Abstract
As the highest place of the world, the Tibetan plateau is a fragile ecosystem. Given the importance of microbial communities in driving soil nutrient cycling, it is of interest to document the microbial biogeographic pattern here. We adopted a microarray-based tool named GeoChip 4.0 to investigate grassland microbial functional genes along an elevation gradient from 3200 to 3800 m above sea level open to free grazing by local herdsmen and wild animals. Interestingly, microbial functional diversities increase with elevation, so does the relative abundances of genes associated with carbon degradation, nitrogen cycling, methane production, cold shock and oxygen limitation. The range of Shannon diversities (10.27–10.58) showed considerably smaller variation than what was previously observed at ungrazed sites nearby (9.95–10.65), suggesting the important role of livestock grazing on microbial diversities. Closer examination showed that the dissimilarity of microbial community at our study sites increased with elevations, revealing an elevation-decay relationship of microbial functional genes. Both microbial functional diversity and the number of unique genes increased with elevations. Furthermore, we detected a tight linkage of greenhouse gas (CO2) and relative abundances of carbon cycling genes. Our biogeographic study provides insights on microbial functional diversity and soil biogeochemical cycling in Tibetan pastures.
Highlights
It is estimated that two–thirds of the Tibetan plateau, the highest and largest plateau on earth characterized by cold climate, low oxygen level, strong UV irradiation and poor primary productivity, are comprised of alpine grasslands (Qiu, 2008)
Soil temperature (T) and pH decreased along the altitudinal gradient (Table 1), while soil moisture, nitrate (NO3−) and total nitrogen (TN) measured at the 10–20 cm depth (TN10−20 cm) increased with elevations
total organic carbon (TOC) measured at the 10–20 cm depth (TOC10−20 cm), TN measured at the 0–10 cm depth (TN0−10 cm) and vegetation diversity were higher at 3400 and 3600 m than those at 3200 and 3800 m
Summary
It is estimated that two–thirds of the Tibetan plateau, the highest and largest plateau on earth characterized by cold climate, low oxygen level, strong UV irradiation and poor primary productivity, are comprised of alpine grasslands (Qiu, 2008). Since soil is considered to be the most complex ecosystem on earth and plays a vital role in mediating biogeochemical cycling (Falkowski et al, 2008; Bardgett and van der Putten, 2014), it is of great interest to examine the biogeography of soil microbial communities in such a fragile ecosystem (Wu et al, 2016a). GeoChip, a microarray-based tool, is excellent in detecting microbial functional genes. It contains DNA probes targeting a variety of functional genes, including those associated with elemental cycling, stress response, metal resistance and complex carbon degradation (He et al, 2007). It was shown that measurements of relative abundances of functional genes were predictive of in situ CO2 and N2O emissions (Morales et al, 2010) and nitrification potential (Zhao et al, 2014) to certain extent
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
