阿尔卑斯超镁铁岩的演化及上地幔的局部熔融

西藏新疆超镁铁岩是上地幔局部熔融的产物。超镁铁岩在矿物成分上的演化表现为两个平行的演化系列:一是随各亚类岩石的递变,硅酸盐矿物的100Mg,(Mg+Fe~(2+))值递增,即硅酸盐矿物向富镁方向演化;二是副矿物铬尖晶石的100Cr/(Cr+Al)值相应递增,向富铬方向演化;上述演化趋势与岩浆分异演化趋势相反。在组构上则由原粒结构向熔融残余、后成合晶,碎斑结构,然后递变为等粒镶嵌;板状镶嵌结构。二辉橄榄岩的熔融实验资料清楚表明、阿尔卑斯超镁铁岩的演化乃是地幔岩熔融的结果。各亚类岩石代表了不同程度的局部熔融,岩体所显示的上部偏基性,下部偏酸性的垂直分带实属地幔岩的熔融分带。     

开垦对高寒草甸土壤有机碳影响的初步研究

在中国科学院海北高寒草甸生态系统定位站地区,选择高寒草甸开垦后形成的一年生人工草地作为研究对象,开垦年限分别为0、1、11、16和20年,利用土壤有机碳密度分组法,进行了0~40cm土层土壤有机碳及不同组分（轻组有机碳,重组有机碳）含量及随开垦年限变化关系的研究。结果表明：高寒草甸开垦后其土壤有机碳的变化主要发生在0~10cm土层,土壤中SOC、LFOC和HFOC呈下降趋势,至20年时分别下降了10.5 %、26.7%、8.1 %,主要原因为当地较为强烈的风蚀作用、耕作侵蚀和开垦加剧了表层（0 ~10cm）土壤有机质的氧化分解,表层土壤中的粗有机物质在降水淋溶作用下,在土体下部重新淀积。而0 ~40 cm土体内,SOC、LFOC和HFOC略有增加,开垦20年,他们的累积速率分别为0.08 t C·hm-2·yr-1、0.07 t C·hm-2·yr-1、0.14 t C·hm-2·yr-1。人工草地长期种植虽然没有改变高寒草甸作为碳汇的基本功能,但却大大降低了其碳汇效应,植物-土壤系统年固定碳量由未开垦前的7.38t C·hm-2·yr-1下降至6.89 t C·hm-2·yr-1。     

土地利用变化对高寒草甸土壤有机质更新的影响

对青藏高原海北站区的自然土壤和扰动土壤进行高分辨率采样,测定土壤根系、有机碳及其¹⁴C含量;用¹⁴C示踪技术探讨土地利用变化对高寒草甸土壤有机质更新的影响.研究表明,土地利用变化对高寒草甸土壤碳循环影响显著.耕作活动导致扰动土壤有机碳储量比自然土壤增加29.35%;扰动土壤剖面10~50 cm深土壤有机质的¹⁴C含量相对富集;自然土壤大多数有机碳储存在土壤表层,更新时间<50 a,同一深度扰动土壤有机碳储量显著少,更新时间长(171~294 a);自然土壤10 cm以下有机碳主要为更新时间>1 000 a的稳定碳所控制,扰动土壤的相应值出现在40 cm以下;自然土壤有机质更新产生的CO₂通量为114 gC·m^-2·a^-1,扰动土壤为48.7 gC·m^-2·a^-1.     

甘肃酒泉盆地早白垩世植物化石及其古气候意义

首次较系统报道了产于甘肃酒泉盆地下白垩统的植物化石,分为两个植物组合。Athrotaxites-Solenites组合产于赤金堡组上段,有Solenites luanpingensis Wang,Pityocladus cf.i waianus(ishi)Chow,Pityocladus sp.,Athrotaxites berryi Bell等,时代大致为早白垩世早期,反映潮湿或半干旱半潮湿气候。Brachyphyllum-Pseudofrenelopsis组合见于中沟组上部,包括Sphenopterissp.,Pseudofrenelopsis dalatzensis(Chowet Tsao)Cao ex Zhou,Cupressinocladus elegans(Chow)Chow,Cupressinocladus sp.,Pagiophyllumyumenense sp.nov.,Pagiophyllumcompressum sp.nov.,Pagiophyllum sp.,Brachyphyllumningshiaense Chow et Tsao,Brachyphyllumobtusum Chow et Tsao,Elatocladus sp.,Podozamites sp.,Carpolithus sp.等12种,时代为Aptian-Albian期,反映干旱型气候。     

Perceptions of Local People toward Wild Edible Plant Gathering and Consumption: Insights from the Q-method in Hani Terraces

Wild edible plants (WEPs) can provide a variety of provisioning services and cultural services but they are currently under-utilized. Understanding farmers’ perceptions of the collection and consumption of wild edible plant resources is essential for promoting local socio-ecological system resilience and local wild plant resource use. This paper uses the Q-method to investigate the main perspectives of farmers toward collecting and consuming wild edible plants in the Honghe Hani Terraces region of Yunnan Province. This analysis identified four main perspective types among the farmers, including market-driven, household user-driven, cultural service seekers, and tradition followers. It revealed the main factors that limit and facilitate farmers’ WEP collection and consumption, including limitations due to loss of traditional knowledge, and changes in socioeconomic conditions that negatively affect WEP collection and consumption; while, on the other hand, the demand for WEP-related cultural services and the presence of a strong culture slowed down changes in dietary structure, which in turn have maintained WEP collection and consumption. The Q-method can help in identifying the relationship between community residents and local wild plant resource use in rapidly transitioning areas and in identifying the barriers that affect the resilience of local socio-ecological systems.     

川西高寒山地土壤有机碳与铁、铝矿物复合体分布特征

为了量化川西高寒山地土壤与铁、铝矿物相关的有机碳含量以及探讨川西高寒山地土壤铁、铝矿物对有机碳稳定性和累积方式的影响,采用选择性提取法研究了川西高寒山地的山地灰化土（MP)和高山草甸土（AM）中土壤有机碳与晶质金属氧化物（DH）提取、短程有序（HH）提取、矿物复合体以及有机—金属配合物（PP）提取中的有机碳和铁、铝的分布。结果表明,MP中DH,HH和PP提取的碳含量分别为(10.91±6.23) g/kg、(5.92±1.66) g/kg和(8.76±2.29) g/kg,分别占有机碳的20.92%,12.07%和19.93%;而AM中DH、HH和PP提取的碳含量分别为(9.05±1.33) g/kg、(5.52±1.02) g/kg和(9.12±3.21) g/kg,分别占有机碳的21.04%、12.47%和19.34%。3种提取剂提取的碳含量以及其占有机碳的百分比在MP和AW的A层土壤中均表现为PP > DH > HH,而在B层土壤中则表现为DH > PP ≈ HH。随着土壤深度的增加,深层土壤中次级矿物和晶体矿物丰度的显著增加,导致有机碳与铁、铝矿物复合体由有机—金属配合物主导转变为有机碳与晶质金属氧化物形成的复合体主导。PP提取的碳和其所占有机碳的百分比表现为A层高于B层,而DH和HH提取的碳含量和其所占有机碳的百分比大体表现为A层低于B层。由于MP特殊的土壤性质,这种差异在MP中更为明显。3种提取剂提取的金属（Al+Fe）含量在两种土壤中均表现为DH > HH > PP。而其提取的碳与金属的摩尔比表现为DH < HH < PP,说明随着铁、铝矿物的结晶度增加,其与有机质的作用从共沉淀、络合而向吸附作用转变。DH,HH和PP提取的碳与SOC的相关分析表明,MP中土壤有机碳的累积在一定程度上受晶质铁、铝矿物与有机质的相互作用而驱动;AM中土壤有机碳的累积在一定程度上受短程有序矿物与有机质的相互作用以及有机—金属配合物的驱动。本文研究表明,土壤中的铁、铝矿物与有机碳形成的复合体在一定程度上驱动着川西高寒山地土壤有机碳的积累,不同土壤类型中,与矿物相关的有机碳的分布不同,其有机碳的积累方式也不同。     

Comparing water use patterns of sand-binding species in an alpine semi-arid desert

The processes of species obtaining water resources are crucial to evaluate the adaptability of plantations, which can affect the establishment and survival of restored ecosystems and functions of water-limited ecosystems. However, there are still limitations in understanding water use patterns of different four plantations (Populus sylvestris, Salix cheliophe, Hippophae rhamnoides and Artemisia ordosica) in the Qinghai Lake basin. Stable isotopes of xylem water of four individual species were analysed at different dunes located at the eastern shore of Qinghai Lake in 2018 and 2019. The purpose of this study was to explore potential water sources used by different life form plants, to identify whether the soil moisture content and root distribution determined the plants water use patterns. Results from the Bayesian mixing model MixSIAR showed that all species mainly uses three levels of soil water, but they extracted soil water from different layers in different growing seasons among species. All species primarily depended on water from upper soil layers at the early growing stage, but P. sylvestris and S. cheliophe also absorbed much proportion middle and deep soil layers' water in dry year of 2019. All four species shift to use middle or deep soil layer water rather than shallow water in July with the most rainfall and soil water content (SWC). However, it was only used by P. sylvestris and H. rhamnoides in 2018. In all, seasonal water use pattern of different species was affected by SWC, soil texture and root distribution. Compared with moratorium plantations such as S. cheliophe, mixed afforestation of P. sylvestris and H. rhamnoides maximized of soil water sources absorbed by the plants. The study can shed light on plant–water relationships to facilitate the woody species for afforestation and desertification restoration management in the semi-arid desert ecosystem.