Browsing by Author "Liu, Xinyi"

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    Climate and vegetation and their impact on stable C and N isotope ratios in bat guano
    Reid, Rachel E. B.; Waples, James T.; Jensen, David A.; Edwards, Christine E.; Liu, Xinyi (Frontiers, 2022-09)
    Cave guano deposits represent a relatively untapped paleoecological archive that can provide information about past vegetation, climate, and bat diet over several millennia. Recent research suggests that carbon isotope values (delta C-13) measured in guano accumulations from insectivorous bats reflect the relative abundance of C-3 and C-4 plants on the landscape while nitrogen isotope values (delta N-15) may reflect precipitation amount. Together, these proxies can provide useful information for restoration practitioners seeking to understand how plant species composition has changed over time in relation to climate and land use. To better calibrate these proxies for use in restoration, we compared instrumental records of precipitation and satellite imagery of vegetation with isotope values measured in modern bat guano from Mary Lawson Cave, a large limestone cavern located in central Missouri. Mary Lawson Cave hosts a maternity colony of insectivorous gray bats (Myotis grisescens), and as such, contains significant guano accumulations. In the fall of 2018, we collected a 60 cm long guano core that dates to 1999 cal AD at its base. Guano core delta C-13 values decrease from the base toward the surface (from similar to-26 to -27 parts per thousand) whereas delta N-15 values increase toward the surface even after accounting for ammonia volatilization (from similar to 3 to 5 parts per thousand). Presently, the landscape around Mary Lawson Cave is dominated by a deciduous forest and pasture. Given that the land cover has changed very little over this period, the decline in delta C-13 values toward the present likely reflects a shift in land management on farms and/or increases in invasive C-3 species. Rainfall amounts from nearby Lebanon, Missouri, are significantly positively correlated with guano delta N-15 values, a relationship that is notably opposite that observed previously in soil and plants. We argue that heavy fertilizer application and significant grazing intensity could lead to the accumulation of large pools of excess labile nitrogen which would be vulnerable to leaching during precipitation events. The relationship between guano delta N-15 values and precipitation may differ for materials from less agriculturally impacted locations or periods and should be extended into the past with caution.
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    A comprehensive investigation of Bronze Age human dietary strategies from different altitudinal environments in the Inner Asian Mountain Corridor
    Wang, Wei; Liu, Yi; Duan, Futao; Zhang, Jie; Liu, Xinyi; Reid, Rachel E. B.; Zhang, Man; Dong, Weimiao; Wang, Yongqiang; Ruan, Qiurong; Li, Wenying; An, Cheng-Bang (2020-09)
    The early presence of crops from East Asia and Southwest Asia in the Inner Asian Mountain Corridor (IAMC) has drawn attention to the Bronze Age mountain archaeology of Central Asia. Namely, the Bronze Age diffusion and utilization of grains in this region remains unknown as contrasts and extremes characterize the territory in environmental terms, especially elevation. Researchers continue to reflect on how, during the second millennium BC, Bronze Age populations used new crops and local animal resources to adapt to different elevation environments of the IAMC. In this study, we analyzed the 41 latest stable carbon and nitrogen isotopic results from human and faunal bones from six Bronze Age sites in the IAMC, 261 previously published stable isotopic datasets, and 12 archaeobotanical and four zooarchaeological results to investigate the dietary strategies of populations from different elevation environments in the Bronze Age IAMC. The results show an altitudinal gradient in dietary choices among Bronze Age populations in the IAMC, with mixed C-4 and C-3 consumption at the low-mid elevations and notable C-3 consumption at the high elevations. Archaeobotanical and faunal remains also support these isotopic results. Our study further highlights that the differentiated dietary strategies adopted by the Bronze Age population in IAMC may have been the product of adaptation to local geographic environments. Social interaction may have also played a role in certain types of special dietary consumption.
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    Localized management of non-indigenous animal domesticates in Northwestern China during the Bronze Age
    Vaiglova, Petra; Reid, Rachel E. B.; Lightfoot, Emma; Birch, Suzanne E. Pilaar; Wang, Hui; Chen, Guoke; Li, Shuicheng; Jones, Martin; Liu, Xinyi (Springer, 2021-08-26)
    The movements of ancient crop and animal domesticates across prehistoric Eurasia are well-documented in the archaeological record. What is less well understood are the precise mechanisms that farmers and herders employed to incorporate newly introduced domesticates into their long-standing husbandry and culinary traditions. This paper presents stable isotope values (δ13C, δ15N) of humans, animals, and a small number of plants from the Hexi Corridor, a key region that facilitated the movement of ancient crops between Central and East Asia. The data show that the role of animal products in human diets was more significant than previously thought. In addition, the diets of domestic herbivores (sheep/goat, and cattle) suggest that these two groups of domesticates were managed in distinct ways in the two main ecozones of the Hexi Corridor: the drier Northwestern region and the wetter Southeastern region. Whereas sheep and goat diets are consistent with consumption of naturally available vegetation, cattle exhibit a higher input of C4 plants in places where these plants contributed little to the natural vegetation. This suggests that cattle consumed diets that were more influenced by human provisioning, and may therefore have been reared closer to the human settlements, than sheep and goats.