf-fall and leaf-out. It is generally thought that changes in the light environment affect understory plants’ ecophysiological traits. Thus, to project and estimate annual energy, water, and carbon exchange between forests and the atmosphere, it is necessary to investigate seasonal variation in the ecophysiological activities of both evergreen trees in the understory and deciduous trees that make up the canopy/overstory. We conducted leaf-scale gas-exchange measurements and nitrogen content analyses for six tree species along their heights throughout a complete year. Photosynthetic capacity as represented by the maximum carboxylation rate (Vcmax25) and photosynthetic nitrogen use efficiency (PNUE) of deciduous canopy trees peaked immediately after leaf-out in late May, declined and stabilised during the mid-growing season, and drastically decreased just before leaf-fall. On the other hand, the timing of lowest Vcmax25 and PNUE for evergreen understory trees coincided with that of the highest values for canopy trees. Furthermore, understory trees’ highest values appeared just before canopy tree leaf-out, when incident radiation in the understory was highest. This implies that failing to consider seasonal variation in leaf ecophysiological traits for both canopy and understory trees could lead to serious errors in estimating ecosystem productivity and energy balance for temperate forests.
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U2 - 10.1007/s00468-015-1347-4
DO - 10.1007/s00468-015-1347-4
M3 - Article
AN - SCOPUS:84954175584
VL - 30
SP - 1083
EP - 1093
JO - Trees - Structure and Function
JF - Trees - Structure and Function
SN - 0931-1890
IS - 4
ER -