Effects of British Columbia Tree Species on Forest Floor Chemistry

Abstract

Although the question of tree species effects on soils has been of scientific interest for decades, two big questions remain largely unanswered. First, are there consistent effects of tree species on soil and forest floor properties? And second, how large are species effects compared with influences of other site factors? Here we address these questions by reviewing studies of the effects of tree species native to British Columbia, Canada, on forest floor chemistry, to determine if there are consistent patterns. Then we examine studies that provide some indication of the relative influences of tree species and other site factors, to assess the importance of species effects. The province of British Columbia (BC), by virtue of its size and variety of climatic zones, has a large number of tree species, which also occur in neighboring provinces and U.S. states. In addition to comprising the natural and planted forests of BC, several of these species have been introduced into reforestation and afforestation projects in many European countries. The effects of BC tree species on forest floor properties have been investigated in several studies in North America and in Europe. In this paper we review what is known about the forest floors created by tree species native to British Columbia, particularly with respect to nutrient concentrations, rates of nitrogen mineralization, proportions of ammonium and nitrate, and microbial communities. Given the substantial influence of foliar litter on nutrient cycling in the forest floor (Prescott, 2002), we also discuss nutrient concentrations and rates of decay of foliar litter of BC tree species. Much of this information is drawn from common garden experiments both in BC