The traditional tenon and mortise joint has low processing efficiency and a weak theoretical basis,making the structure easy to deform and damage,reducing the safety,and increasing waste of resources.This study aims t...The traditional tenon and mortise joint has low processing efficiency and a weak theoretical basis,making the structure easy to deform and damage,reducing the safety,and increasing waste of resources.This study aims to determine the optimum dowel center spacing parameter for chamfered-joint components and the maximum value of the strength of joints loaded into bending strength and tensile strength.In this study,an integrated opti-mization method combining the single-factor test and one-way ANOVA analysis was proposed to study the influ-ence of the dowel center spacing on the bending strength and the tensile strength of chamfered-joint components made by Cupressus funebris wood.The results revealed that the bending strength of chamfered-joint components decreases linearly with the increase of the dowel center spacing.In addition,the tensile strength of chamfered-joint components increases first and then decreases with the increase of the dowel center spacing,showing para-bola change.The relational expression between dowel center spacing,the bending strength,dowel center spacing and the tensile strength were obtained.展开更多
[Objective] Breeding and genetic improvement for Cupressus funebris was performed based on the extensive genetic variation among provenances and fami- lies. [Method] The two-year-old Cupressus funebris, from 4 provena...[Objective] Breeding and genetic improvement for Cupressus funebris was performed based on the extensive genetic variation among provenances and fami- lies. [Method] The two-year-old Cupressus funebris, from 4 provenances and 34 superior Cupressus funebris families introduced from Chongqing and Qiandao Lake of Zhejiang Province, was used as test material, and the differences in growth traits among provenances and families at the seedling stage of Cupressus funebris were investigated. [Result] The height and ground diameter of seedlings differed signifi- cantly among provenances and families. Their variation coefficients among families were 11.37% and 18.89%, and among provenances were 7.25% and 12.58% re- spectively. [Conclusion] There was relatively rich genetic variation in height and ground diameter among provenances and families of Cupressus funebris. It has a certain breeding potential.展开更多
[Objective] This study aimed to investigate the variation in growth traits of Cupressus funebris in Chongqing Municipality, thus laying the foundation for further breeding and improvement of fine varieties. [Method] G...[Objective] This study aimed to investigate the variation in growth traits of Cupressus funebris in Chongqing Municipality, thus laying the foundation for further breeding and improvement of fine varieties. [Method] Growth traits of three fine stands of C. funebris in Qijiang, Pengshui and Youyang of Chongqing Municipality were investigated. [Result] The results showed that C. funebris stand in Pengshui exhibited the best growth performance, followed by C. funebris stand in Qijiang; C. funebris stand in Youyang exhibited the poorest growth performance. The average volume growth of C. funebris in Pengshui, Qijiang and Youyang was 0.14, 0.11 and 0.06 m^3, respectively. Among different stands, variation coefficients of major growth traits were above 11.31%, and the maximum variation coefficient of the volume was 39.11%; within the stands, variation coefficients of plant height were basically the same （about 20%）. The variation coefficient of diameter at breast height in Qijiang reached the maximum of 42.42%, followed by that in Youyang. The variation coeffi- cients of volume and diameter at breast height were consistent; seed bearing coefficient （SBC） of C. funebris stand in Pengshui exhibited the maximum variation, which indicated that C. funebris stand in Pengshui was conducive to establishing seed stands and constructing seed orchard by using the selected stands. [Conclusion] It is necessary to conduct provenance selection.展开更多
Based on the 6-year-old young forests of 40 cypress(Cupressus funebris) families from four provenances(Fengdu County, Youyang County and Zhong County of Chongqing City, and Qiandao Lake in Zhejiang Province), differen...Based on the 6-year-old young forests of 40 cypress(Cupressus funebris) families from four provenances(Fengdu County, Youyang County and Zhong County of Chongqing City, and Qiandao Lake in Zhejiang Province), differences in growth traits between families and provenances were studied to select excellent families, so as to provide necessary data support for the upgrading of cypress seed gardens and inferior thinning of seed gardens. The results showed that there were significant differences in tree height, diameter at one meter height, crown width and growth potential between families and provenances. The coefficients of variation among families were 10.25%, 7.19%, 5.91% and 0.98%, respectively, and the coefficients of variation in tree height and diameter at one meter height among provenances were 7.25% and 12.58%, respectively, indicating that the tree height and diameter at one meter height of the superior cypress tree families were rich in variation among families and provenances, and there was potential for high-generation breeding. According to the selection rate of 15%, six excellent families for afforestation(Feng 8, Shi 4, Feng 1, Ye 14, Shi 3, and Ye 6) were screened. The average diameter at one meter height, tree height and crown width of the six excellent families were, respectively, 2.97 cm, 3.39 and 0.78 m, which were 18.82%, 12.70% and 15.42% higher than the family average, respectively, and 15.09%, 9.79% and 15.53% higher than the control group, respectively.展开更多
【目的】针对川中丘陵区普遍存在的柏木人工林密度过大、木材生产力低、林下灌草盖度低和天然更新不良等问题，开展生态疏伐试验，探讨间伐强度对林分生长和林下植物的影响，为开展柏木生态经济型防护林的营林活动提供参考。【方法】以2...【目的】针对川中丘陵区普遍存在的柏木人工林密度过大、木材生产力低、林下灌草盖度低和天然更新不良等问题，开展生态疏伐试验，探讨间伐强度对林分生长和林下植物的影响，为开展柏木生态经济型防护林的营林活动提供参考。【方法】以25年生柏木人工林为研究对象，采用随机区组方法，设置4种间伐强度（20%～25%，15%～20%，10%～15%和对照）的处理，观察林分胸径、树高、蓄积量、生物多样性和天然更新幼苗数量，探讨间伐强度对其影响。【结果】不同强度间伐5年后林分平均胸径和胸径连年生长量在各处理之间均存在显著差异，胸径生长量随间伐强度加大而增加；平均树高以20%～25%间伐强度最大，达10.7 m，但20%～25%间伐强度与15%～20%间伐强度和10%～15%间伐强度之间无显著差异，而树高连年生长量在不同处理之间差异显著；20%～25%，15%～20%和10%～15%不同强度间伐5年后林分蓄积量分别为97.35，93.43和93.19 m3·hm －2，均比对照小，但蓄积连年生长量随间伐强度由高到低分别为6.11，4.58和3.66 m3·hm －2 a －1，均高于对照；20%～25%间伐强度林分的灌木和草本 Simpson 指数分别为0.7695和0.4446，Shannon-Wiener 指数分别为1.7025和0.7690，都比其他处理高；不同间伐强度天然更新幼苗株数仅在苗高5～30 cm 等级存在显著差异，30～50和50～150 cm 的幼苗在不同处理之间差异不明显；评价结果表明，综合得分以20%～25%间伐强度最大，且随间伐强度降低而减小。【结论】间伐后保留木的生长空间和营养空间得到有效改善，林分胸径和树高生长量随间伐强度增大而增加，但不同间伐强度蓄积量差异不显著；适度间伐可提高林下灌木和草本生物多样性指数；林分更新幼苗数量也随着间伐强度的增大而增加；就本研究的4种间伐强度而言，中龄阶段柏木人工林的适宜间伐强度为20%～25%。展开更多
基金support of the Ministry of Education Humanities and Social Sciences Research Project of China(Grant No.19YJC760009)the Key Research and Development Project of Sichuan Science and Technology Plan Projects(Grant No.2020YFS0357)the Project of Modern Design and Culture Research Centre(Grant No.MD18Z002)。
文摘The traditional tenon and mortise joint has low processing efficiency and a weak theoretical basis,making the structure easy to deform and damage,reducing the safety,and increasing waste of resources.This study aims to determine the optimum dowel center spacing parameter for chamfered-joint components and the maximum value of the strength of joints loaded into bending strength and tensile strength.In this study,an integrated opti-mization method combining the single-factor test and one-way ANOVA analysis was proposed to study the influ-ence of the dowel center spacing on the bending strength and the tensile strength of chamfered-joint components made by Cupressus funebris wood.The results revealed that the bending strength of chamfered-joint components decreases linearly with the increase of the dowel center spacing.In addition,the tensile strength of chamfered-joint components increases first and then decreases with the increase of the dowel center spacing,showing para-bola change.The relational expression between dowel center spacing,the bending strength,dowel center spacing and the tensile strength were obtained.
基金Supported by Key Science and Technology Program of ChongqingFoundation for Forest Tree Breeding in ChongqingNational Wildlife Conservation and Nature Reserve Construction Project~~
文摘[Objective] Breeding and genetic improvement for Cupressus funebris was performed based on the extensive genetic variation among provenances and fami- lies. [Method] The two-year-old Cupressus funebris, from 4 provenances and 34 superior Cupressus funebris families introduced from Chongqing and Qiandao Lake of Zhejiang Province, was used as test material, and the differences in growth traits among provenances and families at the seedling stage of Cupressus funebris were investigated. [Result] The height and ground diameter of seedlings differed signifi- cantly among provenances and families. Their variation coefficients among families were 11.37% and 18.89%, and among provenances were 7.25% and 12.58% re- spectively. [Conclusion] There was relatively rich genetic variation in height and ground diameter among provenances and families of Cupressus funebris. It has a certain breeding potential.
文摘[Objective] This study aimed to investigate the variation in growth traits of Cupressus funebris in Chongqing Municipality, thus laying the foundation for further breeding and improvement of fine varieties. [Method] Growth traits of three fine stands of C. funebris in Qijiang, Pengshui and Youyang of Chongqing Municipality were investigated. [Result] The results showed that C. funebris stand in Pengshui exhibited the best growth performance, followed by C. funebris stand in Qijiang; C. funebris stand in Youyang exhibited the poorest growth performance. The average volume growth of C. funebris in Pengshui, Qijiang and Youyang was 0.14, 0.11 and 0.06 m^3, respectively. Among different stands, variation coefficients of major growth traits were above 11.31%, and the maximum variation coefficient of the volume was 39.11%; within the stands, variation coefficients of plant height were basically the same （about 20%）. The variation coefficient of diameter at breast height in Qijiang reached the maximum of 42.42%, followed by that in Youyang. The variation coeffi- cients of volume and diameter at breast height were consistent; seed bearing coefficient （SBC） of C. funebris stand in Pengshui exhibited the maximum variation, which indicated that C. funebris stand in Pengshui was conducive to establishing seed stands and constructing seed orchard by using the selected stands. [Conclusion] It is necessary to conduct provenance selection.
基金Supported by Assistance Fund for National Seed Base of Forest Tree
文摘Based on the 6-year-old young forests of 40 cypress(Cupressus funebris) families from four provenances(Fengdu County, Youyang County and Zhong County of Chongqing City, and Qiandao Lake in Zhejiang Province), differences in growth traits between families and provenances were studied to select excellent families, so as to provide necessary data support for the upgrading of cypress seed gardens and inferior thinning of seed gardens. The results showed that there were significant differences in tree height, diameter at one meter height, crown width and growth potential between families and provenances. The coefficients of variation among families were 10.25%, 7.19%, 5.91% and 0.98%, respectively, and the coefficients of variation in tree height and diameter at one meter height among provenances were 7.25% and 12.58%, respectively, indicating that the tree height and diameter at one meter height of the superior cypress tree families were rich in variation among families and provenances, and there was potential for high-generation breeding. According to the selection rate of 15%, six excellent families for afforestation(Feng 8, Shi 4, Feng 1, Ye 14, Shi 3, and Ye 6) were screened. The average diameter at one meter height, tree height and crown width of the six excellent families were, respectively, 2.97 cm, 3.39 and 0.78 m, which were 18.82%, 12.70% and 15.42% higher than the family average, respectively, and 15.09%, 9.79% and 15.53% higher than the control group, respectively.
文摘【目的】针对川中丘陵区普遍存在的柏木人工林密度过大、木材生产力低、林下灌草盖度低和天然更新不良等问题，开展生态疏伐试验，探讨间伐强度对林分生长和林下植物的影响，为开展柏木生态经济型防护林的营林活动提供参考。【方法】以25年生柏木人工林为研究对象，采用随机区组方法，设置4种间伐强度（20%～25%，15%～20%，10%～15%和对照）的处理，观察林分胸径、树高、蓄积量、生物多样性和天然更新幼苗数量，探讨间伐强度对其影响。【结果】不同强度间伐5年后林分平均胸径和胸径连年生长量在各处理之间均存在显著差异，胸径生长量随间伐强度加大而增加；平均树高以20%～25%间伐强度最大，达10.7 m，但20%～25%间伐强度与15%～20%间伐强度和10%～15%间伐强度之间无显著差异，而树高连年生长量在不同处理之间差异显著；20%～25%，15%～20%和10%～15%不同强度间伐5年后林分蓄积量分别为97.35，93.43和93.19 m3·hm －2，均比对照小，但蓄积连年生长量随间伐强度由高到低分别为6.11，4.58和3.66 m3·hm －2 a －1，均高于对照；20%～25%间伐强度林分的灌木和草本 Simpson 指数分别为0.7695和0.4446，Shannon-Wiener 指数分别为1.7025和0.7690，都比其他处理高；不同间伐强度天然更新幼苗株数仅在苗高5～30 cm 等级存在显著差异，30～50和50～150 cm 的幼苗在不同处理之间差异不明显；评价结果表明，综合得分以20%～25%间伐强度最大，且随间伐强度降低而减小。【结论】间伐后保留木的生长空间和营养空间得到有效改善，林分胸径和树高生长量随间伐强度增大而增加，但不同间伐强度蓄积量差异不显著；适度间伐可提高林下灌木和草本生物多样性指数；林分更新幼苗数量也随着间伐强度的增大而增加；就本研究的4种间伐强度而言，中龄阶段柏木人工林的适宜间伐强度为20%～25%。
