The ecological stoichiometry and interrelationship between litter and soil under seasonal snowfall in Tianshan Mountain

Abstract

Changes in snow cover caused by global climate change will profoundly affect the process of litter decomposition and soil nutrient cycling in terrestrial ecosystems. The presence of seasonal snow cover during the winter has a significant impact on forest ecosystems. The goals of this study were to explore how seasonal snow cover modulates litter decomposition dynamics and elemental cycling in forest ecosystems, and to characterize the ecological stoichiometry of nutrients in the leaf litter and soils over time. Seasonal snowfall leads to different snow depths on the ground, especially when comparing forest gaps to closed canopy. Snow cover in this study was categorized as absent, thin, intermediate, and thick according to depth (n = 4 treatments). Leaf litter and underlying soils were sampled in plots from each category of snow cover over the course of multiple seasons (i.e., the freeze–thaw period, deep‐freeze period, thaw period, pre‐growth season, and late growth season). The carbon, nitrogen, and phosphorus concentration of leaf litter and soils were determined at each stage. The litter decomposition rate and nutrient concentration were largely dependent on the thickness of the snowpack formed by seasonal snowfall. Overall, variability in the ecological stoichiometry of elements in the leaf litter and soils was small. However, in the leaf litter, carbon, nitrogen, and phosphorus concentrations and their stoichiometric ratios differed across the snow cover gradient during the winter when snow was present, but not when snow was absent in the warmer months. Thicker snowpacks better maintained litter decomposition and kept nutrient levels stable. Furthermore, correlations between leaf litter and soil ecological stoichiometry were affected by seasonal snow cover, with element concentration also varying over time.

Schrenk spruce leaf litter decomposition varies with snow depth in the Tianshan Mountains

“…As mentioned above, winter forest litter decomposition plays an important role in decomposing litter, and the decomposition may vary with snow cover depth, however, few studies have investigated the decomposition of Schrenk spruce forest litter in the Tianshan Mountains. Seasonal snow cover is the most active and sensitive environmental factor in this region, and the snow cover usually lasts for 5-6 months 29 . Furthermore, snowfall and the seasonal freeze-thaw cycle can produce a natural snow cover gradient associated with forest gaps 29,30 .…”

“…Seasonal snow cover is the most active and sensitive environmental factor in this region, and the snow cover usually lasts for 5-6 months 29 . Furthermore, snowfall and the seasonal freeze-thaw cycle can produce a natural snow cover gradient associated with forest gaps 29,30 . To date, the following questions remain unanswered: what are the characteristics of litter decomposition and the regularity of C, nitrogen (N), and phosphorus (P) release in Schrenk spruce forests during the snow cover period in this area?…”

Ecological stoichiometry of Cinnamomum migao leaf litter and soil nutrients under nitrogen deposition in a karst region

“…Many factors jointly influence the litter decomposition process, such as litter quality, climate change, soil nutrients, and soil microorganisms, and fauna, all of which participate directly or indirectly in the decaying of litter material on the ground (Liu andGreaver 2010, Zhang et al 2016). While many studies have compared the C, N, P, C:N, and C:P of litter (Yang et al 2011, Zhang et al 2016, Chen et al 2018b, Sun et al 2018, far less information is available on potassium (K), typically the most abundant macronutrient in soils (Reitemeier 1951) and among the most important metal elements influencing plant metabolism and growth (Penuelas et al 2011, Rosenstock et al 2016.…”

The response of fine root morphological and physiological traits to added nitrogen in Schrenk’s spruce (Picea schrenkiana) of the Tianshan mountains, China

“…Root physiology is often closely related to root morphological characteristics (Wang et al, 2018c). Research into fine root responses to N addition has long concentrated on rates of fine root decomposition and respiration, as well as alterations to anatomy (Sun et al, 2016; Chen, Gong & Liu, 2018; Burton et al, 2012). However, little research has examined the links between fine root morphological and physiological traits under conditions of exogenous N addition.…”

“…Tianshan is the largest mountain system in Central Asia and is a vital component of the mountain–oasis–basin system in the arid region of Western China (Li et al, 2010; Gillespie et al, 2017). The forests in Tianshan are mainly temperate coniferous forests in the north, dominated by Schrenk’s spruce ( Picea schrenkiana ) (Xu et al, 2016; Zhang et al, 2017; Chen, Gong & Liu, 2018). Given the high rates of N deposition in this arid region, knowing how fine root growth and functional traits react to nitrogen addition in arid forests will offer significant insights into the mechanisms of hidden adaptation.…”