Phenology of leaf morphological, photosynthetic, and nitrogen use characteristics of canopy trees in a cool‐temperate deciduous broadleaf forest at Takayama, central Japan

Abstract

We studied interannual variations in single‐leaf phenology, i.e., temporal changes in leaf ecophysiological parameters that are responsible for forest canopy function, in a cool‐temperate deciduous broadleaf forest at Takayama, central Japan. We conducted long‐term in situ research from 2003 to 2010 (excluding 2008). We measured leaf mass per unit area (LMA), leaf chlorophyll and nitrogen contents, and leaf photosynthetic and respiratory characteristics [dark respiration, light‐saturated photosynthetic rate (Amax), maximum carboxylation rate (Vcmax), and electron transport rate (Jmax)] of leaves of mature canopy trees of Betula ermanii Cham. and Quercus crispula Blume, from leaf expansion to senescence. All leaf characteristics changed markedly from leaf expansion (late May) through senescence (mid–late October). The photosynthetic capacity of B. ermanii leaves rapidly increased during leaf expansion and decreased during senescence, while that of Q. crispula leaves changed gradually. The relationships among LMA, photosynthetic capacity, and nitrogen content changed throughout the season. The timings (calendar dates) of leaf expansion, maturity, and senescence differed among the 7 years, indicating that interannual variations in micrometeorological conditions strongly affected leaf phenological events. We examined the seasonal changes as a function of the date or cumulative air temperatures. From leaf expansion to maturity, the increases in chlorophyll content, Amax, Vcmax, Jmax, and LMA were explained well by the growing‐degree days, and their decreases in autumn were explained well by chilling‐degree days. Our findings will be useful for predicting the effects of current variations in climatic conditions and future climate change on forest canopy structure and function.

Estimation of Leaf Area Index in a Mountain Forest of Central Japan with a 30-m Spatial Resolution Based on Landsat Operational Land Imager Imagery: An Application of a Simple Model for Seasonal Monitoring

“…The dependence of LAI on temperature has been evidenced in numerous ecological studies with respect to spatial variations [1,7,23,40,67] and leaf seasonality [2,38]. This study demonstrated the importance of accurate, fine-resolution spatial LAI estimation for ecological studies in areas of complex topography and high vegetative heterogeneity.…”

“…To estimate the seasonal LAI of deciduous forests, we implemented an empirical in situ logistic model [38,39] that describes the seasonal variations of LAI as a function, ƒ(x), of the CET > 2 °C at a daily time step,…”

“…Parameters a, b, and d are non-negative, and c is positive in the leaf-expansion and negative in leaf-senescence periods [38]. The above logistic model was based on field measurements at TKY, which has been an intensive multi-year observational station for carbon cycle research [2] (Figure 2).…”

Effects of canopy phenology on deciduous overstory and evergreen understory carbon budgets in a cool‐temperate forest ecosystem under ongoing climate change

“…To further improve our phenology model, we should consider the canopy phenology of each tree species in the forest, including representation of the effects of interspecies longevity differences and of succession. Inoue et al (2014) found differences in the start of leaf expansion and end of leaf-fall among tree species at TKY, and differences in their phenological sensitivity to Other recent studies have suggested that temperature sensitivity of canopy phenology differed among tree species (Noda et al 2014;Primack 2011, 2013) and warming experiments (Chung et al 2013). This may mean that natural succession would change future temperature sensitivity of wholeecosystem canopy phenology.…”

Spatio-temporal variations in photosynthesis

“…For the roles of cyclic electron transport around PSI in protecting PSI photoinhibition in the fluctuating light, the readers may refer to recent papers and reviews (Soursa et al 2012, Allahverdiyeva et al 2015. The readers who are interested in the studies at the forest ecosystem level including the satellite ecology, refer to recent reviews (Muraoka and Koizumi 2009, Muraoka et al 2010, Chung et al 2013, Noda et al 2014, Ruidish et al 2014) which can be found in a joint virtual special issue by Journal of Plant Research and Ecological Research 'Long-term and multidisciplinary research of the forest carbon cycle at the Takayama site, Japan (http://www.springer. com/life+sciences/plant+sciences/journal/10265)'.…”