Longitudinal patterns of periphyton biomass in Qinghai-Tibetan Plateau streams: An indicator of pasture degradation?

Periphyton communities play a key role in stream ecosystems, and are usually used as an indicator for long-term biological monitoring, management and evaluation. This study examined the relationships between environmental variables and stream periphyton biomass, investigated the longitudinal patterns of periphyton biomass, and explored the relationships between these longitudinal patterns and pasture degradations in Qinghai-Tibetan Plateau. Isolated environmental variables did not have significant impacts on periphyton biomass and did not clearly respond to the influence of pasture degradation. The longitudinal patterns of stream periphyton biomass were consistent with pasture degradation trends. The more serious the pasture degradation, the lower is the periphyton biomass. Longitudinal gradient is a comprehensive variable, which represents a number of space-related environmental factors. In Qinghai-Tibetan Plateau, the pasture ecosystems are fragile and have been severely degraded. The longitudinal patterns of periphyton biomass were closely related to ecological degradation and can be used as an indicator to monitor and evaluate pasture degradation in Qinghai-Tibetan Plateau.