A dendrochronological analysis of black spruce productivity in wetlands and adjacent uplands of Nova Scotia, Canada

Abstract

Coniferous forest uplands and wetlands are abundant in Nova Scotia. Tree growth in wetlands is known to be stunted compared to uplands. The objective of this study was to compare the growth of black spruce trees in wetlands and uplands of four Nova Scotia sites. Along a transect at each site, tree cores were taken from selected black spruce trees, for which tree height and diameter at breast height (DBH) was also measured. Data on peat moss and soil moisture were collected to determine whether trees were in wetland or upland. Black spruce age and tree ring productivity were assessed by analyzing tree cores with Windendro software. The average width of the outermost ten tree rings of each tree core was used as a measure of recent growth and productivity. Black spruce age and growth were relatively consistent across all habitats. Spruce radial growth was not always greater in upland environments, but trees were taller in uplands than wetlands at two of the study sites. Favourable environmental factors for tree growth often resulted in taller trees in upland habitats because the soils are drier. More recent tree growth appears to be indifferent to soil moisture on forested wetland landscapes; I presume it is because of unmeasured effects such as climate change and competition.