Arctic mosses govern below-ground environment and ecosystem processes

Area of Science:

• Ecology
• Arctic Biology
• Soil Science

Background:

• Mosses are crucial components of northern ecosystems, regulating soil thermal and hydrological conditions.
• Climate change and herbivory pose threats to moss layers, necessitating an understanding of their ecological role.
• The functional significance of mosses in shaping soil characteristics is essential for predicting ecosystem responses.

Purpose of the Study:

• To investigate the impact of varying moss layer depths on arctic soil thermal and hydrological regimes.
• To assess how moss depth influences soil microbial biomass, activity, and nutrient availability.
• To determine the consequences of moss layer alterations for arctic ecosystem function.

Main Methods:

• Field manipulations in Spitsbergen (78°N) established shallow (3 cm), intermediate (6 cm), and deep (12 cm) moss layers.
• Soil temperature, thaw depth, and moisture content were monitored across treatments.
• Laboratory experiments assessed microbial biomass, activity, and nitrogen availability in relation to moss depth.

Main Results:

• Deep moss layers significantly reduced soil temperature and delayed organic layer thaw by 4 weeks, shortening the vascular plant growing season by 40%.
• Thinner moss layers resulted in warmer, wetter soils with increased plant-available nitrogen, promoting microbial biomass and activity.
• Moss depth exerted a greater influence on soil moisture than landscape-scale topography.

Conclusions:

• Spatial and temporal variations in moss layer depth have profound effects on arctic ecosystem processes, including nutrient cycling and energy transfer.
• Disturbances reducing moss layer depth can alleviate temperature and moisture limitations in mesic tundra.
• Understanding moss layer dynamics is critical for predicting the ecological consequences of environmental change in arctic regions.