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Journal of Desert Research ›› 2025, Vol. 45 ›› Issue (5): 45-54.DOI: 10.7522/j.issn.1000-694X.2025.00006

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Characteristics and implications of leaf wax n-alkanes in typical vegetation of the northern Ulan Buh Desert

Shangzhe Zhoua,b(), Lei Xia,b, Mengchun Cuia,b, Guipeng Cuia,b,c, Weiyuan Konga,b,c, Pan Gaoa,b, Qi Lua,b,c()   

  1. a.Institute of Ecological Conservation and Restoration /, Chinese Academy of Forestry,Beijing 100091,China
    b.Institute of Desertification Studies /, Chinese Academy of Forestry,Beijing 100091,China
    c.Institute of Great Green Wall, Chinese Academy of Forestry,Beijing 100091,China
  • Received:2024-09-25 Revised:2024-12-24 Online:2025-09-20 Published:2025-09-27
  • Contact: Qi Lu

Abstract:

Long-chain n-alkane biomarker compounds in sediments are mainly originated from higher plant leaf waxes and are important indicators of paleoclimatic and paleoenvironmental reconstruction in desert areas. Environmental factors such as temperature, precipitation and altitude have a profound impact on the abundance and distribution characteristics of leaf wax n-alkanes in extant desert plants. However, the effects and mechanisms of these environmental factors on the synthesis of leaf wax n-alkanes in desert regions are not yet clear. For this reason, the Ulan Buh Desert, which is highly sensitive to the response to climate and environmental changes, is selected as study area, and the n-alkane composition and distribution, as well as the indicators of total n-alkane abundance (∑ALK), average carbon chain length (ACL), and carbon predominance index (CPI) of the typical vegetation in the northern part of the desert were analyzed and compared. We found that n-alkane distribution pattern of Nitraria roborowskii shows a predominance of n-C27Haloxylon ammodendron shows a predominance of n-C27 and n-C29, while Ammopiptanthus mongolicus shows a predominance of n-C29; mean values of ∑ALK and CPI are 86 μg·g-1 and 10.4 for H. ammodendron, 410 μg·g-1 and 23.3 for N. roborowskii, and 7 383 μg·g-1 and 47.1 for A. mongolicus, and the n-alkane characteristics differs significantly among the three typical vegetation types, with A. mongolicus being particularly distinctive. We also found that the leaf wax n-alkane ∑ALK of Ulan Buh Desert vegetation is strongly influenced by environmental precipitation, and in general ∑ALK shows an increasing trend with increasing precipitation; additionally, as the leaf morphology of desert plants adapted to drought stress, i.e., from ovate to lanceolate, and ultimately to scale (assimilative shoot), the leaf wax n-alkane characteristics also show adaptive variations, i.e., the ACL and CPI shows a gradual decrease. Overall, the leaf wax n-alkane ∑ALK, ACL and CPI characteristics of Ulan Buh Desert vegetation are effective for indicating wet and dry changes in the area.

Key words: n-alkanes, desert plants, Ulan Buh Desert, paleoclimatic reconstruction, paleoenvironmental reconstruction

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