Effects of multiple environmental variables on tundra ecosystem respiration in maritime Antarctica

Tao Bao,Renbin Zhu,Wenjuan Ye,Xiao Cheng,Xianglan Li

doi:10.1038/s41598-018-30263-6

Tao Bao, Renbin Zhu + Show 3 more

Open Access

https://doi.org/10.1038/s41598-018-30263-6

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Abstract

Summertime ecosystem respiration (ER) rates through seven sites were measured at an upland tundra on Fildes Peninsula in maritime Antarctica to investigate effects of topographic gradient, vegetation types and climatic factors on tundra ER rates. Overall the highest ER rates occurred at the tundra top, followed at the middle slope, and the lowest rates at the lower slope. The daily highest ER rates occurred at noon whereas the lowest at 6 am. There was a significant positive correlation (P < 0.05) between tundra ER and 0–10 cm soil temperature, but a significant negative correlation (P < 0.01) between ER and soil moisture. A high Q10 value of 2.69 was obtained when all the data were combined, indicating soil temperature sensitivity of tundra ER. The mean ER at the tundra sites with moss coverage (72.2 ± 4.4 mg CO2 m−2 h−1) was significantly higher (P < 0.01) than that at the sites with lichen coverage (46.8 ± 8.7 mg CO2 m−2 h−1). The tundra sites without snow coverage experienced significant CO2 release, whereas the emission through ER was very low at the tundra sites with snow coverage. Our results indicated that topographic gradient, soil temperature, soil moisture, vegetation types and snow coverage might affect tundra ER in maritime Antarctica.

Highlights

Carbon dioxide (CO2) is key active greenhouse gas (GHG) contributing to global warming[1]
The air temperature, ground temperature (GT) and 10 cm soil temperature (ST10) showed a similar change at the sites GW1, GW2 and GW3, and they increased gradually from December, 2014 to January, 2015, but soil temperatures decreased with soil depths (Fig. 2)
Previous climate model simulations have shown that both annul and seasonal responses of terrestrial carbon cycle to climate change will change in the 21th century, but with large uncertainty at high latitudes (Antarctic and Arctic)[26,27]

Summary

Introduction

Carbon dioxide (CO2) is key active greenhouse gas (GHG) contributing to global warming[1]. The results from Arctic regions or the McMurdo Dry Valleys of continental Antarctica might not be applied to maritime Antarctic tundra due to differences in vegetation communities, soil nutrients and climatic conditions. The most common moss vegetation (Bryum Pseudotriquetrum and Bryum muelenbeckii) and native vascular plant species (Colobanthus quitensis and Deschampsia antarctica Desv) have recently been expanding in maritime Antarctic tundra[16,18,19,20] These changes would affect tundra ER rates, and net CO2 fluxes since tundra vegetation composition and soil physical properties are related to soil organic carbon content, potential mineralization and microorganism activity[4,21,22]. More data about tundra ER are required to improve our knowledge about CO2 exchange

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