Community assemblage of free-living diazotrophs along the elevational gradient of Mount Gongga

Mountain systems are unique for studying the responses of species distribution and diversity to environmental changes along elevational gradients.It is well known that free-living diazotrophic microorganisms are important to nitrogen cycling in mountain systems.However,the elevational patterns of free-living diazotrophs and the underlying ecological processes in controlling their turnover along broader gradients are less well documented.Here,we investigated the pattern of diazotrophic diversity along the elevational gradient(1800 m-4100 m)in Mount Gongga of China.The results showed that the α-diversity of diazotrophs did not change with the elevation from 1800 m to 2800 m,but decreased at elevations above 3000 m.Such diversity pattern was driven mainly by soil total carbon,nitrogen,and plant richness.Various diazotrophic taxa showed differential abundance-elevation relationships.Ecological processes determining diazotrophic community assemblage shift along the elevations.Deterministic processes were relatively stronger at both low and high elevations,whereas stochastic processes were stronger at the middle elevation.This study also suggested a strong relationship among aboveground plants and diazotrophs,highlighting their potential interactions,even for free-living diazotrophs.

Variations in carbon isotope ratios of C_3 plants and distribution of C_4 plants along an altitudinal transect on the eastern slope of Mount Gongga

Variations in carbon isotopic ratios (δ 13C) of C3 plants and distribution of C4 plants were investigated along an altitudinal transect on the eastern slope of Mount Gongga, and the environmental effects on them were discussed. It is shown that plants with C4 photosynthetic pathway mainly occur at altitudes below 2100 m a.s.l., suggesting that the low summer temperature is responsible for the distributional pattern. In addition, δ 13C of C3 plants increases with elevation at the region above 2000 m a.s.l. with the characteristics of humid climate, and the increase rate in δ 13C for C3 plants is about 1.3‰ per kilometer. Temperature determines the altitudinal trend of δ 13C.

Heterogeneity in supraglacial debris thickness and its role in glacier mass changes of the Mount Gongga

在西藏的高原，许多冰河在他们的脱离地区有 supraglacial 碎片的广泛的封面，它由改变冰融化和集体损失的空间模式影响冰河反应到气候变化。不够的碎片厚度数据使分析地区性的碎片封面效果困难。山 Gongga 的海上的冰河被实质的减小在最近的十年在冰河区域和冰质量描绘了。从遥远地察觉到的数据估计的碎片层的热性质表明盖住碎片的冰河在这个区域，到全部的冰河区域的碎片盖子的比例从 1.74% ～ 53.0% 在上变化是主导的。用一个身体上基于的碎片封面效果评价模型，我们发现尽管 supraglacial 碎片的存在在重重地盖住碎片的冰河上有重要绝缘效果，融化在~上加速冰10.2%全部的脱离地区并且生产~的快速的消耗量25%盖住碎片的冰河，导致在盖住碎片、没有碎片的冰河之间的类似的集体损失。普遍碎片盖子也便于活跃终点区域的发展。在碎片封面效果的地区性的差别是明显的，强调为冰河质量在全世界在西藏的高原和另外的山脉改变的理解的碎片盖子的重要性。

δ^(13)C difference between plants and soil organic matter along the eastern slope of Mount Gongga

Carbon isotope ratios (δ 13C) of plants, litter and soil organic matter (0–5 cm, 5–10 cm and 10–20 cm) on the eastern slope of Mount Gongga were measured. The results show that δ 13C values of plants, litter and soil organic matter all decrease first and then increase with altitude, i.e. δ 13C values gradually decrease from 1200 to 2100 m a.s.l., and increase from 2100 to 4500 m a.s.l. The δ 13C altitudinal variations are related to the distribution of C3 and C4 plants on the eastern slope of Mount Gongga, because C4 plants are observed to grow only below 2100 m, while C3 plants occur at all altitudes. There are significantly positive correlations among δ 13C of vegetation, δ 13C of litter and δ 13C of soil organic matter, and litter, 0–5 cm, 5–10 cm and 10–20 cm soil organic matter are 0.56‰, 2.87‰, 3.04‰ and 3.49‰ greater in δ 13C than vegetation, respectively. Considering the influences of rising concentration of atmospheric CO2 and decreasing δ 13C of atmospheric CO2 since the industry revolution on δ 13C of plants, 1.57‰ is proposed to be the smallest correction value for reconstruction of paleovegetation using δ 13C of soil organic matter.

贡嘎山东麓第四纪冰川作用与磨西台地成因探讨

青藏高原东部的最高峰贡嘎山 (海拔 75 5 6m)东麓磨西河流域发育了三次更新世冰期 ,分别为雅家埂、南门关、贡嘎冰期 ,其中燕子沟的倒数第二次冰期 (南门关冰期 )的冰川一直伸到磨西镇下街磨西饭店北 .古冰川阻塞主谷 ,在新兴与南门关沟之间的堡子坝区形成冰川阻塞湖 ,在磨西镇上街东 ,该期古冰川覆盖在谢家河坝东面山坡上 ,融水深切形成峡谷 .冰退过程中又在峡谷西基岩丘陵旁形成冰水湖 ,南门关冰期后的间冰期时 ,小湖变干发育了红色古土壤层 ,该期的红色古土壤层在磨西镇下街南的古冰川与冰川泥石流沉积层顶面也有保存 .证明磨西台地的主体为倒数第二次冰期的冰川堆积物 ,其中也包括有冰水砂砾层透镜体和冰湖相等沉积 .磨西台地出露地表的巨大砾石 ,直径在 10～ 2 0m之间 ,多数为冰川表面的消融碛 ,也可能有冰川泥石流夹带的大岩块 .磨西台地两侧断续分布有 4级冰水阶地以及磨西饭店以下的磨西台地尾部均为末次冰期后期至全新世的冰水沉积 ,其中也含有泥石流堆积物 .

风景名胜区范围界定探讨——以四川贡嘎山风景区为例

确定风景区范围是风景区开发和保护的基础,它包括新建风景区范围的确定和原有风景区范围的重新界定。新的贡嘎山风景区范围由贡嘎山主景片和木格措、伍须海、瓦灰山3个外围景片组成,景片与景片间为外围保护区,这样界定更有利于促进当地资源的有效保护和合理利用。

贡嘎山现代植物叶蜡脂肪酸氢同位素组成及对海拔变化的响应

文章探讨了贡嘎山东坡不同海拔高度植物和土壤饱和脂肪酸的δD_(wax)值,结果显示,土壤δD_(wax)值与海拔显著负相关(R^2=0.71),与前人报道的贡嘎山东坡土壤水、土壤正构烷烃δD值与海拔间的关系存在相同的趋势。植物δD_(wax)值与海拔间的关系与土壤水及土壤相似,但相关性不明显(R^2=0.11),然而,研究结果显示木本植物和草本植物的δD_(wax)值随海拔变化存在明显的差异,总体上草本植物的氢同位素要更负。贡嘎山木本植物、草本植物和土壤的δD_(wax)值随海拔的变化波动较小,但木本植物的加权平均δD_(wax)值和ε_(wsx-sw)值(土壤水和叶蜡之间的氢同位素分馏系数)比草本植物大约偏正38‰和43‰,表明它们各自对随海拔高度降水同位素变化有不同的响应。也即,沿海拔植物δD_(wax)值同时受降水δD值和植物类型两个因素控制。因此,结果揭示土壤δD_(wax)值随海拔的变化与木本植物和草本植物存在相同的趋势,木本植物的δD值比草本植物大约偏正了38‰,这个趋势显示植物类型的变化将不可避免的影响土壤饱和脂肪酸δD_(wax)值与海拔间的关系。由于植物类型随海拔增加会有较大的变化,建议利用饱和脂肪酸δD_(wax)值重建古海拔前需要对植物类型进行评估。

贡嘎山国家地质公园与石棉县生态旅游发展

系统阐述了国内外地质公园建设和管理模式现状,运用地质遗迹分类法分析了石棉县地质旅游资源,对比石棉县主要旅游资源、贡嘎山地质遗迹的区域地质背景、地质遗迹景观类型、特色,海螺沟在贡嘎山的地位与影响,建立贡嘎山世界地质公园的优势为地域相邻优势、借贡嘎山.海螺沟知名度之势、国家地质公园之势,贡嘎山世界地质公园申报之势,提出申报建立贡嘎山国家地质公园有利于石棉县生态旅游发展。

1990—2019年贡嘎山地区典型冰川表碛覆盖变化及其空间差异

表碛覆盖型冰川是中国西部较为常见的冰川类型。表碛层存在于大气—冰川冰界面,强烈影响大气圈与冰冻圈之间的热交换。表碛厚度的空间异质性可极大地改变冰川的消融率和物质平衡过程,进而影响冰川径流过程和下游水资源。基于Landsat TM/TIRS数据,运用能量平衡方程反演了贡嘎山地区冰川表碛厚度,研究了贡嘎山地区冰川在1990—2019年间表碛覆盖范围及厚度变化情况,同时对比了东西坡差异。结果表明:①贡嘎山地区冰川表碛扩张总面积达43.824 km^(2)。其中,海螺沟冰川扩张2.606 km^(2)、磨子沟冰川1.959 km^(2)、燕子沟冰川1.243 km^(2)、大贡巴冰川0.896 km^(2)、小贡巴冰川0.509 km^(2)、南门关沟冰川2.264 km^(2),年均扩张率分别为3.2%、11.1%、1.5%、0.9%、1.0%和6.5%;②海螺沟冰川、磨子沟冰川、燕子沟冰川、大贡巴冰川、小贡巴冰川、南门关沟冰川表碛平均增厚分别为5.2 cm、3.1 cm、3.7 cm、6.8 cm、7.3 cm和13.1 cm;③西坡冰川表碛覆盖度高,表碛覆盖年均扩张率低,冰川末端退缩量小;东坡冰川表碛覆盖年均扩张率高,但表碛覆盖度总体低于西坡,冰川末端退缩量大。