Methods 1

 

Clonal trial

Trees used in the study were clonally propagated from roots. To get the roots for use in clonal propagation mature aspen trees were selected from natural forest adjacent to host agency participating in project.

Tree selection criteria consisted of locating trees that were at least 1.6 km away from each using the following criteria: Phenotypically good looking trees with nice form have straight main bole. No obvious signs of insect or disease on tree. Once tree is located the following tree and site attributes where collected:
1.Height in meters.
2.Diameter at Brest height (DBH).
3.Location recorded as latitude and longitude with elevation in meters. Location information read from Garmin hand held GPS unit.

Typically tree selection is done in the fall or spring of the year while trees are in leaf off condition to help with the visual assessment of the trees. With only a few exceptions where frozen ground conditions are needed for access will trees be selected in winter due to harsh enviroment. 

For clonal propagation trees are revisited in the spring once the ground has thawed which is around May 13 for west central portion of Alberta .

Roots are hand dug with various tools such as axe, pick, and shovel.  On some years excavation can start as early as the last week of April. To allow for uniform crop of sprout to be produced during summer the last roots should be harvested by mid June. Typically each company participating in a study would collect between 20 to 30 roots which would be sent to a common processing facility. For these trail all roots were processed at Weyerhaeuser Tree Improvement Centre.