The application of dendrometers to alpine dwarf shrubs – a case study to investigate stem growth responses to environmental conditions

[摘要] Considering the recent widespread greening and browning trendsassociated with shrubs in arctic–alpine ecosystems, further understanding ofhow these shrubs respond in a rapidly changing environment is of crucialimportance. We here monitor shrub growth, using high-precision dendrometers to producefine-scale intra-annual growth patterns from hourly stem diametervariability in a widespread evergreen species ( Empetrum nigrum ssp. hermaphroditum ). Measurements weretaken at a micrometer scale for the period 2015 till 2018 on exposed andmostly snow-free ridge positions. With the same temporal resolution, wecollected near-ground environmental data and identified on-site controls ofgrowth behavior. We found high inter-plant variability in radial stem growth but strongsimilarities in response patterns to the local environment. Our resultssuggest that the evergreen species is highly adapted to the specific localconditions, remaining partly photosynthetically active during the snow-freewinter, which facilitates carbohydrate accumulation for early-seasonphysiological activities. Additionally, we discovered a phase of radial stemshrinkage during the winter months, which can be attributed to an activecell water reduction to protect the plant from frost damage. We conclude that soil moisture availability and winter snow conditions arethe main drivers of radial stem growth of E. hermaphroditum in arctic and alpine regions andcould negatively affect the species' distribution in a warming climate.

[学科分类] 大气科学