Forest Trees - Bioenergy Crop Plants - page 372

after many field trials Populus emerged as one of the top candidates for further research. Poplars
emerged because they are genetically diverse, amenable to genetic improvement, fast growing, easy
to propagate and well-studied (Dickmann et al. 2001). A key factor in the acceleration of research
on poplars for bioenergy was the OPEC oil embargo of 1973. Soon after the huge increase in oil
prices, the oil importing countries began seeking alternative sources of energy including biomass
(Dickmann 2006). Research and development efforts were soon initiated on bioenergy by many
governmental agencies. For example, the International Energy Agency (IEA) was formed to foster
international research and development on energy in 1974. IEA includes a Bioenergy Task 30—
Short Rotation Crops for Bioenergy Systems. In 1978, the U.S. Department of Energy (DOE) initi-
ated a Short Rotation Woody Crops Program, which was later was renamed the Biofuels Feedstock
Development Program. This program provided funds for poplar cultivation, genetics, physiology,
pest management, growth and yield for 25 years. This continuous source of funding provided the
research continuity needed to advance poplar bioenergy research significantly (Stettler et al. 1992).
Similar bioenergy funding for poplars became available in the Canadian Forest Service and Energy
Agency. In 1995 the USDA Forest Service, the U.S. DOE, and the Electric Power Research Institute
(EPRI) also established the Short Rotation Woody Crop Operations Working Group to pursue
efficient development of practices of culture, harvest and handling of woody biomass plantations.
Further details of the history of poplar production and bioenergy in the United States and Canada
are provided by Thielges and Land (1976), Dickmann (2006) and Richardson et al. (2007).
Published data on biomass production rates in North America range from 2 to 35 mt/ha per year
(Table 15.4). Realistic yields are probably in the range of 5-20 mt/ha per year (Stanturf et al. 2001;
Dickmann 2006; Davis 2008). The reasons for the large variation are many. Some reports were from
small plot experiments and unreplicated demonstrations whereas others are from larger replicated
field studies, or genetic trials with adequate border rows, or plots within commercial operational

taBle 15.4
chronological synthesis of Poplar Biomass Production Field studies and Plantations
by location in north america

clone/
species*

age
(years)

spacing
(m)

Productivity
(mt/ha per year)

location reference

W US T 2 0.3 13.4-20.9 Heilman et al. (1972)

W US/Canada T Multiple 0.3-1.2 9.0-11 Smith and DeBell (1973)

S US D 5-20 3.0 10-11 Switzer et al. (1976)

NE US DN 4 0.12-0.76 7.7 Bowersox and Ward (1976)

NC US DN 4 0.23-0.61 11.3-13.8 Ek and Dawson (1976)

E Canada DN Multiple Multiple 5-19 Anderson (1979)

W US T 8 0.3-1.2 5.8-9.7 Heilman and Peabody (1981)

NC US B 5 1.2 4.2 Isebrands et al. (1982)

W US T,TD 4 1.2 5.2-27.8 Heilman and Stettler (1985)

W US T,TD 4 1.2 11.3-12.6 Heilman and Stettler (1990)

NC US DN,B Multiple Multiple 4.9-12.8 Strong and Hansen (1993)

W US TD 5 0.18-0.3 6.4-30 DeBell et al. (1993)

W US TD 7 0.5-2.0 10.1-18.2 DeBell et al. (1996)

W US T,TD 7 1.0 11-18 DeBell et al. (1997)

W US T,TD 4 1.0 14-35 Scarascia et al. (1999)

NC US DN 7-12 2.4 4.7-10 Netzer et al. (2002)

W Canada TD 4-13 3.0 9.2-13.6 Zabek and Prescott (2006)

*B, P. balsamifera ; D, P. deltoides ; N, P. nigra , T, P. trichocarpa ; DN, D × N; TD, T × D; N, north; E, east; S, south;
W, west; C, central; US, United States.