DOI: 10.5281/zenodo.15609004
title: Below-ground litter decomposition in the Otindag Sandy Land

description: Litter decomposition drives carbon and nutrient cycling in complex sandy grassland ecosystems of arid and semiarid regions. A one-year field experiment was conducted in the Otindag Sandy Land using standardized litter materials—readily decomposable green tea and more recalcitrant red tea—to simulate belowground decomposition across four grassland types (desert, sandy, typical, and open forest grasslands/temperate savanna). High-throughput sequencing was employed to assess soil bacterial and fungal community composition and diversity, enabling evaluation of tea bag mass loss as influenced by biotic (e.g., plant and microbial diversity) and abiotic (e.g., climate, soil properties) factors and their interactions. Green tea decomposed fastest in temperate savanna, followed by typical, desert, and sandy grasslands; red tea decomposition did not differ significantly among sites. Green tea loss was primarily driven by biotic factors, whereas red tea decay was affected by both biotic and environmental variables. Further analysis indicated that climate (temperature, precipitation) and plant diversity indirectly influenced decomposition by modulating microbial diversity. Our study offers valuable insights into nutrient cycling and ecosystem functioning in dryland areas.
description: 1. File: glm.csv

Description: This document presents the calculation of cumulative corrected R² for factors affecting teabag mass loss.

Variables

· AGB:above-ground biomass

· BGB:below-ground biomass

· MAT:mean annual temperature

· AP:annual precipitation

· BD:soil bulk density

· EC:electrical conductivity

· MBC:microbial biomass carbon

· MBN:microbial biomass nitrogen

2. File: SEM.csv

Description: This document is used to construct Structural Equation Models depicting direct and indirect drivers of teabags mass loss.

Variables

· MAT:mean annual temperature

· AP:annual precipitation
description: 34 sampling sites were established to investigate the differences in litter decomposition among desert grassland, sandy grassland, typical grassland and temperate savanna in the Otindag Sandy Land. In different grasslands, we recorded plant species composition, abundance, and cover, and collected topsoil samples (0–10 cm depth) using a soil auger. Slope was measured with a clinometer, while aspect was determined via a handheld GPS compass (with 0° as due north, increasing clockwise). Based on the GPS coordinates of each quadrat, annual mean temperature and precipitation data were extracted from Google Earth Engine.

This study used the tea bag decomposition method to compare the decomposition rates of underground litter in different grassland types. To simulate litter decomposition in the topsoil layer, Lipton green tea and Rooibos tea bags (2 g each) were buried at 10 cm depth in each sampling site. Soil samples for microbial biomass analysis were collected by extracting soil from the same depth using a soil corer.

After one year of decomposition, we returned to the decomposition sites between August 15 and August 25, 2022, to recover the decomposed tea bags. The recovered tea bags were dried in a 60 °C oven for 48 hours, weighed, and their mass recorded. The percentage of mass loss was calculated based on the difference between the initial and final mass of the tea bags.