Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are a family of bacterial lipids widely used for temperature and pH reconstructions in terrestrial settings. 3-hydroxy fatty acids (3-OH FAs) with 10–18 carbon atoms, produced by Gram-negative bacteria, have been recently proposed as independent and complementary proxies of temperature and pH in terrestrial environments. Nevertheless, the correlations between mean annual air temperature (MAAT)/pH and bacterial lipid (brGDGTs/3-OH FAs) distributions show a large degree of scatter, as the relative abundance of these lipids is influenced by factors other than temperature and pH. A full understanding of the environmental parameters influencing bacterial lipid distribution in soils is required to increase the reliability of the temperature and pH proxies based on these compounds in terrestrial environments. The aim of this work was to determine and quantify the cumulative effect of environmental parameters on the distribution of both brGDGTs and 3-OH FAs along a well-documented composite altitudinal transect in the French Alps (234–2748 m). Redundancy analysis revealed that the influence of local parameters (pH and to a lesser extent, soil moisture and grain size, related to vegetation and soil types) on brGDGT and 3-OH FA distributions amounted to 48.1% and 26.1%, respectively, and was predominant over MAAT. This likely explained the weak or lack of relationships between MAAT and brGDGT-/3-OH FA-based indices in this region. The identification of lipids whose fractional abundance is correlated with MAAT or pH allowed the development of local calibrations with MAAT/pH applicable in the French Alps, which are representative of highly contrasted microenvironments, reflecting different types of soil and vegetation. The present study highlighted the importance of constraining the environmental factors affecting the distribution of 3-OH FAs and brGDGTs in terrestrial settings prior to any paleoenvironmental reconstruction. Such an approach should be reproduced in other sites, where local factors could also strongly influence the bacterial lipid distribution.

支链甘油二烷基甘油四醚（brGDGTs）是一类细菌脂质，广泛用于陆地环境中的温度和pH值重建。革兰氏阴性细菌产生的具有10-18个碳原子的3-羟基脂肪酸（3-OH FAs）最近被提出作为陆地环境中温度和pH值的独立和互补代表。但是，年平均气温（MAAT）/ pH与细菌脂质（brGDGTs / 3-OH FAs）分布之间的相关关系显示出很大程度的分散性，因为这些脂质的相对丰度受温度和pH值以外的因素影响。需要全面了解影响土壤中细菌脂质分布的环境参数，以提高基于陆地环境中这些化合物的温度和pH值代理的可靠性。这项工作的目的是确定和量化环境参数对brGDGT和3-OH FAs在法国阿尔卑斯山（234–2748 m）上有据可查的复合垂直样带分布的累积影响。冗余分析表明，局部参数（pH和较小程度的土壤湿度和粒径，与植被和土壤类型有关）对brGDGT和3-OH FA分布的影响分别为48.1％和26.1％，并且主要超过MAAT。这可能解释了该地区MAAT与基于brGDGT- / 3-OH FA的指数之间关系的弱或缺乏。通过鉴定脂类的丰度与MAAT或pH相关的脂质，可以开发适用于法国阿尔卑斯山的MAAT / pH局部校准方法，该方法可代表高对比度的微环境，反映了不同类型的土壤和植被。本研究强调在任何古环境重建之前，限制影响3-OH FAs和brGDGTs在陆地环境中分布的环境因素的重要性。这种方法应在其他场所复制，这些场所的局部因素也可能强烈影响细菌脂质的分布。通过鉴定脂类的丰度与MAAT或pH相关的脂质，可以开发适用于法国阿尔卑斯山的MAAT / pH局部校准方法，该方法可代表高对比度的微环境，反映了不同类型的土壤和植被。本研究强调在任何古环境重建之前，限制影响3-OH FAs和brGDGTs在陆地环境中分布的环境因素的重要性。这种方法应在其他场所复制，这些场所的局部因素也可能强烈影响细菌脂质的分布。通过鉴定脂类的丰度与MAAT或pH相关的脂质，可以开发适用于法国阿尔卑斯山的MAAT / pH局部校准方法，该方法可代表高对比度的微环境，反映了不同类型的土壤和植被。本研究强调在任何古环境重建之前，限制影响3-OH FAs和brGDGTs在陆地环境中分布的环境因素的重要性。这种方法应在其他场所复制，这些场所的局部因素也可能强烈影响细菌脂质的分布。本研究强调了在任何古环境重建之前，限制影响3-OH FAs和brGDGTs在陆地环境中分布的环境因素的重要性。这种方法应在其他场所复制，这些场所的局部因素也可能强烈影响细菌脂质的分布。本研究强调在任何古环境重建之前，限制影响3-OH FAs和brGDGTs在陆地环境中分布的环境因素的重要性。这种方法应在其他场所复制，这些场所的局部因素也可能强烈影响细菌脂质的分布。