The earliest stages of ecosystem succession in high-elevation (5000 metres above sea level), recently deglaciated soils

Abstract

Global climate change has accelerated the pace of glacial retreat in high-latitude and high-elevation environments, exposing lands that remain devoid of vegetation for many years. The exposure of 'new' soil is particularly apparent at high elevations (5000 metres above sea level) in the Peruvian Andes, where extreme environmental conditions hinder plant colonization. Nonetheless, these seemingly barren soils contain a diverse microbial community; yet the biogeochemical role of micro-organisms at these extreme elevations remains unknown. Using biogeochemical and molecular techniques, we investigated the biological community structure and ecosystem functioning of the pre-plant stages of primary succession in soils along a high-Andean chronosequence. We found that recently glaciated soils were colonized by a diverse community of cyanobacteria during the first 4-5 years following glacial retreat. This significant increase in cyanobacterial diversity corresponded with equally dramatic increases in soil stability, heterotrophic microbial biomass, soil enzyme activity and the presence and abundance of photosynthetic and photoprotective pigments. Furthermore, we found that soil nitrogen-fixation rates increased almost two orders of magnitude during the first 4-5 years of succession, many years before the establishment of mosses, lichens or vascular plants. Carbon analyses (pyrolysis-gas chromatography/mass spectroscopy) of soil organic matter suggested that soil carbon along the chronosequence was of microbial origin. This indicates that inputs of nutrients and organic matter during early ecosystem development at these sites are dominated by microbial carbon and nitrogen fixation. Overall, our results indicate that photosynthetic and nitrogen-fixing bacteria play important roles in acquiring nutrients and facilitating ecological succession in soils near some of the highest elevation receding glaciers on the Earth.

Culturable bacteria community development in postglacial soils of Ecology Glacier, King George Island, Antarctica

“…However, total organic carbon was lower than in the high Arctic (Schmidt et al 2008). The high total carbon contents at point '0' (close to the glacier) were striking, considering the lower levels 100-200 m away from the glacier, where microbial photosynthesis would be expected to provide organic carbon.…”

“…Deglaciated terrain presents a chronosequence of soil formation, primary succession, and ecosystem development. Distance from a retreating glacier reflects soil age, with vegetation-free sandy deposits at the front of the glacier contrasting with more differentiated soils further away (Schmidt et al 2008). Antarctic soils that only recently became ice-free are considered to be nutrient limited (Sigler et al 2002;Darmody et al 2005), despite the influence of local meltwater streams, organic and inorganic inputs from marine aerosols, guano deposits in penguin and other seabird rookeries, slow-growing cryptogamic plants, and marine algae deposited on the shore and dispersed by wind (Orchard and Corderoy 1983;Tibbles and Harris 1996;Beyer et al 1999;Tockner et al 2002;Grzesiak et al 2009).…”

The last 50 years of climate‐induced melting of the Maliy Aktru glacier (Altai Mountains, Russia) revealed in a primary ecological succession

“…However, microorganism diversity remains almost stable along the whole succession, as proved by the absence of a significant trend of the AWCD. This, as also reported by other previous studies (Nemergut et al., 2007; Schmidt et al., 2008), could mean that along the succession there is a microorganism replacement that does not change significantly their species richness, even though their abundance is positively correlated with the successional time. In contrast, fungal diversity in terms of both OTUs and genera fluctuates significantly with a trend where there are several intermediate stages along the succession, in which diversity is high, that are interspersed by samples that have high dominance of few taxa with a lower diversity.…”

“…Recently, deglaciated soils are colonized by a diverse community of bacteria and fungi even during the first 4–5 years following glacial retreat (Schmidt et al., 2008). Photosynthetic and nitrogen‐fixing bacteria play important roles in acquiring nutrients and facilitating ecological succession in soils near some of the highest elevation receding glaciers.…”

La vida temprana en la Tierra y los primeros ecosistemas terrestres

“…Sigler et al, 2002;Schmidt et al, 2008;Fierer et al, 2010), se espera que organismos heterótrofos también formaran parte de las comunidades terrestres primitivas, ya que parecen ser un complemento inevitable en estos consorcios. Bajo esta perspectiva, los ecosistemas microbianos primitivos estarían compuestos por productores primarios autótrofos, pero también por una miríada de otros microbios que encuentran su nicho en microambientes pre-existentes.…”