森林资源连续清查固定样地复位的探讨

在介绍固定样地及其复位概念的基础上,着重论述了影响固定样地复位的主要因素和提高固定样地复位率的主要途径以及查找样地的主要方法与经验。     

浅议森林资源清查样地复位

通过分析影响森林资源连续清查样地复位率的因子,寻找样地复位的途径,以提高森林资源连续清查样地复位率。     

广西森林资源连续清查角规样地体系评价

广西森林资源连续清查(以下简称"广西连清)"角规样地体系,是我国唯一的以点抽样理论为基础,以固定角规样地为监测载体的省(区)级森林资源连续清查体系。广西连清第7次复查,除了增设的方形样地调查以外,还对原有的角规样地进行了复查,因此本文得以用同时进行调查的方形样地调查结果作为参照对象,对角规样地体系的优点和存在的问题进行定性和定量相结合的综合分析评价。分析评价结果表明,与方形样地比较,角规样地除了具有显著的隐蔽性外,外业工作量只相当于方形样地的53%,两套体系的活立木蓄积量差异仅为3.16%,角规样地和方形样地体系总蓄积量抽样精度分别为94.47%与94.57%,均达到国家森林资源连续清查技术规定要求(≥90%)。角规样地复位率大于规定的98%,样木复位率远大于规定的95%,达97%以上,能满足林木蓄积生长量和消耗量监测的要求。角规样地体系的不足主要是由于漏测木和进测木的存在,导致森林资源的现状估计值偏低,且动态估计精度明显低于方形样地体系。     

浅谈提高森林资源连续清查样地复位率的途径

保证固定样地复位率,是提高动态估测精度的关键,是关系到森林资源连续清查（以下简称连清）成败的大问题。本文根据几年连清工作的实践,就固定样地复位技术问题和复位途径提出浅见,供同行们参考。     

关于提高森林资源连续清查样地样木复位率途径的探讨

本文运用层次分析法和ＡＢＣ分类法进行了森林资源连续清查样地复位率影响因素的分析，据此探讨了提高样地复位率的途径。     

关于提高森林资源连续清查样地复位率的几点体会

就森林资源连续清查而言,清查是目的,连续是关键。只有建立在样地复位连续清查的基础上,才具有资料数据的可比性、分析性。根据山东省第五次森林资源连续清查的实践经验,从五个方面介绍了如何提高样地复位率。     

关于提高森林资源连续清查样地样木复位率途径的探讨─—层次分析法和ABC分类法的运用

本文运用层次分析法和ＡＢＣ分类法进行了森林资源连续清查样地复位率影响因素的分析，据此探讨了提高样地复位率的途径。     

森林资源规划设计中样地复位率影响因素分析

结合第三次森林资源规划设计样地调查工作实践，对影响样地调查复位的原因进行分析，并提出相应的对策。     

抽样调查中复合样地设计方法研究

通过对现行各种样地设计方法进行分析比较，提升出一种一般意义上的样地设计方法－复合样地设计法；复合样地设计的基本思想是，将样本划分成n类，在固定面积为S的样地上套设n个面积不同的子样地，每一类样木对应于一个子样地，在各子样地上分别获得各类样木的估计值，经换算后获得整个样地的估计值，文中给出多种同时具有角规样地和固定样地优点的具体复合样地形式，并以贵州省的方形样地材料予以验证。     

森林资源连续清查中固定样地标志的改进

固定样地是森林资源清查体系最基本的抽样单元，通过对所有固定样地多期的调查监测，最终得出各地区森林资源的现状及动态变化情况，所以固定样地的准确复位便成为森林资源清查体系的核心工作。目前，我国森林资源连续清查主要依靠人工设置一些固定样地标志，以保持样地位置的固定，并保证样地在以后的调查监测工作中不再发生位置和形状的改变。     

角规复合样地的动态估计方法研究

从角规样地的动态估计方法入手,以角规样地与样圆的复合样地为例,对角规复合样地的动态估计方法进行研究和探讨,提出了两套估计方案,并结合示例对各种方法的优劣进行了对比分析.     

北京市森林资源固定样地调查体系研究

结合当前北京市林业发展形势及需求,针对现有森林资源监测体系的不足,提出建立北京市森林固定样地调查体系,以完善森林资源动态监测。本文从固定样地抽样及布设、样地调查内容、数据应用等方面做出阐述,全面介绍了北京市森林固定样地调查体系的构建。     

森林资源外业调查特殊情况分析及

以2020年湖北省森林资源调查为例，结合操作细则和外业调查经验，列举样地复位、样地因子调查、样木因子调查中的特殊情况，分析原因，明确处理方法，旨在统一工作标准，保证工作质量，提高工作效率。     

Effects of field plot configurations on the uncertainties of ALS-assisted forest resource estimates

The effects of field plot configurations on the uncertainties of plot-level forest resource estimates were analyzed using airborne laser scanner data, aerial photographs and field measurements. The aim was to select a field sample plot configuration that can be used for both large area and management inventories. Error estimates were evaluated at the plot level using six different training plot configurations. Additionally, separate plots with two different sizes were used for evaluation. Stem volume and five other forest resource characteristics were considered. The field measurement costs of the different plot configurations were also studied. RMSEs and mean deviations for airborne laser scanning ALS-assisted estimates were practically the same for the fixed radius plot, the two concentric plots and the angle count plot with a basal area factor of q = 1 for all three evaluation plot sizes. Angle count plots with basal area factors of q = 1.5 and 2 increased the RMSEs. For the former plot configurations, the RMSEs for the ALS-assisted estimates could be attributed to inaccuracy in the predicted relationships between the field data and ALS data, not to the training plot configuration. Tree measurements and costs can, therefore, be reduced from those of the Finnish management inventories without increasing RMSEs.     

野生花卉资源样地调查法研究简报

报道了一种新的野生花卉资源样地调查样方法，即利用县级森林资源调查固定样地的调查成果，在固定样地中抽取并测设里生花卉资源查样地，该方法科学性较高，能达到调查成本低，效率高，精度有保证的目的，对野生经济植物资源调查具有推广价值和指导意义，文中对野生卉资源样地调查方法和蕴藏量估算作了简要介绍。     

基于蓄积的森林生物量估算方法的对比分析

正森林生物量是指一个森林群落在一定时间内积累的有机质总量,是森林生态系统重要的特征数据,因此世界各国越来越重视对森林生物量的监测与研究[1-3],建立的生物量模型众多[4-6]。大尺度森林生物量监测,是以省、流域、国家乃至全球为对象,在估算方法一致的前提下,对多个时间点的森林生物     

Efficiency of inventory plot patterns in quantitative analysis of vegetation: a case study of tropical woodland and dense forest in Benin

The main issue in forest inventory is the reliability of data collected, which depends on the shape and size of inventoried plots. There is also a need for harmonisation of inventoried plot patterns in West Africa. This study focused on the impact of plot patterns on the quantitative analysis of two vegetation types of West Africa based on case studies from Benin. Twenty and fifteen plots of 1 ha each were demarcated in dense forest and woodland, respectively. Each 1 ha plot was divided into 100 quadrats of 100 m² each and diameter at breast height (dbh) of trees was recorded in each quadrat. The required time to measuring trees diameter in each 1 ha plot was also recorded to compute the mean inventory effort. From the 100 quadrats in each 1 ha plot, 14 subplots of different shapes and sizes were considered by grouping together adjacent quadrats. The basal area of each subplot was computed and the relationship between estimation bias of the basal area and the size of subplots was modeled using Smith's Law (Smith 1938). The mean absolute error of the shape parameter c of Weibull distribution was computed for each of the subplot shape, size and direction. The direction and shape of subplots did not influence significantly (P > 0.05) the precision of the quantitative analysis of vegetation. However, square subplots were suitable in practice. On the contrary, plot size was significantly (P < 0.05) and inversely correlated to estimation efficiency. The optimal plot size for quantitative analysis of vegetation was 1 800 and 2 000 m2 with an inventory effort of 0.51 and 0.85 man-days per subplot in woodland and dense forest, respectively. It is concluded that use of standard sample sizes will help to harmonise a forestry database and to carry out comparisons at regional level.     

杉木无性系生长与材性测定的适宜无性系株数与小区株数

对 1块 7年生杉木无性系试验林在不同无性系株数、小区株数抽样下 ,进行树高、胸径、材积及木材密度的无性系排序、遗传参数估算 ,并作效果比较 ,结果如下 :对于生长量测定 ,适宜无性系株数应在 2 0株以上 ,以 30株测定效果较佳 ;适宜小区株数在不同无性系株数下 ,结果不太一致 ,普遍表现为参试无性系株数少 ,宜采用少株小区 ;参试无性系株数多 ,则宜采用多株小区。试验株数为 6、12、2 4株时 ,分别采用 2、4、3或 4株小区的效果较好。对于测定木材密度的适宜无性系采样株数宜在 6株以上 ,而适宜小区采样株数为 1株 ,且为所在小区最优株     

Final results from a trial to test the effect of plot size on Eucalyptus hybrid clonal ranking in coastal Zululand,South Africa

Hybrid clones with Eucalyptus grandis as one parent and, generally, E. urophylla as the other parent, are deployed commercially as monoclonal blocks by Sappi in the subtropical region of coastal Zululand, South Africa. In monoclonal blocks genotypes are grown in self-competition. Performance under this scenario may not necessarily correlate well with performance where genotypes are competing for resources with a number of genetically dissimilar genotypes. There is an uncertainty whether plot configuration or size influences clonal ranking and therefore selection of clones for commercialisation. Final results at age eight years of a trial testing eight selected Eucalyptus hybrid clones in single-tree, eight-tree line, and eight x eight tree square plots are reported in this paper. Ranking of the eight clones between the half rotation (44 months) and full rotation (94 months) measurement have remained stable in the single-tree and line plots, but there have been some changes in the square plots. At 94 months, clonal ranking between the single-tree and line plots was consistent (r_p = 0.98) with only two clones changing ranks. When comparing the clonal ranking of the single-tree plots to the large square plots rank changes have been significant (r_p = 0.65). The overall means for the three different plot types are very similar. The range of the clonal means for tree volume in the single-tree plots (0.4042 m³) is more than five times the range for the square plots (0.0709 m³). Gain predictions using data from the single-tree plots overestimated the realised gains measured in the square plots. The top-performing clone in the single-tree plots had a predicted gain of 74% over the trial mean, but only yielded 7% more in the square plots. Similarly, the worst-ranked clone in the single-tree plots did not perform as poorly as what was predicted (?59%) and produced only 13% less than the trial mean on the square plots.