森林粗死木质残体的概念及其分类

森林粗死木残体 (Coarse woody debris,CWD)在不同的文献中有不同的定义 ,没有通用而确切的概念用来描述 CWD,对研究结果的比较造成了很大障碍。 2 0世纪 90年代以来 ,随着景观生态学的发展 ,以及对 CWD生态功能的深入研究 ,国外的森林管理和研究机构 (例如 USDA Forest Service和 L TER)为了把 CWD放在区域以及景观尺度上进行比较 ,对 CWD的概念等进行了统一 ,将其直径标准由原来的≥ 2 .5 cm调整到≥ 10 cm,但是我国在此方面还没有与国际接轨 ,仍采用旧标准 (≥ 2 .5 cm ) ,这样的研究结果难于和国外进行比较 ,不利于我国 CWD的长期深入研究。另外 ,有关 CWD的分类一直以来也没有形成一个完整的分类系统 ,我国也缺少 CWD分类方法的介绍。鉴于以上情况 ,综合国内外近年来在 CWD方面的研究动态 ,综述了 CWD的概念和分类情况 ,并初步提出较综合的 CWD概念及其分类系统 ,以供相关研究者讨论和参考 ,为我国的 CWD研究起到推动作用     

森林生态系统粗死木质残体碳储量研究进展

粗死木质残体(CWD)是森林生态系统重要的结构性与功能性单元,作为连接植被碳库与土壤碳库的关键纽带,对全球森林生态系统碳循环发挥着重要而独特的作用,越来越多的学者开始关注CWD碳储量相关研究。系统阐述了国内外CWD碳储量研究的发展历程、研究范围与基本特征等内容,总结概括了CWD体积测算、CWD碳浓度估算等碳计量相关方法的研究进展。通过梳理发现:国内外学者对CWD碳储量的研究仍处于初级阶段,主要集中于探讨不同树种、不同林龄、不同腐解等级、不同海拔、不同存在形式的森林CWD碳储量分布特征,而较少关注CWD碳库对土壤碳库和植被碳库的作用机制以及对未来气候变化的响应和反馈机制;CWD碳计量方法较为单一,普遍采用的是传统的"生物量-碳浓度法",而运用机器学习算法对CWD碳储量进行估算的研究尚不多见。此外,相对国外研究而言,国内研究主要局限于小尺度范围。文章据此提出未来CWD碳储量研究的发展方向:(1)拓展研究尺度,建立CWD碳储量长期观测体系;(2)深入开展不同森林生态系统CWD碳储量对气候变化的响应机制研究;(3)探索更加多元化的CWD碳储量计量方法;(4)深入探讨CWD碳库对土壤碳库与植被碳...     

广州三种森林粗死木质残体（CWD）的储量与分解特征

粗死木质残体(Coarse Woody Debris, CWD)对森林生态系统的稳定性具有不可忽视的贡献.对广州3种森林CWD的储量与分解特征进行了调查分析,结果表明:(1)CWD储量及其与相应森林总生物量比值均表现为常绿阔叶林>针阔混交林>针叶林;枯立木与倒木为CWD的主要成分,其中,针叶CWD主要物种为马尾松(Pinus massonianai),阔叶CWD物种主要为荷木(Schima superba)与黄杞(Engelhardtia chrysolepis)等.(2)CWD径级主要集中在<10cm的范围内,存在状态主要为中级腐烂状态,干扰与竞争是3种森林CWD产生的主要因素.(3)针叶林、针阔混交林与常绿阔叶林CWD的分解常数k分别为0 0244、0.0407和0.0487,即分解速率为常绿阔叶林>混交林>针叶林;随着CWD的分解,N、P与木质素的含量逐渐升高,C、C/N与木质素/N呈降低趋势.     

鼎湖山季风常绿阔叶林粗死木质残体的研究

在3次样地调查的基础上对鼎湖山季风常绿阔叶林内粗死木质残体的贮量、输入量进行了研究,并通过比较林窗范围内土壤养分含量,初步评述了粗死木质残体在森林生态系统养分循环中的作用。研究结果表明:1)季风常绿阔叶林粗死木质残体的贮量为25.278t·hm~(-2),立木、倒木、大枝所占的比例分别为32.02％、49.62％和18.36％;2)1994～1999年间群落的死亡率为24％·a~(-1),死亡个体以胸径小于5cm的为主,粗死木质残体的平均输入量为4.128t·hm~(-2)·a~(-1);3)倒木主体所在的样方土壤有机质和速效钾的含量较高。     

覆盖与间作对亚热带丘陵茶园地温时空变化的影响

研究了亚热带丘陵茶园连续4年进行稻草覆盖与白三叶草间作对茶园地温时空动态变化的影响.结果表明,茶园地温具有明显的时空动态变化特征和位相滞后现象,与茶树的年生长发育周期各阶段的最适温度非常吻合.稻草覆盖与白三叶草间作改变了土壤热量交换层（地表层）的性质,具有升温时降温和降温时增温、保温的双向动态调控作用,降低了日较差,增强了同一土层温度的稳定性,其调控效果为随着土壤深度增加而降低,13：00>19：00>7：00,降温大于增温和保温,降温幅度随气温的升高而增大,增温和保温随气温的下降而加强,间作白三叶草的降温效果大于稻草覆盖,保温效果则相反.茶园地温时空变化转换点得到调节,显著地降低了有害高温的出现次数,明显地降低了持续高温期的土壤温度,有效地缩短了极限高温时间.     

秦岭巴山冷杉林粗死木质残体研究

 对秦岭巴山冷杉林粗死木质残体的研究表明：1)林内粗死木质残体的现存量为15.848t·hm-2,平均死亡增枯量1.877t·hm-2·a-1,平均分解量1.310t·hm-2·a-1,周转时间约为12.09年;2)粗死木质残体在碳素和养分的保持方面具有一定作用,在野生动植物生境构成中的作用较大。     

西双版纳热带季节雨林的粗死木质残体及其养分元素

对西双版纳热带季节雨林的粗死木质残体及养分元素贮量进行了研究。结果表明,西双版纳热带季节雨林粗死木质残体的贮量为16.2 t·hm^-2,约占地上活体生物量的4%左右。其中枯立木占32.5%,倒木占33.2%,倒木残体占12.6%,大枝占21.7%。本研究的粗死木质残体贮量低于巴西和东南亚的热带雨林,处于全球热带雨林的下限。粗死木质残体的氮、磷、钾、钙、镁5种元素的贮量分别为61.8、3.4、30.4、118.3和16.5 kg·hm^-2。其中倒木所占比例最大,为31.9%～44.8%;枯立木次之（21.5%～28.7%）;倒木残体占10.3%～25.5%;3个径级的大枝占14.4%～28.9%。枯立木的C/N、C/P和N/P要高于倒木、倒木残体和大枝。     

粗木质物残体生态研究历史、现状和趋势

粗木质物残体(Coarse Woody Debris,简称CWD)是森林生态系统或溪流生态系统中残存的一定直径大小的站杆(snag)、倒木、枝桠及根系等死木质物的总称,倒木往往是     

Coarse woody debris in virgin and managed forest

This study treats dead trees and their remnants in the managed and virgin forest of Rajhenavski Rog, Slovenia, at a location of Omphalodo-Fagetum omphalodetosum plant community. The study plots were selected in four forest cycle developmental phases (optimal, mixed, regeneration and juvenile phase) of both managed and virgin forest. The quantity (volume and dry matter) and the structure of coarse woody debris (CWD) were compared between the selected plots within the particular type of the forest, and between the virgin and the managed forest. Belowground CWD was quantified by modeling the tree's biomass and decaying processes of the trees. The results show significant differences in CWD between the virgin forest developmental phases. The highest concentration of CWD in the virgin forest was found in the regeneration phase (626.0 m³/ha and 179.3 t_dry matter/ha), while the juvenile phase (248.3 m³/ha and 40.2 t_dry matter/ha) has the smallest amount of CWD. Managed forest has very evenly distribution of CWD between developmental phases and it ranges from 41.0 m³/ha and 49.0 t_dry matter/ha in the mixed developmental phase to 67.0 m³/ha and 56.2 t_dry matter/ha in the juvenile phase. The main reasons for such a large differences are forest management measures (e.g. wood extraction, short rotation time, reduction of natural tree mortality), which decrease quantity, distribution and size of CWD. It was identified that forest management causes reduction and homogenization of CWD on our study plots, which can trigger degradation processes (e.g. soil erosion, reduction of site productivity, reduction of habitats). Tree heights curves show significant differences in maximum tree's height between the virgin and the managed forest. Maximum tree's height is lower in the managed forest which may indicate the reduction of forest productivity due to reduction of CWD. Study has shown some positive effects of forest management on accumulation of underground CWD in the managed forest (from 40.0 t_dry matter/ha to 48.2 t_dry matter/ha), which significantly exceeds underground CWD in the virgin forest (from 2.0 t_dry matter/ha to 22.8 t_dry matter/ha).     

Coarse woody debris mass and nutrients in forest ecosystems of Korea

Coarse woody debris (CWD) is an essential component of forests. However, quantification of both the mass and nutrient content of CWD within a given environment tends to be a fairly labor-intensive proposition that requires long-term studies to be conducted for viable data to be obtained. As a result, various aspects of CWD in forest ecosystems remain somewhat poorly understood. In this review, we have compiled all available estimates of CWD mass and nutrients from both coniferous and deciduous forests in Korea. The CWD mass data varied substantially by forest type, age, location, and sampling time, ranging from 1.5 to 24.5 Mg ha⁻¹, and for the amount (kg ha⁻¹) of nutrients in the CWD, ranging from 3.5 to 23.6 for nitrogen (N), 0.8 to 4.7 for phosphorus (P), 3.9 to 13.3 for potassium (K), 25.9 to 30.9 for calcium (Ca), 1.4 to 4.2 for magnesium (Mg), and 0.1 to 0.6 for sodium (Na). The mass of CWD transferred from live trees to the forest floor ranged between 0.1 and 4.9 Mg ha⁻¹ year⁻¹, and these values were roughly equivalent to 26–42% of the annual litterfall inputs (2.5–10.8 Mg ha⁻¹ year⁻¹) for mixed Quercus spp. forests within the relevant region. Annual nutrients inputs (kg ha⁻¹ year⁻¹) through CWD decomposition were 0.7–1.6 for N, 0.04–0.3 for P, 0.3–1.0 for K, 1.7–3.1 for Ca, and 0.1–0.3 for Mg. Consequently, these results revealed that the ecological value of CWD for C and nutrient cycling was relatively insignificant. However, only a limited number of studies have been conducted on CWD in different coniferous or mixed deciduous forests in the region. As a direct result of this paucity of data, further long-term studies on CWD mass and nutrients in a variety of forest types are required in order to be able to evaluate accurately the ecological value of CWD on biodiversity and physical properties in Korean forest ecosystems.     

Characteristics in coarse woody debris mediated by forest developmental stage and latest disturbances in a natural secondary forest of Pinus tabulaeformis

Coarse woody debris (CWD) characteristics are expected to reflect forest stand features. Few studies evaluated logging-induced stand characteristics of secondary coniferous forests by quantifying the quality and quantity in CWD. After selective logging, the form of secondary forest of Pinus tabulaeformis in the Qinling Mountains is inferior and the regeneration is poor. We measured the CWD characteristics of the forest which had an average CWD biomass amount of 12.56 t hm⁻², and was predominated by abundant logs (65.68%), followed by snags (33.13%). The CWD biomass of P. tabulaeformis and Toxicodendron vernicifluum was significantly higher than that of other species, which took up 85.51% of the total. Although there was no significant difference among different diameter sizes (P > 0.05), the CWD biomass of diameter 30–40 cm occupied 46.26% of the total (5.81 t hm⁻²). Similarly, the CWD biomass of decay class I and II accounted for 39.89% (5.01 t hm⁻²) and 33.04% (4.15 t hm⁻²) of the total CWD biomass respectively, despite no significant difference among those 5 decay classes (P > 0.05). The results indicated that the combination of young forest developmental stage caused by past selective logging and natural and anthropogenic disturbances such as strong wind, tapping lacquer, firewood collection, and illegal tree felling played a crucial role in distribution characteristics of CWD in this secondary forest of P. tabulaeformis.     

温带森林生态系统粗死木质物动态研究——以中美两个温带天然林生态系统为例

通过对我国长白山自然保护区红松针阔混交林和美国Andrews试验林异叶铁杉林的林木死亡量、粗死木质物(CWD)贮量、分解速率和它们在生态系统养分循环等方面动态研究表明,CWD是温带天然林生态系统的重要组成部分,它们在生态系统功能方面的重要性,因森林类型的不同而不尽相同,CWD在针叶林中比针阔混交林中更为重要。CWD在生态系统养分循环中的一个重要作用,很可能在于系统遭受重大外界扰动后,起到贮藏养分,增加系统稳定性的作用。未来全球森林凋落物C贮量估测时,应该包括CWD,否则将低估全球森林凋落物C贮量2.0—16×10~(13)kg,系统相对误差达2—10％。     

Coarse woody debris in Australian forest ecosystems: A review

Abstract Coarse woody debris (CWD) is the standing and fallen dead wood in a forest and serves an important role in ecosystem functioning. There have been several studies that include estimates of CWD in Australian forests but little synthesis of these results. This paper presents findings from a literature review of CWD and fine litter quantities. Estimates of forest‐floor CWD, snags and litter from the literature are presented for woodland, rainforest, open forest and tall open forest, pine plantation and native hardwood plantation. Mean mass of forest floor CWD in Australian native forests ranged from 19 t ha^?1 in woodland to 134 t ha^?1 in tall open forest. These values were generally within the range of those observed for similar ecosystems in other parts of the world. Quantities in tall open forests were found to be considerably higher than those observed for hardwood forests in North America, and more similar to the amounts reported for coniferous forests with large sized trees on the west coast of the USA and Canada. Mean proportion of total above‐ground biomass as forest floor CWD was approximately 18% in open forests, 16% in tall open forests, 13% in rainforests, and 4% in eucalypt plantations. CWD can be high in exotic pine plantations when there are considerable quantities of residue from previous native forest stands. Mean snag biomass in Australian forests was generally lower than the US mean for snags in conifer forests and higher than hardwood forest. These results are of value for studies of carbon and nutrient stocks and dynamics, habitat values and fire hazards.     

Coarse woody debris as a refuge from predation in aquatic communities

This study demonstrates experimentally that coarse woody debris (CWD) can provide refuge from predation in aquatic habitats. In the Rhode River subestuary of Chesapeake Bay, Maryland, (USA), we (1) measured the abundance of CWD, (2) examined the utilization of CWD by mobile epibenthic fish and crustaceans, and (3) tested experimentally the value of CWD as a refuge from predation. CWD was the dominant above-bottom physical structure in shallow water, ranging in size from small branches (<2 cm diameter) to fallen trees (>50 cm diameter). In response to experimental additions of CWD, densities of common epibenthic cpecies (Callinectes sapidus, Fundulus heteroclitus, Fundulus majalis, Gobiosoma bosc, Gobiesox strumosus, Palaemonetes pugio, and Rithropanopeus harrisii) increased significantly compared to control sites without CWD. In laboratory experiments, grass shrimp (P. pugio) responded to predatory fish (F. heteroclitus and Micropogonias undulatus) by utilizing shelter at CWD more frequently than in absence of fish. Access to CWD increased survivorship of grass shrimp in laboratory and field experiments. These experimental results (1) support the hypothesis, commonly proposed but untested for freshwater habitats, that CWD can provide a refuge from predation for epibenthic fish and invertebrates and (2) extend the recognized functional importance of CWD in freshwater to estuarine and marine communities. We hypothesize that CWD is an especially important refuge habitat in the many estuarine and freshwater systems for which alternative physical structure (e.g., vegetation or oyster reefs) are absent or in low abundance.     

Leaching of dissolved organic carbon,dissolved organic nitrogen,and other solutes from coarse woody debris and litter in a mixed forest in New York State

Coarse woody debris (CWD) may play a role in nutrient cycling in temperate forests through the leaching of solutes, including dissolved organic carbon (DOC) and dissolved organic nitrogen (DON), to the underlying soil. These fluxes need to be considered in element budget calculations, and have the potential to influence microbial activity, soil development, and other processes in the underlying soil, but studies on leaching from CWD are rare. In this study, we collected throughfall, litter leachate, and CWD leachate in situ at a young mixed lowland forest in NY State, USA over one year. We measured the concentrations of DOC, DON, NH₄⁺, NO₃⁻, dissolved organic sulfur, SO₄²⁻, Cl⁻, Al, Ca, K, Mg, Na, and P, estimated the flux of these solutes in throughfall, and measured the cover of CWD to gain some insight into possible fluxes from CWD. Concentrations of DOC were much higher in CWD leachate than in throughfall or litter leachate (15 vs. 0.7 and 1.6 mM, respectively), and greater than reported values for other leachates from within forested ecosystems. Other solutes showed a similar pattern, with inorganic N being an exception. Our results suggest that microsite scale fluxes of DOC from CWD may be An high relative to throughfall and litter leaching fluxes, but since CWD covered a relatively small fraction (2%) of the forest floor in our study, ecosystem scale fluxes from CWD may be negligible for this site. Soil directly beneath CWD may be influenced by CWD leaching, in terms of soil organic matter, microbial activity, and N availability. Concentrations of some metals showed correlations to DOC concentrations, highlighting the possibility of complexation by DOM. Several solute concentrations in throughfall, including DOC, showed positive correlations to mean air temperature, and fewer showed positive correlations in litter leachate, while negative correlations were observed to precipitation, suggesting both biological and hydrologic control of solute concentrations.     

Contribution of woody debris to trout habitat modification in small streams in secondary deciduous forest, northern Japan

Field studies to examine the influence of woody debris on rainbow trout (Oncorhynchus mykiss) abundance through habitat modification were conducted in two small streams, the Horonai and Uenae streams, running through secondary deciduous forest in south-western Hokkaido, northern Japan. Reach-based woody debris volume (total woody debris volume per 100 m² of study reach) was significantly correlated with the total basal area of riparian stands along the margins of the Horonai stream, but no significant relationship was evident between them for the Uenae stream. This inconsistency between the streams was considered to be a result of the difference in stream size (width, depth and discharge). Woody debris was the principal agent for pool formation, although it had a far smaller volume than that found in streams draining old-growth coniferous forest in North America, where most of the previous studies have been carried out. Untransported debris pieces of larger volume more effectively contributed to pool formation than smaller transported pieces. The volume of individual debris scour pools was positively correlated with the volume of woody debris associated with each. Similarly, reach-based pool volume increased with total woody debris volume, but the relationship was less clear in the Uenae stream, having more abundant transported woody debris than the Horonai stream. The biomass of rainbow trout in individual pools, which were regarded as the most preferred habitat type for stream salmonids, was correlated with pool volume. A positive relationship also existed between reach-based standing crop and pool volume. These results revealed that secondary deciduous forest, like old-growth coniferous forest, plays an important role in enhancing the carrying capacity for rainbow trout by supplying woody debris which promoted preferred habitat formation.