Effects of Different Thinning Intensities on the Natural Regeneration of Larix principis-rupprechtii Plantations
The objective of this study was to investigate the effects of different thinning intensities on the spatial pattern and interspecific correlation of the natural regeneration of 30-year-old Larix principis-rup-prechtii plantations that is crucial for adjusting the spatial structure and conserving natural regeneration of the artificial forests in the Saihanba Forest Farm.The pure forest of L.principis-rupprechtii in Saihanba area was selected as the research object.Three kinds of thinning intensity were set up:high(60％-65％),medium(45％-50％)and low(35％-40％),and three fixed plots each with an area of 900 m2 were set respectively.The average tree density before thinning was 2 611 trees/hm2.The g(r)and g12(r)functions were utilized to investigate the changes in individual characteristics of natural regeneration,the spatial pat-tern between dominant canopy trees and natural regeneration,and the interspecific correlation under differ-ent thinning intensities.The results indicated no significant differences in species richness among the vari-ous thinning intensities.The medium thinning intensity exhibited the highest values for average height,av-erage diameter at breast height,and average crown width,reaching 52.68 cm,5.18 cm,and 34.49 cm,re-spectively.Only the average density was the lowest under the medium thinning intensity,at 93 stems/hm2.The spatial pattern of the dominant canopy layer was primarily random,while that of natural regeneration was predominantly aggregated.The interspecific correlation between natural regeneration and the dominant canopy layer was mainly unrelated.The resuls of this study suggests that a medium thinning intensity(45％-50％)is advantageous for adjusting the spatial structure of pure L.principis-rupprechtii planta-tions and conserving natural regeneration in the Saihanba Forest Farm.
Larix principis-rupprechtiitending thinningnatural regenerationspatial point patterninter-specific association
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