Allometric relationships and dendroecology of the dwarf shrubDryas integrifolianear Churchill, subarctic Manitoba

Abstract

Shrubs have generally been overlooked in dendrochronology, and little information exists on allometric relationships in dwarf shrubs. Dryas integrifolia M. Vahl. has been recognized as an important species in revegetation of disturbed gravel pits in northern areas. In this study, the dimensions (mat, stem, and root) of D. integrifolia shrubs were measured in four populations having recolonized disturbed areas, and anatomical slides containing growth rings were prepared for each individual. The first objective was to compare allometric relationships among descriptors of shrub dimension and between these descriptors and shrub age. Secondary objectives included documenting maximum age and evaluation of the potential for cross-dating among shrubs. Strong, consistent allometric relationships between aboveground dimensions were observed among individuals from all sites, although growth rates varied within and between sites. This indicated that even though aboveground shrub dimensions grow proportionally to one another, these measurements cannot be used to infer age, because of differences in growth rates among D. integrifolia shrubs. However, numerous cross-sections from D. integrifolia shrubs could be successfully cross-dated, and a short chronology was developed. The radial growth – climate association was found to be similar to that of dominant tree species of the region regarding the impact of October conditions. Increased snowfall in October prior to and warm May temperature during the year of ring formation appear to restrict growth of these shrubs by altering the onset of the growing season. This study has demonstrated that it is possible to accurately date D. integrifolia shrubs, and this ability may be applied to future studies involving population dynamics and remediation of open gravel sites. Growth rings also have the potential to be used in other Arctic shrubs.