Biomass distribution of two subalpine dwarf-shrubs in relation to soil moisture and nutrient content

Abstract Question: Do soil water content and/or soil nitrogen (N) content and/or soil phosphorus (P) content affect the biomass of Vaccinium myrtillus and V. vitis-idaea in a sub-alpine heath? Location: Dolomites, northern Italy, 1800 m a.s.l. Methods: We determined above-ground and below-ground biomass of the shrubs at three sites, each on a different substrate type. At each site, we determined soil N- and P-contents. We also determined leaf water potential (ψl), N- and P-concentrations in plant tissues and litter, as well as δ13C and δ15N in mature leaves. Results: V. myrtillus biomass was highest at the silicate site, V. vitis-idaea biomass was highest at the carbonate site. Both shrubs had low biomass at the peat site, possibly due to a toxic effect of waterlogging in wet soils. For both species, pre-dawn ψl indicated optimal hydration and midday ψl did not show any sign of water stress. Water use efficiency (WUE) did not differ among sites for any species. Whole-plant nutrient concentrations showed t...