Active restoration efforts drive community succession and assembly in a desert during the past 53 years

Regreening efforts in deserts have been implemented globally to combat land degradation and desert expansion, but how they affect above- and belowground community succession and assembly processes remains unknown. Here, we examined variations in plant and soil microbial community attributes along a 53-year restoration chronosequence following the establishment of straw checkerboard barriers (SCBs) in the Tengger Desert of China. This approach is a combination of fixing shifting sand and adding organic material (straw) simultaneously to expedite vegetation restoration by enhancing the success of plant establishment. Our findings revealed that the establishment of SCBs significantly triggered plant and soil microbial communities to gradually approximate those of the natural community along restoration duration. We observed positive and negative bidirectional shifts in plant and soil microbial community composition. Critical temporal threshold zones for relatively rapid changes in community composition were identified, with 2-15.5 years for plants, 0.5-8.5 years for bacteria, and 2-8.5 years for fungi. This suggests a delayed response of plant communities to restoration efforts compared with soil microbial communities. Both stochastic and deterministic processes regulated plant and soil microbial community assembly. Stochastic processes played a more important role in plant and fungal community succession, whereas deterministic processes primarily governed bacterial succession. In terms of deterministic processes, temporal variations in community composition mainly resulted from the intrinsic correlations among plant, bacterial, and fungal communities, as well as an increase in soil organic carbon (SOC) with restoration duration. Thus, temporal patterns and functional contributions of bacterial communities appear to be more predictable than those of plant and fungal communities during desert ecosystem restoration. This study emphasizes that plant-bacteria-fungi correlations and increasing SOC content are critical for accelerating community succession and promoting dryland restoration. Future studies should explore and integrate temporal variations and restoration effects of multiple ecosystem functions to better predict dryland development and resilience to global climate changes over a large temporal scale.