Effects of land use changes on winter-active Collembola in Sanjiang Plain of China

Sanjiang Plain is the largest concentrated area of freshwater wetlands in China, however nearly 80% of these freshwater wetlands were drained or reclaimed in the past 50 years. It is important to know whether wetlands reclamation would affect soil invertebrates, especially the winter-active invertebrates. During November 2011 to April 2012, we used pitfall traps and in-field direct observation methods to study the activity of collembolans in wetland, and a reclaimed forest plantation and soybean field. In total, 3465 collembolans were captured and identified to 8 species from 6 families. Desoria sp. 1, Desoria sp. 2 and Desoria sp. 3 were the three dominant species. Collembolan abundance and assemblages were significantly affected by the land use changes. The results showed that (1) Collembola captured by pitfall traps showed a highest abundance in wetland, with similar to 50% decreased abundance in soybean field, and similar to 75% decreased in the forest plantation. (2) Collembola activity changed during the winter season, their activity significantly increased from early winter to late winter; with a peak in March in all three land use types. (3) Collembola assemblages were affected by land use changes with a significant decrease of frequency of Desoria sp. 3 and a significant increase of frequency of Desoria sp. 2 in soybean field and forest plantation. (4) Collembolan densities on the snow surface usually peaked between 1400 hand 1500 h, and decreased quickly when the temperature dropped below freezing. Mean abundance reached 119 individuals m(-2) on the snow surface in wetland, 152 individuals m(-2) in soybean field, and 64 individuals m(-2) in forest plantation. All collembolans moved up and down through the snow profile depending on temperature, no collembolans were found on the snow surface in the evening. Our study indicated that the reclamation of wetland resulted in a significant decrease of abundance and a different assemblage of winter active Collembola in Northeast China, but land use changes did not change their pattern of activity: Collembolans were rarely active in early and middle winter and mostly active in late winter. Their daily densities on the snow surface fluctuated according to both air temperatures and land use types. (C) 2014 Elsevier B.V. All rights reserved.