DOI: 10.5061/dryad.66t1g1k7n
title: Biotic and abiotic properties of biocrus

description: Eukaryotic algae, as the primary group of photosynthetic autotrophs, exert
 a significant influence on the development and functions of biological
 crusts in dryland ecosystems. Despite their importance, there are
 substantial knowledge gaps on the composition of eukaryotic algal
 communities and their effects on the distributions of bacteria and fungi
 in dryland soils. This study examined the eukaryotic algal community along
 a successional sequence of biocrusts in the Gurbantunggut desert, while
 also investigating their patterns of co-occurrence with bacteria and fungi
 through high-throughput sequencing and bioinformatic analyses. The results
 showed that nitrogen and phosphorus levels played a crucial role in the
 regulation of changes in the abundance and composition of the algal
 community. In particular, changes in the structure of the algal community
 arise primarily from fluctuations in the main species, rather than from
 loss and appearance of species during the biocrust succession. The
 accumulation of nitrogen and phosphorus in the biocrust led to increases
 in the relative abundance of algal species in the Chlorophyta. The results
 also indicated that eukaryotic algae played an important role in affecting
 bacterial and fungal communities and significantly improved the stability
 of the microbial community, reflected by the robustness of co-occurrence
 networks. The network analysis further indicated that eukaryotic algae
 affected the stability of microbial co-occurrence networks either by
 acting as keystone taxa or associating with the keystone bacterial and
 fungal taxa. These findings reveal a clear mechanism by which soil
 nitrogen and phosphorus levels affected the composition of eukaryotic
 algae communities and further regulated bacterial and fungal communities
 during biocrust development, providing valuable information on the
 development and functional execution of biocrusts in dryland ecosystems.
description: The soil physicochemical factors were determined according to
 standard methods (Tan 1995). Briefly, nitrate and ammonium were extracted
 with 1 M KCl and determined using an Automated Discrete Analyzer (AQ2+,
 SEAL Analytical Inc., England). Soil organic carbon (SOC) was determined
 using the
 K<sub>2</sub>Cr<sub>2</sub>O<sub>7</sub> method. Total nitrogen (TN) was determined using the kjeldah method, total phosphorus (TP) using the NaOH Melting-Mo Te Sc Colorimetry method, and available phosphorus (AP) using the 0.5 mol/L NaHCO<sub>3</sub> Leaching-Mo Te Sc Colorimetry method. The soil pH was determined using a soil-to-water ratio of 1:2.5 using a pH meter (Sartorius PB-10, Germany). Genomic DNA was extracted from 0.25 g of soil using the SPINeasy Soil DNA Kit (MP Biomedicals, USA) according to the manufacturer’s instructions. The quantity and purity of the extracted DNA were evaluated using the NanoDrop ND2000c spectrophotometer (NanoDrop Technologies, Wilmington, DE, USA). To characterize the abundance of bacteria, fungi and algae in bare sand and biocrust soils, the 18S rRNA gene for microalgae, the internal transcribed spacer (ITS) region of the fungal and the 16S bacterial gene were amplified with the primer set V8f/1510R (Bradley, Pinto & Guest 2016), gITS7/ITS4 (Ihrmark<em> et al.</em> 2012) and 515F/806R (Bates<em> et al.</em> 2011) respectively on a QuantStudio3 Real-Time PCR system (ThermoFisher Scientific, MA, USA). PCR reactions were carried out in a 20 μl volume system containing 1 μl DNA (~10 ng), 1 μl of 10 μM each primer, and 10 μl of SYBR Green Premix (Takara, Japan). The PCR cycle conditions were 95 ° C for 5 min and followed by 35 cycles of 30 s at 95°C, 20 s at 58 ° C (for 16S rRNA), 30 s at 56 ° C (for ITS), and 30 s at 58 ° C (for 18S rRNA), 30 s at 72 ° C. Fluorescence data were collected at the end of the annealing stage. A standard curve was generated using a serial dilution of plasmids containing target gene fragments to calculate the unknown samples.
description: # Biotic and abiotic properties of biocrust
 Dataset comprises of one
 excel sheet containing the physicochemical properties of biocrust. The
 qPCR results of eukaryotic algae, bacterial and fungal abundance were also
 included. The high-throughput sequencing dataset of 18S rRNA, 16S rRNA and
 ITS gene were deposited at the National Center for Biotechnology
 Information, with the following accession numbers: PRJNA1048298 (16S),
 PRJNA1048333 (ITS) and PRJNA1048306 (18S). ## Description of the data and
 file structure Data is structured as written above. BS: bare sand soils,
 Al: algal crust, Li: lichen crust, Mo: moss crust. The qPCR results of
 eukaryotic algae, bacterial and fungal abundance were log10 transformed.
 ## Sharing/Access information There are no other ways at the moment to
 access the data except dryad depository or contacting the researchers in
 person.