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Acta Prataculturae Sinica ›› 2023, Vol. 32 ›› Issue (1): 36-47.DOI: 10.11686/cyxb2022201

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Study on above-ground biomass measurement of Caragana microphylla in shrub-encroached grassland

Rong RONG1(), Bin SUN2,3(), Zhi-tao WU1, Zhi-hai GAO2,3, Zi-qiang DU1, Si-han TENG4   

  1. 1.Institute of Loess Plateau,Shanxi University,Taiyuan 030006,China
    2.Research Institute of Forest Resource Information Techniques,Chinese Academy of Forestry,Beijing 100091,China
    3.Laboratory of Forestry Remote Sensing and Information System,National Forestry and Grassland Administration,Beijing 100091,China
    4.Inner Mongolia Autonomous Region Big Data Center,Hohhot 010000,China
  • Received:2022-05-06 Revised:2022-06-16 Online:2023-01-20 Published:2022-11-07
  • Contact: Bin SUN


Shrub-encroached grassland has become an important vegetation landscape type in arid and semi-arid areas in China. The shrub-encroached grassland of Caragana microphylla in Inner Mongolia is the most typical example of this vegetation landscape type in China. To explore the best measurement method for above-ground biomass of C. microphylla, 17 typical plots were selected in the Bordered Yellow Banner and Zhengxiangbai Banner of Xilin Gol League, and the accuracy of above-ground biomass obtained using two direct measurement methods, “standard branch” and “standard quadrat” , was compared. At the same time, the possibility of indirect measurement of above-ground biomass under noninvasive conditions was studied by using four directly measurable factors, i.e., height and irregular canopy area obtained by real-time kinematic analyses and three derived complex factors. Using these factors, a model to estimate the above-ground biomass of C. microphylla shrub in the study area was established. It was found that: 1) The biomass predicted by the “standard branch” method (R=0.95, P<0.01) was more accurate and less destructive than that predicted by the “standard quadrat” method (R=0.84, P<0.01). 2) In the correlation analysis of easy-to-measure factors, the single factors crown breadth, irregular crown area and irregular crown perimeter were strongly correlated, with correlation coefficients greater than 0.98 (P<0.01), suggesting that they could be used to predict the above-ground biomass of C. microphylla. Height showed a general relationship with each of the single factors, with correlation coefficients ranging from 0.67 to 0.72 (P<0.05). However, three-term complex factors derived from height improved the prediction accuracy. 3) Among the single factors, crown breadth (R=0.92, P<0.01) had the strongest correlation with biomass, while irregular volume (R=0.92, P<0.01) had the strongest correlation with the complex factors. An above-ground biomass prediction model of C. microphylla was established. It consisted of a linear function with crown breadth as an independent variable and a power function with irregular volume an independent variable. These results provide a scientific reference for the estimation of above-ground biomass based on an integrated “space-air-ground” method.

Key words: Caragana microphylla, above-ground biomass, real-time kinematic, standard branch, standard quadrat, estimating model