@misc{KwakChangNaethetal., author = {Kwak, Jin-Hyeob and Chang, Scott X. and Naeth, M. Anne and Schaaf, Wolfgang}, title = {Coarse Woody Debris Increases Microbial Community Functional Diversity but not Enzyme Activities in Reclaimed Oil Sands Soils}, series = {PLoS One}, volume = {10}, journal = {PLoS One}, issn = {1932-6203}, doi = {10.1371/journal.pone.0143857}, pages = {0143857}, abstract = {Forest floor mineral soil mix (FMM) and peat mineral soil mix (PMM) are cover soils commonly used for upland reclamation post open-pit oil sands mining in northern Alberta, Canada. Coarse woody debris (CWD) can be used to regulate soil temperature and water content, to increase organic matter content, and to create microsites for the establishment of microorganisms and vegetation in upland reclamation. We studied the effects of CWD on soil microbial community level physiological profile (CLPP) and soil enzyme activities in FMM and PMM in a reclaimed landscape in the oil sands. This experiment was conducted with a 2 (FMM vs PMM) × 2 (near CWD vs away from CWD) factorial design with 6 replications. The study plots were established with Populus tremuloides (trembling aspen) CWD placed on each plot between November 2007 and February 2008. Soil samples were collected within 5 cm from CWD and more than 100 cm away from CWD in July, August and September 2013 and 2014. Microbial biomass was greater (p<0.05) in FMM than in PMM, in July, and August 2013 and July 2014, and greater (p<0.05) near CWD than away from CWD in FMM in July and August samplings. Soil microbial CLPP differed between FMM and PMM (p<0.01) according to a principal component analysis and CWD changed microbial CLPP in FMM (p<0.05) but not in PMM. Coarse woody debris increased microbial community functional diversity (average well color development in Biolog Ecoplates) in both cover soils (p<0.05) in August and September 2014. Carbon degrading soil enzyme activities were greater in FMM than in PMM (p<0.05) regardless of distance from CWD but were not affected by CWD. Greater microbial biomass and enzyme activities in FMM than in PMM will increase organic matter decomposition and nutrient cycling, improving plant growth. Enhanced microbial community functional diversity by CWD application in upland reclamation has implications for accelerating upland reclamation after oil sands mining.}, language = {en} } @misc{KwakChangNaethetal., author = {Kwak, Jin-Hyeob and Chang, Scott X. and Naeth, M. Anne and Schaaf, Wolfgang}, title = {Coarse woody debris effects on greenhouse gas emission rates depend on cover soil type in oil sands reclamation}, series = {Applied Soil Ecology}, volume = {100}, journal = {Applied Soil Ecology}, issn = {0929-1393}, doi = {10.1016/j.apsoil.2015.12.006}, pages = {124 -- 134}, abstract = {Peat mineral soil mix (PMM) and forest floor mineral soil mix (FMM) are cover soils commonly used for land reclamation, while coarse woody debris (CWD) can be added to create structural diversity and provide an additional source of organic matter. However, the effect of cover soil type and CWD on emission rates of greenhouse gases, such as carbon dioxide (CO₂) methane (CH₄) and nitrous oxide (N₂O) in reclaimed oil sands soils has not been studied. Soil respiration, CH₄ uptake and N₂O emission rates were studied in a factorial experiment consisting of 2 cover soils (FMM vs PMM) × 2 sampling distances from the CWD (near vs away from CWD). Greenhouse gas emission rates were measured in July, August, and September 2012 and 2013 using static chambers. Soil respiration rates were greater in FMM than in PMM regardless of the distance from CWD at each sampling time (p < 0.05). Rates ranged from 461 to 1148 and 293 to 677 mg CO2 m⁻²h⁻¹for FMM and PMM, respectively, in 2012, and from 355 to 1318 and 235 to 700 mg CO2 m⁻²h⁻¹, respectively, in 2013. The CWD increased soil respiration by 22-33\% in FMM but not in PMM. Soil respiration rates were positively related to microbial biomass carbon (p = 0.004) and nitrogen (p < 0.001). Soil respiration rates decreased from July to September in 2012 and 2013, and were positively related to soil temperature (p < 0.01) but not with soil water content measured at 5 cm depth. Methane uptake rates were greater in FMM (0.026-0.037) than in PMM (0.015-0.028 mg CH₄⁻²h⁻¹. The CWD increased CH4 uptake rates only in July and August 2012 in FMM, and were negatively related to soil water content (p < 0.001) but not to soil temperature. Nitrous oxide emission rates (0.001-0.016 mg N₂O m⁻²h⁻¹) were not affected by either cover soil type or CWD. Global warming potential of CO₂, CH₄ and N₂O effluxes was greater in FMM than in PMM and near CWD than away from CWD, especially in FMM. Our study demonstrates that applying CWD for oil sands reclamation increases organic matter decomposition (increased CO₂ evolution), driven by the effect on microbial populations. Results from this study provide support to findings in earlier studies that CWD application benefits vegetation establishment through enhancing soil processes in reclaimed oil sands lands.}, language = {en} }