Positive interactions between the lichen Usnea antarctica ( Parmeliaceae) and the native flora in Maritime Antarctica

• Published in: Journal of Vegetation Science
• Main Authors: Molina‐Montenegro, Marco A., Ricote‐Martínez, Natalia, Muñoz‐Ramírez, Carlos, Gómez‐González, Susana, Torres‐Díaz, Cristian, Salgado‐Luarte, Cristian, Gianoli, Ernesto
• Other Authors: Woods, Kerry
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2012
• Subjects: Antarctic; Antarc*; Antarctica; Usnea antarctica
• Online Access: http://dx.doi.org/10.1111/j.1654-1103.2012.01480.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1654-1103.2012.01480.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1654-1103.2012.01480.x

Abstract Questions Is the macrolichen U snea antarctica a ‘nurse’ species to A ntarctic flora? Are positive plant–plant interactions more frequent than negative interactions in Antarctic ecosystems? Are microclimatic modifications by cushions of U . antarctica responsible for the nurse effect? Location Two sites in A ntarctica: K ing G eorge I sland, S outh S hetland (62°11′ S, 58°56′ W; 62°11′ S, 58°59′ W). Methods We evaluated the association of plant species with U . antarctica cushions by recording species growing – in equivalent areas – within and outside U . antarctica cushions. Additionally, we performed transplant experiments with D eschampsia antarctica individuals to assess if U . antarctica cushions enhance plant survival. In both study sites we monitored temperature, moisture and nutrient status of soil outside and within the cushions to provide insights into potential mechanisms underlying possible interactions between U . antarctica and other plant species. Results Eight out of 13 species were positively associated with cushions of the widespread lichen U . antarctica , while only one species ( U . aurantiaco‐atra ) showed a negative association with U . antarctica . Survival of D eschampsia was enhanced when growing associated with U . antarctica cushions. Our results indicate that cushions ameliorated the extreme conditions of Antarctic islands through increased temperature and soil moisture, decreased radiation and evaporative water loss and increased nutrient availability. Conclusions The nurse effect of U . antarctica is verified. Cushions of this macrolichen may be a key component in structuring the A ntarctic landscape and maintaining local species richness, and their presence might influence range expansion of other species.