stump and root biomass of poplar stands树桩和根生物量的杨树.pdf

Forests 2012, 3, 166-178; doi:10.3390/f3020166 OPEN ACCESS forests ISSN 1999-4907 /journal/forests Article Stump and Root Biomass of Poplar Stands Tord Johansson * and Birger Hjelm Department of Energy and Technology, Swedish University of Agricultural Sciences, Uppsala 75007, Sweden; E-Mail: birger.hjelm@slu.se * Author to whom correspondence should be addressed; E-Mail: tord.johansson@slu.se; Tel.: +46-18-673830; Fax: +46-18-673156. Received: 27 February 2012; in revised form: 18 March 2012 / Accepted: 23 March 2012 / Published: 18 April 2012 Abstract: Today there is an increasing demand for biomass for use in energy production. In this study we investigated stumps and roots from six poplar (Populus sp.) stands growing on former farmland in Sweden, situated between latitudes 55 and 60°N. The mean age of the poplar was 20 years (range 16–23), the mean stand density 1151 stems ha−1 (range 361–3279), and the mean diameter at breast height (over bark) 288 mm (range 81–574). All poplar stands were on clay soils (light and medium clay and light clay tills).The mean dry mass weight of the 72 excavated stumps was 45 ± 39 kg (range 1–185), with the roots ≥ 50 mm weighing 14 ± 16 kg (range 0.2–87). Dry mean stump weight represented 21% (by dry weight) of the stem. The mean total dry weight per hectare for stumps amounted to 34.9 ± 21.8 (range 12.9–66.9) tons and the equivalent value for roots was 12.0 ±