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dc.contributor.authorSorensen, Patricken_US
dc.date.accessioned2016-12-09T15:35:11Z
dc.date.available2016-12-09T15:35:11Z
dc.date.issued2016
dc.identifier.urihttps://hdl.handle.net/2144/19576
dc.description.abstractMean winter air temperatures have risen by 2.5˚C over the last 50 years in the northeastern U.S., reducing mean annual winter snowpack depth by 26 cm and the duration of winter snow cover by four days per decade. Because snow cover insulates soil from below-freezing air temperatures, continued declines in snowpack depth are projected to be accompanied by colder winter soil temperatures and more frequent soil freeze-thaw events. Soil bacteria and fungi will play a significant role in the forest ecosystem response to snowpack loss because they are the primary agents that carry out soil organic matter decomposition and soil nutrient cycling. Additionally, the effect of winter snowpack decline on soil bacterial and fungal communities may act indirectly via winter climate change effects on plant roots. The objectives of my dissertation research were to first determine the effect that reductions in winter snow cover has on microbial exoenzyme activity, microbial respiration, net nitrogen (N) mineralization, and net nitrification rates in two mixed-hardwood forests (Harvard Forest, MA and Hubbard Brook Experimental Forest, NH). Additionally, I sought to determine the relative role that abiotic factors (i.e., winter snow cover or soil frost) versus biotic factors (i.e., altered root-microbe interactions) contribute to overall changes in soil biogeochemical processes as winter snow cover declines. I found that winter snow depth and duration are related positively to microbial exoenzyme activity and microbial respiration following snowmelt in spring, but this relationship is transient and attenuates into the growing season. By contrast, soil freeze-thaw events during winter result in persistent declines in microbial oxidative enzyme activity that are not compensated for by warming soils during the growing season. Together, these results suggest that loss of winter snow cover will result in lower rates of nutrient cycling in northeastern U.S. hardwood forests. Tree roots interact with winter snow depth to affect net mineralization and nitrification rates, as well as bacterial and fungal community composition. Thus, winter climate change portends a reorganization of root-microbe interactions with important consequences for soil biogeochemical cycling in mixed hardwood forests of the northeastern U.S.en_US
dc.language.isoen_US
dc.subjectBiogeochemistryen_US
dc.subjectIlluminaen_US
dc.subjectPlant-microbeen_US
dc.subjectRootsen_US
dc.subjectSnowen_US
dc.subjectSoil carbonen_US
dc.subjectSoil exoenzymesen_US
dc.titleEffects of winter snowpack on microbial activity, community composition, and plant-microbe interactions in mixed-hardwood temperate forestsen_US
dc.typeThesis/Dissertationen_US
dc.date.updated2016-11-09T21:42:52Z
etd.degree.nameDoctor of Philosophyen_US
etd.degree.leveldoctoralen_US
etd.degree.disciplineBiologyen_US
etd.degree.grantorBoston Universityen_US


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