Spatial variability of throughfall water and chemistry and forest floor water content in a Douglas fir forest stand

摘要

This study focuses on spatial variability of throughfall waterand chemistry and forest floor water content within a Douglas fir (Pseudotsugamenziesii, Franco L.) forest plot. Spatial patterns ofwater and chemistry (NH₄+, NO₃￣, SO₄2-,Cl￣, Mg2+, Ca2+, Na+ and K+)were compared and tested for stability over time. The spatial coefficient ofvariation (CV) was between 18 and 26% for amounts of throughfall water and ions,and 17% for forest floor water content. Concentrations and amounts of all ionswere correlated significantly. Ion concentrations were negatively correlatedwith throughfall water amounts, but, except for NH₄+,there was no such relation between throughfall water and ion amounts. Spatialpatterns of throughfall water fluxes and forest floor water contents wereconsistent over time; patterns of ion fluxes were somewhat less stable. Becauseof the spatial variability of forest floor thickness and drainage, it was notpossible to relate patterns in throughfall water directly to patterns in watercontent. The spatial variability of throughfall nitrogen and forest floor watercontents can cause significant variability in NO₃￣production within the plot studied. style="line-height: 20px;">Keywords: nutrient throughfall, forest floor water, spatial variability, time-stability, nitrogen