Fig nbsp xA Mean values of total

High guano inputs in former sites away from the glacier front, create an Fosbretabulin environment with low pH values (Michel et al., 2006 and Simas et al., 2007). These sites become progressively less acid with additional soil development, when the sites are abandoned and fresh guano input ceases (Michel et al., 2006). This is mainly explained by mineral weathering and high amounts of organic carbon that can neutralize part of the acidity at former sites, resulting in a more buffered soil (Michel et al., 2006 and Carvalho et al., 2013). Former sites are also related to high amounts of exchangeable Ca2 +, Mg2 +, K+ and phosphorus (Simas et al., 2007). These sites with moderate to high abundance of nutrients show more diverse vegetation than freshly exposed sites. With glacial retreat, warmer soil temperatures and higher water availability result in deeper microbial active soil layers and promote mineral weathering, which also supports vegetation development (Campbell and Claridge, 1987).