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n‐Alkanes are widely used in paleoenvironmental reconstructions. However, our understanding of changes in the distribution of n‐alkanes with climatic and environmental factors remains unclear in arid/semi‐arid regions. We sampled 26 surface sediments from three climatic zones across the southwestern Tibetan Plateau to evaluate the sensitivity of chain length distributions of n‐alkanes to climatic and environmental parameters. Our observations demonstrate that average chain length (ACL), proportion of aquatic macrophyte (Paq), carbon preference index (CPI) and ratio of the contents of nC27 and nC31 (nC27/nC31) are all sensitive to hydroclimatic conditions. In contrast to commonly‐adopted assumptions, the correlations between these indices and hydrological parameters are not always good, which indicates that the interpretation of n‐alkane indices is special on the southwestern Tibetan Plateau. These might be related to the vegetation characteristics and seasonality of biological activity, and need to be considered in paleoclimatic reconstruction. The impact of seasonal precipitation on n‐alkanes indices was also evaluated. [ABSTRACT FROM AUTHOR]

The abundance and distribution of long-chain n-alkanes in sedimentary archives have been proposed as plant-derived paleoenvironmental proxies. The reliable application of these proxies hinges on comprehensive understandings drawn from investigations of living plants. However, previous studies have predominantly relied on narrow environmental gradients and limited datasets sourced from local and regional sampling. As a result, our comprehension of how n-alkanes in living plants respond to climate factors on larger spatial scales remains unclear, especially across different plant functional types (PFTs). In this study, we analyzed the abundance and distribution of n-alkanes in the leaves of 552 plant samples from diverse regions in China and explored the variability of leaf wax n-alkanes across gradients of climate and PFTs. Average chain length (ACL) and carbon preference index (CPI) exhibit statistically significant differences between various PFTs, and the ratio of C 33 /(C 31 + C 33) holds the potential to distinguish between C 3 and C 4 vegetation types. The n-alkane concentration (Σalk) is primarily controlled by precipitation, with a notable negative correlation between Σalk and mean annual precipitation (MAP) that is independent of PFTs. Overall, ACL is negatively related to MAP and positively to mean annual temperature (MAT), but the relationship varies across PFTs. MAT is a stronger driver of ACL for C 4 herbs and woody plants, while MAP exerts a more pronounced influence on C 3 herbs. CPI in most PFTs shows no correlation with environmental variables. These findings indicate Σalk is a good indicator of precipitation, and ACL is indicative of precipitation or temperature depending on the specific PFT; CPI appears unsuitable as a climate indicator and great caution should be exercised in using CPI records in paleoclimate research. • A study of leaf wax n-alkanes covering the entire mainland China was performed. • Differences in n-alkane distribution among PFTs do not distinguish taxonomically. • Σalk is a good indicator of precipitation. • CPI is poorly sensitive to environmental factors. • ACL is an indicator of precipitation or temperature depending on the specific PFT. [ABSTRACT FROM AUTHOR]