DOI: 10.5061/dryad.t1g1jwtcg
title: The responses of microbial necromass carbon accumulation to climate aridity in alpine meadow soils are dominated by plant species richness

description: Plant diversity loss caused by climate change decreases soil organic
 carbon (SOC) sequestration, but the mechanism involved remains unclear.
 Investigating the changes in soil microbial necromass carbon (MNC)
 accumulation along a climate–plant species diversity gradient can help
 clarify this mechanism, as it is crucial for the stability of SOC. We
 conducted large-scale sampling across a 2500-km transect through
 grasslands on the Tibetan Plateau to investigate the MNC content and its
 contribution to SOC at depths of 0–20 cm and 20–40 cm in response to
 environmental and plant species diversity gradients. Plant species
 richness, plant biomass, and the proportion of aboveground biomass
 accounted for by Cyperaceae (sedges) increased with decreasing aridity
 along the gradient of rising altitude. Meanwhile, the MNC content, its
 contribution to SOC, and the ratio of fungal to bacterial necromass carbon
 in both soil layers also increased with decreasing aridity. These results
 indicate that, in addition to changing climate factors along the
 altitudinal gradient, plant species richness plays a pivotal role in
 facilitating soil MNC accumulation and thus the accrual of SOC. Structural
 equation modeling revealed that plant diversity increases the MNC content
 by enhancing the abundance of Cyperaceae in the grassland. Higher
 abundance of Cyperaceae significantly increased the root biomass and level
 of rhizodeposition, thereby increasing the diversity and activity of soil
 microbes, and ultimately the accumulation of MNC. Synthesis: We conclude
 that changes in plant species richness in response to aridity dominate the
 MNC content and its proportion in SOC on the Tibetan Plateau. These
 findings demonstrate the importance of incorporating plant species
 diversity into conservation efforts in grasslands to mitigate the negative
 impacts of climate change and human activities on SOC.
description: From 15 July to 12 August 2022, we conducted an extensive field
 survey along a 2500-km transect that stretched from the southeastern to
 the northwestern parts of the Tibetan Plateau. There were 30 sites in
 total (each 100 m × 100 m; slope &lt; 5°), at which we collected plant
 and soil samples. The sites spanned a wide range of geographic and
 climatic conditions, with longitudes ranging from 90°11’E to 102°42’E,
 latitudes ranging from 32°53’N to 38°59’N, and elevations ranging between
 2750 and 4357 m. Soils were categorized as Cambisols, with some
 Loess-derived Luvisols, following the classification system established by
 the World Reference Base for Soil Resources (Schad, 2018), with pH values
 in the top 20 cm ranging from 5.78 to 9.18. At each
 site, we randomly selected three 1 m × 1 m plots that were separated by a
 minimum distance of 25 m. All sites had been overgrazed and not
 fertilized, with no significant accumulation of litter on the soil
 surface. For each plot, we defined the plant species richness as the
 number of species, then clipped all plants in the plots at ground level
 and placed the samples into paper bags for transportation to the lab for
 weighing. Plants were categorized into three functional groups: grasses
 (Gramineae), sedges (Cyperaceae), and others. Root biomass was collected
 in the same plots using a root auger with an inner diameter of 7.5 cm at
 depths of 0–20 cm and 20–40 cm. After carefully washing away the soil,
 dead roots were identified based on their internal color and removed from
 the sample. Both shoot and root samples were oven-dried at 65°C until they
 reached a stable weight, and then their weights were recorded.
 Soil samples were collected using a 3-cm-diameter auger at six
 points within each plot at 20-cm intervals to a depth of 100 cm.
 Collection depths were sometimes shallower at sites with a low depth to
 the bedrock. Soil subsamples from comparable depths within each of the six
 samples were pooled to form a composite sample. After removing litter and
 stones, samples were passed through a 2-mm sieve and then split into two
 parts. Approximately 100 g of fresh soil was kept at 4°C for measuring
 soil microbial properties. The remaining sample (about 800 g) was
 air-dried for amino sugar and soil physicochemical analyses. Only samples
 from 0–20 cm and 20–40 cm were analyzed for amino sugars and soil
 physicochemical properties due to the high cost of these
 analyses.
description: # The responses of microbial necromass carbon accumulation to climate
 aridity in alpine meadow soils are dominated by plant species richness
 [https://doi.org/10.5061/dryad.t1g1jwtcg](https://doi.org/10.5061/dryad.t1g1jwtcg) ## Description of the data and file structure From 15 July to 12 August 2022, we conducted an extensive field survey along a 2500-km transect that stretched from the southeastern to the northwestern parts of the Tibetan Plateau. There were 30 sites in total (each 100 m × 100 m; slope &lt; 5°), at which we collected plant and soil samples. we randomly selected three 1 m × 1 m plots that were separated by a minimum distance of 25 m. All sites had been overgrazed and not fertilized, with no significant accumulation of litter on the soil surface. For each plot, we defined the plant species richness as the number of species, then clipped all plants in the plots at ground level and placed the samples into paper bags for transportation to the lab for weighing. Plants were categorized into three functional groups: grasses (Gramineae), sedges (Cyperaceae), and others. Root biomass was collected in the same plots using a root auger with an inner diameter of 7.5 cm at depths of 0–20 cm and 20–40 cm. After carefully washing away the soil, dead roots were identified based on their internal color and removed from the sample. Both shoot and root samples were oven-dried at 65°C until they reached a stable weight, and then their weights were recorded. Soil samples were collected using a 3-cm-diameter auger at six points within each plot at 20-cm intervals to a depth of 100 cm. Collection depths were sometimes shallower at sites with a low depth to the bedrock. Soil subsamples from comparable depths within each of the six samples were pooled to form a composite sample. After removing litter and stones, samples were passed through a 2-mm sieve and then split into two parts. Approximately 100 g of fresh soil was kept at 4°C for measuring soil microbial properties. The remaining sample (about 800 g) was air-dried for amino sugar and soil physicochemical analyses. Only samples from 0–20 cm and 20–40 cm were analyzed for amino sugars and soil physicochemical properties due to the high cost of these analyses. ### Files and variables #### File: Dataset\_for\_microbial\_necromass\_C.xlsx **Description:**  | Abbreviations | | | | :------------ | :----------------------------- | - | | S | Site | | | PSR | Plant species richness | | | SB | Shoot biomass | | | Sedges | Sedges (% of shoot biomass)   | | | Grasses | Grasses (% of shoot biomass)   | | | Others | Others (% of shoot biomass)   | | | SOC | Soil organic carbon | | | MBC | Microbial biomass carbon | | | MNC | Microbial necromass carbon | | | FNC | Fungal necromass carbon | | | BNC | Bacterial necromass carbon | | | MBN | Microbial biomass nitrogen | | | MBP | Microbial biomass phosphorus | | | PH | Soil pH | | ## Code/software Excel can open and view the datas.