Stand recovery and self-organization following large-scale mountain pine beetle induced canopy mortality in northern forests

AMOROSO, MARIANO; COATES, DAVID; ASTRUP, RASMUS

Congreso; 9th International Conference on Dendrochronology; 2014

A  mountain  pine  beetle  (MPB)  epidemic  is  currently  ravaging  large  areas  of  interior  British  Columbia  (BC), Canada  with  significant  implications  for  ecosystem  services  including  future  timber  supply  and  community economic  stability.  Information  is  needed  on  future stand  dynamics  in  areas  of  impacted  forests  that  are unlikely to be salvaged logged. Predicting how surviving trees in these areas respond and grow and thetiming and species composition of natural regeneration ingress is of critical importance for multiple forest values. We undertook a retrospective study in southeastern BC where an intense MPB epidemic peaked in 1979-1980. Our objective was to gain insight into stand recovery and stand self-organization as influenced by species-specific growth responses of different sized secondary structure trees (seedlings, saplings, and canopy trees surviving the epidemic) and post-beetle regeneration dynamics. MPB mortality rates, the percent of basal area killed by beetles, varied from 42 to 100%. In general, all surviving secondary structure released but the extentof growth release exhibited species variability. Ingress of natural regeneration was slow in the first few yearsafter MPB attack  but  there  was  a  strong  pulse  of  recruitment  10-20  years  post  disturbance  which  then  slowed considerably.  Nearly  30  years  after  the  MPB  attack, the  stocking  and  composition  of  the  understories  have changed  dramatically.  Overall,  the  occurrence  of  the  MPB  epidemic  resulted  in  more  structurally  and compositionally  diverse  stands  leading  to  multiple  successional  pathways  different  from  those  of  even-age pine dominated stands.