Shifting of the first-order root foraging strategies of Chinese fir (Cunninghamia lanceolata) under varied environmental conditions

Key messageThe first-order root traits are important for nutrients foraging for plants and their foraging strategies can be influenced by the changing of environmental variables.Fine roots are critical for soil resource acquisition by trees. Understanding root traits and their responses to varied environmental conditions is crucial for root resource foraging under environmental alternations. Data on eight first-order root traits including branching ratio, root diameter (RD), specific root length (SRL), specific root area (SRA), root tissue density (RTD), root carbon (C) concentration, root nitrogen (N) concentration, and arbuscular mycorrhizal colonization of roots (AM colonization) were collected along a large environmental gradient to quantify relationships between first-order root traits and environmental contributing factors in Chinese fir (Cunninghamia lanceolata) plantations of Subtropical China. High mean annual precipitation (MAP) significantly increased AM colonization but decreased root C concentration, resulting in shifting towards a conservative foraging strategy of the first-order roots. Soil pH showed positive correlations with AM colonization and root N concentration, but negative correlations with the branching ratio (number of first-order roots/second-order roots), indicating shifting towards an acquisitive foraging strategy when soil becomes more acidic. However, increased soil C: N and soil P resulted in lower root N, lower RTD, and thicker root diameter of the first-order roots. Our study provides evidence that harsh environmental conditions such as drought and acidity resulted in the growth of more root tips (first-order roots), consequently shifting towards an acquisitive foraging strategy. In contrast, locations with more abundant rainfall and more neutral and fertile soils caused thicker and fewer root tips with higher AM colonization, shifting towards a conservative foraging strategy.

Automated summary

The first-order root traits play a crucial role in nutrient foraging for plants and can be influenced by environmental changes. Understanding the responses of root traits to varied environmental conditions is important for root resource foraging under environmental alternations.