Chin J Plant Ecol ›› 2023, Vol. 47 ›› Issue (12): 1668-1683.DOI: 10.17521/cjpe.2023.0072

• Research Articles • Previous Articles     Next Articles

Effects of biocrusts on surface roughness and seed secondary dispersal of shrubs and grasses on the Loess Plateau, China

ZHANG Xue1,2,3(), HAN Feng-Peng1,2,*(), XIAO Bo2,4,*(), SHEN Si-Ming4   

  1. 1The Research Center of Soil and Water Conservation and Ecological Environment, Chinese Academy of Sciences and Ministry of Education, Yangling, Shaanxi 712100, China
    2Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China
    3University of Chinese Academy of Sciences, Beijing 100049, China
    4College of Land Science and Technology, China Agricultural University, Beijing 100193, China
  • Received:2023-03-13 Accepted:2023-06-15 Online:2023-12-20 Published:2023-06-15
  • Contact: *(Han FP,; Xiao B,
  • Supported by:
    National Natural Science Foundation of China(42077010);“Light of West China” Program of the Chinese Academy of Sciences(2019)


Aims In order to determine whether biocrusts enhance or impede the secondary dispersal of shrub and grass seeds and identify the key factors that influence seed dispersal, we simulated the process of seed secondary dispersal and measured relevant indicators such as the surface roughness of biocrusts.
Methods On the Loess Plateau, we established experimental plots on biocrusts (cyanobacteria- and moss- dominated crusts) and bare soils from aeolian sand and loess soil. For each selected plot, we utilized oblique photogrammetry to measure the surface roughness in both dry and wet conditions. All the treatments were studied in three replicates. Six species seeds of shrubs and grasses (Caragana korshinskii, Hedysarum scoparium, Artemisia ordosica, Setaria viridis, Xanthium sibiricum, and Bidens pilosa) with different morphological characteristics were selected for secondary dispersal experiments, and their seed displacement ratio (SDR), seed loss ratio (SLR), as well as seed displacement distance (SDD), were calculated following the experiments. The Spearman correlation analysis was then performed to identify the dominant factors.
Important findings (1) When compared with bare soils, the surface roughness of cyanobacteria- and moss-dominated crusts on aeolian sand soil increased by 6.69 and 6.13 times and by 2.52 and 1.45 times on loess soil, respectively. (2) Within contrast to wet conditions, the surface roughness of biocrusts increased by 26.56% on dry aeolian sand soil, whereas it reduced by 9.42% on dry loess soil. (3) The surface roughness of biocrusts of the aeolian sand soil rose by 16.84% under dry conditions and decreased by 16.38% under wet conditions compared with that on loess soil. (4) In comparison to bare soils, the SDR, SLR, and SDD of biocrusts dropped by 77.1%, 95.4%, and 72.2% on aeolian sand soil and by 76.5%, 93.8%, and 66.8% on loess soil, respectively. The characteristics of seed dispersal were not significantly affected by soil types or soil water conditions. (5) The SDR, SLR, and SDD were all significantly and negatively correlated with the surface roughness of biocrusts. However, only the SDR and SLR were significantly negatively linked to soil water content, and only the SLR and SDD were significantly negatively correlated with seed density. To summarize, biocrusts obstruct dispersal and enhance aggregation of seeds by increasing land surface roughness, thereby impacting the spatial structures and community dynamics of shrubs and grasses.

Key words: seed dispersal, vascular plant, surface roughness, cyanobacteria crust, moss crust, Loess Plateau