Fig. 4: Historical trends of annual soil P inflows and outflows in the Tibetan alpine permafrost region for the period from the 1980s to the 2020s.
From: Soil phosphorus crisis in the Tibetan alpine permafrost region
a Annual soil P inflows and outflows for the overall ecosystem. b Annual soil P inflows and outflows for grassland. c Annual soil P inflows and outflows for forest. d Annual soil P inflows and outflows for cropland. e Cumulative soil P inflows and outflows for the overall ecosystem. f Cumulative soil P inflows and outflows for grassland. g Cumulative soil P inflows and outflows for forest. h Cumulative soil P inflows and outflows for cropland. The soil P inflow represents the sum of the supply of P from weathering, atmospheric deposition, fertilizer, the deposition of livestock excretions, and the return of plant litter. The soil P outflow represents the sum of P losses from plant absorption, soil erosion, and dissolved P in runoff.
