Date of Award

Spring 2023

Project Type

Thesis

Program or Major

Natural Resources and Environmental Studies

Degree Name

Master of Science

First Advisor

Jeff Garnas

Second Advisor

Alix Contosta

Third Advisor

Matthew Ayres

Abstract

Arthropods are active during the winter in temperate regions, and many use seasonal snowpack to buffer themselves from harsh ambient conditions in a refugium known as the subnivium, an area that occurs under the snowpack and above the soil. This thesis focuses on subnivium arthropod communities, how they differ from summer communities, and how silvicultural management influences these communities. Arthropods were collected using modified pitfall traps from the Second College Grant, a forested township in northern New Hampshire which has areas of land dedicated to the Adaptive Silviculture for Climate Change study. In the first chapter of this thesis we found that the community of arthropods in the subnivium differ from those in the summer in composition and are categorized by moderate levels of diversity and abundance but also much lower overall biomass and abundance. Furthermore, it was found that certain groups and species of arthropods are dominant in the subnivium but are either rare or absent in summer collections, leading us to believe that they may be “subnivium specialists”. The arthropods which were identified to the species level and appeared to be subnivium specialists include a spider, Cicurina brevis, and three rove beetles which belonged to the same sub-family including Arpedium cribratum, Lesteva pallipes, and Porrhodites inflatus. The arthropods which were more abundant in the subnivium could be using the space to feed as there could be higher levels of immobile prey in the subnivium, they could be escaping competition or predation they would experience in other seasons, they could be using the restricted space to seek out mates, or some combination of these factors. The results from the second chapter of this thesis revealed that winter active arthropods are relatively resilient to actions associated with silviculture, with communities differing little between different treatments when looking at larger scales. However, when looking at relatively localized areas where more intense silvicultural measures were implemented, arthropod abundance, composition and to some extend diversity and richness did differ. We also tested the relationship of underlying environmental variables on subnivium arthropod communities. Arthropod richness was related to groundcover type and elevation while diversity was related to snow depth, total basal area, and elevation. These results were significant but accounted for relatively little variance. Additionally, we found that composition was modestly but consistently correlated with snowpack depth, ground cover type, the amount of course woody debris, total basal area, and basal area. With climate change and snowpack decline, these unique communities are likely going to either drastically change or disappear altogether. This research serves as an initial first step in understanding these unique communities and what affects them, but more research should be allocated to understanding subnivium communities.

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