Accurately ageing trees and examining their height‐growth rates: implications for interpreting forest dynamics

Abstract

Summary 1We examined the validity of classifying tree species as early, mid-, or late-successional based on age and height-growth rates, by comparing the age and height-growth rates of trees in the boreal forest. 2 Age was first examined using the traditional method of coring 30 cm above the root collar; then dendrochronology was used to locate the root collar and missing annual growth rings. Traditional ageing differentially underestimates tree age; species classified as early successional ( Populus tremuloides , Betula papyrifera , and Pinus banksiana ) are less severely underestimated than those classified as mid-and late-successional ( Picea glauca , Picea mariana , and Abies balsamea ) (0-11 vs. 0-43 years), and also have relatively fewer locally missing growth rings. Ageing at the root collar shows that all tree species recruit within 5 -10 years after fire and age cannot therefore be used to determine successional status. 3 Mean time taken to grow to each 1-m increment from the root collar was estimated for each species. Species classified as early successional have relatively higher growth rates between the root collar and the first metre; they are therefore less severely underestimated when aged above the root collar, explaining why they often appear older than species classified as mid-and late-successional. The lack of species differences above 1 m means that height-growth rates cannot be used to classify these tree species as early, mid-, or late-successional. 4 In the boreal forest of Saskatchewan, the rapid recruitment of all tree species after fire, and the short fire cycle mean that the forest dynamics between catastrophic wildfires are driven primarily by the mortality rates of each species.

A 229-year dendroclimatic-inferred record of forest fire activity for the Boreal Shield of Canada

“…There is a general agreement that ageing shade-tolerant tree species from tree rings often leads to an underestimation of the true age (DesRochers and Gagnon 1997; Kneeshaw and Claveau 2001;Wong and Lertzman 2001;Girardin et al 2002;Gutsell and Johnson 2002). The time-since-last-fire may also exceed the age of the oldest trees because of individual tree mortality (Fox 1989).…”

A sensitive slope: estimating landscape patterns of forest resilience in a changing climate

“…We evaluated pre-fire and post-fire forest composition by measuring dead trees and new seedlings 7-10 years after fire, when we expected that most of post-fire seedlings that comprise the future canopy would have been recruited (Gutsell and Johnson 2002, Peters et al 2005. Topographic variation has been shown to have a large impact on microclimate conditions in mountainous areas of boreal forest (Van Cleve et al 1991).…”

“…We collected a limited set of stand age data to evaluate whether our expectations of a short, 7-10 year recruitment window after fire (Gutsell and Johnson 2002, Peters et al 2005) were likely to be appropriate for this study area. We randomly selected 6 sites sampled in 2005 (2 in each aspect class) for detailed study of pre-fire stem ages.…”

“…Regeneration of the forest canopy largely occurs from seedlings that recruit within the first decade after fire when seedbeds are optimal for establishment (Gutsell andJohnson 2002, Peters et al 2005). By monitoring patterns of seedling recruitment after fire, we can thus obtain valuable insights into the resilience of forest ecosystems to disturbance (Bruelheide and Luginbuhl 2009).…”

Ecological Structure and Prediction Equations for Estimating Tree Age, and Dendometric Parameters of <i>Acacia senegal</i> in the Senegalese Semi-Arid Zone—Ferlo

“…Dendometric parameters vary with the tree age. Several studies have tried to improve the accuracy of the assessment of the age of wood in general [14][15][16][17] and especially Acacia senegal [18]. But all the techniques used, such as the use of growth rings, the extraction of cores increases or entire cross sections are destructive and inappropriate for degraded ecosystems to which the development of less destructive methods remains a major challenge.…”