CrustNet: Global determinants of biodiversity in biocrusts, and outcomes for ecosystem function, resistance and resilience

Around the world, and for the past ~2 billion years, surfaces of many soils have a “living skin” made by tiny plants and microbes called a biological soil crust (biocrust). Biocrusts are crucially important for helping to support the ecosystems they inhabit, for example making soil fertile, storing or redirecting water and stopping erosion. Biocrusts also boost the variety of living things present in an area (biodiversity). The CrustNet project will determine what controls the biodiversity of biocrusts globally for the first time, and its outcomes. CrustNet is a networked, distributed study of biocrust ecology, with participants around the world. Participants conduct the same set of studies and collect the same types of data to be pooled together to create an unprecedented global database about biocrusts.  CrustNet addresses: (1) The determinants of the global scale functional biodiversity of biocrusts (2) determinants of the variability and shape of the relationship between biodiversity and ecosystem function across ecosystems, (3) effects of biocrust functional biodiversity on ecosystem resistance and resilience to physical disturbance and climate change, and (4) determinants of plant-biocrust co-occurrence patterns. CrustNet uses a tiered research protocol, including low-cost observational studies and manipulative experiments. Tier 1 includes mandatory detailed surveys of the composition of biocrusts, measurement of ecosystem functions along a biocrust development gradient, and contribution of samples to a trait database. Tier 2 includes low-cost experimentally-applied physical disturbance of the soil and subsequent tracking of the response of biocrusts. Tier 3 includes experimental climate manipulations using reciprocal transplantations and rainfall reduction using passive shelters. These studies will be foundational to our understanding of determinants of biocrust diversity, function and response to disturbance. To date, 14 sites in 5 nations have already been established and sampled, and pledged sites are ever increasing (23 additional sites have been proposed by international sampler-partners). In the process of conducting this research, a world-wide collaboration is being established, leading to greater participation of researchers from diverse backgrounds, and unparalleled training opportunities.