Epsilon Archive for Student Projects

Abstract

Stands consisting of poplar stump sprouts and root suckers show high potential of successful establishment and pose a cheap management alternative to the currently planted poplar plantations. Due to the relatively small proportion of presently existing poplar plantations in Sweden, especially second generations, knowledge about production potential and silviculture treatments for poplar is scarce. Thus, this study focused on investigating production potential and response of poplar second generations to thinning treatments under the following 3 hypotheses, namely: (1) Stump sprouts are dominant in stands of poplar sprouts and root suckers, (2) Thinning increases volume production (3) Thinning improves stem growth, production, and stem stability of crop trees.

The results showed that (1) the poplar clone “OP42” (Populus maximowiczii Henry x Populus trichocarpa Torr and Gray) produced significantly higher numbers of stump sprouts in comparison to root suckers seven years after harvest. Notably, the number of root suckers shared 42 % of the total number of stems in the stands; (2) Standing volume was significantly higher in the unthinned control treatment (6000 stems ha-1) in comparison to all thinning schemes; (3) Thinning increased stem diameter, volume growth, and stability of crop trees.

In conclusion, it is important to include poplar root suckers in investigations regarding second generations of poplar stands. Thinning schemes of densities up to 1100 stems ha-1 are recommended to optimize growth, production and wind stability for pulp production. Heavy thinning schemes of 550 stems ha-1 are recommended for high quality timber production. For bioenergy-based production, no thinning (6000 stems ha-1) is recommended. Row thinning (3000 stems ha-1) might not be recommended.