Provenance- and life-history stage-specific responses of the dwarf shrub Calluna vulgaris to elevated vapour pressure deficit

• Published in: Plant ecology 2020-12, Vol.221 (12), p.1219-1232
• Main Authors: Ibe, Karin, Walmsley, David, Fichtner, Andreas, Coners, Heinz, Leuschner, Christoph, Härdtle, Werner
• Format: Article
• Language: English
• Subjects: Applied Ecology; Assisted migration; Atmospheric water; Biodiversity; Biomass; Biomedical and Life Sciences; Calluna vulgaris; Climate change; Community & Population Ecology; Ecology; Ecosystem assessment; Ecosystems; Global temperature changes; Life history; Life Sciences; Moisture content; Moors and heaths; Morphology; Physiological aspects; Plant Ecology; Plant growth; Pressure; Pressure effects; Provenance; Signatures; Soil moisture; Soil water; Terrestial Ecology; Vapor pressure; Water vapor
• ISSN: 1385-0237; 1573-5052
• DOI: 10.1007/s11258-020-01076-3

Climate change may alter microscale-effective ecosystem properties such as atmospheric water vapour pressure, but consequences for plant growth are insufficiently understood. Within a northwest German heathland an open-top chamber experiment was established to analyse the effects of elevated vapour pressure deficit (eVPD) on growth responses of Calluna vulgaris considering both plant origin (Atlantic (AP), sub-Atlantic (SAP), sub-Continental (SCP)) and life-history stage (1-year vs. 10-year old plants). We hypothesised that the plants’ sensitivity to eVPD decreases (i) from AP to SCP and (ii) with progressing life-history stage. Elevated VPD caused a provenance-specific decrease of shoot increment whilst aboveground biomass productivity remained unaffected. AP and SAP responded with increasing belowground biomass δ¹³C signatures to eVPD, whereas δ¹³C values decreased for SCP. Moreover, eVPD increased and decreased belowground biomass δ¹³C signatures of 1- and 10-year old plants, respectively. These responses to eVPD were related to differences in morphological-chemical traits and the plants’ trait plasticity in response to eVPD. SCP showed the highest aboveground tissue mass density and significantly increased tissue C:N ratios under eVPD. One-year old plants had a tenfold higher shoot:root ratio than 10-year old plants, making young plants more sensitive to eVPD. Our findings demonstrate that the atmospheric water status affects the morphology and physiology of Calluna independent of the soil water status. The results have implications for the conservation of heathlands under climate change: (i) SCP may constitute an appropriate ecotype for assisted migration-approaches, and (ii) management needs to weigh different options for heathland rejuvenation.