Changes in Litterfall Along a Gradient in Altitude

Abstract

(1) Above-ground litterfall was measured in twenty-five stands along a 700 m gradient in altitude in the White Mountains, New Hampshire, U.S.A. Vegetation changed along this gradient from deciduous forest, to coniferous forest, to krummholz. (2) The pattern of change with altitude for annual deposition of deciduous leaf, total leaf, and total fine litterfall was an initial steep decline from 670 m to c. 870 m, associated with the decrease in deciduous trees. From 1000 to 1295 m, deposition of these litterfall components remained constant. A second steep decline occurred between 1295 and 1370 m where the mainly coniferous forest became reduced to low krummholz. (3) In contrast, coniferous leaf litterfall increased steeply from 670 m to approximately 870 m, was roughly flat to 1295 m, and then also declined in the krummholz zone. This pattern reflected the distribution of coniferous trees across the gradient. (4) Because features of climate correlated linearly (but inversely) with altitude in this gradient, patterns of litterfall for parts of the gradient changed with mean July temperature, degree days, and actual evapotranspiration in an inverse way to those with altitude.