Biomass and volume yield after 6 years in multiclonal hybrid poplar riparian buffer strips

In this paper the potential of five hybrid poplar clones (Populus spp.) to provide biomass and wood volume in the riparian zone is assessed in four agroecosystems of southern Quebec (Canada). For all variables measured, significant Site effects were detected. Survival, biomass yield and volume yield were highest at the Bromptonville site. After 6 years of growth, total aboveground biomass production (stems + branches + leaves) reached 112.8 tDM/ha and total leafless biomass production (stems + branches) reached 101.1 tDM/ha at this site, while stem wood volume attained 237.5 m3/ha. Yields as low as 14.2 tDM/ha for total biomass and 24.8 m3/ha for total stem volume were also observed at the Magog site. Highest yields were obtained on the most fertile sites, particularly in terms of NO3 supply rate. Mean stem volume per tree was highly correlated with NO3 supply rate in soils (R2 = 0.58, p < 0.001). Clone effects were also detected for most of the variables measured. Total aboveground biomass and total stem volume production were high for clone 3729 (Populus nigra × P. maximowiczii) (73.1 tDM/ha and 134.2 m3/ha), although not statistically different from clone 915311 (P. maximowiczii × P. balsamifera). However, mean whole-tree biomass (including leaves) was significantly higher for clone 3729 (38.8 kgDM/tree). Multifunctional agroforestry systems such as hybrid poplar riparian buffer strips are among the most sustainable ways to produce a high amount of biomass and wood in a short time period, while contributing to alleviate environmental problems such as agricultural non-point source pollution.