| Cypress(Cupressus funebris)is one of the main afforestation tree species in subtropical region of china.Due to the seventies of the 20th century by limit of scientific level,a large area of funebris forest constructed,leading to the then create a cultivation of high stand density,understory plant species were scarce,the destruction of biodiversity,wood dry shoot and die,to slow the growth of forest,forest soil maintaining ecological protective function decline.Based on this,this study in hilly area of central Sichuan Basin 33a inefficient Cupressus funebris plantation as the research object,study the thinning 2a after different thinning intensities of forest growth and forest grass layer plant species,quantity,species richness,diverse and soil physicochemical properties Guan,to inefficient Cupressus funebris plantation in hilly area of Central Sichuan Basin and enhance the shrub grass layer restoration and ecosystem structure optimization to provide the reference.Trials were set up five kinds of thinning treatment,that is,the weak thinning(T1,15%),moderate thinning(T2,25%),thinning intensity in(T3 35%),thinning intensity(T4,50%)and control(CK,0%).Each treatment three repetitions.The main results are as follows:(1)2a after thinning,the thinning intensity average DBH of inefficient Cupressus funebris plantation,tree height,crown width compared to controls were significantly increased(P<0.05),the performance for the T4>T3>T2>T1.Individual volume growth rate has decreased with increasing thinning intensity increases and the trend to T4 reached a maximum of 32.61%.Variance analysis showed that the thinning intensity of single tree volume growth rate was significantly higher than that of control(P<0.05).This suggests that the thinning the cypress inefficient artificial forest growth conditions improved,stand tree volume growth rate was significantly higher than that of the unthinned stand.(2)This study recorded plants of 36 subjects and 56 genera,a total of 8114 plants of 61 species.There were 25 species,20 subjects and 25 genera of shrubs,19 subjects,31 genera and 36 species of herbs.The CK has 37 genera and 26 subjects,a total of 1297 plants of 38 species;T1 40 genera and 28 subjects,totaling 1526 plants of 43 species;T2 have 47 genera and 32 subjects,a total of 1669 plants of 49 species.T3 has 30 subjects,47 genera,totaling 1765 plants of 49 species;T4 has 43 genera and 30 subjects,a total of 1857 plants of 47 species.(3)Inefficient Cupressus funebris plantation after thinning 2a,the thinning intensity of forest plant density than that of the control were increased by 0.27 million lines·hm-2(T1),4.49 million lines·hm-2(T2),6.58 million plants·hm-2(T3)and 9.28 million lines ·hm-2(T4);analysis of variance showed that the density of T2,T3,T4 thinning intensity was significantly higher than that of T1 and CK(P<0.05)and T4 thinning intensity was significantly higher than that of T2,dealing with the rest of the difference was not significant.That thinning cypress plantation growth efficiency.(4)After thinning 2a,cypress inefficient plantations in shrub layer of the Shannon-Wiener index(H)and Simpson dominance index(C)size in T2 and T3 thinning intensity maximum,was significantly higher than that of CK(P<0.05).Under different thinning intensities shrub layer,Pielou uniformity index(JSW)differences did not reach significant level;herb layer of the Shannon-Wiener index(H)performance as the thinning intensity>very thinning intensity>moderate thinning>weak thinning>control,the thinning intensity and control differences reached significant levels(P<0.05).Simpson dominance index(C)and Pielou uniformity index(JSW)showed for the difference between the very intensity of thinning and control significant(P<0.05).This suggests that the thinning makes inefficient artificial forest of Cupressus funebris vegetation diversity is improved,the intensity and the intensity of thinning effect is the most significant.(5)After cypress inefficient in artificial forest cutting 2a,in the 0-10 cm layer,the thinning intensity of soil bulk density decreased,m3 of extent of change,with significant difference as compared with the control(P<0.05).T3 thinning intensity of soil maximum moisture capacity,capillary water holding capacity,minimum holding capacity,non capillary porosity,capillary porosity and total porosity were significantly increased by 23.56%,12.84%,15.82%,21.72%,15.73%,17.29%(P<0.05)compared with the control.The thinning intensity of soil organic matter and total nitrogen content increased,the largest increase is T3.Available P and available K contents in addition to T4 thinning intensity was lower than that of the control,the rest of the thinning intensity increased,which T1,T3 and the control group,the difference was significantly(P<0.05).The thinning intensity of pH did not change significantly.The change trends of 10-20cm soil layer and 0-10cm soil layer are basically the same.That is conducive to improving the efficiency of thinning cypress plantation soil physicochemical properties,in order to improve the best effect of thinning.In summary,thinning have to improve cypress inefficient plantation tree growth conditions,forest shrub grass diversity and soil physical and chemical properties and the thinning intensity is the best way to improve. |
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