Fine‐root decomposition characteristics of four typical shrubs in sandy areas of an arid and semiarid alpine region in western China

Abstract

Background and aims Research into the variability of fine‐root decomposition and nutrient cycling processes in arid and semiarid ecosystems is highly significant not only for investigations of regional and global carbon and nitrogen cycling but also for offering a theoretical basis for vegetation restoration and reconstruction. In particular, information is limited on fine‐root decomposition processes and nutrient releasing characteristics in the high‐altitude Qinghai Gonghe basin, which has different tree species and variable fine‐root diameters. Materials and methods Four types of Salicaceae and Caragana shrubs were selected at the Qinghai Gonghe desert ecosystem research station. The litterbag method was adopted to measure decomposition rates of fine‐roots with three diameter classes (1–2 mm, 0.5–1 mm, and 0–0.5 mm). Chemical analysis was performed to determine nutrient (C, N, P, and K) concentrations of fine‐root, and nutrient release rates were compared among fine‐roots with different diameters during different decomposition periods. The differences in mass residual ratio and nutrient release rate among different diameter classes were studied with one‐way ANOVA. Results Fine‐root decomposition rates were in the order Caragana intermedia > Caragana korshinskii > Salix psammophila > Salix cheilophila . Fine‐root decomposition showed a trend of “fast‐slow‐fast” variation, and decomposition rate increased as the diameter of fine‐roots increased, irrespective of tree species. During the decomposition process, the nutrients C, N, and P of fine‐root were in a release state for the four shrubs with different fine‐root diameters, and the corresponding release rates of Caragana shrubs were higher than those of Salicaceae shrubs. Release rates of nutrients C and N accelerated as fine‐root diameter increased, whereas release rates of nutrients P and K had no observed relation with fine‐root diameter. Fine‐root decomposition ratio was significantly correlated with initial values of N, P, C/N, C/P, and N/P of fine‐root. Fine‐root mass loss ratio was significantly correlated with initial concentration of soil nutrient K, and the correlation was positive for fine‐roots with diameters of 0–0.5 mm and 0.5–1 mm; however, no other significant correlation was observed between fine‐root mass loss ratio and initial soil environmental factors within this study. Conclusions Our study showed that tree species and fine‐root diameter strongly affected decomposition rates, whereas diameter class exerted little effect on nutrient release rates.

Fine root dynamic characteristics and effect on plantation’s carbon sequestration of three Salix shrub plantations in Tibetan Plateau alpine sandy land

“…The elements of dead root with higher initial concentration were easily to had been released in forest (Vogt et al., 1986), N and P of plant residue decomposition had been released into the soil in the form of minerals, when the concentration of N and P in the organism had reached critical values (Manzoni et al., 2008). Our study was conducted in an alpine sandy land in Qinghai at an altitude of 2,871~3,870 m that lower activities of cellulose and lignin degrading enzymes had occurred in soil and microbial activity (He et al., 2019; Parton et al., 2007). Therefore, fine root decomposition rate differed distinctly even for the same species as the study area varied.…”

“…of 2,871~3,870 m that lower activities of cellulose and lignin degrading enzymes had occurred in soil and microbial activity (He et al, 2019;Parton et al, 2007). Therefore, fine root decomposition rate differed distinctly even for the same species as the study area varied.…”

“…In April 1990, the study object of S. cheilophila, S. psammophila, and S. microstachya plantations were planted using cuttage (row spacing of 2 m) in the inter sand dune with sample plot areas F I G U R E 1 Location of the study area, Gonghe County, Qinghai Province, China (He et al, 2019) 100 m × 100 m, respectively. Fences were used to enclose the vegetation restoration areas for none grazing and fertilization.…”

Fine-Root Decomposition and Nutrient Return in Moso Bamboo (Phyllostachys pubescens J.Houz.) Plantations in Southeast China

“…Therefore, the changes in concentration of these elements in the process of fine-root decomposition are also different; furthermore, the main patterns of change in mineral element contents are release-enrichment-release, enrichment-release, and direct release (Blair, 1988). Release occurs mostly at the early stage of fine-root decomposition, and the duration of enrichment varies with the type of element (He et al, 2019). In many cases, enrichment and release occur alternately, which inevitably presents an irregular fluctuation of the remaining ratio of different elements in the process of fine-root decomposition.…”

Decomposition characteristics of long-established Salix psammophila sand barriers in an arid area, Northwestern China

“…The decomposition of natural biomaterials and their nutrient release change the carbon and nutrient cycles of ecosystems and their responses to environmental changes, and they have important effects on the accumulation of soil organic matter and the dynamics and availability of major nutrients. Decomposition plays an important role in important ecological processes, such as material circulation, structure, and functional maintenance of ecosystems (Goebel et al 2011;Xu et al 2013;He et al 2019). Thus, there is a need to better understand the general laws of nutrient release and its response to the environment during the degradation of S. psammophila sand barriers to predict the biogeochemical cycle of the desert ecosystem.…”