Inconsistent Responses of Above- and Below-ground to 8 Years Increased Snow Depth at the Alpine Meadow in the Permafrost Region of the Tibetan Plateau

Variations in snow depth are significantly altering the soil environment in the permafrost regions of the Tibetan Plateau, which in turn affects vegetation growth. However, how plant leaf and root traits and their relationship respond to increased snow depth remains unclear. Thus, the present study aimed to examine the influence of increased snow depth on plant growth and functional traits of leaf and root in the alpine meadow of the Tibet, exploring how plant above-ground and below-ground parts cascading responded to increased snow depth. This study employs snow fences to artificially increase snow depth and measures above-ground biomass, root biomass, specific leaf area (SLA), leaf carbon concentration (C), leaf nitrogen concentration (N), and leaf phosphorus concentration (P), specific root area (SRA), specific root length (SRL), root tissue density (RTD), root diameter (RD), root carbon concentration (C), root N concentration, and root P concentrations. Increased snow depth significantly increased root biomass compared to ambient controls, but didn’t change above-ground biomass. Increased snow depth significantly decreased SLA but increased leaf C, N and P concentrations. For root functional traits, increased snow depth increased SRL and SRA, but decreased RTD and AD. Effect size result showed that plant leaves was less affected by increased snow depth as compared with root. Particularly, leaf traits changed larger in physiological plasicity traits (leaf C, N, P cocentrations) as compared with morphological plasticity traits (AGB, SLA). In converse, root traits changed larger in morphological plasticity traits (BGB, SRL, SRA, RTD, RD) rather than physiological plasicity traits(root C, N, P cocentration). Principal component analysis showed that leaf functional traits are primarily driven by leaf C, N, and P concentrations, while root functional traits are mainly driven by morphological traits such as SRL, SRA, and RTD. The inconsistently respond of plant leaf and root to increased snow depth in the alpine meadow of the Tibetan Plateau suggested that trade-offs between above- and below- functions are necessary for plant to optimize resource use under changing environment. Our results also emphasize the importance of feedback between above- and below-ground plant traits to better understand plant community responses to future climate change.