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• Three ostracod species were identified and related ecological information are reported in the Badain Jaran Desert. • The node formation of Limnocythere inopinata is affected by a combination of the salinity and Ca2+ content of lake water. • The relationship between the percentage of noded individuals and salinity of lake water is complex. Limnocythere inopinata (Baird, 1843) is a widely distributed ostracod in modern non-marine waters and Quaternary sediments. Based on its morphological variation (the number and position of its nodes), different phenotypes have been identified. However, the factors controlling its morphological variation are currently open to debate, which hinders palaeoecological reconstructions based on this species. In this study, ostracod distribution and hydrochemical analyses of the ambient environment of 21 lakes in the Badain Jaran Desert were carried out. Three ostracod species belonging to two genera are identified as Limnocyhtere inopinata , Cypris cf. granulate and Cypris sp. with the dominant species L. inopinata represented by six phenotypes. The distribution features of these ostracods in the lakes and related ecological information are reported. In addition, the factors controlling the morphological variations of L. inopinata were analysed. Our data indicate that the noded individuals of L. inopinata prefer water with appropriate Ca2+ content (30–40 mg L−1) and low salinities (below 4.60 g L−1). The percentage of noded individuals of L. inopinata increases with increasing salinity only within a certain salinity range. Hence, caution should be exercised in reconstructions of palaeosalinity based on the morphological variability of L. inopinata. [ABSTRACT FROM AUTHOR]

The relationship between the variation of CO 2 flux and the pH of inorganic factors. [Display omitted] • The difference of CO 2 absorption and release is obvious during the day and night. • Yindeer Lake was a net sink of CO 2 during the study period. • The lakes can absorb large amounts of CO 2 every year to slow down global warming. • Meteorological factors controlling CO 2 fluxes differed by time scale. • pH is the main influencing factor controlling CO 2 absorption and release. Carbon sequestration levels in lakes are often underestimated despite being vital for the comprehensive analysis of CO 2 budget and significantly influencing inland lakes in arid areas. In this study, the eddy covariance (EC) technique was used to measure CO 2 flux for six consecutive years during 2012–2017 in a small salt-lake (Yindeer Lake) replenished by groundwater in southeastern Badain Jaran Desert, China. The results indicate that: (1) Yindeer Lake was a net sink of CO 2 , which led to the estimate that the lakes in the Badain Jaran Desert can absorb approximately 1.91 × 103 t of CO 2 per year and help slow down the rate of global warming. (2) The effects of meteorological factors on the CO 2 flux of the lake vary with timescales. (3) Inorganic processes, in which pH is the main influence mechanism, control CO 2 absorption and releases in Yindeer Lake. Thus, the study results provide a new guide for solving the "missing sink" problem. [ABSTRACT FROM AUTHOR]

Plant phenology is a commonly used indicator representing the impacts on vegetation by the climate and other environmental factors. The use of repeated digital photography provides an opportunity to conduct long-term monitoring of plant phenology and to extract phenological transition dates. Here, we tracked the phenological changes in the flowering tree, Elaeagnus angustifolia L., in the Cherigele (CRGL) of the Badain Jaran Desert (BJD) and the nearby Lianggejing (LGJ); using one-year near-surface digital repeat photography and meteorological data, the phenological difference between the two sites was revealed. We found that the use of digital cameras allowed for the monitoring of plant phenology with high temporal and spatial accuracy in these dryland ecosystems. Furthermore, in the lake group region of BJD, the onset of greening occurred 23 days earlier, the onset of dormancy began 13 days later and the growing season was 36 days longer, compared to those of the surrounding area. This difference is partly related to the higher altitude in the LGJ; however, it is dominantly related to the warm island effect in the lake group region. This effect resulted in the mean annual temperature in the CRGL being ~1.6 °C higher than in the LGJ. • This study fills the gap in phenological research using digital cameras in desert ecosystems in China. • The onset of greening was earlier, that of dormancy was later in the lake group region of BJD than in the surrounding area. • Phenological disparity between the two sites was mainly caused by the warm island effect in the lake group region of the BJD. [ABSTRACT FROM AUTHOR]

The upper reaches of the Yellow River (URYR) comprise the main water-producing zone of the Yellow River Basin. Quantifying the contribution rates of climate change and human activities (CCHAs) to the changes in runoff in the URYR is critical for formulating rational water resource management strategies in the entire basin. The main objective of this study is to combine the advantages of flexible sample entropy and multiscale entropy to propose a new three-stage method (TSM) to quantify the contribution rates of CCHAs to changes in runoff in the URYR above the city of Lanzhou during 1956–2015. The results show that climate change is the dominant factor affecting the changes in runoff in the study area over the period of study. However, compared with the baseline period (BP; 1956–1986), the variation period (VP; 1987–2015) experienced notably different impacts of CCHAs on the runoff changes. Human activities constituted the dominant factor impacting the changes in runoff in the Huangshui River and the lower section of the URYR (average contribution rate of 70.9%). Meanwhile, climate change was the dominant factor affecting changes in runoff in other regions of the URYR (average contribution rate of 91.8%). Declining precipitation, increasing temperature and evaporation, changing watershed surfaces, the construction of reservoirs and water diversion projects, and increasing human water consumption have resulted in varying degrees of runoff complexity. The novelty and uniqueness of this study can be ascribed to the TSM that (1) considers the impacts of human activities on changes in runoff during the BP and combines the advantages of single time-scale and multiscale entropy for the first time; and (2) uses positive and negative contribution rates to represent the increase and decrease in runoff complexity, respectively. The method exhibits appreciable performance and applicability in the URYR and other watersheds to effectively calculate the contribution rates of the CCHAs to changes in runoff. Image 1 • A new complexity-based three-stage method (TSM) was proposed to quantify impacts of climate change and human activities (HAs) on runoff changes (RCs). • The TSM considers the impact of HAs on RCs during the baseline period (1956–1986). • The TSM uses positive/negative contribution rate (CR) to represent runoff complexity increase/decrease. • HAs are the dominant factor influencing RCs, with a 70.9% CR in the lower section of the upper Yellow River. • The TSM performs well and is applicable to this study and other areas. [ABSTRACT FROM AUTHOR]