The influence of stocking levels, clone, fertilization, and weed control on surface CO2 efflux in a mid-rotation Pinus radiata D. Don plantation in Canterbury, New Zealand

• Published in: Journal of forestry research Vol. 32; no. 6; pp. 2567 - 2575
• Main Authors: KC, Mohan, Mason, Euan G., Bown, Horacio E.
• Format: Journal Article
• Language: English
• Published: Singapore Springer Singapore 01-12-2021; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Carbon; Carbon dioxide; Carbon sequestration; Climate change; Climate effects; Decisions; Efflux; Fertilization; Forest management; Forestry; Life Sciences; Moisture content; Original Paper; Pinus radiata; Plantations; Rotation; Silvicultural practices; Silviculture; Soil surfaces; Soil temperature; Soil water; Soils; Stems; Stocking; Water content; Weed control; Weeds; New Zealand; Weed control; Silvicultural practices; efflux; Soil CO; Clone; Stocking
• ISSN: 1007-662X; 1993-0607
• DOI: 10.1007/s11676-021-01298-9

Silvicultural practices applied in managed forest plantations may help counteract the effects of climate change by influencing soil surface CO
2
efflux (
F
s
). Understanding the effects of silvicultural practices on
F
s
will provide unbiased estimates of carbon fluxes and allow better silvicultural decisions for carbon sequestration. Therefore, we assessed how
F
s
differed seasonally across silvicultural practices (i.e., stocking levels, clone, fertilization and weed control treatments) and evaluated the effects of soil temperature (
T
s
) and soil volumetric water content (
θ
v
) on
F
s
across these practices for a mid-rotation (14 year-old)
Pinus radiata
plantation in the Canterbury region of New Zealand. There were significant differences in
F
s
(
p
 < 0.05) over the four seasons, three levels of stocking, and five clones. The effects of fertilization and weed control applied 12 years previously on
F
s
were insignificant. Annual estimate of
F
s
(mean ± 1 standard deviation) from the study site was 22.7 ± 7.1 t ha
−1
a
−1
in the form of CO
2
(6.2 ± 2.1 t ha
−1
a
−1
in the form of C).
F
s
values were consistently higher in plots with 1250 stems ha
−1
compared to 2500 stems ha
−1
, which may be related to a strong soil resource limitation because of the close spacing in the latter plantation. Significant differences in
F
s
across clones suggest that variations in carbon partitioning might explain their growth performance. Silvicultural treatments influenced
F
s
response to soil temperature (
p
 < 0.05), resulting in models explaining 28–49% of the total variance in
F
s
. These findings provide insights into how silvicultural management decisions may impact
F
s
in mid-rotation radiata pine plantations, contributing towards developing more precise and unbiased plantation carbon budgets.