Microarthropod Abundance and Community Structure along a Chronosequence within the Tanana River Floodplain, Alaska

ABSTRACT We investigated abundance and community structure of soil microarthropods in three stages of a primary successional chronosequence along the Tanana River in interior Alaska: early-successional alder stands, mid-successional balsam poplar stands and late successional white spruce stands. Microarthropod abundances in alder stands were uniformly low and tended to increase in balsam popular stands where abundances were highly variable among sites. White spruce stands had the highest abundances, almost 8 times those of alder sites. Arthropod taxon and Oribatida family richness also increased (alder: 29 taxa, 6 families; balsam poplar: 34 taxa, 10 families; white spruce: 40 taxa, 14 families). Non-metric multidimensional ordination of arthropod taxa indicated microarthropod communities became more similar within stand types later in succession and environmental fit of the site characteristics found organic matter thickness, soil degree days, organic layer phosphorus (P), mineral layer concentrations of carbon (C), nitrogen (N), and manganese (Mn), and white spruce basal area were significant (p < 0.05). Regression analysis indicated prey abundance and predator abundance were positively correlated (R2 = 0.43; p< 0.001). Our findings point to the importance of vegetation, soil development and temperature, site stability, microarthropod colonization time, and possibly predator abundance in shaping these microarthropod communities.