再论全国森林资源年度出数方法

基于笔者2013年研究提出的全国森林资源年度出数方法,结合当前对国家"十二五"规划纲要目标进行评估的实际需求,再次研究提出2种改进的年度出数方法,即顺序平移出数和综合折中出数;同时,利用第五次全国森林资源清查以来的多次清查数据,对几种不同的年度出数方法进行了对比,并从时效性、稳定性和确定性等方面对其结果进行了分析。森林资源年度出数方法的优劣,需根据年度出数结果进行综合分析评估,在考虑数据时效性的同时还需兼顾年度数据与定期发布数据之间的衔接性。     

分层抽样下的森林资源清查数据年度更新探讨

根据江苏省森林资源清查的历史数据和宏观区域规划信息,对以省为单位的调查总体进行分层。然后,在资源动态变化较大的各层内随机抽取一定量的样地进行地面调查,而在资源变化相对稳定的层,直接引用前一年度的固定样地调查数据,进行分层抽样估计,从而以较小的成本实现森林资源清查数据年度更新。同时,利用江苏省2000—2005年的森林资源清查样地数据进行了验证,结果表明此方法可行。     

关于森林资源年度监测总体方案的思考

森林资源年度监测是近年来一直备受关注的重要主题。基于我国森林资源清查现状及存在的问题,借鉴国外森林资源清查与监测的成功经验和做法,提出了国家森林资源年度监测的指导思想、基本原则和总体思路,以及调整现行体系的目标方案和过渡方案,并对年度监测方案的优缺点进行了分析和评价,可为第十次全国森林资源清查的优化改革提供参考依据。     

山西省森林资源多功能经营初探

文章基于2015年第九次全国森林资源清查山西省清查和全省二类调查的实测数据,介绍了山西省森林资源的现状与森林资源特点,提出了森林多功能森林经营方法,以期为山西省森林资源质量提高提供参考。     

广东省“十四五”期间森林资源保护与发展思考

以2017年第九次全国森林资源清查广东省第八次复查数据为基础,从分析广东省多期森林资源清查数据规律入手,揭示广东省森林资源的特点和变化趋势,结合广东省发展战略,提出了今后一段时间,特别是"十四五"期间森林资源发展、生态建设和产业发展的相关策略。     

“十二五”时期我国人工林结构变化趋势分析

依据第八次全国森林资源连续清查分省、分林种和树种的人工林数据,综合分析其本底结构,结合相关年度营造林综合核查调查数据,对"十二五"期间人工林结构变化趋势进行分析。     

省级森林资源年度出数方法探讨

如何实现森林资源年度出数,一直都备受关注。参照近年提出的国家层面森林资源年度出数方法,提出了省级森林资源年度出数的基本原则和技术思路,并利用近期贵州、辽宁两省的森林资源连续清查数据,对每年调查1/5样地、采用移动平均数进行年度估计的方法进行了深入分析。通过采用不同权重方案进行对比分析后发现,每年取相等权重的方案尽管在时效性方面会有所损失,但数据的稳定性最高,能客观反映森林资源年度数据的变化趋势,是可选的最佳方案。     

全国森林资源清查样地标准化和时间归一化数据库的建立

为实现森林生物量和碳储量的年度监测,准确把握森林资源的消长动态,研究探讨了全国森林资源清查样地数据标准化和归一化的技术方法和路线,对以省为单位的最新两期或多期(1999—2015年)森林资源清查地面样地数据进行标准化和时间归一化,获取目标年度的森林资源样地和样木数据,建立了全国范围的2005,2012和2014年3个年度样地和样木数据库,为我国森林资源数据分析、森林蓄积量和生物量估算等多项工作提供有效地面数据支撑。     

河北省主要树种单木和林分生长率模型研建

利用第六次至第九次全国森林资源清查河北省2001,2006,2011,2016年4个年度的固定样地调查数据,采用非线性回归估计方法,建立了18个树种组的单木胸径生长率和材积生长率模型,以及12个树种组的林分材积生长率模型。结果表明,单木生长率模型的平均预估误差(MPE)基本都在3%以内,而平均百分标准误差(MPSE)、胸径生长率模型大都在10%以内,材积生长率模型大都在20%左右;林分生长率模型的平均预估误差(MPE)基本都在5%以内,平均百分标准误差(MPSE)大都在25%以内。所建模型可为河北省开展森林资源年度更新提供技术支撑。     

江苏省第8次森林资源清查技术特点与思考

江苏是一个平原少林地区,林地面积和林木蓄积量都较少,新中国建立以来,根据全国森林资源连续清查统一部署,全省共开展了6次森林资源连续清查（一类清查）,分别为1979年开展初查,1988年、1990年、1995年、2000年、2005年开展了5次复查,根据《森林法》有关规定,2009~2014年全国开展第8次森林资源清查工作,根据2004年国家林业局出台的国家森林资源连续清查技术规定和有关补充规定,江苏本次清查在掌握森林资源现状及动态的基础上,加强了森林生态系统和森林生物量等调查因子,采集了大量生态调查数据,扩充了森林资源清查生态状况监测内容。笔者结合江苏省森林资源实际情况,对清查技术标准作了系统的分析和思考,供林业调查及决策参考。     

Valuing forest recreation on the national level in a transition economy: The case of Poland

Recreation benefits constitute a substantial part of the total economic value of forests, and are important for the choice of multi-functional forest policies. The application of methods valuing such benefits is in its infancy in transition economies in Central and Eastern Europe (CEE), so value estimates for policy use are sometimes transferred from Western Europe proportionally scaled down by GDP. However, little is known about how recreation values vary with income, and one risks underestimating benefits in CEE. This paper reports the findings of the first comprehensive, national-level study in any CEE country estimating annual and per trip forest recreation values in Poland using the Travel Cost (TC) and Contingent Valuation (CV) methods. Two in-person interview surveys of forest recreation behaviour were carried out. The first was administered on-site in ten representative forest areas, and the other in the homes of a national sample of adult Poles. Results show that forest recreation is highly valued in Poland, at Euros 0.64–6.93 per trip per person, depending on the valuation method. Both trip frequency and per trip values are higher than the average in Western Europe, despite a lower income level. Thus, a simple GDP-adjusted transfer from Western Europe would substantially undervalue forest recreation in Poland. Further, a comparison of TC consumer surplus estimates and GDP/capita in Europe shows no clear relationship, indicating that a range of cultural, institutional and other factors may be important.     

未来中国森林碳蓄积预估初步研究

根据我国林业部分的规划,在持续、有序绿化的前提下,从2005~2044年,中国森林从大气中净吸收的C可达到51.74×108~125.30×108t,约占同期我国CO2排放总量的27.1%~65.6%。年吸收量呈逐年递增态势,2025~2044年间的年平均吸收量可达1.91×108t。在实现国土绿化的过程中,我国森林资源将强烈抑制大气CO2的升高,具有极其可观的生态效益、环境效益。我国森林资源CO2同化能力和碳蓄积量的双双提高,将为我国的经济发展预留更广阔的CO2排放空间,对我国参与国际间环境以碳排放的谈判具有实质性意义。     

基于林分生长模型的森林资源年度档案更新技术探讨——以江西省森林资源年度档案更新为例

森林资源档案是森林经营管理的一项重要内容,准确及时的掌握区域森林资源年度更新数据,是实施科学规划合理经营的依据.在吸取当前我国森林资源监测体系相关成果基础上,通过对影响林分生长的自然因素多项因子综合分析,研建林木生长模型和林分生长模型两个层次模型,建立基于林分生长模型的森林资源年度档案更新技术体系.以期为以林地“一张图”为基础的林地保护利用数据年度变更提供参考.     

Estimating CO(2) flux from snowpacks at three sites in the Rocky Mountains

Soil surface CO(2) flux (F(s)) is the dominant respiratory flux in many temperate forest ecosystems. Snowpacks increase this dominance by insulating the soil against the low temperature to which aboveground components are exposed. However, measurement of F(s) in winter may be impeded by snow cover. Likewise, developing annual F(s) models is complicated by seasonal variation in root and microbial metabolism. We compared three methods of measuring sub-snow F(s): (1) dynamic chamber measurements at the upper snowpack surface (F(snow)), (2) dynamic chamber measurements at the soil surface via snowpits (F(soil)), and (3) static estimates based on measured concentrations of carbon dioxide ([CO(2)]) and conductance properties of the snowpack (F(diffusional)). Methods were compared at a mid-elevation forest in northeastern Washington, a mid-elevation forest in northern Idaho, and a high-elevation forest and neighboring meadow in Wyoming. The methods that minimized snowpack disturbance, F(diffusional) and F(snow), yielded similar estimates of F(s). In contrast, F(soil) yielded rates two to three times higher than F(snow) at the forested sites, and seven times higher at the subalpine meadow. The ratio F(soil)/F(snow) increased with increasing snow depth when compared across all sites. Snow removal appears to induce elevated soil flux as a result of lateral CO(2) diffusion into the pit. We chose F(snow) as our preferred method and used it to estimate annual CO(2) fluxes. The snowpack was present for 36% of the year at this site, during which time 132 g C m(-2), or 17% of the annual flux, occurred. We conclude that snowpack CO(2) flux is quantitatively important in annual carbon budgets for these forests and that the static and dynamic methods yield similar and reasonable estimates of the flux, as long as snowpack disturbance is minimized.     

Mapping and spatial uncertainty analysis of forest vegetation carbon by combining national forest inventory data and satellite images

Forests play an important role in carbon sinks and mitigation of atmospheric concentrations of carbon dioxide and greenhouse effect. Given that sample plots used for collection of forest carbon observations are often much smaller than the map units of forest carbon at regional, national, and global scales, scientists are currently experiencing two challenges. The first challenge is to produce reliable maps of forest carbon using the data from inconsistent sizes of plots and image pixels. Also, because estimates of forest carbon normally contain uncertainties, the second challenge is to accurately model propagation of uncertainties from input data to output results. In this study, a methodology for mapping and analyzing spatial uncertainty of forest carbon estimates was developed to address these challenges. The methodological framework consisted of two methods. The first one was up-scaling method that combined and scaled up existing national forest inventory plot data and satellite images from smaller sample plots and image pixels to larger map units. The second one was spatial uncertainty analysis and error budget method that entailed modeling propagated uncertainties through a geostatistical mapping system. A case study using 46 permanent national forest inventory plots from Wu-Yuan County, Jiangxi, China, was undertaken to test this methodology. The results showed that this method reproduced not only the spatial distribution of forest carbon but also the spatial pattern of variances of its estimates and was able to quantify the contributions of uncertainties from the field plot data and satellite images to the uncertainties of forest carbon estimates. Thus, this study, to some extent, overcame the gaps that currently exist in the generation and assessment of forest carbon estimation maps. Moreover, the results showed that in this case study, the variation of the band ratio defined as (TM2 + TM3 + TM5)/TM7 contributed more uncertainties to the estimates of forest carbon than the variation of the plot data. In addition, we also found out that the product of the input plot forest carbon variance and the band ratio variance, implying the interaction between these two variables, reduced the uncertainties of the forest carbon estimates.     

试论森林环境资源核算

环境资源核算是当前国际社会最关注的热门课题之一。作者指出了现行国民经济核算体系的缺陷, 论述了世界环境资源核算的研究现状及发展前景, 重点介绍了环境资源核算研究的指导思想、环境资源核算的新概念及其分类、价值和计算方法、环境产业问题等, 并对我国开展森林环境资源核算研究提出了几点建议。     

Annual volume increment of the European forests—description and evaluation of the national methods used

Key message

In order to obtain the necessary information for decision making etc., it is of increasing importance to be able to assess increment in a reliable way. Only repeated measurements on permanent sample plots in national forest inventories can provide accurate and comprehensive information on the various components of annual increment. Such inventory systems are increasingly employed in European countries. The felling/increment ratio, characterizing wood use sustainability, should be expressed as the ratio of felled living trees (excluding dead trees) and net increment.

Context

Reporting of gross and net annual increment is an element of international forest resource assessments and crucial for sustainable forest management. A number of approaches exist for the estimation of increment and its various sub-components.

Aims

The main objectives of the study are to assess in detail what methods European countries have used and are planning to use in the future for international reporting of increment. Also, the usefulness of the various approaches for the assessment of increment is evaluated.

Methods

A questionnaire asking about their assessment methods was distributed among the UNECE/FAO national correspondents of all European countries and members of the UNECE/FAO Team of Specialists on Monitoring Sustainable Forest Management. Databases of the Temperate and Boreal Forest Resource Assessment 2000 and of the State of Europe’s Forests 2011 were also used. Furthermore, the methodological background was described on the basis of relevant literature sources and some examples for country groups presented.

Results

Countries have indicated what methods they used for assessment of various increment components, and the percentage of countries, forest area, and growing stock corresponding to these replies has been calculated. With regard to gross annual increment, these metrics represent about one third for inventories based on permanent sample plots, but this percentage is on the increase.

Conclusion

The concept of the “control method” for forest management was developed more than 100 years ago but only utilized at the local level. The same methodology is now widely used at the national and regional level due to the implementation of modern national forest inventories using permanent sample plots. Care should be taken to utilize the data correctly for international forest resource assessments, in order to, e.g., avoid double counting of dead trees.

     

Variation in biomass expansion factors for China’s forests in relation to forest type, climate, and stand development

? Context

Biomass expansion factors (BEFs, defined as the ratios of tree component biomass (branch, leaf, aboveground section, root, and whole) to stem biomass) are important parameters for quantifying forest biomass and carbon stock. However, little information is available about possible causes of the variability in BEFs at large scales.

? Aims

We examined whether and how BEFs vary with forest types, climate (mean annual temperature, MAT; mean annual precipitation, MAP), and stand development (stand age and size) at the national scale for China.

? Method

Using our compiled biomass dataset, we calculated values for BEFs and explored their relationships to forest types, climate, and stand development.

? Results

BEFs varied greatly across forest types and functional groups. They were significantly related to climate and stand development (especially tree height). However, the relationships between BEFs and MAT and MAP were generally different in deciduous forests and evergreen forests, and BEF–climate relationships were weaker in deciduous forests than in evergreen forests and pine forests.

? Conclusion

To reduce uncertainties induced by BEFs in estimates of forest biomass and carbon stock, values for BEFs should be applied for a specified forest, and BEF functions with influencing factors (e.g., tree height and climate) should be developed as predictor variables for the specified forest.     

基于固定样地的县级森林资源动态监测技术方法

2008年杭州市开展了以固定样地为基础的森林资源与生态状况监测,为将所辖县(市、区)的小班数据更新到2008年度,以建德市为例,提出了以小班档案台帐更新、补充调查、复位调查和模型推算更新为监测手段的县级森林资源动态监测技术方法,同时探讨了基于固定样地的小班蓄积量动态模型研建技术。