Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Influence of grazing and precipitation on ecosystem carbon cycling in a mixed-grass prairie | Chimner and Welker Pastoralism Research Policy and Practice 2011 1 20 http content 1 1 20 o Pastoralism a SpringerOpen Journal RESEARCH Open Access Influence of grazing and precipitation on ecosystem carbon cycling in a mixed-grass prairie Rodney A Chimner1 and Jeffery M Welker2 3 Correspondence rchimner@mtu. edu 1School of Forest Resources and Environmental Science Michigan Technological University 1400 Townsend Drive Houghton MI USA Full list of author information is available at the end of the article Springer Abstract Grasslands sequester and store large amounts of soil carbon which is primarily controlled by herbivory and precipitation. However few studies have examined the combined effects of these two factors and quantified how they control carbon cycling in temperate grasslands. The objective of this study was to quantify how grazing intensity affects the magnitudes and patterns of net CO2 exchange in the mixed-grass prairie the largest native grassland ecosystem in North America. The study was conducted during two contrasting precipitation years dry vs. wet summer which allowed investigation of the interaction between precipitation and grazing intensity on the magnitudes and patterns of net CO2 exchange. Our three grazing regimes have been in place for 20 years and consist of light and heavy grazing and ungrazed exclosures. Ecosystem CO2 exchange rates were strongly influenced by changes in summer precipitation. Decreasing summer precipitation reduced ecosystem respiration RE by 45 gross ecosystem production GEP by 75 and net ecosystem exchange NEE by 70 . The lightly grazed pastures had the greatest rates of RE GEP and NEE during the wet summer however NEE did not differ between grazing treatments in the dry summer. These results indicate that grazing intensity and precipitation interact to influence carbon cycling on mixed-grass prairie ecosystems. Keywords carbon cycling carbon storage plant production grazing grasslands .
