Canadian Forest Service Publications

Red and black spruce provenance growth and allocation under ambient and elevated CO2. 2015. Major, J.E., Mosseler, A., Johnsen, K.H., Campbell, M., and Malcolm, J. Trees 29: 1313-1328.

Year: 2015

Available from: Atlantic Forestry Centre

Catalog ID: 36399

Language: English

CFS Availability: PDF (request by e-mail)

Abstract

We compared growth, components of growth, and biomass allocation between two largely sympatric spruces, red spruce (Picea rubens Sarg.; RS) and black spruce (Picea mariana (Mill.) B.S.P.; BS) using 12 populations from across eastern Canada grown under ambient CO2 (aCO2) and elevated CO2 (eCO2) to evaluate absolute and relative responses to this increasing greenhouse gas. The 12 populations originated from continental to maritime environments, with seed collected from two proximate pairs of RS and BS stands from each of three provinces of eastern Canada—Ontario (ON), New Brunswick (NB), and Nova Scotia (NS)—considered here as provenances. Over 4 years, BS displayed increasingly greater height growth compared with RS. By the end of the 4th year, BS on average had 127 % greater total mass and 50 % greater root-collar diameter than RS. Bud flush was earlier for BS than RS, and BS bud flush occurred in the following order: ON, NB, NS. Under eCO2, BS and RS allocated more mass to stem (stem + branches), and further analysis showed that 25 % of this difference in biomass allocation was attributable to increasing tree size, with the balance directly due to eCO2. As expected, BS allocated more to aboveground than belowground mass than RS due their respective status as early and late-successional species. However, under eCO2, BS partitioned more belowground and RS more aboveground than under aCO2. Black spruce had greater growth efficiency (GE; stem mass to needle mass ratio) than RS; GE increased with eCO2, and the increase was greater for BS than RS. Elevated CO2 resulted in a relative biomass enhancement of 10.8 and 18.0 % for BS and RS, respectively. This does not support the theory that faster growing species will have a competitive advantage compared with inherently slower growing plants under eCO2, but agrees with other observations that shade-tolerant species have greater response ratios to eCO2 than shade-intolerant species. Also, despite high possibility of hybridization and introgression between the two species, particularly in the highly fragmented and small remnant populations from ON, the findings show that ON and NB remain true to species type for the major growth parameters, allometry, growth efficiencies, and physiological traits and that the provenance variation is mostly consistent with findings from common-garden studies.

Plain Language Summary

We compared growth, components of growth, and biomass allocation between two largely sympatric spruces, red spruce (Picea rubens Sarg.; RS) and black spruce (Picea mariana (Mill.) B.S.P.; BS) using 12 populations from across eastern Canada grown under ambient CO2 (aCO2) and elevated CO2 (eCO2) to evaluate absolute and relative responses to this increasing greenhouse gas. The 12 populations originated from continental to maritime environments, with seed collected from two proximate pairs of RS and BS stands from each of three provinces of eastern Canada—Ontario (ON), New Brunswick (NB), and Nova Scotia (NS)—considered here as provenances. Under eCO2, BS and RS allocated more mass to stem (stem + branches), and further analysis showed that 25% of this difference in biomass allocation was attributable to increasing tree size, with the balance directly due to eCO2. As expected, BS allocated more to aboveground than belowground mass than RS due their respective status as early and late-successional species. Elevated CO2 resulted in a relative biomass enhancement of 10.8% and 18.0% for BS and RS, respectively. This does not support the theory that faster growing species will have a competitive advantage compared with inherently slower growing plants under eCO2, but agrees with other observations that shade-tolerant species have greater response ratios to eCO2 than shade-intolerant species.

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