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15 June 2016, Volume 8 Issue 5 Previous Issue    Next Issue
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Research Articles
Geochemical weathering of aeolian sand and its palaeoclimatic implications in the Mu Us Desert, northern China, since the Late Holocene
LIU Bing, JIN Heling, SUN Zhong, ZHAO Shuang
Journal of Arid Land. 2016, 8 (5): 647-659.   DOI: 10.1007/s40333-016-0014-y
Abstract ( 1159 )     PDF (733KB) ( 1708 )  
In the semi-arid and arid regions of northern China, geochemical behavior of the aeolian deposit is closely related to climatic and environmental changes, which was used to reconstruct the past history of environmental evolution and possibly forcing mechanisms. However, the related result was still scarce due to the lack of detailed geochemical analysis results in the desert sediments. In the present study, we systematically analyzed the geochemical components and parameters of the paleo-aeolian sand dune and modern mobile sand deposits in the Mu Us Desert and discuss the climatic variation inferred from the paleo-aeolian sand dune during the past 4.2 ka BP. The results indicated that (1) geochemical composition of the sandy deposits were dominated by SiO2, Al2O3 and Na2O and the deposits probably originated from the widespread upper continental crust (UCC) and were formed by long-term weathering, transport and re-deposition; (2) these sandy deposits were subjected to weaker weathering or uneven weathering under cold and dry conditions, and had highly similar material sources and degrees of weathering and leaching in general; and (3) the direct OSL (Optically Stimulated Luminescence) dating ages and geochemical parameters from the palaeosol-aeolian sand dune indicated that the regional climate change experienced several typically cold and warm intervals. These intervals are 4.2, 2.8 ka BP and Little Ice Age and Medieval Warm Period, which probably attributed to periodic variations of the Asian summer monsoonal strength and cold events of the northern Atlantic Ocean in low and high latitudes of the Northern Hemisphere. Our results suggest that the development of the sand dune in the Mu Us Desert provided a suitable archive for understanding the past local climatic change, which is linked to the global climatic change.
Geomorphologic patterns of dune networks in the Tengger Desert, China
WEN Qing, DONG Zhibao
Journal of Arid Land. 2016, 8 (5): 660-669.   DOI: 10.1007/s40333-016-0092-x
Abstract ( 987 )     PDF (685KB) ( 1515 )  
Dune networks are widely distributed in the world’s deserts, which include primary ridges and secondary ridges. However, they have not been sufficiently studied in a systematic manner and their origins and spatial and morphological characteristics remain unclear. To provide information on the geomorphology of dune networks, we analyze the software geomorphologic patterns of the dune networks in China’s Tengger Desert using matrix and laboratory to process remote-sensing images. Based on analysis of image features and their layout in a topographic map, we identify two types of dune networks (square and rectangular dune networks) with different size and morphological structures in the Tengger Desert. Four important geomorphic pattern parameters, ridge length, spacing, orientation and defect density, are analyzed. The length of primary ridges of dune networks decreases from northwest of the desert to the southeast, resulting an increasing spacing and a transition from rectangular dune networks to square dune networks. Wind regime and sediment supply are responsible for the variation in pattern parameters. We use the spacing and defect density data to estimate the construction time of dune networks and found that the dune networks in the Tengger Desert formed since about 1.3 ka BP.
Pattern analysis of a linear dune field on the northern margin of Qarhan Salt Lake, northwestern China
LI Jiyan, DONG Zhibao, QIAN Guangqiang, ZHANG Zhengcai, LUO Wanyin, LU Junfeng, WANG Meng
Journal of Arid Land. 2016, 8 (5): 670-680.   DOI: 10.1007/s40333-016-0052-5
Abstract ( 946 )     PDF (415KB) ( 1404 )  
In terms of formation mechanisms of linear dunes, there are open arguments for their widespread distribution and multi-morphological diversities. In order to clarify the formation mechanism of linear dunes of Qarhan Salt Lake, we used pattern analysis method to analyze the statistical characteristics and spatial variation of their pattern parameters. Except at the west-northwest margin, the pattern parameters showed regular spatial variation from the up-middle part towards the downwind end of the dune field. Based on the cumulative probability plots for inter-crest spacing and crest length, we divided the linear dunes into three groups, which corresponding to the three evolution stages of these dunes. The first group comprises erosional relics, with shorter crests, smaller inter-crest spacing and more random dune orientation. The second group comprises dunes whose sand supply is just sufficient to maintain stability and these dunes are approaching the net erosion stage. The crest length and inter-crest spacing of these dunes are much larger than those of the first group, and dune orientation is closer to the resultant drift direction (RDD). The last group comprises linear dunes that are still undergoing vertical accretion and longitudinal elongation, which follows the RDD of the modern wind regime. The presence of regular spatial variation of pattern parameters and a similar geometry with the vegetated linear dunes suggest that deposition and erosion coexist in the development and evolution of linear dunes of Qarhan Salt Lake, i.e. deposition predominates at the downwind end of linear dunes in the vertical accretion and longitudinal elongation stage, whereas erosion mainly occurs at the upwind end of linear dunes in the degradation stage. Therefore, the formation mechanism of linear dunes in Qarhan Salt Lake can be reasonably explained by the combination of depositional and erosional theories.
Sensitivity of runoff to climatic variability in the northern and southern slopes of the Middle Tianshan Mountains, China
ZHANG Feiyun, BAI Lei, LI Lanhai, WANG Quan
Journal of Arid Land. 2016, 8 (5): 681-693.   DOI: 10.1007/s40333-016-0015-x
Abstract ( 1060 )     PDF (324KB) ( 1434 )  
emperature and precipitation play an important role in the distribution of intra-annual runoff by influencing the timing and contribution of different water sources. In the northern and southern slopes of the Middle Tianshan Mountains in China, the water sources of rivers are similar; however, the proportion and dominance of water sources contributing to runoff are different. Using the Manas River watershed in the northern slope and the Kaidu River watershed in the southern slope of the Middle Tianshan Mountains as case studies, we investigated the changes in annual runoff under climate change. A modified hydrological model was used to simulate runoff in the Kaidu River and Manas River watersheds. The results indicated that runoff was sensitive to precipitation variation in the southern slope and to temperature variation in the northern slope of the Middle Tianshan Mountains. Variations in temperature and precipitation substantially influence annual and seasonal runoff. An increase in temperature did not influence the volume of spring runoff; but it resulted in earlier spring peaks with higher levels of peak flow. Damages caused by spring peak flow from both slopes of the Middle Tianshan Mountains should be given more attention in future studies.
Groundwater contributions in water-salt balances of the lakes in the Badain Jaran Desert, China
GONG Yanping, WANG Xusheng, HU B Xiao, ZHOU Yangxiao, HAO Chunbo, WAN Li
Journal of Arid Land. 2016, 8 (5): 694-706.   DOI: 10.1007/s40333-016-0086-8
Abstract ( 1049 )     PDF (474KB) ( 1462 )  
Groundwater-fed lakes are essential for the ecology in arid and semiarid regions. As a typical arid region, the Badain Jaran Desert (BJD) is famous in the world for the presence of a large number of groundwater-fed saline lakes among the mega dunes. Based on the up to date geological surveys and observations, this study analyzed the groundwater contributions in water-salt balances of the lakes in the desert. We found different types of springs, including the sublacustrine springs that indicate an upward flow of groundwater under the lakebed. A simplified water balance model was developed to analyze the seasonal variations of water level in the SumuBarunJaran Lake, which revealed an approximately steady groundwater discharge in the lake and explained why the amplitude of seasonal changes in lake level is less than 0.5 m. In addition, a salt balance model was developed to evaluate the salt accumulations in the groundwater-fed lakes. The relative salt accumulation time is 800–7,000 years in typical saline lakes, which were estimated from the concentration of Cl, indicating a long history evolution for the lakes in the BJD. Further researches are recommended to provide comprehensive investigations on the interactions between the lakes and groundwater in the BJD.
Coastal environment of the past millennium recorded by a coastal dune in Fujian, China
JIN Jianhui, LI Zhizhong, JIANG Feng, DENG Tao, HU Fan’gen, LING Zhiyong
Journal of Arid Land. 2016, 8 (5): 707-721.   DOI: 10.1007/s40333-016-0053-4
Abstract ( 1054 )     PDF (605KB) ( 1486 )  
Coastal dune is a common aeolian geomorphology in a sandy coast, which records the evolution process of the aeolian landscape system and reflects the complex interaction among land surface, atmosphere and ocean. Coast is a sensitive area to global climate change. Restricted by chronology, most previous researches in China focused only on the cause of formation of coastal dunes. In recent years, the development of optically stimulated luminescence (OSL) dating provides a good method and acts as a carrier for coastal dunes to paleoclimate and paleoenvironmental studies. In this study, we selected an aeolian dune at the Anshan archaeological site, Fujian, China as the research object based on field observations. For determining their sedimentary stages and the primary influencing factors, we used the OSL dating method to construct a chronological framework for the aeolian dune. In addition, the sizes of grains were analyzed for identifying factors influencing the winter monsoon during the Medieval Warm Period (MWP) and the Little Ice Age (LIA) in this area. The results showed that the deposition of the aeolian dune was closely related to variations in the winter monsoon intensity. The changes of the winter monsoon were similar to the tendency of the East Asian winter monsoon, although there were several sub-fluctuations. From an overall perspective, the winter monsoon was strengthened during the MWP (1050–1300). The results of a power spectrum analysis showed that the intensity of the East Asian winter monsoon is correlated with sunspot activity.
Grain size distribution at four developmental stages of crescent dunes in the hinterland of the Taklimakan Desert, China
JIA Wenru, ZHANG Chunlai, LI Shengyu, WANG Haifeng, MA Xuexi, WANG Ningbo
Journal of Arid Land. 2016, 8 (5): 722-733.   DOI: 10.1007/s40333-016-0016-9
Abstract ( 1011 )     PDF (425KB) ( 1317 )  
Although scientists have performed many studies on crescent (barchan) dunes in the Taklimakan Desert, few studies reported the changes in grain size at different development stages of crescent dunes. In order to evaluate the changing trends of surface sediment grain size with dune development, we investigated the grain size characteristics at four developmental stages (oval sand pile, shield dune, incipient crescent dune and mature crescent dune) of crescent dunes by measuring the morphology of sand dune and observing the near-surface wind regime. The dunes have developed in a wide inter-dune corridor between high compound longitudinal ridges in China’s Taklimakan Desert. The surface sediments at four developmental stages of the crescent dunes were primarily composed of fine sands, followed by very fine and medium sands. Mean grain sizes ranged from 2.8 to 3.1 φ, with a unimodal distribution. The sands were moderately well-sorted, their distribution varied from platykurtic to very platykurtic, and symmetrical or skewed towards the fine particles. From oval sand piles through shield and incipient crescent dunes to mature crescent dunes, incipient grain size gradually increased, particles became finer, sorting became better, kurtosis and skewness increased. Grain sizes on the surface layer became coarser upwards from the toe of the windward slope and then became finer towards the bottom of the leeward slope. We found that the coarsest particles at different positions at the four developmental stages were different. The coarsest particles were distributed at the top of the oval sand piles and shield dunes, versus at the middle of the windward slope of the incipient and mature crescent dunes. Correlations between the mean grain size and other grain size parameters showed that as mean grain size became finer, sorting became better and kurtosis became wider, but skewness changed only slightly. In addition, grain size variation in the surface sediments correlated with the movement speed of the dunes in the study area. In the open ground among tall-complex longitudinal ridges in the hinterland of the Taklimakan Desert where aeolian environment is characterized by comparatively strong wind and unsaturated sand flow, faster dune movement corresponded to coarser grain size.
Modeling spatio-temporal distribution of soil moisture by deep learning-based cellular automata model
SONG Xiaodong, ZHANG Ganlin, LIU Feng, LI Decheng, ZHAO Yuguo, YANG Jinling
Journal of Arid Land. 2016, 8 (5): 734-748.   DOI: 10.1007/s40333-016-0049-0
Abstract ( 1503 )     PDF (524KB) ( 2647 )  
Soil moisture content (SMC) is a key hydrological parameter in agriculture, meteorology and climate change, and understanding of spatio-temporal distributions of SMC in farmlands is important to address the precise irrigation scheduling. However, the hybrid interaction of static and dynamic environmental parameters makes it particularly difficult to accurately and reliably model the distribution of SMC. At present, deep learning wins numerous contests in machine learning and hence deep belief network (DBN), a breakthrough in deep learning is trained to extract the transition functions for the simulation of the cell state changes. In this study, we used a novel macroscopic cellular automata (MCA) model by combining DBN to predict the SMC over an irrigated corn field (an area of 22 km2) in the Zhangye oasis, Northwest China. Static and dynamic environmental variables were prepared with regard to the complex hydrological processes. The widely used neural network, multi-layer perceptron (MLP), was utilized for comparison to DBN. The hybrid models (MLP-MCA and DBN-MCA) were calibrated and validated on SMC data within four months, i.e. June to September 2012, which were automatically observed by a wireless sensor network (WSN). Compared with MLP-MCA, the DBN-MCA model led to a decrease in root mean squared error (RMSE) by 18%. Thus, the differences of prediction errors increased due to the propagating errors of variables, difficulties of knowing soil properties and recording irrigation amount in practice. The sequential Gaussian simulation (sGs) was performed to assess the uncertainty of soil moisture estimations. Calculated with a threshold of SMC for each grid cell, the local uncertainty of simulated results in the post processing suggested that the probability of SMC less than 25% will be difference in different areas at different time periods. The current results showed that the DBN-MCA model performs better than the MLP-MCA model, and the DBN-MCA model provides a powerful tool for predicting SMC in highly non-linear forms. Moreover, because modeling soil moisture by using environmental variables is gaining increasing popularity, DBN techniques could contribute a lot to enhancing the calibration of MCA-based SMC estimations and hence provide an alternative approach for SMC monitoring in irrigation systems on the basis of canals.
Effects of freezing intensity on soil solution nitrogen and microbial biomass nitrogen in an alpine grassland ecosystem on the Tibetan Plateau, China
YANG Zhaoping, GAO Jixi, YANG Meng, SUN Zhizhong
Journal of Arid Land. 2016, 8 (5): 749-759.   DOI: 10.1007/s40333-016-0012-0
Abstract ( 1255 )     PDF (235KB) ( 1369 )  
The change of freeze-thaw pattern of the Tibetan Plateau under climate warming is bound to have a profound impact on the soil process of alpine grassland ecosystem; however, the research on the impact of the freeze-thaw action on nitrogen processes of the alpine grassland ecosystem on the Tibetan Plateau has not yet attracted much attention. In this study, the impact of the freezing strength on the soil nitrogen components of alpine grassland on the Tibetan Plateau was studied through laboratory freeze-thaw simulation experiments. The 0–10 cm topsoil was collected from the alpine marsh meadow and alpine meadow in the permafrost region of Beilu River. In the experiment, the soil samples were cultivated at –10°C, –7°C, –5°C, –3°C and –1°C, respectively for three days and then thawed at 2°C for one day. The results showed that after the freeze-thaw process, the soil microbial biomass nitrogen significantly decreased while the dissolved organic nitrogen and inorganic nitrogen significantly increased. When the freezing temperature was below –7°C, there was no significant difference between the content of nitrogen components, which implied a change of each nitrogen component might have a response threshold toward the freezing temperature. As the freeze-thaw process can lead to the risk of nitrogen loss in the alpine grassland ecosystem, more attention should be paid to the response of the soil nitrogen cycle of alpine grasslands on the Tibetan Plateau to the freeze-thaw process.
Soil polygon disaggregation through similarity-based prediction with legacy pedons
LIU Feng, GENG Xiaoyuan, ZHU A-xing, Walter FRASER, SONG Xiaodong, ZHANG Ganlin
Journal of Arid Land. 2016, 8 (5): 760-772.   DOI: 10.1007/s40333-016-0087-7
Abstract ( 935 )     PDF (436KB) ( 1284 )  
Conventional soil maps generally contain one or more soil types within a single soil polygon. But their geographic locations within the polygon are not specified. This restricts current applications of the maps in site-specific agricultural management and environmental modelling. We examined the utility of legacy pedon data for disaggregating soil polygons and the effectiveness of similarity-based prediction for making use of the under- or over-sampled legacy pedon data for the disaggregation. The method consisted of three steps. First, environmental similarities between the pedon sites and each location were computed based on soil formative environmental factors. Second, according to soil types of the pedon sites, the similarities were aggregated to derive similarity distribution for each soil type. Third, a hardening process was performed on the maps to allocate candidate soil types within the polygons. The study was conducted at the soil subgroup level in a semi-arid area situated in Manitoba, Canada. Based on 186 independent pedon sites, the evaluation of the disaggregated map of soil subgroups showed an overall accuracy of 67% and a Kappa statistic of 0.62. The map represented a better spatial pattern of soil subgroups in both detail and accuracy compared to a dominant soil subgroup map, which was commonly used in practice. Incorrect predictions mainly occurred in the agricultural plain area and the soil subgroups that are very similar in taxonomy, indicating that new environmental covariates need to be developed. We concluded that the combination of legacy pedon data with similarity-based prediction is an effective solution for soil polygon disaggregation.
Warming effects on plant biomass allocation and correlations with the soil environment in an alpine meadow, China
XU Manhou, LIU Min, XUE Xian, ZHAI Datong
Journal of Arid Land. 2016, 8 (5): 773-786.   DOI: 10.1007/s40333-016-0013-z
Abstract ( 1135 )     PDF (431KB) ( 1986 )  
Alpine meadow ecosystem is fragile and highly sensitive to climate change. An understanding of the allocation of above- and below-ground plant biomass and correlations with environmental factors in alpine meadow ecosystem can result in better protection and effective utilization of alpine meadow vegetation. We chose an alpine meadow in the Qinghai-Tibetan Plateau of China as the study area and designed experimental warming plots using a randomized block experimental design. We used single-tube infrared radiators as warming devices, established the warming treatments, and measured plant above- (AGB) and below-ground biomass (BGB) during the growing seasons (May to September) in 2012 and 2013. We determined the allocation of biomass and the relationship between biomass and soil environment under the warming treatment. Biomass indices including above-ground biomass, below-ground biomass and the ratio of root to shoot (R/S), and soil factors including soil moisture and soil temperature at different depths were measured. The results showed that (1) BGB of the alpine meadow had the most significant allometric correlation with its AGB (y=298.7x0.44, P<0.001), but the relationship decreased under warming treatment and the determination coefficient of the functional equation was 0.102 which was less than that of 0.188 of the unwarming treatment (control); (2) BGB increased, especially in the deeper soil layers under warming treatment (P>0.05). At 0–10 cm soil depth, the percentages of BGB under warming treatment were smaller than those of the control treatment with the decreases being 8.52% and 8.23% in 2012 and 2013, respectively. However, the BGB increased 2.13% and 2.06% in 2012 and 2013, respectively, at 10–50 cm soil depths; (3) BGB had significant positive correlations with soil moisture at 100 cm depth and with soil temperature at 20–100 cm depths (P<0.05), but the mean correlation coefficient of soil temperature was 0.354, greater than the 0.245 of soil moisture. R/S ratio had a significant negative correlation with soil temperature at 20 cm depth (P<0.05). The warmer soil temperatures in shallow layers increased the biomass allocation to above-ground plant parts, which leading to the increase in AGB; whereas the enhanced thawing of frozen soil in deep layers causing by warming treatment produced more moisture that affected plant biomass allocation.
Plant assemblage and diversity variation with human disturbances in coastal habitats of the western Arabian Gulf
Raafat H ABD EL-WAHAB
Journal of Arid Land. 2016, 8 (5): 787-798.   DOI: 10.1007/s40333-016-0084-x
Abstract ( 1009 )     PDF (248KB) ( 1542 )  
Knowledge about plant diversity along disturbance gradients is essential for conservation and management of fragmented coastal habitats. This study examined the effects of human disturbance intensity in coastal habitats of Kuwait on diversity, composition, identity and assemblage of vascular plant species. Plant survey data from 113 plots (5 m×5 m each) were randomly selected in 51 sites at coastal fragmented habitats at three levels of disturbance intensities (high, moderate and low) and were statistically analyzed. The results revealed that about 76% of the recorded species are considered threatened species in Kuwait, most of which are being lost in high disturbed habitats. Disturbance led to the dominance of Zygophyllum qatarense, Cornulaca aucheri and Salsola imbricata, which are species of disturbance indicators. Richness, total plant cover and species diversity were higher in moderate and low disturbed habitats than in high disturbed habitats. Beta diversity between high and low disturbed habitats was higher than either between high and moderate, or between moderate and low disturbed habitats. Cluster analyses showed statistically significant differences in composition of plant assemblages, which indicate high beta diversity between the habitat types. Intensive urbanization and industrialization are among the most serious threats that contribute to declines in biological diversity and rapid fragmentation of coastal habitats in Kuwait. Establishing protective enclosures in the disturbed habitats, planting endangered and vulnerable species, and establishing a natural reserve at Nuwaiseeb are recommended conservation actions to avoid loss of the fragmented coastal habitats and to facilitate restoration of native plants.
Altitudinal changes of surface pollen and vegetation on the north slope of the Middle Tianshan Mountains, China
YANG Zhenjing, ZHANG Yun, REN Haibao, YAN Shun, KONG Zhaochen, MA Keping, NI Jian
Journal of Arid Land. 2016, 8 (5): 799-810.   DOI: 10.1007/s40333-016-0085-9
Abstract ( 1114 )     PDF (476KB) ( 1635 )  
To provide information on vegetation patterns and altitudinal distributions of pollen assemblage in surface soil layers, their complicated relationships in a dryland mountain-basin system in northwestern China and a realistic basis for paleovegetational reconstruction, we investigated 86 vegetation quadrats and analyzed 80 soil samples from the surface soil layers along an altitudinal transect on the north slope of the Middle Tianshan Mountains from alpine cushion vegetation at 3,510 m near glacier to desert vegetation at 460 m in the Gurbantunggut Desert. According to surface pollen assemblages and the results of the detrended correspondence analysis, the transect can be divided into six major altitudinal pollen zones as alpine cushion vegetation, alpine and subalpine meadows, montane Picea forest, forest-steppe ecotone, Artemisia desert and typical desert, which basically reflect the characteristics of the mountainous vegetation patterns on the north slope of the Middle Tianshan Mountains. However, Picea pollen also exists outside the spruce forest, Chenopodiaceae and Artemisia pollen appeared above the elevation of 1,300 m, indicating that most of them might be introduced from lower elevations by upslope winds. Airborne pollen researches from three regions at different elevations further suggest that a high-frequency northwest anabatic wind has a remarkable influence on the transportation and dispersion of surface pollen in the area.
News
Protecting wild yak (Bos mutus) species and preventing its hybrid in China
WANG Shengli, NAN Zhongren, Daniel PRETE
Journal of Arid Land. 2016, 8 (5): 811-814.   DOI: 10.1007/s40333-016-0051-6
Abstract ( 1168 )     PDF (165KB) ( 1588 )  
China has made efforts to protect wild yak (Bos mutus) species and prevent the hybrids between wild yak and domestic yak (Bos grunniens) species. At present, wild yak population of a reasonable estimate would be over 70,000. Due to conservation efforts in environmental protection and ecological construction such as the Wildlife Protection and Nature Reserve Construction Project, the “Grain-for-Green” Project and the Natural Forest Resources Protection Project, the number of wild yaks is increasing. In general, Tibetan Plateau’s ecosystem is getting better and its environmental quality shows a gradual improving trend. Tibetan Plateau is one of the world’s cleanest regions called as the “Third Pole”. In order to preserve the genetic pool of wild yaks, local pastoralists and polices drive off the wild male yaks from the domestic yak herds by making noise (banging washbasins, pots, etc.) or driving cars. Local government also incentivizes the culling of domestic yaks found in wild herds. For the sake of the biological and genetic features of this wild species, and the pastoralist way of life, wild yaks should continuously be protected to keep their genetic integrity. We appeal plans to investigate the gene pollution of wild yaks in some important distribution regions of this species. In the face of hybridizing with domestic yaks, proper guidance is urgently needed to address genetic pollution and protect the genetic integrity of wild yaks.
Glaucous gull (Larus hyperboreus): a new bird record in Xinjiang, China
XIA Yong, Paul HOLT, WANG Yaotian, GOU Jun, CAI Xinbin, WANG Chuanbo, DING Peng, LIN Xuanlong
Journal of Arid Land. 2016, 8 (5): 815-818.   DOI: 10.1007/s40333-016-0093-9
Abstract ( 1110 )     PDF (182KB) ( 1276 )  
XIA Yong and WANG Yaotian saw a first-year glaucous gull (Larus hyperboreus) at Beihu Lake, Shihezi (a city of Xinjiang Uygur autonomous region; 44°22′N, 86°07′E; 416 m asl) on 2 January 2016. The gull was also seen and photographed by other observers in the period of 19 December 2015 to10 January, 2016.