Studies On The Diversity And Edge Effect Of Ground-dwelling Beetles In The Baijitan National Nature Reserve Of Ningxia

The desert ecosystem is one of the most vulnerable systems in terrestrial ecosystems, due to its unique type of landscape ecology, desert insects in species composition, distribution and pattern is unique. The Baijitan National Nature Reserve of Ningxia is one of the typical nature reserve with desert ecosystem as its main protected object. This study was based on theories of the traditional insect systematics, ecology, and the latest landscape ecology, using pitfall trap method to investigate the species composition and quantity distribution of ground-dwelling beetles in several representative plots of this protected area, exploring diversity and temporal dynamics of ground-dwelling beetle communities in the different desert habitat types, and analysised the edge effect of the two more common edge types in this protected area. The main conclusions are as follows:①From May to September2012, a total of6760beetles were collected in this study, these beetles belong to19families,49genera and68species. At the family level, Tenebrionidae is the absolute dominant group of the ground-dwelling beetles in this region, its number of individuals is the largest, accounting for78.43percent of the total number of individuals; followed by Carabidae, Melolonthidae, Curculionidae and Chrysomelidae. At the species level, the number of individuals of Microdera kraatz alashanica, Anatolica potanini, Anutolica mirabilis and Anatolica mucronata were greater than10%accounting for the total number of individuals, Microdera kraatz alashanica was the most in this four species accounting for18.71%; followed by Anatolica potanini accounting for17.47%, they were the dominant species of the ground-dwelling beetles in this region.②Distribution and diversity of ground-dwelling beetles varied in different habitats. Number of individuals:the fixed and semi-fixed sand land> the desert steppe> the sand-fixation caragana plantation, the former and the latter two are significantly different; Number of species:the fixed and semi-fixed sand land> the desert steppe> the sand-fixation caragana plantation, and significant differences among the three; Diversity (H’):the fixed and semi-fixed sand land> the sand-fixation caragana plantation> the desert steppe, the former and the latter two are significantly different; Evenness (J):the fixed and semi-fixed sand land> the sand-fixation caragana plantation> the desert steppe, and significant differences among the three; Richness (D):the fixed and semi-fixed sand land> the desert steppe> the sand-fixation caragana plantation, the former significant difference with the third; Dominance (C):the desert steppe> the fixed and semi-fixed sand land> the sand-fixation caragana plantation, however, no significant difference among the three. This result suggested that there was a close correlation between the community composition of ground-dwelling beetles and habitat types:the higher habitat heterogeneity, the more rich community composition of ground-dwelling beetles; the more similar two habitats were, the more similar community structure of ground-dwelling beetles.③Time dynamic studies have showed that the occurrence and activity of ground-dwelling beetles appeared two peaks in May and July-August. The peak periods of ground-dwelling beetles of the fixed and semi-fixed sand land and the sand-fixation caragana plantation were both appeared in May and July, but the peak periods of ground-dwelling beetles of the desert steppe was appeared in May and August. Correlation analysis showed that ground-dwelling beetles’ species number and individuals number were both showed significant positive correlation in three habitats of the different months, diversity index (H’) and richness index (D) also showed a significant positive correlation. The hierarchical cluster analysis showed that ground-dwelling beetle communities in three habitats of the different months both can be clustered into three categories, which reflected the peak periods, the relatively stable stage before and after the peak periods, and the number reduced period in autumn.④The edge effect studies have shown that the edge habitats of the two edge types have a higher richness index (D) than the internal core habitats of the adjacent patches; The edge of the desert steppe-the sand-fixation caragana plantation has an EH’valued less than1but very close to1, and an EC valued slightly greater than1, this showed that the edge was negative edge effect, but the negative effect was very weak; The edge of the desert steppe-the fixed and semi-fixed sand land has an EH-valued greater than1, and an Ec valued less than1, this showed that the edge was positive edge effect.For the research and conservation of biodiversity in this nature reserve, guide us reasonable artificial desertification control, as well as maintain ecological balance of the desert steppe, etc., this study has some guiding significance.