Hailuogou Glacier Research Articles

Understanding of landslides induced by 2022 Luding earthquake, China

On September 5, 2022, at least 10,855 landslides had been triggered by a magnitude Mw 6.7 (Ms 6.8) earthquake on the eastern margin of the Tibetan Plateau. Unfortunately, a detailed analysis of the spatial patterns of landslides in the eastern margin of the Baryan Har block is lacking. The observations show that the highest landslide concentrations are distributed along the seismogenic fault (Moxi fault) and Dadu River valley, coinciding with the effects of the hanging wall and microepicenter. Seismogenic tectonics controlled the regional distribution of new landslides, and the local topography influenced the detailed positions on the slopes. The total landslide mass wasting volume was 223.1 × 106 m3, and the maximum occurred in the Wandong Basin (value of 74 × 106 m3). Thirty landslide dams were temporarily existing. Although some local collapses occurred at the toe of the Hailuogou glacier, seismic shaking had no obvious influence on the overall stability of the glacier. A post debris flow assessment indicates that some large basins contained much loose material and that some steep small basins had high debris flow susceptibility. On the eastern margin of the Bayan Har block, the landslide-triggering thrust and strike-slip events both follow the distributions of the hanging wall.

Pengzhenrongella frigida sp. nov., isolated from a glacier.

A Gram-stain-positive, rod-shaped bacterium, designated as HLT2-17T, was isolated from soil sample taken from the Hailuogou glacier in Sichuan province, PR China. Strain HLT2-17T was capable of growing at 4-25°C and in NaCl concentrations ranging from 0 to 2% (w/v). The highest level of 16S rRNA gene sequence similarity was observed with Pengzhenrongella phosphoraccumulans M0-14T (98.3 %) and Pengzhenrongella sicca LRZ-2T (98.2 %). The average nucleotide identity and digital DNA-DNA hybridization values between strain HLT2-17T and its closest relatives, P. phosphoraccumulans M0-14T and P. sicca LRZ-2T, were 80.0-84.0 % and 23.3-27.7 %, respectively. Phylogenomic analysis indicated that strain HLT2-17T clustered together with strains P. phosphoraccumulans M0-14T and P. sicca LRZ-2T. Strain HLT2-17T contained C16 : 0 and anteiso-C15 : 0 as the major fatty acids, and MK-9(H4) as the menaquinone. Therefore, based on a polyphasic approach, we propose that strain HLT2-17T (=CGMCC 1.11116T= NBRC 110443T) represents a novel species of the genus Pengzhenrongella and suggest the name Pengzhenrongella frigida sp. nov.

Dynamics of the spatiotemporal velocity of glaciers on the eastern slope of Mount Gongga, China, under climate change

The quantitative assessment of glacier flow velocity dynamics plays a pivotal role in understanding its response mechanisms concerning climate warming. This work provides a systematic quantitative assessment of the deceleration status of glaciers in this region by investigating the motion evolution of typical glaciers in Mount Gongga in recent years, thereby revealing the seasonal dynamics and inter-annual evolution over an extensive time span. We used the optical flow-small baseline subset (OF-SBAS) method to compute the time-series velocities of the Hailuogou Glacier and the Mozigou Glacier using 178 archived Sentinel-1 satellite synthetic aperture radar (SAR) images from 2014 to 2021. The findings revealed a prominent seasonal pattern in glacier motion, characterised by cyclic variations in velocity from cold to warm seasons. Moreover, we identified variations in velocities across distinct regions of the glacier surface, underscored by the lag in the peak time node of glacier flow with increasing elevation. This pattern may have been determined by a combination of internal and external factors, including mass accumulation and ablation-driven subglacial drainage, as well as the glacier geomorphological setting. Furthermore, during 2015–2021, the glaciers on the eastern slope of Mount Gongga exhibited an overarching trend of deceleration. Notably, the ablation area of the Hailuogou Glacier recorded the most substantial deceleration, exceeding 8% per year. This study underscores the efficacy of the OF-SBAS method in extracting long-term glacier velocities. This work also establishes a robust foundation for the analysis of spatiotemporal fluctuations in glacier movement within the context of climate warming.

Plant water source effects on plant-soil feedback for primary succession of terrestrial ecosystems in a glacier region in China

Despite the extensive research conducted on plant-soil-water interactions, the understanding of the role of plant water sources in different plant successional stages remains limited. In this study, we employed a combination of water isotopes (δ2H and δ18O) and leaf δ13C to investigate water use patterns and leaf water use efficiency (WUE) during the growing season (May to September 2021) in Hailuogou glacier forefronts in China. Our findings revealed that surface soil water and soil nutrient gradually increased during primary succession. Dominant plant species exhibited a preference for upper soil water uptake during the peak leaf out period (June to August), while they relied more on lower soil water sources during the post-leaf out period (May) or senescence (September to October). Furthermore, plants in late successional stages showed higher rates of water uptake from uppermost soil layers. Notably, there was a significant positive correlation between the percentage of water uptake by plants and available soil water content in middle and late stages. Additionally, our results indicated a gradual decrease in WUE with progression through succession, with shallow soil moisture utilization negatively impacting overall WUE across all succession stages. Path analysis further highlighted that surface soil moisture (0– 20 cm) and middle layer nutrient availability (20– 50 cm) played crucial roles in determining WUE. Overall, this research emphasizes the critical influence of water source selection on plant succession dynamics while elucidating underlying mechanisms linking succession with plant water consumption.

Multidecadal Changes in the Flow Velocity and Mass Balance of the Hailuogou Glacier in Mount Gongga, Southeastern Tibetan Plateau

Maritime glaciers in the southeastern Tibetan Plateau (TP) have experienced important changes in mass and dynamics over the past decades, challenging the regional water supply and glacier-related hazards. However, knowledge about long-term variations in the surface velocity and mass balance of maritime glaciers remains incomplete due to the lack of representative observations in the southeastern TP. In this study, offset tracking is employed to measure spatiotemporal variation in the surface velocity of the Hailuogou Glacier (HLG) in Mount Gongga of the southeastern TP using Sentinel-1A imagery, while the time series of the HLG mass balance is reconstructed since 1950 by a physically based energy–mass balance model. Our satellite-based results find that HLG surface velocity shows significant spatial heterogeneity with a double-peak pattern along the flow line, and sustained slowdown below the icefall zone has been observed during the past nearly 40 years, although the icefall zone and the area above it have become relatively active. Our modeling indicates a persistent increase in mass loss over the last seven decades with an average rate of −0.58 m water equivalent (w.e.) year−1, which has accelerated in the past two decades. Sustained slowdown on the glacier is concomitant with pronounced negative mass balance, thereby enhancing glacier wastage in recent decades. The long-term trend in HLG mass loss is mainly driven by an increase in positive air temperature that decreases surface albedo and solid precipitation ratio and increases longwave incoming radiation, besides the influence of supraglacial debris cover. Large-scale atmospheric circulation patterns in the Eurasian region provide important implications for regional-to-local climate variability, unsustainably intensifying the trend of the negative mass balance of the HLG in the southeastern TP in the past two decades.

The Stability Analysis of Mt. Gongga Glaciers Affected by the 2022 Luding MS 6.8 Earthquake Based on LuTan-1 and Sentinel-1 Data

On 5 September 2022, an MS 6.8 earthquake occurred in Luding county, Sichuan province, China, with the epicenter located approximately 20 km from the main peak of Mount (Mt.) Gongga. The dynamic situation of Mt. Gongga glaciers has received widespread attention. In this study, Mt. Gongga was selected as the study area, and L-band LuTan-1 (LT-1) satellite data were used for differential interferometric synthetic aperture radar (D-InSAR) processing to obtain the coseismic landform in Luding. Based on Sentinel-1A images, pixel offset tracking (POT) technology was used to obtain the surface movement velocities of the glaciers before, during, and after the earthquake. The results showed that the overall preseismic movement of the glaciers was fast in the area where the ice cascade of the Hailuogou Glacier reached a maximum average deformation rate of 0.94 m/d. Moreover, time-series monitoring of the postseismic glaciers showed that the surface flow velocities of some glaciers in the study area increased after the earthquake. The flow velocity at the main peak of Mt. Gongga and the tongue of the Mozigou Glacier accelerated for a period after the earthquake. The study concluded that the earthquake was one of the direct causes of the increase in glacier flow velocity, which returned to a stable state more than 70 days after the earthquake. The relevant monitoring results and research data can provide a reference for earthquake-triggered glacial hazards and indicate the effectiveness of LT-1 in identifying and monitoring geological hazards.

Soil development following glacier retreat shapes metagenomic and metabolomic functioning associated with asynchronous C and N accumulation

Glacier retreat caused by global warming may result in the variation of soil organic carbon and nutrient cycling. Yet, the dynamic change of soil microbial functional profiles, especially C metabolism-related, with soil development following glacier retreat are still unclear. In the present study, we investigated the soil microbial communities, metagenomic functioning, and metabolomic profiles along the Hailuogou Glacier forefield representing a 120-year chronosequence. The alpha diversity indices of soil bacteria, protozoa and nifH genes showed an upward trend with increased soil ages, and the beta diversity of soil archaea, bacteria, fungi, protozoa, nifH and nirS genes were significantly correlated with soil ages, in which increasing soil C and P while decreased C/N and pH significantly contributed to the differences of soil microbial communities among the analyzed environmental variables. The metagenomic functional genes related to the metabolisms of Glycogen and Cellulosome, Iron Acquisition and Metabolism were significantly decreased with chronosequence, while the utilization of Xylose and Lactate, Potassium Metabolism, Sulfur Metabolism showing an upward trend with soil ages, in which soil C/N ratios and pH were the most influential factors. In addition, soil C and C/N ratios were also significantly correlated to metabolomic compositions, in which the complexity of the metabolite structure increased with soil ages. Our results indicate that glacier retreat may lead to the asynchronous C and N accumulation along the chronosequence, thereby affecting the metagenomic and metabolomic functioning of soil microbial communities related to C metabolisms during soil development following glacier retreat.

Diversity and co-occurrence networks of bacterial and fungal communities on two typical debris-covered glaciers, southeastern Tibetan Plateau

Debris-covered glaciers (DCGs) are globally distributed and thought to contain greater microbial diversity than clean surface continental glaciers, but the ecological characteristics of microbial communities on the surface of DCGs have remained underexplored. Here, we investigated bacterial and fungal diversity and co-occurrence networks on the supraglacial debris habitat of two DCGs (Hailuogou and Dagongba Glaciers) in the southeastern Tibetan Plateau. We found that the supraglacial debris harbored abundant microbes with Proteobacteria occupying more than half (51.5%) of the total bacteria operational taxonomic units. The composition, diversity, and co-occurrence networks of both bacterial and fungal communities in the debris were significantly different between Hailuogou Glacier and Dagongba Glacier even though the glaciers are geographically adjacent within the same mountain range. Bacteria were more diverse in the debris of the Dagongba Glacier, where a lower surface velocity and thicker debris layer allowed the supraglacial debris to continuously weather and accumulate nutrients. Fungi were more diverse in the debris of the Hailuogou Glacier, which experiences a wetter monsoonal climate, is richer in calcium, has greater debris instability, and greater ice velocity than the Dagongba Glacier. These factors may provide ideal conditions for the dispersal and propagation of fungi spores on the Hailuogou Glacier. In addition, we found an obvious gradient of bacterial diversity along the supraglacial debris transect on the Hailuogou Glacier. Bacterial diversity was lower where debris cover was thin and scattered and became more diverse near the glacial terminus in thick, slow-moving debris. No such increasing bacterial pattern was detected on the Dagongba Glacier, which implies a positive relationship of debris age, thickness, and weathering on bacterial diversity. Additionally, a highly connected bacterial co-occurrence network with low modularity was found in the debris of the Hailuogou Glacier. In contrast, debris from the Dagongba Glacier exhibited less connected but more modularized co-occurrence networks of both bacterial and fungal communities. These findings indicate that less disturbed supraglacial debris conditions are crucial for microbes to form stable communities on DCGs.

Analysis of Seismic Impact on Hailuogou Glacier after the 2022 Luding Ms 6.8 Earthquake, China, Using SAR Offset Tracking Technology

An Ms 6.8 earthquake struck Luding County, Ganzi Prefecture, Sichuan Province on 5 September 2022, with the epicenter about 10 km away from Hailuogou Glacier. How Hailuogou Glacier was affected by the earthquake was of major concern to society. Sentinel-1 SAR satellite imaging was used to monitor the glacier surface velocity during different periods before and after the Luding earthquake based on pixel offset tracking (POT) technology, which applies a feature-tracking algorithm to overcome the phase co-registration problems commonly encountered in large displacement monitoring. The results indicated that the velocity had a positive correlation with the average daily maximum temperature and the slope gradient on the small-slope surfaces. The correlation was not apparent on the steeper surfaces, which corresponded spatially with the identified ice avalanche region in the Planet images. It was deduced that this may be because of the occurrence of ice avalanches on surfaces steeper than 25°, or that the narrower front channel impeded the glacier’s movement. The Luding earthquake did not cause a significant increase in the velocity of Hailuogou Glacier within a large range, but it disturbed the front area of the ice cascade, where the maximum velocity reached 2.5 m/d. Although the possibility of directly-induced destruction by ice avalanches after the earthquake was low, and the buffering in the downstream glacier tongue further reduced the risk of ice avalanches, the risk of some secondary hazards such as debris flow increased. The proposed method in this study might be the most efficient in monitoring and evaluating the effects of strong earthquakes on glaciers because it would not be limited by undesirable weather or traffic blockage.

Changes of Soil Dissolved Organic Matter and Its Relationship with Microbial Community along the Hailuogou Glacier Forefield Chronosequence.

Glacier-retreated areas are ideal areas to study soil biogeochemical processes during vegetation succession, because of the limited effect of other environmental and climatic factors. In this study, the changes of soil dissolved organic matter (DOM) and its relationship with microbial communities along the Hailuogou Glacier forefield chronosequence were investigated. Both microbial diversity and DOM molecular chemodiversity recovered rapidly at the initial stage, indicating the pioneering role of microorganisms in soil formation and development. The chemical stability of soil organic matter enhanced with vegetation succession due to the retaining of compounds with high oxidation state and aromaticity. The molecular composition of DOM affected microbial communities, while microorganisms tended to utilize labile components to form refractory components. This complex relationship network between microorganisms and DOM components played an important role in the development of soil organic matter as well as the formation of stable soil carbon pool in glacier-retreated areas.

Nitrogen Preference of Dominant Species during Hailuogou Glacier Retreat Succession on the Eastern Tibetan Plateau

Plant nitrogen (N) uptake preference is a key factor affecting plant nutrient acquisition, vegetation composition and ecosystem function. However, few studies have investigated the contribution of different N sources to plant N strategies, especially during the process of primary succession of a glacial retreat area. By measuring the natural abundance of N isotopes (δ15N) of dominant plants and soil, we estimated the relative contribution of different N forms (ammonium-NH4+, nitrate-NO3- and soluble organic N-DON) and absorption preferences of nine dominant plants of three stages (12, 40 and 120 years old) of the Hailuogou glacier retreat area. Along with the chronosequence of primary succession, dominant plants preferred to absorb NO3- in the early (73.5%) and middle (46.5%) stages. At the late stage, soil NH4+ contributed more than 60.0%, In addition, the contribution of DON to the total N uptake of plants was nearly 19.4%. Thus, the dominant plants' preference for NO3- in the first two stages changes to NH4+ in the late stages during primary succession. The contribution of DON to the N source of dominant plants should not be ignored. It suggests that the shift of N uptake preference of dominant plants may reflect the adjustment of their N acquisition strategy, in response to the changes in their physiological traits and soil nutrient conditions. Better knowledge of plant preferences for different N forms could significantly improve our understanding on the potential feedbacks of plant N acquisition strategies to environmental changes, and provide valuable suggestions for the sustainable management of plantations during different successional stages.

Microbial assemblies with distinct trophic strategies drive changes in soil microbial carbon use efficiency along vegetation primary succession in a glacier retreat area of the southeastern Tibetan Plateau

Soil microbial carbon use efficiency (CUE) is a vital physiological parameter in assessing carbon turnover. Yet, how the microbial assemblies with distinct trophic strategies regulate the soil microbial CUE remains elusive. Based on the oligotrophic-copiotrophic framework, we explored the role of microbial taxa with different trophic strategies in mediating microbial CUE (determined by a 13C-labeled approach) along the vegetation primary succession in Hailuogou glacier retreat area of the southeastern Tibetan Plateau. Results showed that soil microbial CUE ranged from 0.54 to 0.72 (averaging 0.62 ± 0.01 across all samples) and increased staggeringly along the vegetation succession. Microbial assemblies with distinct trophic strategies were crucial regulators of soil microbial CUE. Specifically, microbial CUE increased with microbial oligotroph: copiotroph ratios, oligotroph-dominated stage had a higher microbial CUE than copiotroph-dominated ones. The prevalence of oligotrophic members would be the underlying microbial mechanism for the high microbial CUE. Given that oligotrophs predominate in more recalcitrant carbon soils and their higher microbial CUE, we speculate that oligotrophs are likely to potentially enhance carbon sequestration in soils. In addition, the responses of the microbial CUE to fungal oligotroph: copiotroph ratios were higher than bacterial ones. Fungal taxa may play a dominant role in shaping microbial CUE relative to bacterial members. Overall, our results constructed close associations between microbial trophic strategies and CUE and provide direct evidence regarding how microbial trophic strategies regulate microbial CUE. This study is a significant step forward for elucidating the physiological mechanisms regulating microbial CUE and has significant implications for understanding microbial-mediated carbon cycling processes.

A dataset of glacier crevasse distribution in the ablation areas of Hailuogou Glacier, Mt. Gongga (2016–2021)

The distribution of crevasses in mountain glaciers is of great significance for the study on glacier dynamics, ablation, and glacial instability-induced disasters. From 2016 to 2021, based on repeated aerial surveys during ablation seasons in the Hailuogou Glacier ablation areas on the eastern slope of Gongga Mountain, we obtained the annual high-resolution orthophoto images of the 4 km ice tongue of the glacier during the ablation period. Based on these co-registered images, the crevasses in Hailuogou ice tongue were visually interpreted and delineated from 2016 to 2021. We preliminarily analyzed the distribution characteristics and inter-annual variation of the crevasses. This dataset contains spatial information attributes like the crevasse length and orientation. It is the first set of survey results related to the structural glaciology of mountain glaciers in western China and it can provide data reference for the study on glacial hydrology, mass balance and dynamic models.

Analysis of the Reciprocal Feedback between Glacier Tourism Development and Regional Economic Growth in Hailuogou

Ice and snow tourism has yielded considerable socioeconomic benefits, especially for the countries and regions that are rich in ice and snow resources. Boosted by the Beijing Winter Olympics, China’s ice and snow tourism economy is likely to usher in a period of high-quality development. This study utilized Hailuogou Glacier Forest Park, a relatively well-developed glacier tourism area in China, as the study area. We used data on the regional GDP of Ganzi Prefecture and the comprehensive tourism revenue of Hailuogou scenic area from the period of 1990–2021 to quantitatively analyze the reciprocal feedback relationships between the regional economic growth of Ganzi Prefecture and the development of Hailuogou glacier tourism. The analyses were performed through the construction of a VAR model and through conducting robustness tests using the instrumental variable method. The results show that there is a long-term equilibrium cointegration relationship between regional economic growth in Ganzi Prefecture and tourism development in the Hailuogou scenic area, with each 1% increase in the former driving a corresponding growth of 2.01% in the latter. There is an asymmetric reciprocal feedback relationship between the economic growth of Ganzi Prefecture and the development of tourism in the Hailuogou scenic area. Economic growth in Ganzi Prefecture significantly contributes to the development of glacier tourism in Hailuogou over a longer period of time, with a contribution rate of 49%; meanwhile, the development of tourism in the Hailuogou scenic area has a limited effect on the quality and acceleration of economic development in Ganzi Prefecture, with a contribution rate of 16%. Based on the above results, relevant policy recommendations are proposed to provide a theoretical basis and decision-making reference for the high-quality development of the Hailuogou scenic area in the post-COVID-19 and post-Winter Olympics era.

Recent (2018–2021) glaciological, hydrological and geomorphological landscape changes of Hailuogou Glacier tongue, southeastern Tibetan Plateau

ABSTRACT Glaciers in the Tibetan Plateau are melting at an unprecedented recently rate in the context of global warming. Time-sequenced landform mapping for the Hailuogou Glacier, a partly debris-covered glacier in the southeastern Tibetan Plateau, shows the detailed evolution of glacier changes as the ice recedes. This study presents four maps of the Hailuogou Glacier tongue, a partly debris-covered glacier in the southeastern Tibetan Plateau, documenting the spatial evolution of glaciological, hydrological, and geomorphological features from 2018 to 2021. Structure from Motion with Multiview Stereo software was applied to images captured by from uncrewed aerial vehicles were used to produce digital surface models and orthophoto mosaics. These datasets were used, and then to identify and map the features based on pre-defined mapping criteria. From 2018 to 2021, the glacier underwent continuous recession, with the terminus retreating, intense crevassing in the lower part of the ablation zone, and continuous expansion of the terminal disintegration area. The recent evolution of the glacier implies that the gradual disintegration of the lower glacier tongue is likely to be exacerbated over the next decades by the continuous climate warming.

The Effects of Place Attachment and Emotional Solidarity on Community Residents’ Attitudes toward Glacier Tourism

The perceptions and attitudes of community residents are a “mirror” of tourism development. Little research has been conducted on the effects of place attachment and emotional solidarity on community residents’ attitudes toward tourism in China’s glacier tourism-related areas. In this paper, we selected the southernmost marine glacier in China, Hailuogou Glacier Forest Park, as a case study, and constructed a structural equation model of residents’ tourism perceptions and attitudes based on 358 valid questionnaires obtained from fieldwork. We analyzed the logical connection and influencing relationship between place attachment, residents’ perceptions (residents’ benefits and environmental perceptions), and community residents’ attitudes (security, support, satisfaction), and explored countermeasures and suggestions for building a harmonious host–customer relationship in the Hailuogou area to improve glacier tourism. The results of the study show that the influence of place attachment and residents’ perceptions on emotional solidarity is different from the degree of influence of emotional solidarity on residents’ tourism attitudes, with the most significant positive influence of place attachment on emotional solidarity and the greatest influence of emotional solidarity on sense of security. Emotional solidarity had a certain mediating effect between place attachment, residents’ perceptions, and residents’ tourism attitudes. Significantly, emotional solidarity had the most fully mediated effect between place attachment and support, reaching 73.61%. The moderating effect of place attachment reflects that the higher the place attachment, the weaker the correlation between residents’ perceptions and residents’ tourism attitudes. Meanwhile, residents’ tourism attitudes will weaken their influence with the increase in emotional solidarity. Based on the above results, relevant suggestions are made to provide a theoretical basis and decision-making reference for the development and management of glacier tourism destinations.

Stability of the Hailuogou glacier during the “9.5” Luding Earthquake: a preliminary assessment based on multi-source observations

Stability of the Hailuogou glacier during the “9.5” Luding Earthquake: a preliminary assessment based on multi-source observations

Methane dynamics in the Hailuogou Glacier forefield, Southwest China

Soils in glacier forefields have a significant capacity for atmospheric CH4 uptake, but this pattern could be changed by high soil water content (SWC). The Hailuogou Glacier in SW China is a typical temperate monsoon glacier on siliceous bedrock, where a forefield soil chronosequence has developed with progressive glacier recession. To understand CH4 dynamics and their potential regulatory factors, we measured the concentrations and stable carbon (C) isotope compositions of CH4 and CO2, soil physicochemical properties, and perfromed a high-throughput sequencing. Among nine sampling sites, soil CH4 concentrations of six sites were below atmospheric levels and δ13C–CH4 values were similar to atmospheric levels. The average value was approximately −48.6‰ and without obvious fractionation. The soil CH4 concentrations exceeded atmospheric levels for the remaining three sites, and the δ13C–CH4 values were more enriched with increasing soil CH4 concentration. We calculated the soil-atmosphere CH4 flux (Jatm) using the concentration gradient method based on the soil CH4 concentration, sampling depth, and soil porosity. Jatm ranges from −0.08 to −0.52 mg m−2 d−1, acting as an atmospheric CH4 sink. It also shows that the correlation with soil exposure age or vegetation succession was insignificant. But the CH4 emission shows a larger variation changing from 0.05 to 1.8 mg m−2 d−1, which could result from local CH4 production differences catalyzed by aceticlastic methanogens. The results showed that not all sites acted as a net CH4 sink. SWC may have an important influence on CH4 dynamics in the Hailuogou Glacier forefield (HGF).

A Responsible Tourism System at Glacier Tourism Sites: Reducing the Impacts of Tourism Activities on Glaciers

The anthropogenic heat release from tourism activities has a cumulative effect on glacial retreat when coupled with climate change. Mitigating the impacts of glacial tourism activities on glaciers and promoting the sustainable development of glacial tourism have become urgent issues. Taking Yulong and Hailuogou glacier tourism destinations as examples, we collected survey questionnaires related to glacial tourists (n=1113) and tourism companies (n=329) by systematic field surveys during 2016–2017, and we obtained data on energy consumption from catering, accommodation, transportation, sightseeing, shopping, entertainment, and waste disposal. This study builds a responsible tourism system and discusses the strategies and measures used to engage stakeholders (mainly tourism companies, tourists, local governments, tourism associations, and the central government) in responsible tourism in order to reduce the impacts of tourism activities on glaciers. These strategies mainly include: improving the energy efficiency of the supply of tourism products and services, promoting the consumption of low-energy tourism products and services, strengthening the supervision and management of low-energy consumption tourism development, creating an environment for energy savings and consumption reduction, and establishing a long-term operational mechanism for responsible tourism management. A rewsponsible tourism system allows stakeholders to properly address this dilemma, internalize sustainable development goals to find their intrinsic self-discipline, and work together to fulfill the public responsibility of realizing the sustainable development of glacial tourism.

Microorganisms drive stabilization and accumulation of organic phosphorus: An incubation experiment

At the earliest stage of pedogenesis, microorganisms are the main biological drivers of nutrient transformation and mobilization from rock minerals. However, this driving process is not yet well understood despite its importance for the formation and fertility of soil. The aim of this study was to determine the microbial accumulation of organic phosphorus (Po) and microbial release of bioavailable phosphorus (bio-P) from rock minerals and to analyse which factors control these processes. We hypothesized that microorganisms contribute to stabilization and accumulation of Po. For this purpose, we carried out a series of incubation experiments with model soils (with soil Po removed) and soil extracts of natural soil from the earliest stage of pedogenesis in the newest retreat area of the Hailuogou glacier. A modified Hedley fractionation method was used to characterize the P forms in soils. Microbial synthesis of Po was clearly observed in this study. In view of the fact that carbon (C) and nitrogen (N) are the main energy and material sources of microorganisms and that their stoichiometry plays an important role in microbial metabolism, we hypothesized that the C and N (ratio and level) play a regulatory role in microbial transformation of P. Therefore, the different C/N gradients were constructed in our incubation experiments. Results showed addition of C and N resulted in an accumulation of stable Po and decrease in pH in soils. These results suggest that not all microbial biomass P is easily degraded. Along two C/N ratio gradients (same ratio but keeping C vs N constant), opposite patterns of total Po (TPo) changes was observed. Opposite patterns were also observed for bio-P along the two C/N ratio gradients. Regardless of the C/N ratio, high CN additions always led to lower TPo accumulations, higher bio-P releases and higher phosphatase activity compared to low CN additions. We conclude that microbial synthesis of Po contributed to the P fractions in soil stable residual pools and that microbial release of bioavailable P was driven by two modes (i.e., N-driven mode and C-driven mode). Our study highlights that microorganisms drive the accumulation of soil Po during the earliest stage of pedogenesis in our study area.