The impact of vine maple on site fertility of coastal temperate forests

Abstract

Vine maple ( Acer circinatum Pursh) has often been viewed as a competitor with conifers in coastal forests of the Pacific Northwest. Few researchers have examined vine maple’s ecological role in forest ecosystems with much of the literature focusing on its role as a weed species. We studied vine maple to determine if it enhanced site fertility in mature coastal forests and whether the nutrient status of adjacent Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) was improved by the presence of vine maple. Site fertility was assessed by analyzing litterfall, forest floor and Douglas-fir foliage using plots where vine maple was present or absent. Paired plots were established in a 75-year-old and a 130-year-old stand in southwestern British Columbia, Canada. At both stands, total autumn litterfall collected from vine maple plots had significantly higher N content than litterfall from conifer plots. Both stands had autumn, needle litterfall from vine maple plots with significantly higher N concentrations relative to needle litterfall from conifer plots. At the 130-year-old stand, N concentration in Douglas-fir foliage had a weak tendency to be higher for vine maple plots compared to conifer plots, with Douglas-fir adjacent to vine maple having larger boles. At both stands, total B concentrations and contents in the forest floor were higher in vine maple compared to conifer plots. At the 75-year-old stand, Douglas-fir adjacent to vine maple had foliage with greater B concentrations and contents which appeared to alleviate a B deficiency. Vine maple may be desirable in managed stands of temperate coastal forests due to the positive impact on site fertility and the potential to influence Douglas-fir growth.