(Acari: Oribatida) in the Grassland Habitats of Eastern Mongolia Badamdorj Bayartogtokh National University of Mongolia, [email protected]
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University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Erforschung biologischer Ressourcen der Mongolei Institut für Biologie der Martin-Luther-Universität / Exploration into the Biological Resources of Halle-Wittenberg Mongolia, ISSN 0440-1298 2005 Biodiversity and Ecology of Soil Oribatid Mites (Acari: Oribatida) in the Grassland Habitats of Eastern Mongolia Badamdorj Bayartogtokh National University of Mongolia, [email protected] Follow this and additional works at: http://digitalcommons.unl.edu/biolmongol Part of the Asian Studies Commons, Biodiversity Commons, Desert Ecology Commons, Environmental Sciences Commons, Nature and Society Relations Commons, Other Animal Sciences Commons, Terrestrial and Aquatic Ecology Commons, and the Zoology Commons Bayartogtokh, Badamdorj, "Biodiversity and Ecology of Soil Oribatid Mites (Acari: Oribatida) in the Grassland Habitats of Eastern Mongolia" (2005). Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298. 121. http://digitalcommons.unl.edu/biolmongol/121 This Article is brought to you for free and open access by the Institut für Biologie der Martin-Luther-Universität Halle-Wittenberg at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298 by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. In: Proceedings of the symposium ”Ecosystem Research in the Arid Environments of Central Asia: Results, Challenges, and Perspectives,” Ulaanbaatar, Mongolia, June 23-24, 2004. Erforschung biologischer Ressourcen der Mongolei (2005) 5. Copyright 2005, Martin-Luther-Universität. Used by permission. Erforsch. biol. Ress. Mongolei (Halle/Saale) 2005 (9): 59–70 Biodiversity and Ecology of Soil Oribatid Mites (Acari: Oribatida) in the Grassland Habitats of Eastern Mongolia B. Bayartogtokh Abstract Composition, abundance, distribution, and diversity of oribatid mite communities were inves- tigated at five study areas in Eastern Mongolia. A total of 88 species of oribatid mites were recorded from the studied areas. The largest number of species (51 spp.) was found in the habitats of river valleys, while the plain steppe which covers the largest area contained the lowest species richness (24 spp.). Three other sub-regions with similar landscape types show approximately the same species richness (39 to 45 spp.), although they are located relatively far from each other. The oribatid mite faunas of all sub-regions were essentially similar to each other. The abundances of oribatid mites were higher in mountain-steppes (5240 to 9800 ind./ m2), and lower in the plain steppe and river basins (3520 to 3535 ind./ m2). Oribatid mite commu- nities were characterized by species with relatively similar abundances. The results of species diversity and evenness indices indicate species-rich assemblages with low dominance. Keywords Biodiversity, species richness, oribatid mites, grassland, Eastern Mongolia. Introduction The Eastern Mongolia ecosystem encompasses the forest–steppe landscape situated at the south- eastern end of the Siberian taiga forest, plus the tall and short grass steppe of the south-western part of the Manchurian steppe, and the small mountains and hills which are situated in the western edge of the Great Hinggan Mountains. The region includes various habitats such as wetlands along the basin of rivers and lakes, bogs, moors, hummocks and hills etc. in addition to the large area of grassland (Obruchev, 1947; Dashnyam, 1974). Although types of ecosystems similar to the Eastern Mongolian steppe can be found in Eastern Europe, North America, Northern Africa, Middle Asia and Australia, these are greatly affected by human activities and have mostly changed their ecological conditions. Eastern Mongolia is largely covered by extended steppe landscapes with short and tall grasses. Several protected ar- eas such as ’Khalkh Numrug’, ’Mongol Daguur’ and ’Eastern Mongolia’ national parks, ’Ugtam’, or ’Lkhachinvandad’, ’Yakhi Nuur’ and ’Ganga Nuur’ nature reserves have been established in this landscape covering about 1,340,943 hectare in order to protect the characteristic wildlife and landscape features of the region (Enebish & Myagmarsuren, 2000). Many endangered or rare animal species registered in the International Red Data Book or in the Mongolian Red Data Book such as elk, otter, black-tailed gazelle, sea-gull etc. inhabit the Eastern Mongolian steppe. Moreover, the Eastern Mongolian steppe is one of the main habitats for various species of birds and mammals included in the CITES and Ramsar conventions. However, during the last decades human influence has increased in this region due to active development of agriculture and industry (Batjargal et al., 2001). Up to date, there is no thorough research on biodiversity and ecology of the soil dwelling organisms in the Eastern Mongolian steppe, especially the soil arthropods. Most of the previous research works on insects and other arthropods was conducted mainly in the central, northern and western regions of the country, but the eastern part of the country remained poorly studied, probably due to its remote location and difficult accessibility. 59 Figure 1: Study areas in Eastern Mongolia. A: Yazaar area in District Bayanmunkh, Province Khentiy, B. Menengiin Tal area in District Matad, Province Dornod, C: Numrug and Degee Gol area in District Khalkh Gol, Province Dornod, D: Shiliin Bogd area in District Dariganga, Province Sukhbaatar, E: Lkhachinvandad area in District Erdenetsagaan, Province Sukhbaatar. However, for a better understanding of the ecological processes occurring within the protected areas of Eastern Mongolia it is important to examine the biodiversity and ecology of the various soil organisms living there. The study of oribatid mite biodiversity in grassland habitats of Eastern Mongolia is part of ongoing research on biodiversity assessments in various habitats in this region. The present paper deals with data on composition, diversity, and distribution patterns of oribatid mite communities in the different sub-regions of Eastern Mongolia. Study area The study areas were selected according to two main criteria: geographical location and vegeta- tion characteristics, thus representing the principal habitat types in the research region. Sample sites were grouped into five sub-regions according to the geographical location and the habi- tat types, and are identified by the short location names such as ’Numrug’, ’Lkhachinvandad’, ’Menengiin Tal’, etc. The region named ’Numrug’ covers the wetland habitats along the basin of rivers Numrug and Degee, and small mountains and hills along the river basins; ’Lkachinvandad’ includes the areas of mountain-steppe around Mt. Lkhachinvandad; ’Menegiin Tal’ represents the large area of plain grassland habitats in Eastern Mongolia; ’Shiliin Bogd’ includes the short-grass steppe habitats with small hills around this mountain, and ’Yazaar’ covers mountain-steppe habitats with sparse broadleaved stands in the region around this mountain (figure 1). Each sub-region includes typical associations of habitats, which are similar to one another not only with respect to the geographical location, but also with regard to the habitat types (figure 2). 60 Figure 2: Different landscapes of study areas. A: Grassland habitat in Menengiin Tal area, B: Mountain steppe in Yazaar area, C and D: Dry mountain steppes in Lkhachinvandad and Shiliin Bogd areas, E: River valley in Numrug area. Methods A total of 114 soil samples were collected from 68 locations covering all the main habitats in this area. Soil cores were taken using a cubic sampler of 100 cm2 in surface area and 10 cm in depth. 61 Sampling was performed in May and June of 2003. Soil samples were brought to the laboratory for extraction of animals using Tulgren funnels, and extracted more than 12,000 specimens of soil microarthropods. The following indices were used for data analysis as applied and summarized by Magurran (1988), Krebs (1989), and Southwood (1996). In each sub-region, the species richness (S) of oribatid mites was assessed by counting the number of species present. Also, the total theoretical oribatid species richness for each sub- region was calculated using the jacknife estimator (S). The jacknife uses the number of species actually observed plus the number of species unique to any sample, weighted by the number of samples to estimate a overall species richness: n − Sˆ s 1 k = + n (1) where s is the observed total number of species present in n quadrants, n – total number of quadrants sampled, k – number of unique species. Species diversity was calculated using the Shannon-Wiener index (H). i X N N H i · i = N log2 N (2) n =1 where Ni is the number of individuals belonging to the ith species, N – total number of indi- viduals, S – number of species. Evenness of oribatid communities was expressed by Pielou’s index (J ): H H J = = (3) Hmax log2 S The Soerensen’s index of similarity (Ss) was used to compare oribatid mite communities between studied sub-regions: 2a S = (4) S 2a + b + c where a is the number of species shared among compared sub-regions, b – number of species in the first sub-region, c – number of species in the second sub-region. Figures of oribatid density refer to the mean number of individuals per square meter of soils. The community structure of oribatid mites