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Data from: Site characteristics set the trajectory for biocrust restoration: Identical treatments produce differing outcomes in a North American desert

Griffen, Keven1; Antoninka, Anita1; Nuñez-Solano, Karen2; Raymond, Kara3; Reed, Sasha4; Bowker, Matthew1

Published Sep 17, 2026 on Dryad. https://doi.org/10.5061/dryad.pc866t25t

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Sep 17, 2026 version files 473.43 KB

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Abstract

Biocrusts enhance ecosystem function across multiple scales, stabilizing soils, increasing fertility, and protecting ecosystem health. Human land use and other disturbances have reduced late-successional biocrust cover globally, yet methods for restoring late-successional biocrusts, and particularly the interactive effects of biocrust inoculum source, application rate, and delivery method, remain poorly understood. We compared wild-harvested versus cultivated biocrust inoculum applied in a continuous regression design (rates of 0–40% cover) across three Sonoran Desert sites with different disturbance histories. We crossed these treatments with a range of 0–34 g of psyllium husk, intended to retain inoculum. We subsequently measured biocrust cover, soil chlorophyll-a content, and indices of erosion resistance. Most treatment combinations increased biocrust cover, but efficacy varied by site and individual treatment. In a structural equation model, wild inoculum produced more late-successional biocrust cover than cultivated. Higher inoculation rates produced more biocrust. Psyllium husk had mixed effects. Late-successional biocrust cover correlated with higher soil aggregate stability at two sites, suggesting enhanced erosion resistance. Chlorophyll-a content did not respond strongly to treatment. Wild-inoculated plots were more lichen- and moss-rich at two sites (p = 0.026; p = 0.009). We conclude that site characteristics determine the degree of restoration success, but wild-collected biocrust inoculum applied at high rates consistently produced more diverse, higher-coverage biocrusts with benefits for ecosystem function. Synthesis and applications: Though rooted in the Sonoran Desert, our results provide insights for biocrust restoration worldwide. Despite innovations in biocrust cultivation methods, wild-harvested biocrust inoculum is still more effective for late-successional biocrust restoration than cultivated, and higher application rates produce greater biocrust cover. Since wild-harvesting disturbs intact biocrusts, practitioners should seek opportunities for biocrust salvage and incorporate cultivated inoculum as cultivation methods improve to mitigate this impact. Our study also confirms the site-dependency of treatment success; we suggest that practitioners should conduct pilot studies and tailor treatments to fit site conditions. Based on our findings, wetter sites or those disturbed by fire may be better candidates for restoration using high-rate, wild-harvested biocrust inoculation, while drier or more physically disturbed sites may require different strategies.