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1. chinaXiv:202011.00128 [pdf]

Degradation leads to dramatic decrease in topsoil but not subsoil root biomass in an alpine meadow on the Tibetan Plateau, China

ZHANG,Zhenchao; LIU,Miao; SUN,Jian; WEI,Tianxing
Subjects: Geosciences >> Geography

Understanding the effects of degradation on belowground biomass (BGB) is essential for assessment of carbon budget of the alpine meadow ecosystem on the Tibetan Plateau, China. This ecosystem has been undergoing serious degradation owing to climate change and anthropogenic activities. This study examined the response of the vertical distribution of plant BGB to degradation and explored the underlying mechanisms in an alpine meadow on the Tibetan Plateau. A field survey was conducted in an alpine meadow with seven sequential degrees of degradation in the Zoige Plateau on the Tibetan Plateau during the peak growing season of 2018. We measured aboveground biomass (AGB), BGB, soil water content (SWC), soil bulk density (SBD), soil compaction (SCOM), soil organic carbon (SOC), soil total nitrogen (STN), soil total phosphorus (STP), soil available nitrogen (SAN), and soil available phosphorus (STP) in the 0–30 cm soil layers. Our results show that degradation dramatically decreased the BGB in the 0–10 cm soil layer (BGB0–10) but slightly increased the subsoil BGB. The main reason may be that the physical-chemical properties of surface soil were more sensitive to degradation than those of subsoil, as indicated by the remarked positive associations of the trade-off value of BGB0–10 with SWC, SCOM, SOC, STN, SAN, and STP, as well as the negative correlation between the trade-off value of BGB0–10 and SBD in the soil layer of 0–10 cm. In addition, an increase in the proportion of forbs with increasing degradation degree directly affected the BGB vertical distribution. The findings suggest that the decrease in the trade-off value of BGB0–10 in response to degradation might be an adaptive strategy for the degradation-induced drought and infertile soil conditions. This study can provide theoretical support for assessing the effects of degradation on the carbon budget and sustainable development in the alpine meadow ecosystem on the Tibetan Plateau as well as other similar ecosystems in the world.

submitted time 2020-11-25 From cooperative journals:《Journal of Arid Land》 Hits2123Downloads267 Comment 0

2. chinaXiv:201609.00888 [pdf]

The study of the aging behavior on large area MCP-PMT

WANG Wen-Wen; QIAN Sen; QI Minga XIA Jing-Kai; CHENG Ya-Ping; NING Zhe; LUO Feng-Jiao; HENG Yue-Kun; LIU Shu-Lin; SI Shu-Guang; Sun Jian-Ning; LI Dong; WANG Xing-Chao; HUANG Guo-Rui; TIAN Jing-Shou; WEI Yong-Lin; LIU Hu-Lin; LI Wei-Hua; WANG Xing; XIN Li-Wei
Subjects: Physics >> Nuclear Physics

Aging experiments of a novel type of large area MCP-PMT made by JUNO collaboration were conducted.In these aging experiments, the multi-photoelectron spectrum and single photoelectron spectrum were measured daily,as well as the MCP resistance of the second PMT before and after the experiment. Two PMTs were aged successivelyfor cross check. The first PMT was aged for 52 days, while the other one was aged for 84 days. In order to study the mechanism of the aging process, the high voltage on the second PMT was increased to accelerate its aging process when the cumulative output of charge from its anode was about 4 C. From our study, it can be known that large area MCP-PMT aging had a strong relationship with the related MCPs. In accordance with the PMT aging curve,a PMT aging model was setup and a general aging formula was given.

submitted time 2016-09-13 Hits1069Downloads621 Comment 0

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