Soil Crust InterNational SCIN

The aim of SCIN (Soil Crust InterNational) is to achieve both better appreciation of the functioning and importance of biological soil crusts (BSCs) in Europe and to add value by contributing to the development of better and simpler soil protection practices and policies. BSCs are the biologically modified soil surface that form naturally in open areas. They are typically composed of cyanobacteria, algae, micro fungi, lichens and bryophytes in varying amounts and can be the only vegetation cover in arid and semi-arid regions such as hot and cold deserts or xerothermic steppe vegetation. They are also the first colonizers of disturbed soils and have major impacts on the soil properties through stabilization, erosion limitation, better water infiltration and facilitation of colonization by higher plants. BSCs are thought to contribute as many as 6% of the annual global CO2-fixation and 10-40% of the annual global nitrogen input into the earth`s ecosystems. Despite these immensely important properties that provide protection to large, particularly marginal areas, soil crusts are neither well understood nor well appreciated by conservation and regularity authorities who are missing opportunities for improved policies and actions in the area of land protection. SCIN is a project that will provide a much improved understanding of BSC functionality in Europe, from the severest desert to the alpine ecosystems. Estimates of annual productivity will be achieved through continual, in situ, and monitoring of BSC activity linked to detailed photosynthetic measurements. Rates of change and recovery will be determined leading to indices of sensitivity. The functional studies will be backed by detailed biodiversity assessments that aim to reveal the key organisms in BSC functioning over a wide latitudinal, altitudinal and climatic range. Information transfer to stakeholders such as local conservation and land management authorities, and to policy makers will be achieved through a series of consultations and reports including highly visual material that will support the work of these organisations. Scientific transfer will be achieved by regular publication in peer reviewed journals and the holding of an international workshop in Year 2 of the project. Smaller local workshops will be held in Year 3 to link the science to stakeholders. European added value will not only be through policy and protection but by improved scientific excellence through the collaboration of diverse groups targeting BSCs. This will provide a unique opportunity for the transfer of skills and knowledge to young scientists. How common are Biological Soil Crusts (BSC) along the climatic gradient. Key questions: How is their taxonomic composition and how diverse are the BSC itself. How is diversity and productivity linked? What is their role in the referring ecosystems (e.g. N + C input, soil stabilization, enhancement of succession). What do they contribute to the ecosystems CO2-fixation/N-input?

Biological Soil Crusts (BSCs) are complex communities of microorganisms, including cyanobacteria, micro fungi, green algae, lichens and bryophytes, which form a thin layer of soil surface in open areas. BSCs are worldwide distributed and can be the only vegetation cover in arid and semi-arid regions. They are also the first colonizers of disturbed soils and have major impacts on the soil properties trough soil stabilization, erosion limitation, and facilitation of colonisation by higher plants. In the present project, four research sites across Europe, spanning from the semi-deserts in Tabernas (Spain) to the high altitude site on the Hochtor (Grossglockner High Alpine Road, Austria) were chosen, with the aim to investigate pedological characteristics, species composition, physio-ecological and morphological adaptation of different crust organisms, as well as their genetic characteristics. The better understanding of BSCs should be the basis for land conservation policy. Our team in Salzburg investigated i) the effect of BSC on the underlying soil, ii) the change of physico-chemical properties of soil after complete removal of BSC for 3 years, and iii) the diversity of lichens at all four sites. The genetic analysis on the key species Psora decipiens showed that its wide ecological distribution is closely related to the variety of its associated green algae. In contrast to the BSCs of the other three sites that were rather dry and mainly composed of lichens and bryophytes, the BSCs on the Hochtor were dominated by dark-colored cyanobacteria, what can be explained with the permanent humid and cold climate conditions on the Hochtor site. Compared to the underlying soil, the BSC-layer showed higher concentrations of plant available nutrients and higher N turnover (determined by 15N/14N-isotope ratio). In addition, higher total organic carbon was also observed in BSCs. Dust deposits on the rough surface of crusts were regarded as an important source of nutrients. The higher water holding capacity and aggregate stability of BSCs indicated the importance of BSCs in soil protection. In the recovery experiments where the BSC-layer was completely removed (10 plots/site), no considerable recovery progress of BSCs was identified after 3 years of observation. However, the vertical sections of uncrusted soil surface after 2 years already exhibited a thin layer of bacteria. Looking at the seedling reestablishment on the Hochtor site, up to 800 seedlings were accounted per square meter during summer periods. However, all seedlings had been disappeared in the following spring after snow melting. Only 1 to 2 rosettes or stolons of higher plants have established in some plots. Similar to that, also some small individuals of lichen thalli could be observed. All our results were communicated to the landowners, the Austrian Alpine Association and the National Park Authority. In particular it was pointed out that trampling disturbs the formation of fragile crusts and interrupts the succession process to stable plant communities.