Hydrocarbon emissions from spruce species using environmental chamber and branch enclosure methods

Abstract

Isoprene emission rates from Engelmann ( Picea engelmannii), red ( Picea rubens), and black ( Picea mariana) spruce were measured from groups of seedlings in a controlled environmental chamber. Standard isoprene emission rate factors, obtained from measurements over an array of light and temperature conditions, ranged from 1 to 16 μgCg −1h −1 at 30°C and 1000 μmolm −2s −1 photosynthetically active radiation. Emission measurements were also collected using a dynamic enclosure technique from branches of a mature white spruce ( Picea glauca) through a complete growing season. These data indicate that isoprene emissions, normalized to standard conditions, are moderate in spring and fall (∼ 7 μgC g −1 h −1 at 30°C, 1000 μmol m −2 s −1) with a maximum in mid-summer (∼ 12 μgCg −1 h −1 at 30°C, 1000 μmolm −2s −1) Isoprene from white spruce represented more than 90% of the total identified hydrocarbons. Branch enclosure measurements from limited survey samples for blue spruce ( Picea pungens) yielded a standard emission rate of 12 μgC g −1 h −1 while samples for Norway spruce ( Picea abies) indicated very little isoprene emitted (< 0.5 μgC g −1 h −1). The wide range of isoprene emissions from these different spruce species suggest that improvements in hydrocarbon emission inventories may require detailed species distribution data. On a regional basis, this may be especially true in Europe where 22% of isoprene emissions are estimated to be from spruce and in boreal regions where spruce is a dominant part of the ecosystem.