森林生态系统碳蓄积研究方法进展

作为陆地生态系统的主体,森林生态系统的碳循环与碳蓄积对研究陆地生态系统碳循环起着重要作用.生物量、生产力、土壤有机质以及凋落物量及其分解等相互关系决定了森林生态系统的碳库量和碳交换量.本文简单地介绍了在碳蓄积研究中森林生物量和生产力的几种研究方法,并对研究过程中的问题(大尺度生物量的精确估算,地下生物量的研究,森林生态系统土壤碳库估算)进行了探讨.     

长白落叶松人工林带状间伐方式对土壤有机碳含量的影响

土壤是陆地生态系统碳循环过程中最大的有机碳库,其碳储存量高达1500Gt,为大气碳库的3倍,陆地生物量的2.5倍(Valentinietal.,2000)。土壤有机碳含量的微小变化,都会较大程度地影响陆地生态系统碳循环(陈亮中等,2007;于贵瑞,2003)。森林土壤碳储量占全球土壤碳储量的73%(崔骁勇等,2001),其积累和分解直接影响到全球的碳平衡(李德基等,1992)。因此,森林土壤有机碳储量变化备受关注,成为全球气候变化研究的核心内容之一(王绍强等,1999)。     

土壤有机碳影响因素及测定方法探讨

土壤有机碳是土壤碳库的重要成分,在碳循环中起重要作用。本文主要从不同陆地生态系统的角度阐述了影响土壤有机碳的自然因素和人为因素、研究方法以及空间分布的研究进展,为陆地生态系统的可持续发展提供理论依据,也为全球碳循环的研究提供依据。     

杉木人工林土壤碳库动态研究现状及展望

土壤有机碳(SOC)是陆地生态系统中最大的有机碳库,在全球碳循环中发挥着重要的作用。因此,土壤有机碳动态是生态系统碳循环研究中的关键。杉木人工林是我国亚热带主要的人工林,综述了杉木经营过程中土壤有机质动态变化研究现状,以及采伐、整地、炼山等人类活动对土壤有机碳库影响等相关研究。     

土壤水分对土壤呼吸的影响

土壤呼吸是陆地生态系统碳循环的重要环节,在维持全球碳平衡中发挥着十分重要的作用.全球气候变暖会改变大气环流和全球水文循环,进而导致全球的降水格局发生变化,其最直接的影响就是改变土壤的水分状况,关于土壤水分状况对土壤呼吸的影响机理的研究对于预测未来土壤碳储量变化具有重要意义.本文总结了国内外关于土壤水分对土壤呼吸的影响方面的研究,系统分析了土壤水分是怎样影响土壤呼吸的各组成部分的,并简单介绍了土壤水分对Q10值的影响,最后针对当前相关研究存在的问题,对今后的研究方向加以展望.     

林火对森林土壤有机碳影响的研究进展

指出了森林生态系统土壤有机碳是全球碳循环的重要组成,在全球生态系统碳循环和全球变化的研究中占据着重要的地位。火因子是干扰森林生态系统发展的重要因子之一,对森林生态系统中土壤与大气的碳素交换过程有着重要的影响。因此,加强火干扰对森林生态系统土壤有机碳的研究,了解林火对森林生态系统土壤有机碳循环过程的具体影响,对发现火干扰下森林土壤中碳循环的机理,特别是土壤有机碳的动态变化有着重要的作用。综述了林火对森林土壤有机碳的研究进展,讨论了测定土壤有机碳的几种不同方法,比较了其适用性,探讨了在不同林火强度和不同土壤深度条件下土壤有机碳的变化情况。对实际工作中遇到的问题以及今后森林土壤有机碳研究进行了展望。     

森林生态系统碳循环研究的模型方法

森林生态系统碳循环是陆地碳循环研究中的重要内容,碳循环模型已成为研究森林碳循环的必要方法.其中气候变化、大气CO2 浓度上升及CH4的生成导致森林生态系统在结构、功能、组成和分布等方面的变化及其反馈关系对森林生态系统碳循环的影响是模型模拟的关键问题.碳循环模型可用经验模型、机理模型和混合模型的建模方法.目前森林生态系统碳循环模型的发展趋势为:综合生物地理模型和生物地球化学模型的特点建立区域动态碳循环模型;从单一碳循环模拟向碳、氮、磷等多种元素循环相耦合的模拟;碳循环模型与遥感、GIS 技术结合,模拟大尺度的碳循环过程;CH4生成及对森林碳循环的影响方面的研究.     

土壤活性有机碳的研究进展

土壤活性有机碳（Soil active organic carbon）是陆地生态系统的重要组成成分,在陆地碳循环研究中具有非常重要作用。土壤活性有机碳的组分为：微生物有机碳、溶解性有机碳、矿化有机碳、易氧化有机碳和轻组有机碳等。主要综述了代表很大比例土壤有机碳库的土壤活性有机碳的表征、分组及影响土壤活性有机碳周转的主要因素,如水分、湿度、温度、季节和土地利用方式等。     

森林土壤活性有机碳影响因素

森林土壤有机碳是全球碳循环的重要组成部分,其中,活性部分占总有机碳的很小一部分,却直接参与土壤生物和化学转化过程,因而,土壤有机碳活性组分对土壤碳库平衡和土壤化学、生物化学肥力保持具有重要意义。研究发现,气候、植被、土壤理化性质以及人类活动等因子影响着土壤有机碳在碳循环过程中的动态平衡。本文从以下三个方面综述森林土壤活性有机碳组分的主要影响因子,土壤含水量、季节变化与温度和土地利用与管理措施等对土壤活性有机碳影响较大。     

格氏栲人工林和杉木人工林碳吸存与碳平衡

森林是陆地生态系统中最大的碳库,其碳贮量占全球陆地总碳贮量的46%(Watson et al.,2000).因而,开展森林生态系统碳平衡动态研究,对于科学预测森林对全球碳平衡和气候变化的作用具有重要意义,并已成为国际陆地碳循环研究的热点.     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.