Effects of topography on soil and litter mites (Acari: Oribatida, Mesostigmata) in a tropical monsoon forest in Southern Vietnam

Abstract

The effects of topographic variables (elevation above sea level, slope position, topographic (wetness) index, and global solar radiation) on mite abundances and on quantitative composition of Oribatida communities in soil and litter have been studied in six sites along a hill slope in a tropical lowland forest in the Bu Gia Map National Park, Southern Vietnam. A positive relationship existed between abundance and species richness of Oribatida in soil cores, and global solar radiation (W h m(-2)) which quantifies the total sun energy available to the local ecosystem. There was no significant relationship between abundance of Mesostigmata and topographic variables. The Oribatida community composition in soil and in litter was significantly different, with a large number of species unique to either litter or soil. The canonical correspondence analysis (CCA) showed that the topographic variables together explained 75% (in litter) and 83% (in soil) of the variation in Oribatida community structure. The species-topography relationship was globally significant in the litter, weaker in the soil; the eigenvalue of the CCA axis 1 (related to elevation and global solar radiation) was significant in both substrates. CCA ordinations identified groups of species associated with high landscape positions (hill crest, high elevation, high global solar radiation) versus species associated with low-lying landscape positions, where moisture tends to accumulate (hill footslope, low elevation, low solar radiation, high topographic index values). The importance of relief and geographical position for soil Oribatida is discussed.

Ecological indication potential of oribatid mites

“…At high groundwater tables, hygrophilous species will dominate, and at low groundwater tables, species preferring drier, warmer conditions will predominate ( 2004). Soil moisture content is also determined by topography, valleys accumulate precipitation and the moisture content is higher there, however, in some cases the soil can also become saturated, which tends to reduce the density (Minor and Ermilov, 2015).…”

Study on soil biology in Vietnam - achievements and challenges

“…Some of their data on the geographical locations, names of locations and natural conditions of Vietnam have been obtained from illegal sources [22]. Particularly, the administrative maps of the socialist republic of Vietnam in their publications were presented wrongly, lacking islands and the island regions [21,23,24]. Therefore, the data on Vietnam's oribatid mites given by the Russian colleague Sergey G. Ermilov must be checked and revised carefully before consulting them [21].…”

SUPPLEMENTARY DESCRIPTION OF <i>PERGALUMNA HAWAIIENSIS HAWAIIENSIS</i> (JACOT, 1934) (ACARI, ORIBATIDA, GALUMNIDAE) WITH ADDENDUM TO THE CHECKLIST OF ORIBATID MITES OF VIETNAM

“…This work is part of our continuing study of oribatid mites (Acari, Oribatida) of Vietnam (e.g. Ermilov 2015Ermilov , 2016Ermilov , 2017Minor and Ermilov 2015;Minor et al 2017). In addition, an addendum of new taxa to the checklist of oribatid mites of Vietnam (Ermilov 2015) is presented.…”