Intraspecific variation in growth‐related traits—from leaf to whole‐tree—in three provenances of Cryptomeria japonica canopy trees grown in a common garden

Abstract

To elucidate the physiological and morphological factors underlying intraspecific variation in growth rate, we examined the variation in leaf and whole-tree traits for three geographical variations of ca. 45-year-old Japanese cedar (Cryptomeria japonica D. Don) with contrasting heights and radial growth in a common garden. Traits that reflect leaf-level photosynthesis, water relations, and whole-tree level crown structure in relation to light use and hydraulic architecture were measured. Overall, intraspecific variation in growth characteristics in field-grown adult trees was regulated by whole-tree properties rather than leaf properties. Most leaf traits were similar among provenances. Nevertheless, the leaf traits exhibited highest maximum net photosynthetic rate, dark respiration rate, and light compensation point in provenances whose native habitats are most similar to the common garden in the present study. Together with previous reports that this provenance has higher root nutrient acquisition capacity than the other two provenances, it can be said that organ-level resource use strategies are coupled in a tandem manner. At the whole-tree level, hydraulic architecture-as explained by axial variation in the hydraulically weighted tracheid diameter-can be linked to leaf distribution with respect to light use strategies as well as water transport capacity, leading to differences in growth characteristics among provenances. The study of intraspecific variation in growth characteristics in trees with a wide range of native habitats is expected to be a useful indicator for predicting changes in growth potential and forest dynamics in response to climate change in each habitat.

Genotypic variations appear in fine root morphological traits of Cryptomeria japonica trees grown in a common garden

“…In addition, differences in the 1st order root morphology among the tree provenances might be related to mycorrhizal associations. Some C. japonica ne roots can form arbuscular mycorrhizas (AM) primarily in the 1st root order (Hishi et As Yaku cedar has distinctly low aboveground productivity during the early growth stage in its native habitat (Takashima et al 2009;Itaka et al 2013) and in the common garden (Ohta et al 2019;Azuma et al 2023), ne root morphological traits of Yaku cedar were also differentiated from trees of other provenances, despite large differences in soil chemical properties between the present common garden and its unique native habitat on Yakushima Island where higher soil phosphorus contents are observed owing to volcanic ash (Mukai et al 2016). Furthermore, Yaku cedar has a relatively long genetic distance from Yanase and Yoshino cedars (Tsumura 2023), implying the limits of functional plasticity against growing environments and the consistency of inherent characteristics determined by the genetic background.…”

“…1' E). The native habitats of Yanase, Yoshino, and Yaku receive high precipitation (see Azuma et al 2023) and are covered by very thin soils, the basement rocks of which are sandstone and shale, sedimentary rocks, and granite, respectively (Geological Survey of Japan 2015). The Yoshino and Yanase cedars had relatively high aboveground growth rates during the early growth stage (ca.…”

“…The soil properties had been differentiated among stands, presumably due to plant-soil interactions during stand growth (Ohta et Field survey for sampling of intact ne root systems in the common garden Field surveys for root sampling in the common garden were conducted twice in 2018 and 2019 consecutively. In August 2018, three individuals representing typical growth were selected from each of the three provenances to evaluate aboveground growth and physiological characteristics (Azuma et al 2023) and root morphological traits. Subsequently, two distal root systems that included individual roots from 1st to 4th root orders were sampled from each selected individual tree as follows.…”

“…Three similar-aged (ca. 50 years old) C. japonica stands, comprising cedars from the Yanase, Yoshino, or Yaku provenances, have already been investigated for aboveground growth and physiological characteristics in a common garden where this study was conducted (Ohta et al 2019;Azuma et al 2023). The growth characteristics and productivity (e.g., the annual stem height and radial growth rates and litterfall production) of Yaku cedar were signi cantly lower than those of Yanase and Yoshino cedars in this common garden.…”

“…In addition, Yaku cedar showed higher sapwood density and lower crown depth than the other two cedar provenances. Meanwhile, root nitrogen concentration, which increases with increasing SRL (Jia et al 2013), and root exudation rate of low-molecular-mass organic acids (LMMOA) in Yoshino cedar was possibly higher than those in the other two cedar provenances (Ohta et al 2019), indicating distinct root morphological traits and nutrient acquisition strategies compared with the Yanase cedar which exhibits similar growth characteristics to Yoshino in the aboveground parts (Azuma et al 2023). Based on the ndings of these studies, different belowground resource acquisition strategies for Yanase, Yoshino, and Yaku cedars were hypothesized as follows: 1) Yanase cedar has root morphological traits that indicate short-lived absorptive root traits (e.g., high SRL) in lower root orders to enhance the turnover rate and maintain nutrient acquisition because of the high productivity of the aboveground parts.…”