UVM Theses and Dissertations
Format:
Print
Author:
Yurchenco, Helen
Dept./Program:
Natural Resources
Year:
2013
Degree:
MS
Abstract:
As global temperatures rise and weather fluctuations become more frequent, one of the likely impacts of climate change on northeastern forests is an increase in soil freezing due to a decreased depth of insulative snowpack and duration of the season of snow cover. Changes in snowpack and soil freezing could have varied and cascading effects on ecosystem processes and biodiversity. We examined the effects of soil freezing from reduced snowpack, and other environmental site characteristics on the abundance and species richness of ground-dwelling insects and terrestrial snails at the Hubbard Brook Experimental Forest in West Thornton, NH. Our study consisted of four 13 m² plots each of three treatments: understory vegetation and snow removal (VSR), understory vegetation removal (VR), and control (C).
We removed snow for the first eight weeks of winter 2010 -2011 from the VSR treatment. We measured soil temperature, pH, and exchangeable cations in the VSR and VR treatments (but not in the C treatment). We measured percent vegetative cover, microtopography, and presence of fine woody debris and rocks in all treatments. We collected insects from pitfall traps, and snails from leaf Iitter and cardboard traps, in all treatments.
The VSR treatment was associated with significantly lower minimum soil temperatures and pH. There were significant associations of the VR and VSR treatments with abundance of individual insect taxa on multiple dates. In addition, the VSR treatment was associated with significantly lower yearly abundance of Sphaeroderus, a snail predator, with highest abundance in the C treatment. In addition there were fewer Sphaeroderus spp. in the VSR than VR treatment.
There were no significant associations of the VSR treatment with abundance of total snails or abundance of any snail taxa. However there were significant associations of the VR treatment with total snail abundance, and abundance of multiple snail taxa. There were significant associations of both the VR and VSR treatments with Shannon Hand Simpson l-D diversity.
Our results suggest reduced snowpack could have multiple effects on northern hardwood forest ecosystems, including soil temperature, soil acidity, tree growth, and abundance of one taxon (Sphaeroderus spp.). Reduced understory vegetative cover also has impacts on abundance of multiple insect taxa, as well as on multiple snail taxa. Understanding the effects of reduced snowpack on biodiversity of ground-dwelling insects and snails, which are important faunal components of forested ecosystems, will help to elucidate potential effects of soil freezing on other dependent organisms such as birds. Our results were consistent with results of the previous collection year and suggest long-term effects of reduced snowpack and reduced understory vegetation on northern hardwood forests.
We removed snow for the first eight weeks of winter 2010 -2011 from the VSR treatment. We measured soil temperature, pH, and exchangeable cations in the VSR and VR treatments (but not in the C treatment). We measured percent vegetative cover, microtopography, and presence of fine woody debris and rocks in all treatments. We collected insects from pitfall traps, and snails from leaf Iitter and cardboard traps, in all treatments.
The VSR treatment was associated with significantly lower minimum soil temperatures and pH. There were significant associations of the VR and VSR treatments with abundance of individual insect taxa on multiple dates. In addition, the VSR treatment was associated with significantly lower yearly abundance of Sphaeroderus, a snail predator, with highest abundance in the C treatment. In addition there were fewer Sphaeroderus spp. in the VSR than VR treatment.
There were no significant associations of the VSR treatment with abundance of total snails or abundance of any snail taxa. However there were significant associations of the VR treatment with total snail abundance, and abundance of multiple snail taxa. There were significant associations of both the VR and VSR treatments with Shannon Hand Simpson l-D diversity.
Our results suggest reduced snowpack could have multiple effects on northern hardwood forest ecosystems, including soil temperature, soil acidity, tree growth, and abundance of one taxon (Sphaeroderus spp.). Reduced understory vegetative cover also has impacts on abundance of multiple insect taxa, as well as on multiple snail taxa. Understanding the effects of reduced snowpack on biodiversity of ground-dwelling insects and snails, which are important faunal components of forested ecosystems, will help to elucidate potential effects of soil freezing on other dependent organisms such as birds. Our results were consistent with results of the previous collection year and suggest long-term effects of reduced snowpack and reduced understory vegetation on northern hardwood forests.