Secondary Succession




The growth and development of non-crop vegetation, though important for maintaining biodiversity and community structure, is often detrimental to the establishment of a commercial timber crop, either through natural or artificial means. This study was established to assess the vegetation changes resulting from the different harvesting intensities and to determine how understorey plant communities respond to different levels of canopy removal.
 
 
CLEARCUT 60% REMOVAL 30% REMOVAL
Clearcut - 2 yrs post treat. 60% - 2 yrs post treat. 30% - 2 yrs post treat.
A clearcut, two growing seasons after logging.  This harvest system has created the most uniform and widespread change.  The feathermosses are gone and aspen, birch and cottonwood are establishing quickly due to an increase in light availability and the warmer, more exposed soils. A 60% removal harvest unit two growing seasons after logging.  This harvest system has created the greatest diversity in plant communities.  Large gaps have vegetation similar to clearcuts but less vigourous, while small openings are more similar to the uncut forest. A 30% removal harvest unit two growing seasons after logging.  This harvest system has created the least amount of change to the vegetation community.  Most of the original plant community diversity remains intact with only minimal reduction in vigour.
CLEARCUT
60% REMOVAL
30% REMOVAL
Clearcut - 5 yrs post treat. 60% - 5 yrs post treat 30% - 5 yrs post treat.
Five growing seasons after logging.  Deciduous trees are well established and growing quickly.  Shrub and herb layer is extensive and providing strong competition for light for conifer growth.  Conifers that are able to get ahead of the competition grow fastest here. The same cutblock as above, five growing seasons after logging.  Fireweed is well established.  In the larger gaps, growth of deciduous trees and shrubs is quite rapid but typically slower than in the clearcut.  Planted conifers are growing well and survival is excellent.. 30% removal block five years after logging.  Moss layer has recovered and there is little visual evidence of the initial disturbace to the understory vegetation caused by the harvest.  Light levels are generally low and growth of planted conifers is quite slow.

For further information, Contact: Allen Banner or Karen McKeown.
 
 

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