Good neighbors: Bryophytes’ role as water regulators in alpine grasslands.

Our understanding of bryophytes’ role in ecosystems points to important functions in hydrology. However, data on bryophytes’ traits related to hydrology have been absent from or limited in climate and ecosystem studies. Certain morphological traits allow bryophytes to hold a lot of water relative to other plant functional groups. This gives them an important role in the ecosystem by regulating soil moisture and temperature. Water holding capacity (WHC) in bryophytes may be context dependent, with variation in direct factors such as temperature and precipitation and indirect effects of biotic interactions. To investigate these factors’ influence on WHC, we harvested bryophytes from The Vestland Climate Grid. This unique experimental grid consists of 12 alpine grassland sites in a climate grid of three levels of mean summer temperature (7.5, 9.5, and 12.5°C) and four levels of mean annual precipitation (600, 1200, 2000, and 2700mm). Total bryophyte community biomass was harvested from plots where graminoids and forbs have been removed annually since 2015 (GF) and from control plots (C). We conducted a laboratory experiment to measure WHC on these biomass samples. Preliminary results from the GF plots indicate that there is less variation in WHC across the precipitation gradient in the alpine bryophyte communities compared to that of their sub-alpine and boreal equivalents. Insights from this project will develop our understanding of these organisms’ role in climate regulation and biotic interactions. In particular, our work will contribute to improved representation of bryophytes and hydrological processes within land surface models, resulting in more accurate predictions of future climate-vegetation interactions in high-latitude systems.