Shrub willow biomass crops (SWBC) have been
developed as a biomass feedstock for bioenergy, biofuels, and
bioproducts in the northeastern and midwestern USA as well
as in Europe. A previous life cycle analysis in North America
showed that the SWBC production system is a low-carbon
fuel source. However, this analysis is potentially inaccurate
due to the limited belowground biomass data and the lack of
aboveground stool biomass data. This study provides new
information on the above- and belowground biomass, the
carbon–nitrogen (C/N) ratio, and the root/shoot (R/S) ratio
of willow biomass crops (Salix × dasyclados [SV1]), which
have been in production from 5 to 19 years. The measured
amounts of biomass were: 2.6 to 4.1 odt ha−1 for foliage, 4.9 to
10.9 odt ha−1 for aboveground stool (AGS), 2.9 to 5.7 odt ha−1
for coarse roots (CR), 3.1 to 10.2 odt ha−1 for belowground
stool (BGS), and 5.6 to 9.9 odt ha−1 for standing fine root
(FR). The stem biomass production ranged from 7.0 to
18.0 odt ha−1
year−1 for the 5- and 19-year-old willows, respectively.
C/N ratios ranged from 23 for foliage to 209 for belowground
stool. An average R/S ratio of 2.0, calculated as total
belowground biomass (BGS, CR, and FR) plus AGS divided
by annual stem biomass, can be applied to estimate the total
belowground biomass production of a mature SWBC. Based
on AGS, BGS, and CR and standing FR biomass data, SWBC
showed a net GHG potential of −42.9 Mg CO2 eqha−1 at the
end of seven 3-year rotations.
Shrub willow biomass crops (SWBC) have beendeveloped as a biomass feedstock for bioenergy, biofuels, andbioproducts in the northeastern and midwestern USA as wellas in Europe. A previous life cycle analysis in North Americashowed that the SWBC production system is a low-carbonfuel source. However, this analysis is potentially inaccuratedue to the limited belowground biomass data and the lack ofaboveground stool biomass data. This study provides newinformation on the above- and belowground biomass, thecarbon–nitrogen (C/N) ratio, and the root/shoot (R/S) ratioof willow biomass crops (Salix × dasyclados [SV1]), whichhave been in production from 5 to 19 years. The measuredamounts of biomass were: 2.6 to 4.1 odt ha−1 for foliage, 4.9 to10.9 odt ha−1 for aboveground stool (AGS), 2.9 to 5.7 odt ha−1for coarse roots (CR), 3.1 to 10.2 odt ha−1 for belowgroundstool (BGS), and 5.6 to 9.9 odt ha−1 for standing fine root(FR). The stem biomass production ranged from 7.0 to18.0 odt ha−1year−1 for the 5- and 19-year-old willows, respectively.C/N ratios ranged from 23 for foliage to 209 for belowgroundstool. An average R/S ratio of 2.0, calculated as totalbelowground biomass (BGS, CR, and FR) plus AGS dividedby annual stem biomass, can be applied to estimate the totalbelowground biomass production of a mature SWBC. Basedon AGS, BGS, and CR and standing FR biomass data, SWBCshowed a net GHG potential of −42.9 Mg CO2 eqha−1 at theจุดสิ้นสุดของหมุนเวียน 3 ปีเจ็ด
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