E-mail : simard@wisc.edu

Black spruce decline in the lichen woodlands of the Parc des Grands-Jardins: a dendroecological and dendroarchitectural analysis
 
Supervisor : Serge Payette


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Black spruce (Picea mariana (Mill.) BSP) is the dominant tree species of the southernmost (48°N) lichen woodlands in eastern Canada. Most spruce trees in mature lichen woodlands appear to be declining, as shown by the massive invasion of the epiphytic lichen Bryoria on dead branches of dying trees. A dendroecological study was undertaken to identify the main causal factors of the decline. A decline index based on the abundance of Bryoria on spruce trees was used to distinguish healthy from damaged lichen–spruce woodlands and to select sampling sites for tree-ring measurements. Three conifer species (black spruce, balsam fir (Abies balsamea (L.) Mill.), and jack pine (Pinus banksiana Lamb.)) were sampled to compare their growth patterns in time and space. In the late 1970s and mid-1980s, black spruce and balsam fir experienced sharp and synchronous radial-growth reductions, a high frequency of incomplete and missing rings, and mass mortality likely caused by spruce budworm (Choristoneura fumiferana (Clem.)) defoliation. Jack pine, a non-host species, showed no such trend. Because black spruce layers were spared, lichen woodlands will eventually regenerate unless fire occurs in the following years. Black spruce decline can thus be considered as a normal stage in the natural dynamics of the southern lichen woodlands.

Publications

Payette, S., A. Delwaide & M. Simard, 2010. Frost-ring chronologies as dendroclimatic proxies of boreal environments. Geophysical Research Letters Vol. 37, L02711, doi:10.1029/2009GL041849.

Simard, M., Payette, S., 2005. Reduction of black spruce seed bank by spruce budworm infestation compromises postfire stand regeneration. Canadian Journal of Forest Research, 35: 1686-1696.


Simard, M., Payette, S., 2003. Accurate dating of spruce budworm infestation using tree growth anomalies. Écoscience, 10 : 204-216.


Simard, M., Payette, S., 2001. Black spruce decline triggered by spruce budworm at the southern limit of lichen woodland in eastern Canada. Canadian Journal of Forest Research, 31: 2160-2172.


Payette, S., Bhiry, N., Delwaide, A., Simard, M., 2000. Origin of the lichen woodland at its southern range limit in eastern Canada: the catastrophic impact of insect defoliators and fire on the spruce-moss forest. Canadian Journal of Forest Research, 30: 288-305.