Use of Soil-dwelling Arthropods as Bioindicators Across a Successional Gradient of Norway Spruce in Schoharie, NY

Abstract

Soil is a living ecosystem which provides habitat for many microarthropods that contribute to decomposition and the formation of organic matter. Because of their strong affiliation with organic matter content, certain microarthropods can also serve as bioindicators of soil quality. This study utilizes microarthropod bioindicators to evaluate the changes that occur in soil quality during the course of forest succession. Samples were obtained from three planted Norway Spruce (Picea abies) plots ranging in levels of succession within the Burnt-Rossman Hills State Forest in Summit, NY. Leaf litter samples were taken 3 times between October-November of 2015. A total of 21 Norway spruce trees were randomly selected per stand (N=63) and samples were taken within a 2m diameter at the base of each randomly selected tree, which were measured for their diameter at breast height (DBH). Samples were placed in Tullgren funnels for 48 hours and extracted arthropods were preserved in 70% ethanol. Additional soil samples were collected from each plot to analyze percent organic matter and percent soil moisture content. Sub-samples of arthropods were identified and recorded as one of four groups; oribatid mites, other mites (e.g. Mesostigmata), springtails (Collembola), and other arthropods. A single factor analysis of variance (ANOVA) was performed on the calculated mean abundance of oribatid mites, other mites, all mites, other arthropods, and springtails in each stand. Results show that there was a statistically significant difference between the successional stages in the groups “other mites” (F=5.51, df2, P<0.05) and “other arthropods” (F=4.41, df2, P<0.05). Both oribatid mites and springtails exhibited a general trend of higher abundance in the late successional stages. Mites other than those in the order Oribatida also have differing levels of tolerance to soil disturbance. Sensitive taxa within these groups may be contributing to the higher abundance of the total mite group. Trends exhibited between successional stages suggest that soil structure and quality may change as woodland habitat ages. Further studies are needed to define any differences that might exist in soil arthropod community composition between successional stages.