Below-ground growth characteristics of 13-year-old Pinus densiflora on different contour conditions in a post-fire plantation in Samcheuk,Korea

We estimated the growth volume of artificially reforested Pinus densiflora in a post-fire area on three different contour conditions by comparing and analyzing the vertical and horizontal distributions of below-ground roots on each contour. The main roots at the south-facing slope (SS) developed in a long and straight form, and those on the north-facing slope (NS) in a twisted form. The side roots developed more than the main roots on the Ridge. The depth of taproots decreased in the following order: SS?>?NS?>?Ridge. The roots on the SS developed in a pile-form root structure whereas those in the Ridge and NS developed concentrically near the root collar. The amount of root development decreased in the following order: SS?>?NS?>?Ridge. The ratio of fine roots from the whole-root development decreased in the following order: Ridge?>?SS?>?NS. These results can guide considerations of growth differences according to the planting contour conditions for future establishment of P. densiflora artificial plantations.

Decomposition dynamics and ecological stoichiometry of Quercus acutissima and Pinus densiflora litter in the Grain to Green Program Area of northern China

Litter decomposition and ecological stoichiometry of nutrient release is an important part of material cycling and energy flow in forest ecosystems.In a study of the ecological stoichiometry and nutrient release during litter decomposition in a pine–oak forest ecosystem of the Grain to Green Program(GTGP)area of northern China,a typical pine and oak species(PDS:Pinus densiflora Sieb.,QAC:Quercus acutissima Carr.)were selected in the Taiyi Mountain study area.The ecological stoichiometry characteristics of carbon(C),nitrogen(N)and phosphorus(P)and litter decomposition dynamics were studied by field sampling and quantitative analyses.The results showed the following.(1)The decomposition dynamics of both litters was slow-fast-slow.The most important climatic factor affecting the litter decomposition rate from May to October was precipitation and temperature from November to April of the following year.(2)Throughout the 300-day study,in both litters,C of the two litters was released,N first accumulated and was then released,and P exhibited a release-accumulate-release pattern.(3)C:P was significantly higher than C:N and N:P(p<0.05);the C:N of PSD litter was higher than that of QAC(p<0.05),but the N:P of QAC litter was higher than that of PSD litter(p<0.05).The C:N of both litters was very high in the study area,indicating that the nutrient release ability during litter decomposition in the two typical pine–oak forest ecosystems was relatively weak;therefore,more attention should be paid to nitrogen-fixing species and mixed forests in the GTGP area of northern China.

Effect of stand density and humus removal on regeneration of Pinus densiflora seedlings in a mixed conifer and broad-leaved forest

We studied the impact of stand density and forest floor humus removal on regeneration ofPinus densiflora in a mixed co- nifer and broad-leaved forest on the Daimonji-Yama Mountain, Kyoto, Japan. Three levels of stand density were set, i.e., a clear-cut site, a heavily thinned site and a lightly thinned site. In each density treatment, comparisons were carried out between humus removal （A0-free） and humus intact （A0-intact） subplots. We counted the emergence of sown pine seeds and measured survival and growth of pine seedlings over the next four years. In addition, light conditions and the recovery of understory were monitored. Results show that thinning intensity and humus removal promoted the establishment and growth of seedlings. One exception, however, was that seedling growth was minimal in the heavily thinned A0-intact subplots. This was due to a strong response of understory vegetation growth on the treatment combination, which hindered the pine seedling growth. Furthermore, we found that the canopy openness measured at 1.3-m height remained at least 35% for the heavily thinned site in 2008. The results suggest that the removal of the A0 layer after heavy thinning is the most effective and labor-saving operation for P. densifiora regeneration.

Study on the Practical and Ideal Mature Age of Pinus densiflora

This study was conducted on the analytic tree and got the fitting empirical equation of tree growth, in which the tree growth rate was used as the variable and time as the independent variable. The arithmetical operation to the function got the mature age of tree growth, and the practical and ideal mature ages of Pinus densiflora were 58 and 123.5 a, respectively. In addition, the application research direction and matters needing attention were proposed.

北方砂石山2种常见灌木对刺槐、赤松纯林生长胁迫性

为研究北方砂石山构树(Broussonetia papyrifera)、黄荆(Vitex negundo)与刺槐(Robinia pseudoacacia)、赤松(Pinus densiflora)纯林共生期间的种间制约关系,探索对刺槐过熟林更新、赤松林复壮的最佳方法,选取了曲阜市国有石门寺林场有代表性的刺槐、赤松纯林为研究对象。研究结果表明,49年树龄刺槐、赤松林截至2020年,活立木保有量分别为28株/667m^(2)、40株/667m^(2),死亡率为2000年活立木保有量的74.5%、38.5%,同比增长36%、7.7%,通过样本相关系数的计算公式得出,构树、黄荆与刺槐、赤松纯林树高、冠幅生长量成显著负相关关系。2000年林分出现“天窗”后,通过天然下种林下植物群落逐渐形成,由于构树、黄荆极强的适应性对刺槐、赤松生长形成了很强的胁迫性,加剧了乔灌种间土壤水分恶性竞争,进一步加快了刺槐、赤松死亡速度。

磴口县彰武松和沙地赤松引种试验

2017年春磴口县中国林业科学研究院沙漠林业实验中心进行引种彰武松(Pinus densifloraSieb.et Zucc.var.Zhangwuensis Zhang,Li et Yuan)和沙地赤松(Pinus densiflora Sieb.et Zucc.)试验。结果表明,尽管引种区与原产地在土壤营养成分存在着较大差异,但彰武松和沙地赤松基本保持了良好的生长态势,初步认为磴口县适合彰武松和沙地赤松生长。

彰武松半同胞子代表型分析

以彰武松(Pinus densiflora var.zhangwuensis)半同胞子代林为对象,研究其树高、胸径、针叶长度和侧枝生长量等性状的表型变异。综合分析了半同胞子代数量性状的遗传效应和分化趋势。研究结果表明,半同胞家系间树高、胸径、针叶长度和侧枝生长量4个性状存在一定的变异,变异系数分别为21.09%、32.56%、29.97%和37.44%,且4个性状的差异极显著;半同胞子代的性状受遗传基因控制程度较高,遗传力较强,遗传增益较高,4个性状的遗传力分别为0.826、0.832、0.956和0.636,遗传增益分别为13.922%、21.631%、22.924%和19.742%。彰武松子代存在性状分离现象,但性状大多处于高值区。说明子代群体在性状分离过程中较多遗传母本的优良特性,为下一步选优、纯化提供了基础和先决条件。

辽东半岛赤松群落结构与多样性变量

根据辽东半岛赤松(Pinus densiflora sieb et Zucc)群落对环境条件的响应,对赤松群落结构与多样性变量进行研究,有利于群落内功能特征从生态位分布空间上的功能分异度的研究向基于性状的研究转变。根据CFERN行业标准,在已经建立的动态监测指标体系基础上,通过功能距离和谱系结构在共有性状连续变化轴上的分类位置为依据,对辽东半岛赤松群落结构与功能等一系列变量进行分析。结果表明:赤松种群分布的同质性最强,可控制范围最大;蒙古栎在AⅢ波段后呈现出随龄级递增而周期振幅减小的变化趋势,群落总波序值均较小;群落内功能的覆盖度和耐受性可以用个体全距和移动全距来解释。得出结论,采用林龄和生长量降低性状的数量,可以预测具有功能的物种之间各林龄段的波序,证明能量流动和物质循环在各段的优势显著性;利用植物功能类型的变量,帮助我们理解生态服务的作用机制及各种服务之间的权衡关系,是一种必要的研究手段。