Soil chemical changes associated with roosting birds

Extreme high mortality of shortleaf and loblolly pines was attributed to bird roosting in experimental plots during the winter of 1980–81. Soil samples had been collected in these plots in 1964 and stored. Samples were collected from the same plots in 1982 after the birds had roosted, and soil nutrients and pH were determined on all samples in 1983. There was a fourfold increase in available P, a threefold increase in exchangeable K, and a slight increase in Kjeldahl N in the 30-cm soil depth between the soil sampling dates, which was attributed to bird excrement. Exchangeable Ca and pH decreased significantly during this period, which was attributed to soil buffering and normal leaching and indirectly to bird excrement. Soil nutrient levels under the dead pines in 1982 were below those reported to be toxic to pine trees.