Land-use practices in Mongolia lead to habitat degradation and consequently affect the structure and function of biological communities. There is no accepted bioassessment technique for determining the ecological consequences of habitat degradation on biological communities and water quality in Mongolia, such that a monitoring and management program suitable for Mongolia is sorely needed. Both a trait-based approach and the North American Rapid Bioassessment Protocol (RBP) metrics were tested with macroinvertebrates to determine the performance and applicability of these approaches for predicting general ecological responses of freshwater and terrestrial communities to habitat variation due to overgrazing and mining in northern Mongolian streams. Significant declines in functional diversity were observed by TBA with greater levels of land use intensity (more grazing and mining), and 13 of 16 traits (such as reproduction, life stages, resistant form, dissemination method, locomotion and substrate relation, feeding habit, food, saprobity, temperature, trophic level, current velocity, and substrate preferendum) varied significantly among different levels of land-use intensity. There were no significant differences observed among traits associated with an r/K reproductive strategy among the sites. In addition, complying with the RBP protocols, taxonomic richness and diversity and the number of taxa deemed intolerant to disturbance were significantly lower in sites with more grazing and mining than in more natural sites. However, despite the fact that mayflies are generally associated with low levels of disturbance, the abundance of mayflies (Ephemeroptera) and the percentage of taxon richness and abundance of mayflies was higher in sites with greater land-use intensity. Also, the RBP biotic index classification system for water quality was not well suited for use with Mongolian taxa. To determine the level of taxonomic resolution needed for accurate functional description, I compared functional diversity and trait responses from a coarse taxonomic level and from species-level resolution in one genus of macroinvertebrates (Simulium). Species-level resolution provided more information than genus-level resolution for some traits related to habitat association, but species-level resolution did not improve discrimination of land-use impacts substantially. Furthermore, I assessed land-use effects on terrestrial communities. Crane flies (Diptera: Tipuloidea) are a diverse group and vulnerable to habitat destruction because of their semi-terrestrial habit. Livestock grazing effects on crane fly diversity were tested among sites with different levels of grazing intensity. Species richness and diversity of crane flies were lower for moderately and highly grazed valleys than for the lightly grazed valleys. Soil moisture, plant biomass, and livestock number were the most significant predictors of variation in crane fly diversity across the grazing gradient. Overall, my study showed a strong relationship between functional and taxonomic structure of the macroinvertebrate community and habitat conditions. Generally, TBA and taxonomic approaches discriminated seminatural sites from sites with greater levels of land-use intensity. However, TBA provided a more direct explanation for macroinvertebrate responses to land-use and therefore may be more reliable for a future freshwater biomonitoring program in Mongolia. Species-level resolution may not be necessary for discriminating intensities of grazing and mining. Semiterrestrial crane fly community responses accurately reflected intensities of grazing in northern Mongolia. Among the results, there is a strong relationship between community structure and habitat condition. Habitat filtering determines variability of macroinvertebrate community observed among sites
