The development of nutrient pools along two holocene chronosequences with contrasting bedrocks in the Swiss Alps

Climate change accelerates glacial retreat worldwide, leaving large areas of unconsolidated terrain. Glacial retreat opens the possibility to study the temporal development of ecosystems, their functions and services by use of a space-for-time-approach. Nutrient pools are important indicators of various ecosystem services as they are critical in supporting the establishment and growth of plant communities, which in t u r n support the food webs and ecological processes that sustain the ecosystem and downstream communities. In this study, we examined the temporal development of nutrient pools in soils and vegetation communities over a period of more than 10,000 years. We analyzed a comprehensive dataset that embraces repeated measurements of carbon (C), ni-trogen (N), potassium (K), calcium (Ca), magnesiu m (Mg) and phosphorous (P) pools in above-and belowground biomass, litter and soi l across alpine chronosequences from two glacier forelands with contrasting bedrocks (silicate vs carbonate). We found that total nutrient pools of C and N, being closely linked to the biomass, increased rapidly along both chronosequences, whereas nutrient pools of K, Ca, Mg , and P were large at first and decreased steadily with time, though at different rates related to the two parent materials. We also observed a remarkable difference in the P pool development between the two glacier forelands. The calcareous soils started out with much more P than the siliceous locations. The plant availability of P was, however, higher in the siliceous soils due to the neutral pH, but decreased with acidification. In the calcareous soils, plant P availabilit y was low at the beginning due to a high pH, but improved as decalcification progressed and pH lowered to slightly acidic conditions. The results of this work highlight that assessing the temporal development of ecosystems services using long-term proglacial chronosequences enhances ou r understanding of landscape evolution.

Automated summary

Climate change accelerates glacial retreat and provides an opportunity to study the temporal development of ecosystems. This study analyzed long-term data and found that carbon and nitrogen nutrient pools increased rapidly over time, while potassium, calcium, magnesium, and phosphorus nutrient pools decreased. The availability of phosphorus also varied between different types of soil.