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| 1 | 黄龙山不同郁闭度油松中龄林林木形质评价显示文摘以黄土高原南部黄龙山林区油松人工中龄林为研究对象,按郁闭度CD<0.65(类型1)、0.65≤CD<0.75(类型2)、0.75≤CD<0.85(类型3)、CD≥0.85(类型4)将样地划分4个等级.综合林木生长、干形和分枝情况,运用层次分析法建立林木形质评价层次结构模型和指标体系,对4种郁闭度类型的油松林林木的形质水平进行了综合评价.结果表明:林木生长、干形和分枝3大类形质评价因素及其包括的胸径、树高、径高比、尖削度、通直度、分杈率、活枝下高、侧枝数、最大侧枝基径和侧枝平均基径10项指标,可以全面地反映油松林木形质水平.其中,通直度、分杈率和胸径3个指标的总权重达0.7382,对林木形质水平影响最大,是油松林木形质的主要决定因素.随着林分郁闭度的减小,林木形质综合得分表现为先升高后下降,类型2郁闭度下达到最高的90.28分,该类郁闭度下林木形质水平最优.本评价方法操作简单,可解决林木形质评价的量化问题,评价模型体系也可在黄土高原其他林木形质评价中借鉴和应用. | 尤健健 张文辉 邓磊 | 2015 | 应用生态学报2015，26，7： | 14 |
| 2 | 抚育间伐对红松人工林林木形质的影响显示文摘以东北地区林口林业局红松人工林为研究对象,将红松人工林的林木生长、树干情况、分枝情况3类评价因素,包括树高平均生长量、胸径年均生长量、冠径比、高径比、尖削度、分杈率、疏松节比例、自然整枝能力、侧枝数(>1.5 cm)、枝粗指数、侧枝平均基径11项指标作为红松林木形质评价指标,采用层次分析法作为主要分析方法,探究不同抚育强度(重度间伐:株数强度65%,蓄积强度43%;中度间伐:株数强度50%,蓄积强度28%;轻度间伐:株数强度40%,蓄积强度18%;对照)对红松林木形质的影响。结果表明:中度间伐的林木形质综合得分最高为73.427,表现为林木形质最好,形质评价等级为Ⅱ级。重度间伐林木形质的综合得分为68.114,形质评价等级为Ⅲ级,轻度间伐林木形质得分为59.150,形质评价等级为Ⅳ级;对照组林木形质综合得分为43.432,形质评价等级为Ⅴ级。树干情况对红松林木形质的影响最大,由形质指标判断矩阵可得出约占65.5%。通过对郁闭情况下的红松林进行适当的抚育间伐能够有效改善保留木的生境进而提高红松林木形质水平,对红松人工林生产经营有重要的指导意义。 | 于雷 贾炜玮 丛培东 | 2021 | 西南林业大学学报(自然科学)2021，41，6： | 6 |
| 3 | A basal area increment model for individual trees in mixed continuous cover forests in Iranian Caspian forests显示文摘The aim of this study was to develop and test a new basal area growth model in mixed species continuous cover forests in northern Iran.Weanalyzed 421 core samples from 6 main species in the forest area to develop our growth model.In each plot,we measured variables such as total tree height(m),diameter at breast height(DBH)(cm)and basal area of larger trees as cumulative basal areas of trees(GCUM)ofDBH[5 cm.The empirical data were analyzed using regression analysis.There was a statistically significant nonlinear function between the annual basal area increment,as the dependent variable,and the basal area of the individual trees and competition as explanatory variables.Reference area from the largest trees,was circular plot with area of 0.1 ha.GCUM was estimated for trees of DBH>5 cm.Furthermore,we investigated the dependencies of diameter growth of different species on stand density at different levels of competition,and diameter development of individual trees through time.The results indicate that competition caused by larger neighborhood trees has a negative effect on growth.In addition,the maximum diameter increment is affected by competition level.Therefore,the maximum diameter increment of species occurs when the trees are about 35–40 cm in dense-forest(40 to 0 m^2 per ha)and when the trees are about 60 to 70 cm in very dense forest(60 to 0 m^2 per ha)which is more likely to Caspian natural forests with high level density due to uneven-aged composition of stands. | Nishtman Hatami Peter Lohmander Mohammad Hadi Moayeri Soleiman Mohammadi Limaei | 2020 | Journal of Forestry Research2020，31，1： | 0 |
| 4 | Analysing the effect of stand density and site conditions on structure and growth of oak species using Nelder trials along an environmental gradient:experimental design,evaluation methods,and results显示文摘Background: Most current approaches in forest science and practice require information about structure and growth of individual trees rather than- or in addition to- sum and mean values of growth and yield at forest stand level as provided by classic experimental designs. By inventing the wheel design, Nelder provided the possibility to turn to the individual tree as basic information unit. Such trials provide valuable insights into the dependency of growth on stand density at particular sites.Methods: Here, we present an extension of the original design and evaluation by Nelder.(i) We established Nelder wheels along an environmental gradient through Europe in atlantic climate in Belgium and Germany, Mediterranean climate in Italy, continental climate in Hungary as well as on high land climate in Mexico. Such disjunct Nelder wheels along an environmental gradient can be regarded and analysed as a two-factor design with the factors of site condition and stand density.(ii) We present an advanced statistical approach to evaluate density dependent growth dynamics of trees planted in form of the Nelder design, which considers spatio-temporal autocorrelation.(iii)We prove the usefulness of the methods in improving ecological theory concerning density related productivity,trade-offs between facilitation and competition, and allometric relations between size variables.Results: First evaluations based on remeasured Nelder wheels in oak(Quercus robur L.) show a size growth differentiation during the first observation period. In particular, height growth is accelerated under higher competition indicating facilitation effects. We detect furthermore a high variability in allometric relations.Conclusions: The proposed design, methods, and results are discussed regarding their impact on forest practice,model building, and ecological theory. We conclude that the extended Nelder approach is highly efficient in providing currently lacking individual tree level information. | Enno Uhl Peter Biber Matthias Ulbricht Michael Heym Tamás Horváth Ferenc Lakatos Janós Gál Leonhard Steinacker Giustino Tonon Maurizio Ventura Hans Pretzsch | 2015 | Forest Ecosystems2015，2，3： | 0 |
| 5 | Group planting of cherry (Prunus avium L.) fosters growth and tree quality is superior to conventional row planting in Germany显示文摘Wild cherry trees produce high-quality timber and provide multiple ecosystem services.However, planting and tending cherry stands in conventional rows are too costly.Therefore, low density group planting was trialled as an alternative to row planting.The mortality, growth, and quality of planted cherry trees were compared between the group and row planting.The influence of neighbourhood competition and light availability on growth and quality was studied.The group and row planting of cherry trees were established at a wind-thrown site in southwestern Germany in the year 2000.In group planting, five cherry seedlings and seven lime seedlings(Tilia cordata Mill.) were planted with a 1×1 m spacing.In total, 60 groups were planted per hectare with a 13×13 m spacing.In contrast, 3300 seedlings(2475 cherries and 825 limes) were planted per hectare in row planting with a 3×1 m spacing.Ten groups and plots(10×10 m) were randomly established in group and row planting stand, respectively.The survival rate, stability(height to diameter ratio), diameter, and height growth were significantly higher in group planting.In the group plantings,40.5% of cherry trees had straight stems and 13.5% had a monopodial crown compared with 15% with straight stems and 2% with a monopodial crown in row planting.The proportion of dominant cherry trees in canopy was 49% in groups compared with 22% in rows.The length of branch free bole was significantly higher in cherries planted in groups than those grown in rows.Intra-and interspecific competition reduced the growth and stability of cherry trees in row planting, but not in group planting.Light availability did not cause any significant effects on growth and quality between group and row planting.This first study on cherry group planting indicates that the survival rate, growth, and tree quality were higher in groups than in rows at this early development stage.The competition by naturally born seedlings was an important reason for the difference in performance between group and row planting.This study will encourage forest practitioners to establish more cherry group planting trials on multiple sites to test the effectiveness of this alternative technique as a tool of regeneration and restoration silviculture. | Somidh Saha | 2018 | Journal of Forestry Research2018，29，4： | 0 |
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