THE PHENOLOGY OF FINE-ROOT GROWTH IN A MAPLE-DOMINATED ECOSYSTEM - RELATIONSHIPS WITH SOME SOIL PROPERTIES

A two-year study was undertaken in a maple-dominated watershed of sout hern Quebec, Canada, to examine relationships between trends in fine r oot growth, stem diameter growth, soil moisture, soil temperature, min eralized-N and extractable-P. Until September, soil temperature was co nsistently higher in 1995 than in 1994. Apart from the first sampling in mid-May, soil moisture was higher in 1994 than in 1995. In 1994, mo st fine roots were produced before leaf expansion, whereas in 1995, fi ne root production peaked in July. Annual fine root production was est imated to be 2.7 times higher in 1994 than in 1995. Stem growth was st rongly associated with the seasonal and annual variation in soil tempe rature. Root and diameter growth were asynchronous in 1994 but not in 1995. Fine root production was associated with two groups of variables : a soil fertility (mineralized-N and extractable-P) group and a physi cal soil environment (moisture and temperature) group. Our results are consistent with the negative effect of high soil-N fertility on fine root production but are inconclusive as to the positive effect of high soil-P fertility. Soil conditions that are detrimental to root growth such as high N availability and anaerobiosis could modify the normal dynamics of fine root growth.