加拿大森林可持续经营研究进展及其对中国的启示

加拿大是蒙特利尔进程倡导者、成员国和进程秘书处所在国,蒙特利尔进程是关于温带及北方森林保护与可持续经营标准与指标的多边联合行动,中国是蒙特利尔进程的成员国,同时也是以温带及北方森林为主体的国家。森林可持续经营是1992年世界环境与发展大会后为解决全球环境与发展问题而出现的新的研究方向,也是联合国森林论坛的议题,加拿大在该领域一直处于领先位置,因此研究加拿大在森林可持续经营方面主要开展的工作及所取得的进展,分析他们的工作方法和经验,对我国开展该领域的工作具有重要的参考价值     

Filling the gap: improving estimates of working tree resources in agricultural landscapes

Agroforestry plantings and other trees intentionally established in rural and urban areas are emerging as innovative management options for addressing resource issues and achieving landscape-level goals. An understanding of the ecosystem services contributed by these and future plantings would provide critical information to policy and program developers, and a comprehensive inventory would contribute to estimating the cumulative effects of these plantings. Trees used in these practices are not explicitly inventoried by the primary national forest resource inventory of the United States: the Forest Inventory and Analysis (FIA) program of the USDA Forest Service. The FIA program currently limits its inventories to trees in forests meeting specific size and density criteria, but the draft FIA Strategic Plan suggests the addition of an “other treed land inventory” (excluding urban forests). In this study, we use FIA data to estimate the agroforestry and other tree resources of the Midwest and document some obstacles to effective inventories of agroforestry practices. We compare our estimates of forestland area in the Midwest to those derived from MODIS (MODerate Resolution Imaging Spectroradiometer) Vegetative Continuous Fields (VCF). The differences between these two estimates, particularly in sparsely forested states, support the idea that the expansion of the FIA program to an all-tree inventory would fill an important gap. We propose minor modifications to the inventory that would lead to an improved assessment of agroforestry and other tree resources and practices.     

Forest carbon storage in the northeastern United States: Net effects of harvesting frequency,post-harvest retention,and wood products

Temperate forests are an important carbon sink, yet there is debate regarding the net effect of forest management practices on carbon storage. Few studies have investigated the effects of different silvicultural systems on forest carbon stocks, and the relative strength of in situ forest carbon versus wood products pools remains in question. Our research describes (1) the impact of harvesting frequency and proportion of post-harvest structural retention on carbon storage in northern hardwood-conifer forests, and (2) tests the significance of including harvested wood products in carbon accounting at the stand scale. We stratified Forest Inventory and Analysis (FIA) plots to control for environmental, forest structural and compositional variables, resulting in 32 FIA plots distributed throughout the northeastern U.S. We used the USDA Forest Service's Forest Vegetation Simulator to project stand development over a 160 year period under nine different forest management scenarios. Simulated treatments represented a gradient of increasing structural retention and decreasing harvesting frequencies, including a “no harvest” scenario. The simulations incorporated carbon flux between aboveground forest biomass (dead and live pools) and harvested wood products. Mean carbon storage over the simulation period was calculated for each silvicultural scenario. We investigated tradeoffs among scenarios using a factorial treatment design and two-way ANOVA. Mean carbon sequestration was significantly (α = 0.05) greater for “no management” compared to any of the active management scenarios. Of the harvest treatments, those favoring high levels of structural retention and decreased harvesting frequency stored the greatest amounts of carbon. Classification and regression tree analysis showed that management scenario was the strongest predictor of total carbon storage, though site-specific variables were important secondary predictors. In order to isolate the effect of in situ forest carbon storage and harvested wood products, we did not include the emissions benefits associated with substituting wood fiber for other construction materials or energy sources. Modeling results from this study show that harvesting frequency and structural retention significantly affect mean carbon storage. Our results illustrate the importance of both post-harvest forest structure and harvesting frequency in carbon storage, and are valuable to land owners interested in managing forests for carbon sequestration.     

Conceptual Origins of Catastrophic Forest Mortality in the Western United States

Estimates of changes this century (1890-1990) in the total mortality from natural causes (wildfire, pests) and harvesting in the Rocky Mountain and Pacific Coastal regions of the United States (excluding Alaska) were based on yearly national forest statistics. Total accrual per year doubled this century as a result of fire suppression and accelerated tree growth. Total depletion per year did not change significantly from 1920 to 1985; after 1985, extensive pest and wildfire mortality sharply increased total losses. A model of accumulated fuel loads and shifts in forest density and species composition was used to account for this catastrophic jump in tree mortality concurrent with severe drought. The implications of a destabilized forest structure are discussed in terms of the needs to "defuel" many dominant forest types and to restore long-term sustainability.     

基于立地条件的森林生产力估算模型与适宜性研究

以广西省宁明县马尾松和桉树为例,利用高分辨率DEM提取研究区地形因子,综合考虑包括地形因子和土壤因子在内的立地条件和树龄,建立森林生产力估算模型,并生成区域潜在森林生产力分布图。研究结果显示:用基于DEM提取的地形因子数据进行森林生产力估算建模,能降低成本,有效提高建模效率;确定树木生长最优树龄后,仅利用立地条件因子就可以建立森林的潜在生产力模型,而两树种建模所需的立地条件因子各有不同;从生成的潜在生产力分布图可得看出宁明县的北部与东部均适宜林木生长,在中部发展林业的条件则相对较差,南部比较适宜种植马尾松,西部适宜桉树地种植。     

Defining and Measuring Forest Health

If forest health is to be approached scientifically, it must be defined and measured. Forest health is a condition of forest ecosystems that sustains their complexity while providing for human needs. We developed this broad definition becaue a wisely acceptable definition is lacking, and forest health is a focal point in discussions of how to sustain forest ecosystems in the United States. Steps for measuring forest health are: (1) select a representative set of indicators for a particular ecosystem; (2) establish baseline data, such as a historical range of variability; (3) develop standards against which to compare current conditions; and (4) establish a monitoring program to assess current conditions and modify baseline data as new trends develop.     

Tree mortality and biomass loss in drought-affected forests of East Texas,USA

Changes in tree mortality due to severe drought can alter forest structure,composition,dynamics,ecosystem services,carbon fluxes,and energy interactions between the atmosphere and land surfaces.We utilized long-term(2000-2017,3 full inventory cycles) Forest Inventory and Analysis(FIA) data to examine tree mortality and biomass loss in drought-affected forests for East Texas,USA.Plots that experienced six or more years of droughts during those censuses were selected based on 12-month moderate drought severity [Standardized Precipitation Evaporation Index(SPEI)-1.0].Plots that experienced other disturbances and inconsistent records were excluded from the analysis.In total,222 plots were retained from nearly 4000 plots.Generalized nonlinear mixed models(GNMMs) were used to examine the changes in tree mortality and recruitment rates for selected plots.The results showed that tree mortality rates and biomass loss to mortality increased overall,and across tree sizes,dominant genera,height classes,and ecoregions.An average mortality rate of 5.89% year~(-1) during the study period could be incited by water stress created by the regional prolonged and episodic drought events.The overall plot and species-group level recruitment rates decreased during the study period.Forest mortality showed mixed results regarding basal area and forest density using all plots together and when analyzed the plots by stand origin and ecoregion.Higher mortality rates of smaller trees were detected and were likely compounded by densitydependent factors.Comparative analysis of drought-induced tree mortality using hydro-meteorological data along with drought severity and length gradient is suggested to better understand the effects of drought on tree mortality and biomass loss around and beyond East Texas in the southeastern United States.     

为林业生产服务的美国林业科技体制

本文着重介绍了美国林业科技队伍状况、科研经费来源、选题和科技成果推广体系。并结合中国国情提出了具体建议。     

美国森林服务管理经验与启示

森林服务管理是融合了生态效益、社会效益、经济效益的管理科学。目标是环境可持续发展、创造社会生产力和服务公众利益，以满足现在和未来人类对环境的需求。美国林务局作为美国森林服务管理的责任机构，其管理水平一直处于世界领先地位。文中从美国林务局历史演变、机构设置、管理模式、服务领域和战略规划等方面对美国森林服务管理模式进行概括和梳理；分析其管理模式的优越性和先进性；提出对完善我国森林服务管理的启示:加大科技投入，健全政策法规，发挥森林多功能效益。     

海岸带木麻黄防护林经营模式的配置研究与筛选

对福建东山赤山林场木麻黄防护林现存的主要配置模式进行了筛选。选取对海岸带防护林体系建设有重要影响的生态防护价值、经济价值、社会价值3大类8个指标,建立评价指标体系,运用应用层次分析法进行定性分析、定量评价。结果表明:在策略层各评价因子中,生态防护功能依然占首位,社会经济价值指标也占了较高的比例。在综合效益上,各配置模式排序为:木麻黄与相思类混交(D1)>林果复合经营(D6)>木麻黄与多树种混交(D4)>木麻黄与桉树类混交(D2)>木麻黄与其他树种混交(D5)>木麻黄与灌木(D7)混交>麻黄与松树类混交(D3)。并根据海岸带立地条件的差异对各模式的梯次配置进行分析。研究结果对海岸带防护林的可持续经营与管理有一定的指导价值。     

2006—2016年昆明市西山林场森林资源碳储量动态分析

基于2006年、2016年森林资源调查数据,运用生物量扩展因子法估算乔木林各优势树种(组)生物量,并根据生物量和含碳系数的大小,计算碳储量、碳密度,藉此对不同优势树种(组)、不同起源林分、不同林龄林分、不同类型林分碳储量、碳密度进行了比较分析。结果表明,10年间昆明市西山林场森林面积、蓄积增加151hm^2、58060m^3;碳储量增加了25230.64 t,达到111530.27 t,比2006年增加了23%。碳密度随林龄的增加而增加。     

Forest carbon sequestration in China and its benefits

Carbon sequestration is important in studying global carbon cycle and budget. Here, we used the National Forest Resource Inventory data for China collected from 2004 to 2008 and forest biomass and soil carbon storage data obtained from direct field measurements to estimate carbon (C) sequestration rate and benefit keeping C out of the atmosphere in forest ecosystems and their spatial distributions. Between 2004 and 2008, forests sequestered on average 0.36 Pg C yr^?1 (1 Pg = 10¹⁵g), with 0.30 Pg C yr^?1 in vegetation and 0.06 Pg C yr^?1 in 0–1 meter soil. Under the different forest categories, total C sequestration rate ranged from 0.02 in bamboo forest to 0.11 Pg C yr^?1 in broadleaf forest. The southwest region had highest C sequestration rate, 30% of total C sequestration, followed by the northeast and south central regions. The C sequestration in the forest ecosystem could offset about 21% of the annual C emissions in China over the same period, especially in provinces of Tibet, Guangxi, and Yunnan, and the benefit was similar to most Annex I countries. These results show that forests play an important role in reducing the increase in atmospheric carbon dioxide in China, and forest C sequestration are closely related to forest area, tree species composition, and site conditions.     

An indicator of tree migration in forests of the eastern United States

Changes in tree species distributions are a potential impact of climate change on forest ecosystems. The examination of tree species shifts in forests of the eastern United States largely has been limited to simulation activities due to a lack of consistent, long-term forest inventory datasets. The goal of this study was to compare current geographic distributions of tree seedlings (trees with a diameter at breast height ≤2.5 cm) with biomass (trees with a diameter at breast height > 2.5 cm) for sets of northern, southern, and general tree species in the eastern United States using a spatially balanced, region-wide forest inventory. Compared to mean latitude of tree biomass, mean latitude of seedlings was significantly farther north (>20 km) for the northern study species, while southern species had no shift, and general species demonstrated southern expansion. Density of seedlings relative to tree biomass of northern tree species was nearly 10 times higher in northern latitudes compared to southern latitudes. For forest inventory plots between 44° and 47° north latitude where southern tree species were identified, their biomass averaged 0.46 tonnes/ha while their seedling counts averaged 2600 ha⁻¹. It is hypothesized that as northern and southern tree species together move northward due to greater regeneration success at higher latitudes, general species may fill their vacated niches in southern locations. The results of this study suggest that the process of northward tree migration in the eastern United States is currently underway with rates approaching 100 km/century for many species.     

美国森林火灾扑救指挥系统及借鉴

扑救森林火灾是一项十分复杂的系统工程,因此建立科学规范高效的指挥系统十分重要。在对美国森林火灾扑救指挥系统简要介绍的基础上,从架构理论和系统特征两方面对其安全高效运行的机制进行了分析,认为借鉴美国森林火灾扑救指挥系统的先进理念和成功经验,可以加快完善我国的森林火灾扑救指挥体系,进一步提升科学指挥的水平。     

流溪河林场森林资源调查与分析

通过二类资源清查数据,分别从林地面积、林种、树种、龄组等方面对流溪河林场森林资源动态变化进行了分析和评价,并对林杨林业的发展提出建议。     

美国国有林管理体制对我国国有林区改革的启示

培训考察团先后访问了美国联邦国有林管理局、美国南部林区(第八区)国有林管理分局、西南林区(第五区)安吉斯林管区和乔治亚州农业厅以及私有林主。美国森林资源丰富,国有林垂直管理体制简单高效,森林经营科学规范。比较了中美两国国有林管理方面的主要差异,分析了我国重点国有林区管理体制存在的问题,以期为我国国有林管理体制改革提供借鉴。     

毛竹林土壤及竹笋重金属含量分析

在浙江遂昌县森林食品基地建设区的垵口乡,测定分析了毛竹林土壤及竹笋中的重金属含量。结果表明,垵口乡土壤中铅、铜、镉的含量和竹笋中铅和镉的含量在区域分布上均呈现从北向南逐渐上升的趋势; 66个冬笋样品和72个春笋样品中重金属含量不合格率也呈现从北向南逐渐上升的趋势。因此,建议对该乡毛竹林实行分类经营,北部地区可以建设笋竹两用林基地,南部地区建设以生产竹材为主的材用林基地。     

Forest biomass estimated from MODIS and FIA data in the Lake States: MN, WI and MI, USA

This study linked the Moderate Resolution Imaging Spectrometerand USDA Forest Service, Forest Inventory and Analysis (FIA)data through empirical models established using high-resolutionLandsat Enhanced Thematic Mapper Plus observations to estimateaboveground biomass (AGB) in three Lake States in the north-centralUSA. While means obtained from larger sample sizes in FIA datasetscan be used as reference numbers over large scales, remote sensing(RS)-based observations have the ability to reflect spatialvariation of properties of interest within a given area. Thus,combining two national on-going datasets may improve our abilityto accurately estimate ecological properties across large scales.Using standard and consistent data sources can reduce uncertaintyand provide more comparable results at both temporal and spatialdimensions. We estimated total forest AGB in the region was1479 T_g (10¹² g, dry weight) in 2001 with mean AGB value of95 mg ha^–1 ranging from 4 to 411 mg ha^–1 (within95 per cent percentiles). Mixed forests featured 66 per centof the total AGB while deciduous and evergreen forests contained32 and 2 per cent of the total AGB, respectively, at 1-km pixelresolution. Spatially, AGB values increased from north-westto south-east in general. The RS-based estimates indicated agreater range in AGB variations than the FIA data. Deciduousforests were more variable (both in absolute and relative terms)than evergreen forests. The standard deviation of AGB for deciduousforests was 137 mg ha^–1, or a coefficient of variationof 92 per cent, that for evergreen forests was 24 mg ha^–1,or a coefficient of variation of 37 per cent.     

Characteristics of aspen infected with heartrot: Implications for cavity-nesting birds

Phellinus tremulae is an important fungal decay agent common to aspen and a critical component to the cavity-nesting bird complex found in western aspen stands. Little information exists on the conditions that facilitate infection and spread of P. tremulae in aspen forests. I used Forest Inventory and Analysis (FIA) data to explore the relationships of several tree and stand characteristics to the presence and frequency of P. tremulae in aspen measured across several western states of the United States. Results suggest a strong relationship between tree age, tree diameter, and compacted crown ratio with infection frequency in trees while stand purity, canopy cover and stand age had a positive relationship with the occurrence of P. tremulae in forest stands containing aspen. Logistic regression modeling identified stand age as the only variable that increased the odds of predicting infection at the stand-level while all tree-level variables were included in the tree model. Data also show that infection rates in the study area were lower than in other parts of aspen's range, and that average size of infected trees was smaller in the study area than those reported elsewhere. These results have important implications to management of aspen for wildlife, especially for birds that use decayed aspen for nesting.     

森林凋落物涵养水源生态功能研究进展

森林凋落物是森林中植物组分产生并归还地面,作为分解者的物质和能量来源,借以维持生态系统功能的所有有机质的总称,有着重要的生态系统功能,其中凋落物的涵养水源功能及其重要。不同林型或树种的凋落物有不同的涵养蓄水能力,且森林凋落物的涵养蓄水能力受不同因素的影响。本文对不同林型凋落物持水性研究及影响其持水能力的影响因素进行了综述,对林业建设过程中的树种选择、林型搭配、林下凋落物处理提供了科学的依据。