Shuitu baochi tongbao (Apr 2023)
Changes in Species Composition and Structure During Vegetation Community Succession in Ziwuling Forest Area
Abstract
[Objective] The changes in plant community composition and vertical structure under natural restoration were studied in order to provide a reference for vegetation construction and high-quality development of the Loess Plateau. [Methods] Using the method of space instead of time, species composition and diversity characteristics of vegetation from abandoned cropland to top community in the Ziwuling forest area were investigated and analyzed. A vegetation vertical structure index was constructed to study the vertical structure of the vegetation community and its changing trend in the succession sequence. [Results] ① A total of 115 species of vegetation in 42 families, 98 genera, and 115 species appeared in the Ziwuling forest zrea, and a total of 32 families, 77 genera, and 88 species of vegetation appeared in the succession sequence. ② In succession, the species diversity index and richness index of the community showed a significant increasing trend, The diversity and richness index values were 0.901 and 1.702 at the beginning of the succession, and 1.998 and 2.665 at the end of the succession. The middle stage showed a unimodal trend, and the two indices were 2.21 and 3.05. The evenness index did not change significantly. ③ During the succession process, each tree factor showed an increasing trend. The DBH was 12.13 cm at the initial stage of succession and increased to 22.19 cm at the end; the crown width increased from 11.64 m2 to 41.54 m2; and the tree biomass increased from 54.07 t/hm2 to 175.13 t/hm2. However, the indicators of shrubs did not change significantly during the succession process. Shrub biomass showed significant peaks in the middle of succession (highest value of 9.56 t/hm2), but showed a rapid fluctuation and declining trend in the subsequent succession process. At the end of succession, shrub biomass was only 1.82 t/hm2. The thickness of the litter layer increased significantly when the shrub community was succeeded by the tree community, but the litter coverage was not significantly different between the succession stages. ④ The overall vertical structure index in the early stage of succession was low and similar, ranging from 0.086 to 0.104, and rapidly increased to 0.349 in the middle stage of succession, reaching a maximum value of 0.477 near the end of the succession. The vertical structure index of understory vegetation was highest in the middle of the succession (0.342), thereafter decreasing and tending to be stable at the end of succession (0.195~0.246). [Conclusion] With natural succession, species diversity and community richness significantly improved, and a single peak appeared in the middle of the succession. The overall vertical structure of the community became more complex, and the vertical structure of understory vegetation degraded during late succession.
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