Phosphorus in Alaskan coastal tundra mainly comes from dead organic matter, with a long residence time. Soil solution phosphorus is quickly used up and needs constant replenishment, mostly through organic matter decomposition. Plant and animal biomass help with this process. Decomposition is the key step in the phosphorus cycle, with most phosphorus being released by microorganisms during population crashes. This determines how much phosphorus plants can take up. Snowmelt triggers a significant release of phosphorus into the soil.