Northwestern Yunnan Research Articles

Geology and antimony mineralization of the Yangla polymetallic orefield in northwestern Yunnan, SW China: Trace element geochemistry of sulfides and calcite

The Yangla is the largest and highest-grade antimony deposit (10 kt Sb @ 14.87 %) in the Jinshajiang suture zone, northwestern Yunnan (SW China). Pyrite and stibnite are the main sulfides, and calcite is the main gangue mineral in the antimony ores. Antimony mineralization can be divided into three stages: pre-ore stage pyrite and quartz, syn-ore stage (incl. early, main and late sub-stage) stibnite-pyrite-calcite-quartz, and supergene stage valentinite and limonite. The trace element compositions of the three pyrite and two stibnite generations have been analyzed by (LA-)ICP-MS here. The bulk ore-related calcite trace element compositions were also measured by ICP-MS. Trace element correlations and principal component analysis (PCA) show that the majority of trace elements occur as solid solution and micro-/nano-inclusions in pyrite and stibnite. In pyrite, the Sb substitutes into the crystal lattice with Tl, Cu and Ag via (Tl++Cu++Ag+) + Sb3+ ↔ 2Fe2+. Gold occurs as invisible gold (Au+) and enters pyrite via the coupled substitution of As3+Au3+□ ↔ 3Fe2+ and/or As3+Au3+□ ↔ 3Cu2+. In stibnite, the Cu, Pb and As enter the crystal lattice via the coupled substitution of 2Sb3+ ↔ Cu+ + Pb2+ + As3+. Trace element features of calcite are highly similar to the Devonian Linong Formation (2nd member) marble, suggesting that the ore-forming fluid is closely associated with the marble. Syn-ore calcite is characterized by its higher Fe, Mn and MREE concentrations than the pre-/post-ore calcite, and can be regarded as a geochemical fingerprint for metallogenic prediction. The δCe (0.67–0.83, avg. 0.75) and δEu (1.40–2.51, avg. 1.89) values suggest that the antimony precipitation occurred under reducing to weakly oxidizing conditions. The atomic Yb/Ca, Yb/La, Tb/Ca, and Tb/La ratios of the syn-ore calcite imply that the antimony mineralization can be attributed to hydrothermal genesis. This deduction is also supported by that data of pyrite Ⅰ, Ⅱ, and Ⅲ mainly plotted inside the hydrothermal fields in the Co/Ni, As/Ag, Sb/Bi and Co-Ni-As discrimination plots. The Yangla stibnite ore samples mimic stibnite from typical hydrothermal mineralization systems (e.g., Woxi Au-Sb-W deposit, South China) in the Cu vs. Pb plot, which further supports a hydrothermal origin of the antimony. Therefore, we propose that the hydrothermal Sb mineralization is closely related to the Devonian carbonate rocks at Yangla.

Diversity and Anti-Infectious Components of Cultivable Rhizosphere Fungi Derived from Three Species of Astragalus Plants in Northwestern Yunnan, China

Diversity and Anti-Infectious Components of Cultivable Rhizosphere Fungi Derived from Three Species of Astragalus Plants in Northwestern Yunnan, China

Identifying complementary conservation and restoration priority areas for plant species

The coverage of protected areas (PAs) remains far from the Kunming-Montreal target and degraded ecosystems are greatly limiting the conservation efficiency of PAs. Therefore, this paper proposes a method to identify conservation and restoration priority areas to supplement existing PAs. A case study was conducted focusing on Yunnan, southwestern China, which intersects with three world biodiversity hotspots. First, the spatial ranges for 3768 representative conservation plant species were mapped using species distribution models. Subsequently, planning units were classified into three restorability categories, namely no-need restoration, potentially restorable and non-restorable units, according to land cover changes between 2000 and 2020. Then, conservation and restoration priority areas were identified by applying a two-step systematic conservation planning process. Finally, replacement cost analysis was applied to compare the effectiveness of existing PAs and the overall 30 % priority areas. Northwestern, southwestern, and southeastern Yunnan have high biodiversity conservation values. Especially in eastern and southeastern Yunnan, large amounts of restoration priority areas were identified. Conservation and restoration priority areas account for 15.80 % and 3.69 % of Yunnan's land, respectively. Compared to existing PAs, conservation priority areas can increase the number of species covered from 2461 to 3277, and further to 3566 when including restoration priority areas. Compared to existing PAs, the mean species coverage in the overall 30 % priority areas has increased from 27.28 % to 72.69 %. Notably, 12.86 % of existing PAs were identified as restoration priority areas. This study indicates that in addition to conservation measures, implementing restoration strategies in high conservation-value areas is equally important.

The identity of Anemone gonggaensis (Ranunculaceae) recently described from Kangding in western Sichuan, China

Based on consultation of literature, examination of herbarium specimens (including type material) and observations of living plants in the wild, we demonstrate that Anemone gonggaensis (Ranunculaceae), recently described from Kangding in western Sichuan, China, is not essentially different from A. rupicola (sometimes treated as Eriocapiitella rupicola), a morphologically very distinctive species widely distributed in the Sino-Himalayan region, including Bhutan, China (western Sichuan, southern and eastern Xizang, northwestern Yunnan), northern India, Kashmir, Nepal, Pakistan, and Sikkim. We therefore place both A. gonggaensis and E. rupicola in synonymy with A. rupicola herein.

Element Migration of Mineralization-Alteration Zones and Its Geological Implication in the Beiya Porphyry–Skarn Deposit, Northwestern Yunnan, China

Porphyry and the associated skarn-type deposit is one of the most important types of ore deposits worldwide, which usually exhibit significant zoning of mineralization-alteration, but the research on element migration in these mineralization-alteration zones is relatively weak. The Beiya porphyry–skarn gold-polymetallic deposit is a super-large Cenozoic deposit located in the Sanjiang metallogenic belt, northwestern Yunnan, China. In this paper, through a detailed analysis of mineralization and alteration zoning and its element migration regularity, the findings are as follows: (1) Three types of hydrothermal alteration—porphyry alteration, contact alteration, and wall-rock alteration—are developed, and porphyry alteration includes potassic, phyllic, propylitic, and argillic alteration; (2) five types of mineralization—porphyry-type Cu–Au–(Mo), skarn-type Au–Fe–(Cu), hydrothermal vein-type Au–Fe, distal hydrothermal-type Pb-polymetallic, and oxidizing-leaching enriched-type Au—occur in a diversity of forms, which are dominantly controlled by structures and lithologies; (3) concentric-banded mineralization-alteration zones are exhibited centrally from the alkaline porphyry outward or upward, namely [porphyry alteration] potassic → phyllic → propylitic → argillic → [contact alteration] skarnitization–marbleization → [wall-rock alteration] marbleization–silicification–calcitization; (4) porphyry-type mineralization predominantly forms within potassic and phyllic zones, while skarn-type mineralization occurs in contact alteration zones, and proximal and distal hydrothermal (vein)-type mineralization are commonly distributed in marbleization–silicification–calcitization alteration zones; and (5) element migration analysis demonstrates a significantly lateral and vertical zoning in the metallogenic element association of Cu–Mo → Cu–Au → Au–Fe–Cu → Au–Fe → Pb–Zn–Au–Ag–Fe from alkaline porphyry outward to the wall-rock. The mineralization-alteration zoning model indicates the Beiya deposit has similar mineralization and alteration zone characteristics to the typical porphyry copper system; and element migration within mineralization-alteration zones provides new scientific information for understanding the metallogenic regularity and prospecting at Beiya, as well as the similar types of deposits in the Sanjiang metallogenic belt and elsewhere in the world.

The complete chloroplast genome and phylogenetic analysis of Garcinia esculenta Y. H. Li. 1981 (Clusiaceae)

Garcinia esculenta Y. H. Li. 1981 (Clusiaceae) is an endemic tree species in China, primarily found in western and northwestern Yunnan Province. In this research, the complete chloroplast genome of G. esculenta was sequenced using the Illumina NovaSeq6000 platform. The result showed that the length of the complete chloroplast genome was 155,853 bp, which was composed of a large single-copy region (LSC) of 84,534 bp, a small single-copy region (SSC) of 17,175 bp, and a pair of inverted repeat (IR) regions of 27,072 bp. The overall GC content was 36.1%. The complete chloroplast genome encompassed 128 genes, comprising 83 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Phylogenetic analysis of the complete chloroplast genome sequences of 22 species revealed that G. esculenta is most closely related to G. oblongifolia.

Characteristics of antimony mineralization in the Yangla polymetallic deposit, northwestern Yunnan, SW China: Insights from calcite Sm-Nd dating and C-O-Sr isotopes

Calcite is the main gangue mineral in antimony (Sb) deposits, and its compositions can reflect the physicochemical conditions of Sb mineralization. The Yangla is the largest Sb deposit (10 kt Sb @ 14.87 %) in the Jinshajiang suture zone (SW China), and the lode-type Sb orebodies are stratabound or developed along NE-trending fracture zones in marble. To constrain the time of Sb mineralization and establish any genetic link with the local magmatism and wallrocks, we performed calcite Sm-Nd dating and bulk C-O and in-situ Sr isotope analyses. The results show that the Sb mineralization (∼155 Ma) was considerably younger than the Cu-Pb-Zn mineralization (∼230 Ma), skarn alteration (∼234 Ma), and granitoid emplacement (∼230 Ma) at Yangla, but much older than the local W mineralization (∼30 Ma). The initial 87Sr/86Sr ratio of calcite (0.71972–0.72208) is much higher than that of the Triassic granodiorite (0.71149– 0.71990) and Carboniferous basalt (0.70562–0.70995), suggesting mixed source of calcite from the ore fluids and Devonian wallrocks. The ore-related calcite has δ13CPDB (−4.53 to − 2.33 ‰) and δ18OSMOW (+14.98 to + 16.30 ‰) values that fall between the granite and marine carbonate isotopic fields. This suggests that the ore-forming fluid may be related to the low-temperature alteration of granites and marine carbonate dissolution. Simulated precipitation temperature calculation for the ore-related calcite yielded 200–150 °C, and the calcite C-O isotopes suggest that fluid mixing, fluid-rock interactions, and CO2 degassing may have precipitated the stibnite in the fracture zones under low-temperature conditions. Our new geochemical results and published data suggest that the Yangla polymetallic mineralization was multiphase, comprising the Indosinian Cu-Pb-Zn (∼230 Ma), Yanshanian Sb (∼155 Ma), and Himalayan W-Sb (∼30 Ma) metallogenic events.

Ownership and Sustainability of Bai Intangible Cultural Heritage ICH: A Comparative Analysis of Educational Approaches

Through a literature review of scholarly and non-scholarly but credible literature, this study has explored the intricate relationship between ownership, sustainability, and education in the context of the Bai ethnic group's Intangible Cultural Heritage (ICH) in northwestern Yunnan, China. The Bai people have diverse ICH. However, as China’s ethnic minority, they face challenges from China's dominant culture and globalization. Therefore, it is critical to sustain their ICH. The review has indicated that the issue of ownership is complex and multifaceted. In most authors have refrain from addressing it. However, there is evidence indicating creating awareness surrounding the ownership of IC can result in social-economic benefits. Such benefits are likely to motivate stakeholders to preserve and certain the. To create awareness and resulting sense of ownership and sustainability, educational approaches, combining formal and informal methods are recommended. So far, this approach exists but they need to be improved further.

Neolithic to Bronze Age human maternal genetic history in Yunnan, China

Yunnan in southwest China is a geographically and ethnically complex region at the intersection of southern China and Southeast Asia, and a focal point for human migrations. To clarify its maternal genetic history, we generated 152 complete mitogenomes from 17 Yunnan archaeological sites. Our results reveal distinct genetic histories segregated by geographical regions. Maternal lineages of ancient populations from northwestern and northern Yunnan exhibit closer affinities with past and present-day populations from northern East Asia and Tibet, providing important genetic evidence for the migration and interaction of populations along the Tibetan-Yi corridor since the Neolithic. Between 5500 and 1800 years ago, central Yunnan populations maintained their internal genetic relationships, including a 7000-year-old basal lineage of the rare and widely dispersed haplogroup M61. At the Xingyi site, changes in mitochondrial DNA haplogroup occurred between the Late Neolithic and Bronze Age, with haplogroup shifting from those predominant in the Yellow River region to those predominant in coastal southern China. These results highlight the high diversity of Yunnan populations during the Neolithic to Bronze Age.

Fine Shallow Structures of Binchuan Basin Inverted From Receiver Functions and Implications for Basin Evolution

AbstractThe understanding of the velocity structure and basement morphology within the basin is crucial for seismic hazard mitigation and the study of basin evolution. To explore the intricate structure of the Binchuan Basin in western Yunnan, China, we deployed a linear dense array in the northern region of the Binchuan Basin, with inter‐station distance ranging from 50 to 100 m. We propose a novel receiver function processing workflow. Initially, we extracted coherent receiver functions based on the dense array, followed by a inversion of basement morphology, S‐wave velocities, and sedimentary layer's average Vp/Vs ratio jointly with frequency‐dependent teleseismic apparent shear velocity and receiver function waveforms. The results show that S‐wave velocity anomalies correspond to the unconsolidated sediments. The thickness of the sedimentary layer ranges from ∼0.5 to ∼0.75 km. The basement morphology suggests the basin is controlled by normal faults. Additionally, intra‐basin faults displayed higher fault displacement to length ratios (∼0.27) than most isolated normal faults (10−3–10−1), which may result from accumulated fault displacement due to interactions between fault segments. These results emphasize the significant role of N–S trending intra‐basin faults in basin evolution, suggesting that micro‐block rotations and transitional movements within the Northwestern Yunnan Rift Zone are primary mechanisms shaping the Binchuan Basin. We further proposed a multi‐stage model for the evolution of the Binchuan Basin. The robustness testing validates that the proposed processing flow is an effective approach to comprehensively image the basin velocity structure and the basement morphology.

In-situ geochemical and isotopic analyses of multiple pyrite generations: Insights for the giant Beiya Au polymetallic ore genesis in southwestern China

The Beiya giant Au polymetallic deposit is located in the Sanjiang Tethyan Orogen, northwestern Yunnan (SW China). The ores occur as disseminations or veinlets in granite porphyry. To unravel the ore genesis at Beiya, we analyzed the ore-related sulfide trace elements and sulfur isotopes. Py-1 is mainly euhedral-subhedral medium-/coarse-grained (size: > 100 μm), with relatively smooth surface and some pores. Py-2 is mostly coarse grained (size: 50–200 μm), with well-developed pores and inclusions. The pyrite is usually Co-Cu rich and V-Ti-Sb poor, resembling typical magmatic-hydrothermal pyrite. In addition, the Co/Ni ratios decrease from pyrite-1 (Py-1) to pyrite-2b (Py-2b), suggesting that their chemical compositions are controlled by magma fractionation. We found that Co, Ni, As, and Se occurred as solid solution in the pyrite lattice, while Pb, Bi, Ag, and Mn occurred mainly in inclusions in the pyrite. Pb and Bi display good positive correlation, suggesting that they occurred as inclusions or nano-particles in pyrite lattice. The pyrite samples have sulfur isotope value (δ34S) of 0.62–3.45 ‰ (avg. 2.35 ‰) for Py-1, 0.18–3.12 ‰ (avg. 1.85 ‰) for Py-2a, and 0.62–4.18 ‰ (avg. 2.51 ‰) for Py-2b. These characteristics may have played a vital role in the initial enrichment of Cu, Mo, Au, and ultimately formed the complex polymetallic system at Beiya.

Ecological security assessment of Yunnan Province, China in the context of Production-Living-Ecological space division.

With the rapid development of population, society and economy, human activities have caused serious adverse impacts on the environment, ecosystems and landscape patterns over the long term. In order to address the series of impacts of human activities on the environment, territorial space and resource use, the study of Production-Living-Ecological Space (PLES) and ecological security have all become academic frontiers in the field of sustainable development. In this study, we applied multi-source data and GIS technology to construct an ecological security evaluation model based on the results of PLES delineation and the Pressure-State-Response (PSR)framework, and carried out the three-period PLES ecological security evaluation for 2000, 2010 and 2020 at the county and grid scales in Yunnan Province. The PLES pattern in Yunnan Province is dominated by ecological space, which accounts for 75%, followed by 23% of production space, with ecological space shrinking from 2000 to 2020. Ecological security in ecological space and living space shows an improving trend from 2000 to 2020. The ecological security of production space improved in 2010 compared to 2000 but then showed a decreasing trend in 2020. Ecological security in ecological space shows that north-western and southern Yunnan is safer than central Yunnan, while ecological security in living space is safer in central Yunnan, and ecological security in production space is better in southern Yunnan than in northern Yunnan. Comparison with related research results shows that the ecological security evaluation results of PLES in Yunnan Province in this study are scientific and reasonable. The ecological security evaluation model of PLES constructed in this study solves the problem of complex and incomplete ecological security evaluation indexes in the past, and the results of the study are more refined and precise, which provides new ideas for the study of regional ecological security.

Response of the functional traits of Schoenoplectus tabernaemontani to simulated warming in the Napahai wetland of northwestern Yunnan, China

The impact of climate warming on wetland ecosystems is a current focal point in ecological research. In this study, the Napahai wetland, a typical plateau wetland in northwest Yunnan Province, was selected as the study site to understand the growth and survival strategies of emergent plants in a plateau wetland under climate warming conditions. Open-top chambers (OTCs) were used to simulate warming in three treatments (i.e., control group, 2.0 ± 0.5°C, and 4.0 ± 0.5°C) in order to study the responses of the functional traits of the dominant emergent plant Schoenoplectus tabernaemontani to simulated warming. The results showed that simulated warming significantly reduced the photosynthetic carbon assimilation capacity and biomass accumulation of S. tabernaemontani, as well as its nitrogen content and vascular bundle density, while it significantly increased the vascular bundle size. The growing season accumulated temperature (AT) and the mean temperature of the hottest month (WT) were the main temperature factors influencing the functional traits of S. tabernaemontani. In summary, simulated warming significantly affected the functional traits of S. tabernaemontani, which demonstrated effective adaptation to warming conditions. As the temperature rises and the light and productivity decrease, S. tabernaemontani prioritizes the supply of limited resources to the underground part to ensure the biomass supply of the reproductive structure. This study provides a case for revealing the response patterns and ecological adaptation strategies of plateau wetland plants to climate warming.

Biphyly of the genus Wendlandia and establishment of a new tribe Clavistigmateae and a new genus Clavistigma of Rubiaceae from Asia

AbstractWendlandia, as currently circumscribed, is a genus of Rubiaceae comprising about 90 species mainly in tropical and subtropical Asia. By sampling species from all four series (Clavigerae, Euexsertae, Montigenae, Subinclusae) and all tribes in the subfamily Dialypetalanthoideae, we examined the monophyly of Wendlandia based on phylogenetic reconstruction using the nuclear ribosomal internal transcribed spacer and four plastid DNA regions. Wendlandia was resolved as biphyletic, consisting of two distantly related lineages that correspond to the monotypic series Clavigerae (Wendlandia pendula), sister to the Chinese endemic genus Trailliaedoxa, and a clade containing the remainder sampled members of Wendlandia. Based on the isolated phylogenetic position of W. pendula and its unique morphological characteristics compared to the recognized tribes of the Vanguerieae alliance, we herein erect a new monotypic genus, Clavistigma, and a new tribe, Clavistigmateae to accommodate the unique species. The secondary pollen presentation and the unique seed morphology were firstly described for the species. The divergence time between Clavistigma and Trailliaedoxa was dated back to 13.8 mya, coinciding with the climate change in northwestern Yunnan driven by the uplift Tibet Plateau and the river incision in the Hengduan Mountains during the Miocene and Late Pliocene.

Decoupling Warming and Monsoon Precipitation Over the Last 3110 Years in Northwestern Yunnan Province, Southwestern China

AbstractUnderstanding the variability and related dynamic mechanisms of the Indian summer monsoon evolution over the past millenniums is crucial for disaster prevention and mitigation in the context of strengthening global warming. Here, we present a high‐resolution hydroclimate reconstruction over the past 3110 years in northwestern Yunnan Province, southwestern China, based on grain size analysis using the End‐member modeling algorithm and other environmental proxies. The results indicate that the temperature in northwestern Yunnan Province generally decreased since 3110 cal. yr BP, aligning with other temperature records on regional and global scales. Precipitation in the study area remained relatively stable before 1000 cal. yr BP, but exhibited an obvious out‐phase change compared with the temperature records over multidecadal to centennial timescale. While after 1000 cal. yr BP, the precipitation steadily increased, revealing the hydroclimate pattern of notably dry Medieval Warm Period (MWP) and relatively wet Little Ice Age (LIA) in the study area. The decoupling combination of temperature and precipitation spanning the MWP and LIA in southwestern China contrasts with that in the East Asian summer monsoon area and the Indian subcontinent which is also controlled by the Indian summer monsoon, indicating the spatial heterogeneity of precipitation in the Asian summer monsoon region. The discussion about dynamic mechanisms points out that solar activity emerges as a significant factor influencing regional temperature changes, and El Niño‐Southern Oscillation and Intertropical Convergence Zone migration jointly impact the precipitation change in the study area and the hydroclimate discrepancy in the Asian summer monsoon region.

Contrasting mineralized and barren porphyries in the Zhongdian Arc, insights from biotite and apatite compositions and halogen fugacity.

Copper mineralization in the Pulang (PL) porphyry deposit, Langdu (LD) porphyry-skarn deposit and Songnuo (SN) porphyry prospect in northwestern Yunnan, China, is closely related to the emplacement of quartz monzonite porphyries. The chemical compositions of biotite and apatite from those porphyries were analyzed to calculate the halogen fugacity and to constrain mineralized and barren porphyries. Our data show that biotites from the PL deposit have higher MgO, SiO2, TiO2 and F contents than those from the LD deposit or SN prospect. Compared to those in the LD deposit and SN prospect, the Mg (atoms per formula unit (apfu)) and AlVI (apfu) value in biotite is greater, and the F content is greater and the SO3 and Ce2O3/Y2O3 ratio in apatite are lower in the PL deposit. Ti-biotite thermometry and apatite-biotite geothermometry show that the crystallization temperature of biotite from the PL deposit is higher than that from the SN prospect or LD deposit. The results suggest that oxygen fugacity, magmatic sulfur, and H2O contents cannot be used to efficiently distinguish the PL deposit from the LD deposit and SN prospect. However, the halogen chemistry of biotite from the PL deposit is distinctly different from that of the LD deposit or SN prospect according to the lower IV (F), indicating that mineralized quartz monzonite porphyries in the PL deposit formed during the late magmatic stage, which is in contrast to those in the LD deposit and SN prospect. The mineralized porphyries display a remarkable negative linear relationship (r = -0.96) with the log (f HF/f HCl) and log (f H2O/f HF) ratio, which can be used to distinguish the mineralized and barren porphyries. Compared with other typical porphyry Cu systems, there is a remarkable positive linear relationship between IV (Cl) and log (f H2O/f HCl). In addition, the linear slope and intercept for log (f H2O/f HCl) ratios and the IV (Cl) of biotite from the potassic and phyllic alteration zones are significantly greater than those from other porphyries.

Pollination Syndrome, Florivory, and Breeding System of Satyrium nepalense var. ciliatum (Orchidaceae) in Central Yunnan, China.

Research on Satyrium nepalense var. ciliatum (Lindl.) Hook. f. has primarily focused on populations in Northwestern Yunnan, with limited studies on pollination syndromes and insect behavior. In addition, it is geographically limited in its breeding system studies. Here, pollination syndromes, florivory, and breeding systems of S. nepalense var. ciliatum from Liangwang Mountain (Central Yunnan, China) were investigated through field work, microscope, scanning electron microscope (SEM), and parafin section. It was revealed that the pollination syndrome was possessing out-crossing, such as bright color, a developed rostellum, nectar glands in the spur, and food hairs at the lip base. The color and nectar attracted flower visitors, and florivory was observed. Some flower visitors pollinated their companion species. Ants were identified as floral visitors for the first time in Satyrium, although substantial pollination was not observed. Ants might be potential pollinators. S. nepalense var. ciliatum possessed a mixed breeding system, including selfing, out-crossing, and apomixis, with apomixis being predominant in nature. It is suggested that the pollination syndrome, florivory, and pollination competition would contribute to its mixed breeding systems, particularly leading to the occurrence of apomixis.

Characteristics of the Rhizospheric AMF Community and Nutrient Contents of the Dominant Grasses in Four Microhabitats of the Subalpine Zone in Northwestern Yunnan, China

At the southeastern periphery of the Tibetan Plateau, the subalpine ecosystem hosts grasses as some of the most substantial species. However, the community and function of arbuscular mycorrhizal fungi (AMF) around the rhizospheres of grasses in the subalpine zone are still poorly understood. In the present study, 28 soils and 11 species of dominant grasses collected from four microhabitats (shrubland, grassland, woodland, and forest) in the subalpine zone of northwestern Yunnan, China, were used to investigate the AMF community by Illumina MiSeq high-throughput sequencing technology as well as nutrient contents. Among the four microhabitats, the maximum soil nutrient levels around the rhizospheres of grasses were observed in woodland. The nitrogen, phosphorus, and potassium concentrations in Dactylis glomerata shoots were significantly higher than those in the other 10 grass species. The AMF diversity of grassland in summer was substantially greater than that of the other three microhabitats (p < 0.05). Discrepancies were observed within a given plant species across microhabitats; for example, in summer, the nitrogen concentration in the shoot of Iris tectorum in woodland was significantly higher than that in both forest and shrubland (p < 0.05). A total of eight genera were detected in the AMF communities, which were dominated by Glomus, with a relative abundance of 45.4–94.4% in summer and 60.5–84.3% in winter. Moreover, the abundance of Glomus was significantly positively correlated with the content of alkali-hydrolyzable nitrogen in soil and nitrogen in grasses according to the Mantel test. As a critical nutrient element in soil, nitrogen is beneficial for plant growth. Thus, these results provide a better understanding of the resilience of soil AMF community and the ecological adaptability of grasses in the subalpine ecosystems of northwestern Yunnan.

Radial growth response of Pinus Yunnanensis to climate in high mountain forests of northwestern Yunnan, southwestern China

Understanding the relationship between tree growth and environmental conditions is essential to elucidating the impact of global climate change on forest ecosystems. We used the dendrochronology method to examine the growth sensitivity of a typical conifer to climate change in mountain forests of Central Hengduan Mountain. The study involved the establishment of tree ring width chronologies of Pinus yunnanensis in both Haba Snow Mountain (HB) and Yulong Snow Mountain (YL) in northwestern Yunnan, enabling the detection of the relationship between its radial growth and climates, i.e., monthly total precipitation, monthly temperatures (average minimum, mean and maximum) and monthly Palmer Drought Severity Index (PDSI). Response function and redundancy analysis (RDA) were used to identify correlations between climate variables and radial growth, and moving interval analysis was applied to determine the stability of climate-growth relationship. The findings demonstrated that the growth of P. yunnanensis had similar response patterns to climate change at two sites, exhibiting growth synchronization and common signals. Specifically, the radial growth of P. yunnanensis was negatively correlated with May temperature, while temperature in current October significantly promoted radial growth. Precipitation in June was the common climate variable with inverse effects between two sites, with positive impacts on YL and negative impacts on HB. The results of moving interval analysis were consistent with response function and RDA, presenting significant correlations in many years for those climatic variables significantly affecting tree growth. Stability analysis also revealed that the climate-growth relationship could fluctuate over a small range of time scales, induced by an abrupt change in climate. A forecast of strengthen in growth of P. yunnanensis forests was expected, since increases in precipitation and temperature of most months would benefit tree growth, and negative impacts of May temperature would be offset by the increase of precipitation in the corresponding month. These results could provide a basis for developing sustainable strategies of forest management under the climate change.

Trace element compositions of pyrite and stibnite: implications for the genesis of antimony mineralization in the Yangla Cu skarn deposit, Northwestern Yunnan, China

Trace element compositions of pyrite and stibnite: implications for the genesis of antimony mineralization in the Yangla Cu skarn deposit, Northwestern Yunnan, China