Nitrogen and phosphorus availability at early stages of soil development in the Damma glacier forefield, Switzerland; implications for establishment of N2-fixing plants

Hans Göransson,Else K Bünemann,Monika Welc,Harry Olde Venterink,Iso Christl

doi:10.1007/s11104-016-2821-5

Abstract

Di-nitrogen (N2)-fixing plants are absent in the pioneer stages of glacial forefields in the European Alps despite low amounts of nitrogen (N) in the soil. We aimed to evaluate whether symbiotic N2-fixation is needed to meet the N demand of plants during the early stages of soil formation, and how phosphorus (P) availability affects plant establishment. We measured total and available N and P in soil and N and P in the vegetation along the 137 year chronosequence in front of the Damma glacier (Switzerland). Available N as determined by in situ resin N decreased from the pioneer stage (<16 years since deglaciation) to the intermediate (57–80 years), likely resulting from increased plant N uptake and reduced funnelling of N by rocks. N concentrations in the vegetation were positively correlated to in situ resin N, and the N:P-ratio of the vegetation was negatively correlated with P concentrations in the vegetation. The N requirement of plants in the pioneer stage of soil development in the forefield is fulfilled by atmospheric N deposition being funnelled between rocks. N2-fixation is not needed as the vegetation is often limited by P, or co-limited by N and P.

Highlights

Glaciers in the European Alps have been withdrawing since the Little ice age ended in 1850, creating chronosequences that can be used to study soil formation and vegetation succession (Matthews 1992)
The in situ resin N from bags incubated in the soil for 110 days was high in pioneer stage sites, and tended to decline (p = 0.06) towards the intermediate stage, and increased again towards the end of the oldest stage of the developmental gradient (Fig. 2b)
The in situ resin N measured from bags incubated for 36–37 days was significantly higher in the pioneer stage sites than in the intermediate, and in the old stages in June-July and July-August (Fig. 3)

Summary

Introduction

Glaciers in the European Alps have been withdrawing since the Little ice age ended in 1850, creating chronosequences that can be used to study soil formation and vegetation succession (Matthews 1992). Total P usually declines with soil development as a result of weathering processes (Menge et al 2012; Walker and Syers 1976) This increase in N and decrease in P means that the factor limiting plant growth may shift after several hundred to many thousands of years from N to P (Chapin et al 1994; Wardle et al 2004). Plant available P has been reported to increase, decrease, or remain constant over the first 100 years of soil development (Darmody et al 2005; Matthews 1992) Some of these differences between studies can be attributed to differences in climate, parent material, or to the methods used such as fertilization experiments and plant tissue nutrient concentration. We aimed to evaluate whether symbiotic N2fixation is needed to meet the N demand of plants during the early stages of soil formation, and how phosphorus (P) availability affects plant establishment

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