Wood composition and energy content in a poplar short rotation plantation on fertilized agricultural land in a future CO2 atmosphere

Abstract

AbstractTo study the influence of elevated CO2 and nitrogen (N) fertilization on wood properties and energy, Populus×euramericana trees were exposed to ambient CO2 (about 370 μmol mol−1 CO2) or elevated CO2 (about 550 μmol mol−1 CO2) using Free Air CO2 Enrichment (FACE) technology in combination with two N levels. Elevated CO2 was maintained for 5 years. After three growing seasons, the plantation was coppiced, one half of each experimental plot was fertilized and secondary sprouts were harvested after two growing seasons. Fourier transform infrared (FT‐IR) spectra of wood revealed significant effects of both elevated CO2 and N fertilization on wood chemistry, in particular, significant increases in lignin and decreases in N content. These results were corroborated by chemical analysis. Neither elevated CO2 nor N fertilization affected the calorific value of wood, which was 19.3 MJ kg−1. N fertilization enhanced the energy production per land area by 16–69% because of higher aboveground woody biomass production than on nonfertilized land. Estimates indicate that high yielding poplar short rotation cultivation may significantly contribute as an alternative feedstock for energy production.