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Chinese Journal of Applied Ecology ›› 2023, Vol. 34 ›› Issue (4): 955-961.doi: 10.13287/j.1001-9332.202304.008

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Spatial heterogeneity of soil available medium- and micro-elements in evergreen-deciduous broadleaved forest in karst

LIAN Ziwen1,2,3, DU Hu1,2,4*, GU Junkun1,2,3, ZENG Fuping1,2,4, PENG Wanxia1,2,4, YIN Lichu3, LONG Qingzhi1,2, LIU Kunping1,2,4, SUN Rui5, TAN Weining5   

  1. 1Key Laboratory of Agro-ecological Processes in Subtropical Region, Public Technology Center, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China;
    2Huanjiang Observation and Research Station of Karst Ecosystem, Chinese Academy of Sciences/Guangxi Key Laboratory of Karst Ecological Processes and Services, Huanjiang 547100, Guang-xi, China;
    3College of Resources and Environment, Hunan Agricultural University, Changsha 410125, China;
    4Guangxi Industrial Technology Research Institute for Karst Rocky Desertification Control, Nanning 530000, Guangxi, China;
    5Administrative Centre of Guangxi Mulun National Nature Reserve, Huanjiang 547100, Guangxi, China
  • Received:2022-09-05 Accepted:2023-02-15 Online:2023-04-15 Published:2023-10-15

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Abstract: Understanding the spatial heterogeneity of soil available medium- and micro-elements in karst area can provide a valuable theoretical guideline for soil nutrient management of karst ecosystem. We collected soil samples at a soil depth of 0-10 cm using grid sampling (20 m×20 m) in a 25 hm2 (500 m×500 m) dynamic monitoring plot. We further analyzed the spatial variability of soil medium- and micro-elements and their drivers, with classic statistics analysis and geo-statistics analysis. The results showed that the average contents of exchangeable Ca and Mg and available Fe, Mn, Cu, Zn, and B were 7870, 1490, 30.24, 149.12, 1.77, 13.54, and 0.65 mg·kg-1, respectively. The coefficient of variation of the nutrients ranged from 34.5% to 68.8%, showing a medium degree of their spatial variation. The coefficient of determination of the best-fit semi-variogram models of each nutrient was higher than 0.90, except for available Zn (0.78), indicating a strong predictive power for the spatial variation of the nutrients. The nugget coefficients for all the nutrients were less than 50%, showing a moderate spatial correlation, and the structural factors played a pivotal role. The spatially autocorrelated variation was within the range of 60.3-485.1 m, among which available Zn showed the lowest range and the deepest fragmentation degree. The spatial distribution of exchangeable Ca, Mg, and available B were consistent, with contents in the depression being significantly lower than that in other habitats. The contents of available Fe, Mn, and Cu declined with the increases of altitude and were significantly lower on the hilltop than in other habitats. The spatial variation of soil medium- and micro-elements was closely related to topographic factors in karst forest. Elevation, slope, soil thickness, and rock exposure rate were the primary drivers of spatial variation of soil elements and need to be considered in soil nutrient management of karst forestlands.

Key words: soil medium- and micro-elements, spatial heterogeneity, topographical factor, forest, karst ecosystem