Roots in the tundra : relations between climate warming and root biomass and implications for vegetation change and carbon dynamics

• Main Author: Wang, Peng
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Wageningen University 2016
• Subjects: biomass; carbon; climatic change; decomposition; ecosystems; global warming; roots; siberia; tundra; vegetation; biomassa; decompositie; ecosystemen; klimaatverandering; koolstof; opwarming van de aarde; siberië; toendra; vegetatie; wortels; Arctic; Global warming; Tundra; Siberia
• Online Access: https://research.wur.nl/en/publications/roots-in-the-tundra-relations-between-climate-warming-and-root-bi; https://doi.org/10.18174/385684

Global climate has been warming up for the last decades and it will continue in this century. The Arctic is the part of the globe that warms fastest and is more sensitive to climate warming. Aboveground productivity of Arctic tundra has been shown to increase in response to warmer climates. However, belowground responses of tundra vegetation are still unclear. As the major part of plant biomass in tundra lies belowground, it is pivotal to investigate changes in the belowground parts of tundra vegetation for our understanding of climate warming effects on tundra ecosystems. To get a general idea of how belowground plant biomass may change in a warmer climate, we synthesized published data on the belowground biomass of tundra vegetation across a broad gradient of mean annual air temperature from −20 to 0 °C. We found that aboveground biomass of tundra biomass indeed increases with mean annual temperature as well as summer air temperature, while belowground biomass did not show a significant relationship with temperature. The increases in the aboveground biomass were significantly larger than belowground biomass, resulting in reduced below/above ratios at higher temperatures. The shifted biomass allocation with temperature can influence the carbon dynamics of tundra ecosystems. Future tundra studies need to focus more on the species or functional type composition of belowground biomass and species or functional type specific belowground responses to climate warming. To determine the seasonal changes and vertical distribution of root biomass of different plant functional types, we sampled roots at a Siberian tundra site in the early and late growing season, from vegetation types dominated by graminoids and shrubs respectively. We distinguished the roots of graminoids and shrubs, and found that shrub roots grew earlier and shallower than graminoid roots, which enables shrubs to gain advantage over graminoids at the early growing season when nutrient pulses occur during snowmelt and soil thaw. The deeper roots of ...