Rhizospheric Cyanoprokaryota Influence Nutrient Availability and Gypsophyte Adaptation in Semiarid Gypsiferous Soils

Gypsum ecosystems are constrained by extreme nutrient and water scarcity, where cyanoprokaryota interact with gypsophyte rhizospheres, influencing plant performance and soil biogeochemistry. This study examines three gypsophytes—Herniaria fruticosa, Helianthemum squamatum, and Teucrium libanitis—during winter and spring to characterize rhizospheric and bulk soil properties, assess enzymatic activity and nutrient cycling, identify cyanoprokaryota communities, and determine bioelement accumulation patterns in both Microcoleus chthonoplastes and gypsophytes. Physical, chemical, microbiological, and microscopic analyses were conducted across seasons. β-glucosidase activity showed species-specific responses to water pulses, particularly in Helianthemum squamatum. Seasonal differences in water-soluble C and N distinguished rhizospheres of Teucrium libanitis and Helianthemum squamatum. Key soil drivers included water-holding capacity to −1500 kPa, total and organic carbon, and Cr content. Cyanoprokaryota exhibited both rhizosphere-specific (Gloeocapsa novacekii, Pseudocapsa dubia) and ubiquitous taxa, with Microcoleus chthonoplastes reflecting bioaccumulation strategies. Bioelement accumulation differed between leaves and roots, especially for K, Mn, Zn, Na, Ni, C, and V, while the Sr:Ca ratio emerged as a potential indicator, especially in Herniaria fruticosa. These findings highlight the role of cyanoprokaryota in regulating nutrient availability and enzymatic activity, supporting gypsophyte adaptation and the ecological sustainability and resilience of gypsum ecosystems, and informing conservation and restoration strategies in these neglected ecosystems.