Correlation of Leaf and Root Traits of Two Angiosperm Tree Species in Northeast China under Contrasting Light and Nitrogen Availabilities

Abstract

Light and nitrogen availability are among the most important environmental factors influencing leaf and root morphological traits and forest ecosystems. Understanding the variation in leaf and root traits is pivotal to the adaptive plasticity and leaf-root-specific traits in response to low light and N availability. The effects of light and N availability on leaf and root traits and their interrelations are still not clear. We aimed to measure the response of leaf and root traits and their interrelations to light and N availability in a temperate region. Thus, a factorial experiment was conducted with two angiosperm tree species under two light (L+, L−) and two nitrogen (N−, N+) levels. Results showed that the leaf density (LD) and leaf mass per area (LMA) increased, while leaf thickness (LT) decreased under low light availability. Under N availability, the LD and LMA decreased, while LT increased in sun-exposed plots and remained stable under low light availability across two species. The root diameter, root length, specific root length (SRL), and specific root area (SRA) decreased, while the root tissue density (TD) increased under low light availability. Root diameter, root length, SRA, and SRL increased, while the TD decreased under N+ in L+ plots and remained stable under L− plots. LMA and LT were significantly positively correlated to root length and SRL while significantly negatively correlated to TD. However, LD was significantly positively correlated to TD. We observed that low light availability has significantly decreased the plant biomass and root mass fraction (RMF) and increased the leaf mass fraction (LMF), while the stem mass fraction (SMF) remained stable―indicating the shade in-tolerances in both species. Correlation analyses revealed that LMF is generally, and particularly under L− conditions, less related to leaf and root morphological traits, while RMF was frequently positively correlated to both leave and root traits under all environmental conditions. This illustrates a divergent regulation of morphological traits above and below ground under varying biomass allocation patterns.

The Impact of Light Availibility on the Functional Traits of Quercus Robur L. And Acer Platanoides L. First-year Seedlings by Direct and Indirect Methods

“…Seedling functional type is a categorical trait that can be used to characterise plant regenerative strategies and plant adaptation to environmental changes [32]. Most of the studies have been carried out on rst-year tree seedlings with phanerocotylar epigeal germination with foliaceous cotyledons and cryptocotylar hypogeal germination with reserve storage cotyledons [31]. Traits of these seedling functional types in uence growth, reproduction, and survival of seedlings in the future [6, 10,34] and are very important indices for understanding how seedlings respond and adapt to changing light conditions [32,33].…”

“…The study of the morphological/ecological characteristics and functional traits of tree seedlings is of keen interest among recent ecological submissions. The seedling stage of trees is particularly critical because survival and performance at this ontogenetic phase of tree development will characterize the future of forest/park ecosystems [31]. All the same, seedling functional types refer to morphology of seedlings in relation to cotyledon function and position.…”