Studies on the Ecology of Mites and Collembola

Abstract

In an oak-hickory community near Jefferson City, Missouri, mites averaged 296 for each square foot of soil to a depth of 10 inches and 162 Collembola for the same area and depth. Peaks in the mite population appeared in December and January with the temperature below freezing. The population was also high in March at a temperature of 8 C. The lowest peak appeared in November. During December, with two inches of rainfall, 4568 mites were taken whereas only 1077 were taken in April with five inches. The highest peak in the population of Collembola appeared in January and February, when 84% of the total number were collected. January had 3 inches of rainfall and March over 4 inches but only a small number was collected in March. Thirty-seven percent of all mites were taken in the litter and 57% in the 0-2 of soil. Fifty-one percent of Collembola were taken from the litter and 47% from the 0-2 level. In a pine community 256 mites and 197 Collembola were taken per ft2 to the depth of 10 inches. The highest peak in the mite population appeared in September with an air temperature of 20 C and a rainfall of 6 inches. Peaks also appeared in July, December and January. Peaks in collembolan population occurred in February and December, months with low temperature and normal rainfall. In this community 69% of mites were taken in the litter and 29% from the 0-2 level. Fifty-seven percent of Collembola were taken from the litter and and 41 % from the 0-2 depth of soil. In the blue grass community the mites averaged only 26 specimens and Collembola 48 for each square foot. In this community 80% of mites were taken from 0-2 depth and 10% from 2-5 depth. From the 0-2 stratum 92% of Collembola were taken, and 6% from the 0-5 depth. INTRODUCTION AND METHODS This study is an attempt to find out more about certain soil organisms, especially mites and collembolans. The emphasis is placed on the depth of the organisms in the soil, their reaction to temperature and rainfall, seasonal variation in numbers, and their distribution in different soil types. The earliest to study the soil fauna was Diem (1903) in Europe. McAtee (1907) computed 1.2 million invertebrates per acre for forest floor and 13.7 million for grassy meadow. The great work of Shelford appeared in 1913. The works of Vestal (1913) and Adams (1915) were significant steps. The first real insect survey was carried on by Cameron (1913) at Manchester, England. Buckle (1921) concluded that the distribution and number of the soil fauna were more stable on grassland than on arable land and the fauna increased in both with the growth of vegetation. Morris (1920) estimated a population 3.6 million per acre, and found that food, aeration and moisture influenced the depth distribution, and that the 1 The investigation was supported by Research Grant G-14065 from the National Science Foundation.