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Effects of logging on soil organic carbon in the Coast Mountains of British
Columbia, Canada
Stephanie Grand and Les M. LavkulichSoil Water Air Laboratory
University of British Columbia, Vancouver, BC, [email protected]
Faculty of Land and Food SystemsInstitute for Resources and the Environment
Objective
Faculty of Land and Food SystemsInstitute for Resources and the Environment
Document the effects of logging on:
Organic matter
Reactive mineral fractions
Available and labile nutrient pools
Measurements
• Soil organic matter • Total C and N• Exchangeable cations• Reactive mineral fraction
Faculty of Land and Food SystemsInstitute for Resources and the Environment
The field sites
Faculty of Land and Food SystemsInstitute for Resources and the Environment
Roberts Creek study forest
Faculty of Land and Food SystemsInstitute for Resources and the Environment
Control plots = mature (140 years) forest
Cleared plots = clear-cut 1 to 5 years prior to sampling
Regenerating plots = clear-cut 8 to 15 years prior to sampling
Faculty of Land and Food SystemsInstitute for Resources and the Environment
Soil type
Albic Gleyic Podzol (Humo-ferric Podzol / Aquentic Haplorthod)
Faculty of Land and Food SystemsInstitute for Resources and the Environment
C stock: control site
Faculty of Land and Food SystemsInstitute for Resources and the Environment
Cleared plots
Faculty of Land and Food SystemsInstitute for Resources and the Environment
Regenerating plots
Faculty of Land and Food SystemsInstitute for Resources and the Environment
Indicators of bulk OM composition
C:N C:SOM CECe:C
Control 24 50% 0.9
Cleared 23 51% 0.9
Regenerating 21 41% 1.3
Faculty of Land and Food SystemsInstitute for Resources and the Environment
-3 0 3 6
-2
0
2
control
cleared
regenerating
PC1 (OM content)
PC3
(OM
imm
atur
ity)
Principle component analysis
Faculty of Land and Food SystemsInstitute for Resources and the Environment
Short-range order mineral phases
Faculty of Land and Food SystemsInstitute for Resources and the Environment
0 1
6
20
73
Ae
38
713
24
19
Bf
41
68
22
23
BCC
% ITM
% FH
% Feoxi
% clayOM
% clay
Short-range order phases
Faculty of Land and Food SystemsInstitute for Resources and the Environment
g/kg ITM (SRO Al phase)
FH (SRO Fe phase)
Control 23.2 3.6
Cleared 29.1 4.8
Regenerating 15.9 2.8
Future work
Faculty of Land and Food SystemsInstitute for Resources and the Environment
• Rate of precipitation and dissolution of short-range order phases
• Rate of formation of organo-mineral complexes
Conclusion• Subsoil C is important
60% of the soil C found below 20 cm depthDeep C pool responsible for overall C trend
• Clear-cutting causes increase in mineral soil C• Short-lived increase
suggesting that new C is not stabilized or that older C is mineralized
• Indication that logging impacts podzolization processReactive mineral phases dynamicsC stabilization potential
Faculty of Land and Food SystemsInstitute for Resources and the Environment
Acknowledgements• PhD thesis advisory committee
Dr. L. Lavkulich, Dr. H. Schreier, Dr. R. Hudson
• Lab technicians Carol Dyck and Keren Fergusson
• Field assistants Peter Shanahan, Marina Romeo and Bryan Forrest
Faculty of Land and Food SystemsInstitute for Resources and the Environment
Special thanks to the French Society for Soil Study (AFES) for financial support
