Open AccessComparative assessment of ecosystem C exchange in Miscanthus and reed canary grass during early establishment
Author(s) -
Ní Choncubhair Órlaith,
Osborne Bruce,
Finnan John,
Lanigan Gary
Publication year - 2017
Publication title -
gcb bioenergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.378
H-Index - 63
eISSN - 1757-1707
pISSN - 1757-1693
DOI - 10.1111/gcbb.12343
Subject(s) - miscanthus , bioenergy , environmental science , agronomy , energy crop , greenhouse gas , primary production , biomass (ecology) , ecosystem , agroforestry , biology , renewable energy , ecology
Land‐use change to bioenergy crop production can contribute towards addressing the dual challenges of greenhouse gas mitigation and energy security. Realisation of the mitigation potential of bioenergy crops is, however, dependent on suitable crop selection and full assessment of the carbon (C) emissions associated with land conversion. Using eddy covariance‐based estimates, ecosystem C exchange was studied during the early‐establishment phase of two perennial crops, C 3 reed canary grass ( RCG ) and C 4 Miscanthus , planted on former grassland in Ireland. Crop development was the main determinant of net carbon exchange in the Miscanthus crop, restricting significant net C uptake during the first 2 years of establishment. The Miscanthus ecosystem switched from being a net C source in the conversion year to a strong net C sink (−411 ± 63 g C m −2 ) in the third year, driven by significant above‐ground growth and leaf expansion. For RCG , early establishment and rapid canopy development facilitated a net C sink in the first 2 years of growth (−319 ± 57 (post‐planting) and −397 ± 114 g C m −2 , respectively). Peak seasonal C uptake occurred three months earlier in RCG (May) than Miscanthus (August), however Miscanthus sustained net C uptake longer into the autumn and was close to C‐neutral in winter. Leaf longevity is therefore a key advantage of C 4 Miscanthus in temperate climates. Further increases in productivity are projected as Miscanthus reaches maturity and are likely to further enhance the C sink potential of Miscanthus relative to RCG .