| dc.description.abstract | To evaluate the hypothesis that microbial populations are affected by
organic biomass removals, a study was designed to complement ongoing work in a
black spruce {Picea mariana [Mill.] B.S.P.) Boreal ecosystem. The treatments
included a control (uncut) and two harvest levels, tree-length (TL) and full-tree
(FT). Soil samples from the organic and mineral horizons were taken from nine
plots, representing three each ofthe treatments. Samples were taken once a month
for four consecutive months; May through August during 1998. Soil respiration
on two dates in September was estimated using the soda-lime technique. Bacterial
cultures were prepared from the soil samples and pure strains identified using
morphological and substrate utilization characteristics (specifically API 20E). Soil
descriptors, including pH, total nitrogen, total phosphorus, organic matter content,
and moisture content, were measured to investigate relationships with microbial
biomass. Microbial biomass carbon (MBc) and nitrogen (MBN) were estimated
using chloroform fumigation extraction. The data were statistically analyzed, using
ANOVA, Pearson and Spearman correlations and, in the case ofthe MBc and
MBN, ANCOVA, to determine if there were any treatment or seasonal effects.
Soil respiration demonstrated a significant treatment effect where the efflux was
significantly greater on the control treatment compared to the harvest treatments.
Five bacterial cultures were identified from the soil samples, Chryseomonas
luteola, Aeoromonas salmonicida, Serratia marcescens, Syntrophomonas
multifilia, and Pseudomonasfluorescens. MBc and MBN values measured were in
agreement with other published values for boreal coniferous soils. The MBc in the
organic horizon was significantly affected by the interaction ofthe treatment and
month factors. There was a significant treatment effect on the MBc in the mineral
horizon, with the control mean significantly higher than those ofthe harvest
treatments. The MBN revealed no significant effects in either the organic or the
mineral horizons. The author concludes that soil moisture and temperature did
affect the values for microbial biomass and that these environmental conditions
were likely impacted by the level of harvest. | |
