Phosphorus Inputs to Terrestrial Ecosystems

This review concentrates on two sources of phosphorus input to terrestrial ecosystems: release by weathering of rock and inputs from the atmosphere. The few direct estimates of P release by weathering give rates from 0.05-1.0 kg P ha{sup -1} yr{sup -1}; however less direct evidence suggests that rates up to 5 kg ha{sup -1} yr{sup -1} may occur. Total P input from the atmosphere collected by funnels can range from 0.07-1.7 kg ha{sup -1} yr{sup -1}. Input to some vegetation may be substantially increased by the canopy trapping suspended fine particles. Major sources of atmospheric P include fine soil particles, pollen, and burning of plant material, coal and oil. Their amount and relative importance varies greatly from place to place. The wide variation in P inputs between sites results in inputs being greater than losses at some sites but less than losses at others. This is likely to have major longterm ecological importance.