Decreasingnutrient concentrations in soils and trees with increasing elevation across a treeline ecotone in Rolwaling Himal, Nepal Decreasingnutrient concentrations in soils and trees with increasing elevation across a treeline ecotone in Rolwaling Himal, Nepal

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Vol14 No.5: 843-858

Title】Decreasingnutrient concentrations in soils and trees with increasing elevation across a treeline ecotone in Rolwaling Himal, Nepal

Author】Simon DROLLINGER1*; Michael MÜLLER2; Timo KOBL2; Niels SCHWAB3; Jürgen BÖHNER3; Udo SCHICKHOFF3; Thomas SCHOLTEN2

Addresses】1 Geoecology, Department of Geography and Regional Research, University of Vienna, Vienna, Austria; 2 Soil Science and Geomorphology, Department of Geosciences, University of Tübingen, Tübingen, Germany; 3 CEN Center for Earth System Research and Sustainability, Institute of Geography, University of Hamburg, Hamburg, Germany

Corresponding author】simon.drollinger@univie.ac.at

Citation】Drollinger S, Müller M, Kobl T, et al. (2017)Decreasing nutrient concentrations in soils and trees with increasing elevation across a treeline ecotone in Rolwaling Himal, Nepal. Journal of Mountain Science 14(5). DOI: 10.1007/s11629-016-4228-4

DOI】10.1007/s11629-016-4228-4

Abstract】At a global scale, tree growth in alpine treeline ecotones is limited by low temperatures. At a local scale, however, tree growth at its upper limit depends on multiple interactions of influencing factors and mechanisms. The aim of our research was to understand local scale effects of soil properties and nutrient cycling on tree growth limitation, and their interactions with other abiotic and biotic factors in a near-natural Himalayan treeline ecotone. Soil samples of different soil horizons, litter, decomposition layers, and foliage samples of standing biomass were collected in four altitudinal zones along three slopes, and were analysed for exchangeable cations and nutrient concentrations, respectively. Additionally, soil and air temperature, soil moisture, precipitation, and tree physiognomy patterns were evaluated. Both soil nutrients and foliar macronutrient concentrations of nitrogen (N), magnesium (Mg), potassium (K), and foliar phosphorus (P) decrease significantly with elevation. Foliar manganese (Mn) concentrations, bycontrast, are extraordinarily high at high elevation sites. Potential constraining factors on tree growth were identified using multivariate statistical approaches. We propose that tree growth, treeline position and vegetation composition are affected by nutrient limitation, which in turn, is governed by low soil temperatures and influenced by soil moisture conditions.

Keywords】Foliar nutrients; Himalaya; Nitrogen; Nutrient cycling; Podzol; Treeline