Water-mediated changes in plant–plant and biological soil crust–plant interactions in a temperate forest ecosystem

PISSOLITO, CLARA; GARIBOTTI, IRENE A.; VARELA, SANTIAGO A.; ARANA, VERÓNICA; GONZALEZ-POLO, MARINA; MARCHELLI, PAULA; BRUZZONE, OCTAVIO

Web Ecology

Copernicus Publications

Año: 2019 vol. 19 p. 27 - 38

In the quest to understand how biotic interactions respond to climate change, one area that remainspoorly explored is how interactions involving organisms other than vascular plants will respond. However theinteractions between plants and biological soil crusts (BSCs) are relevant in many ecosystems and they willlikely respond uniquely to climate change. Simultaneous considerations of both plant?plant and plant?BSCinteractions may substantially improve our understanding of this topic. The aim of this study is to assess whetherwater availability differentially affects the biotic effects of BSCs and pioneer shrubs on the early life-historystage of tree seedling growth.We conducted a greenhouse factorial experiment with soil surface cover (bare soil,soil covered by a creeping shrub and BSC covered soil) and water regime (control and drought) as factors. Wemonitored Nothofagus pumilio (a native tree species of ecological and economic relevance) seedling water statusand growth as well as changes in soil water content and soil properties. The shrub cover had a positive effecton soil water conservation and on the water balance of seedlings under water stress. However, its effect wasnegative for seedling growth under both water conditions. The BSC also contributed to soil water conservationand apparently added nutrients to the soil. The net effect of the BSC on seedling growth was negative underfull-watering conditions but positive under water stress conditions. This result highlights how the studied bioticinteractions, and especially interactions involving BSCs, depend on changes in water availability.