Transport and release of chemicals from plastics to the environment and to wildlife

Plastics debris in the marine environment, including resin pellets, fragments and microscopic plastic fragments, contain organic contaminants, including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons, petroleum hydrocarbons, organochlorine pesticides (2,2′-bis(p-chlorophenyl)-1,1,1-trichloroethane, hexachlorinated hexanes), polybrominated diphenylethers, alkylphenols and bisphenol A, at concentrations from sub ng g^–1 to µg g^–1. Some of these compounds are added during plastics manufacture, while others adsorb from the surrounding seawater. Concentrations of hydrophobic contaminants adsorbed on plastics showed distinct spatial variations reflecting global pollution patterns. Model calculations and experimental observations consistently show that polyethylene accumulates more organic contaminants than other plastics such as polypropylene and polyvinyl chloride. Both a mathematical model using equilibrium partitioning and experimental data have demonstrated the transfer of contaminants from plastic to organisms. A feeding experiment indicated that PCBs could transfer from contaminated plastics to streaked shearwater chicks. Plasticizers, other plastics additives and constitutional monomers also present potential threats in terrestrial environments because they can leach from waste disposal sites into groundwater and/or surface waters. Leaching and degradation of plasticizers and polymers are complex phenomena dependent on environmental conditions in the landfill and the chemical properties of each additive. Bisphenol A concentrations in leachates from municipal waste disposal sites in tropical Asia ranged from sub µg l^–1 to mg l^–1 and were correlated with the level of economic development.     

Increased oceanic microplastic debris enhances oviposition in an endemic pelagic insect

Plastic pollution in the form of small particles (diameter less than 5 mm)-termed 'microplastic'-has been observed in many parts of the world ocean. They are known to interact with biota on the individual level, e.g. through ingestion, but their population-level impacts are largely unknown. One potential mechanism for microplastic-induced alteration of pelagic ecosystems is through the introduction of hard-substrate habitat to ecosystems where it is naturally rare. Here, we show that microplastic concentrations in the North Pacific Subtropical Gyre (NPSG) have increased by two orders of magnitude in the past four decades, and that this increase has released the pelagic insect Halobates sericeus from substrate limitation for oviposition. High concentrations of microplastic in the NPSG resulted in a positive correlation between H. sericeus and microplastic, and an overall increase in H. sericeus egg densities. Predation on H. sericeus eggs and recent hatchlings may facilitate the transfer of energy between pelagic- and substrate-associated assemblages. The dynamics of hard-substrate-associated organisms may be important to understanding the ecological impacts of oceanic microplastic pollution.     

Association of low-dose exposure to persistent organic pollutants with E-cadherin promoter methylation in healthy Koreans

Background: Persistent organic pollutants (POPs), despite their considerably low levels in humans, are an increasing concern for the general populations given their various adverse health problems, including metabolic and carcinogenic effects. DNA methylation deregulation is thought to be a key mechanism in the development of human chronic diseases including cancer.

Methods: In an attempt to identify biomarkers monitoring low-dose exposure and hazard, we explored whether organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) may influence the methylation of tumour suppressor gene E-cadherin (CDH1) using peripheral blood cells from 364 healthy Korean subjects.

Results: CDH1 methylation was observed in 78.3% of study subjects. Serum concentrations of OCPs or PCBs compounds were higher in CDH1 methylation-positive subjects than in methylation-negative ones. After adjusting for various covariates, the odds ratio of CDH1 methylation of the summary measure of PCBs were 1.0, 2.5 (95% confidence interval: 1.2–5.3), 3.6 (1.6–8.1), 3.6 (1.4–8.6), and 2.5 (1.1–5.7) across quintiles of PCBs (P_trend?=?0.01). The values of OCPs were 1.0, 0.9, 1.2, 2.4 (1.0–5.9), and 1.7 (P_trend?=?0.05).

Conclusions: In this exploratory study with a small sample, CDH1 methylation might be served as the epigenetic biomarker associated with POPs exposure and adverse health effect.     

Integrated Human and Ecological Risk Assessment: A Case Study of Persistent Organic Pollutants (POPs) in Humans and Wildlife

Since the mid-1900s, the global environment has become increasingly contaminated with Persistent Organic Pollutants (POPs), including many with dioxin-like properties. These compounds generally have low water solubility, do not degrade readily in the environment, bioaccumulate in food chains, and have been linked to adverse health effects in both humans and wildlife. The presence of such compounds in terrestrial and aquatic food chains is relevant to those concerned with both human health and environmental protection because of the many common exposure pathways and biological effects among different species. In the past, some chemicals with health risks for humans have been identified following reports of adverse effects in wildlife. Integrating human and ecological risk assessments may improve society's ability to manage the design, manufacture, use and disposal of chemicals in a safe and efficient manner. This can be demonstrated with this case study, which summarizes approaches to evaluating the sources, transport and fate of certain POPs, used largely in the past, and their associated health risks to humans and biota.     

Biodegradation of hexachlorobenzene by basidiomycetes in soil contaminated with industrial residues

Hexachlorobenzene (HCB), one of twelve compounds classified as persistent organic pollutants (POP), is a byproduct of the manufacture of organochlorine compounds, and is a cause of environmental contamination in several parts of the world. Its degradation by Brazilian basidiomycetes was studied through chromatographic analyses and monitoring of the production of ¹⁴CO₂ from [¹⁴C]HCB in the soil. Nineteen strains of basidiomycetes were found to be capable of tolerating concentrations of 5000 to 50,000 mg of HCB kg^–1 of soil. In spite of the low rates of production of ¹⁴CO₂, Psilocybe cf. castanella CCB444 and Lentinus cf. zeyheri CCB274 were capable of removing nearly 3150 and 1400 mg of HCB kg^–1 from respective soil samples, during a 65-day study period.     

Phytoextraction of weathered p,p'-DDE by zucchini (Cucurbita pepo) and cucumber (Cucumis sativus) under different cultivation conditions

Previous studies have shown that zucchini (Cucurbita pepo) and cucumber (Cucumis sativus) under field conditions are good and poor accumulators, respectively, of persistent organic pollutants from soil. Here, each species was grown under three cultivation regimes: dense (five plants in 5 kg soil): nondense (one plant in 80 kg soil): and field conditions (two to three plants in approximately 789 kg soil). p,p'-DDE and inorganic element content in roots, stems, leaves, and fruit were determined. In addition. rhizosphere, near-root, and unvegetated soil fractions were analyzed for concentrations of 11 low-molecular-weight organic acids (LMWOA) and 14 water-extractable inorganic elements. Under field conditions, zucchini phytoextracted 1.3% of the weathered p,p'-DDE with 98% of the contaminant in the aerial tissues. Conversely, cucumber removed 0.09% of the p,p'-DDE under field conditions with 83% in the aerial tissues. Under dense cultivation, cucumber produced a fine and fibrous root system not observed in our previous experiments and phytoextracted 0.78% of the contaminant, whereas zucchini removed only 0.59% under similar conditions. However. cucumber roots translocated only 5.7% of the pollutant to the shoot system, while in zucchini 48% of the p,p'-DDE in the plant was present in the aerial tissue. For each species, the concentrations of LMWOA in soil increased with increasing impact by the root system both within a given cultivation regime (i.e., rhizosphere > near-root > unvegetated) and across cultivation regimes (i.e., dense > nondense > field conditions). Under dense cultivation, the rhizosphere concentrations of LMWOAs were significantly greater for cucumber than for zucchini; no species differences were evident in the other two cultivation regimes. To enable direct comparison across cultivation regimes, total in planta p,p'-DDE and inorganic elements were mass normalized or multiplied by the ratio of plant mass to soil mass. For cucumber, differences in total p,p'-DDE and inorganic element content among the cultivation regimes largely disappear upon mass normalization, indicating that greater uptake of both types of constituents in the dense condition is due to greater plant biomass per unit soil. Conversely, for zucchini the mass normalized content of p,p'-DDE and inorganic elements is up to two orders of magnitude greater under field conditions than under dense cultivation, indicating a unique physiological response of C. pepo in the field. The role of cultivation conditions and nutrient availability in controlling root morphology, organic acid exudation, and contaminant uptake is discussed.     

Input of organochlorine compounds by snow to European high mountain lakes

1.  Persistent organic pollutants (POPs) can be trapped by and accumulate in cold regions. To understand POP accumulation in temperate high mountain lakes, we collected samples of snow from the catchments of several high mountain lakes in Europe.
2.  Organochlorine compounds (OCs) are regularly found in snow collected in European high mountain sites. Polychlorobiphenyls (PCBs) were found in all samples examined. Hexachlorocyclohexanes (HCHs) are also common whereas DDTs and hexachlorobenzene were found less frequently.
3.  Comparison of the concentrations of these pollutants in snow with OC levels in the waters of these lakes or atmospheric deposition during cold periods shows that the snowpack constitutes a significant seasonal PCB reservoir in all catchments and that snow trapping is a major mechanism for the incorporation of HCHs in the lakes situated in the coldest sites, e.g. Gossenköllesee in the Alps.
4.  Correlation of the concentrations of the PCB congeners in snow versus mean annual winter temperature shows higher accumulation at lower temperatures. The less volatile PCBs exhibit higher temperature dependences than the more volatile congeners. This trend differs from altitudinal dependences observed in other sites such as Canada and may be related to the specific range of winter temperature in each area of study.     

The imprint of coarse woody debris on soil chemistry in the Western Oregon Cascades

Coarse woody debris (CWD) may create a spatially discrete soil imprint through the release of carbon rich, acidic dissolved organic matter (DOM). DOM has been implicated in many soil processes such as humus formation, nutrient immobilization, podzolization, and the dissolution of soil minerals. We investigated a potential CWD imprint on soil chemistry by sampling leachates and soil solutions under CWD at different stages of decay and under the forest floor as controls. Solutions were analyzed for total dissolved organic carbon (DOC) and polyphenol concentrations. DOC was further separated by chemical fractionation. We also sampled soil from underneath CWD and from control areas without CWD. Samples were analyzed for pH, base saturation, exchangeable acidity, and several aluminum and iron fractions. The pH of CWD leachates was lower (p 0.001) and contained more polyphenols (p 0.0001) and DOC than control leachates, although chemical DOC fractions from CWD and the forest floor were similar. Surface mineral soils under CWD were lower in pH (p 0.005), had more exchangeable acidity (p 0.002) and more exchangeable aluminum (p 0.04) and iron (p 0.06) than forest floor soils. At depths greater than 5 cm, there were no differences between forest floor soils and soils under CWD. Our results suggest that CWD in the middle stages of decay acidifies the surface soil as it decomposes by decreasing exchangeable bases and increasing exchangeable acidity and aluminum. Soils under the most highly decayed CWD, or deeper soils were not affected by CWD. Although we hypothesized that well-decayed CWD would show a spatially explicit imprint on soils, the effect of CWD on soil chemistry was small and limited to surface mineral soils.     

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.     

Atmospheric and riverine inputs of metals,nutrients and persistent organic pollutants into the lagoon of Venice

Atmospheric deposition in the lagoon of Venice and river inputs from the watershed were collected and analysed from 1998 to 1999 using the same analytical methods. The input from riverine sources largely prevails (>70%) over that from the atmosphere for As, Cr, Fe, Mn, Ni, nitrogen and phosphorus. Equivalent amounts of Hg, Pb, PCBs, HCB are discharged into the lagoon from the two sources, whilst atmospheric inputs prevail for Cd, ammonia and dioxins. A comparison with figures of maximum allowable discharges (MAD) for various compounds, recently set by the Italian Ministry for the Environment, showed that total inputs (riverine + atmospheric) of trace metals were below the MAD thresholds only for Cr, Cu, Ni and Zn. The total inputs of Cu and Ni, and Cr and Zn were approximately 20 and 40% of the MAD limit, respectively. The total phosphorus input of 284 t was close to the imposed limit, whilst the inorganic nitrogen load alone (>4000 t) was much higher than the MAD for total nitrogen. For those metals (As, Cd, Hg and Pb) and persistent organic pollutants, such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) where the MAD states that the load should tend to ‘0’ (no discharge), the measured inputs of 4.8 (As) and 5.1 t (Pb), 151 (Cd) and 39 kg (Hg), 18 g (PCDD/Fs) and 440 mg (Toxicity Equivalents, TEQs, of PCDD/Fs) are by definition ‘above’ the MAD. The principal component analysis (PCA) of loading data and input profiles (markers) of production typologies showed that river and atmosphere contributions can be easily separated and recognised due to their different fingerprints. Riverine inputs were similar to chemical and glass work production markers, whereas atmospheric loadings were mainly influenced by chemical industry (PVC and VCM production), metallurgy and paper-mill.     

Invertebrate colonization of woody debris in coastal plain streams

We studied colonization dynamics and habitat preferences of macroinvertebrates associated with submerged woody debris in Louisiana coastal plain streams. In an in situ experiment, Branches of magnolia Magnolia grandiflora and water oak Quercus nigra were anchored over sand and gravel substrate at two sites in the Bogue Falaya River, St. Tammany Parish, Louisiana, U.S.A. Branches were removed from the units weekly for 4 weeks and biweekly for 1 month to assess colonization. Invertebrate numbers were highest at weeks three and six on magnolia over gravel habitat, although numbers of the most dominant taxa (Baetidae, Hydropsyche sp., Cernotina sp., Oecetis sp. and Hydroptilia sp.) peaked at different times during the study. Abundances of Hydropsyche sp. and Cernotina sp. were greatest on magnolia branches secured over gravel substrate, whereas Oecetis sp. abundances were greatest on oak branches secured over sand substrate.We also surveyed six streams in southeast Louisiana to examine the relative importance of wood, gravel and sand as substrate for lotic macroinvertebrates. In fall 1997 and spring 1998, we took water samples and measured in situ water quality characteristics at one site on each stream, and then collected submerged wood (surface area about 3051 cm²) and sand and gravel substrate (Surber samples totaling 2800 cm² for each substrate) to determine the density and taxonomic composition of resident macroinvertebrates. Highest numbers of invertebrates were collected in fall and spring from gravel substrate (P=0.0001). Macronychus sp. were more abundant on wood than gravel or sand (P<0.0003) and Hydropsyche sp. was more abundant on fall wood samples (P=0.0001). Analyses of water quality parameters revealed associations between Hydropsyche sp. abundance and potassium (P=0.0070) and specific conductance (P=0.0080), although both parameters exhibited interactions with substrate type (P<0.0144).     

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.     

Contaminant sources, distribution and fate in the Athabasca, Peace and Slave River Basins, Canada

Northern river ecosystems worldwide are under increasing environmental stress from degrading developments that influence water quality and associated ecological integrity. In particular, contaminant-related threats to these systems are rising from enhanced industrial and municipal effluent discharges along with elevated non-point source inputs related to land-use activities such as forestry, agriculture, mining and long-range atmospheric transport. In this regard, the contaminants program of the Northern River Basins Study (NRBS) in western Canada identified key contaminant sources to the Athabasca, Slave and Peace river basins (particularly related to pulp-mill developments) and assessed their environmental fate and distribution in water and sediments. The study also developed and employed new analytical approaches and generated improved models to predict contaminant transport and fate in the aquatic environment and related food webs. Consequently the study focused on those contaminant families identified in characterization studies as arising from key point- and non-point sources within the basins or as being of greatest toxicological significance. These included resin acids, polychlorinated dioxins and furans, polychlorinated biphenyls, chlorinated phenolics, polyaromatic hydrocarbons and selected heavy metals such as mercury. Low or non-detectable concentrations of a number of contaminant groups were found in the ambient water phase including chlorinated phenolics, some chlorinated dioxins and furans and some resin acids. For both suspended and depositional sediments, significant declines were observed over the study period for the major chlorinated contaminant groups tested, correlating directly with the implementation of improved effluent treatment in many of the pulp mills located in the basins. In general, the environmental levels of chlorinated organic and metal contaminants in water or sediments were low and within Canadian health or environmental guidelines. It is hoped that the approaches used and lessons learned from the NRBS will be of use to others assessing contaminant and multiple stressor issues in other large river ecosystems.     

Woody debris contribution to the carbon budget of selectively logged and maturing mid-latitude forests

Woody debris (WD) is an important component of forest C budgets, both as a C reservoir and source of CO₂ to the atmosphere. We used an infrared gas analyzer and closed dynamic chamber to measure CO₂ efflux from downed coarse WD (CWD; diameter≥7.5 cm) and fine WD (FWD; 7.5 cm>diameter≥2 cm) to assess respiration in a selectively logged forest and a maturing forest (control site) in the northeastern USA. We developed two linear regression models to predict WD respiration: one based on WD temperature, moisture, and size (R ²=0.57), and the other on decay class and air temperature (R ²=0.32). WD respiration (0.28±0.09 Mg C ha⁻¹ year⁻¹) contributed only ≈2% of total ecosystem respiration (12.3±0.7 Mg C ha⁻¹ year⁻¹, 1999–2003), but net C flux from CWD accounted for up to 30% of net ecosystem exchange in the maturing forest. C flux from CWD on the logged site increased modestly, from 0.61±0.29 Mg C ha⁻¹ year⁻¹ prior to logging to 0.77±0.23 Mg C ha⁻¹ year⁻¹ after logging, reflecting increased CWD stocks. FWD biomass and associated respiration flux were ≈7 times and ≈5 times greater, respectively, in the logged site than the control site. The net C flux associated with CWD, including inputs and respiratory outputs, was 0.35±0.19 Mg C ha⁻¹ year⁻¹ (net C sink) in the control site and −0.30±0.30 Mg C ha⁻¹ year⁻¹ (net C source) in the logged site. We infer that accumulation of WD may represent a small net C sink in maturing northern hardwood forests. Disturbance, such as selective logging, can enlarge the WD pool, increasing the net C flux from the WD pool to the atmosphere and potentially causing it to become a net C source.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

The Need for Strategic Environmental Assessment of Fishery Products Regulations in the Taiwan Strait: Taking Health Perspectives of Organochlorine Pesticides in Seafood as an Example

This article proposes an integrated Health Impact Assessment/Strategic Environmental Assessment (HIA/SEA) framework that can be applied to fishery products regulations in Taiwan Strait. In recent years, many studies with regards to organochlorine pesticides (OCPs), especially DDT and its derivatives, in Taiwan's environment and aquatic biota indicated that DDT, DDD, and DDE in seafood, especially oysters, in the Kinmen, Manchu area near China's Fu-Tzien Province, had relatively high concentrations. It was discussed that this may be caused by distribution of OCPs in China's vicinity. In this study, the concentration of DDT, DDD, and DDE reported by many researchers in the last two decades were compared and analyzed. The concentrations of these three chemicals were found to be as high as hundreds of ng/g-dw in seafood produced in Kimmen and Machu near China, whereas those for seafood caught in Taiwan's coastal areas were not significant. The need for trade agreements or regulations on fishery was then discussed. According to the viewpoints of health and environmental sustainability, HIA methodologies were incorporated in the SEA to help identify and analyze the potential impacts on human health caused by OCPs in seafood consumed in Taiwan, which may be caused by the lack of trade regulation mechanisms between Taiwan and China. The integrated HIA-SEA framework for fishery trade agreements or regulations in Taiwan was thus proposed and the procedures were discussed. It is anticipated that the health of Taiwan's residents can be protected through implementing this and the human health perspective can be emphasized in the HIA-SEA procedures.     

Tackling ‘ghost nets’: Local solutions to a global issue in northern Australia

Summary We describe the inception and development of the Carpentaria Ghost Nets Programme, located across the Gulf of Carpentaria, which spans north Queensland and the Northern Territory. The program has grown from a small grass‐roots idea addressing issues around marine debris to become an internationally acknowledged project headed by the Northern Gulf Resource Management Group. This program, involving more than 18 Indigenous communities and over 90 Indigenous rangers, has become a way of building bridges across cultures and communities for a shared, common interest in land and sea protection. By incorporating traditional values and approaches to managing an international issue at a local scale, we have worked with local communities to increase pride and ownership on country whilst providing transferrable job skills. Success of this program ultimately depends upon the continued active engagements of the Indigenous communities and ranger groups. The project aims to address the fundamental issue of tackling the ghost nets problem at its source through cross‐cultural interactions between rangers and fishermen, increasing public, political and economic awareness, and ultimately reducing the incidental and intentional loss of fishing nets that act as ghost nets and result in tremendous biological, cultural and economic impacts. By putting in place long term management measures to ensure monitoring efforts, we can track ghost net debris arrival and changes through time, providing information to policy and cultural changes at regional and international scales.     

Diversity and ecology of wood-inhabiting aphyllophoroid basidiomycetes on fallen woody debris in various forest types in Switzerland

This study on the ecology of aphyllophoroid wood-inhabiting basidiomycetes in Switzerland showed a remarkably high species diversity of both saprophytes and mycorrhiza-forming species. Phlebiella vaga, a saprophytic species, and Amphinema byssoides, a mycorrhizal symbiont, were the two most abundant species. A total of 3339 samples of fungal fruitbodies in 86 plots distributed all over Switzerland belonged to 238 species. The five main biogeographical regions of Switzerland showed different pattern of fungal species richness: while the Plateau at lower altitudes was found to be rather rich, the Northern Alps and Central Alps, with the highest amount of forests cover, yielded less species. Although the Southern Alps exhibited the lowest species richness, this region harbours a specific species set. These findings encourage for further studies in Central Europe, where many species of aphyllophoroid wood-inhabiting basidiomycetes seem to be highly under-investigated.     

森林生态系统中的粗死木质残体及其功能

粗死木质残体（Coarse Woody Debris,CWD)是指所有地上和地下小头直径＞2．5cm的死木质物,林分中CWD主要来源于个体的死亡和干扰所造成的死亡,在森林群落的生长发育过程中,CWD的数量变化呈“U”型,CWD的分解是动物和微生物吸收吸收养分,淋溶和自然破碎综合作用的结果,CWD的分解过程就是其发挥功能的过程,在此过程中各阶段都会有不同类型的生物群体利用其提供生境食物;CD具有吸收和释放养分的能力,是植物生长的营养库,是森林树木更新的良好介质;CWD是许多陆生生物和水生生物的食物来源,栖息地,避难所,哺育地,迁移通道等,在生物多样性保持方面发挥着不同替代的,在CWD的形成过程产生了林窗斑块,推动了森林生态系统的小循环,因此,CWD是森林生态系统中重要的结构性和功能性组成要素,在保持森林生态系统和水生生态系统的生物多样性及其生态过程完整性等方面起着不可替代的作用,应当给予了充分的重视。     

Distribution and hydraulic significance of large woody debris in a lowland Australian river

The line-intersect technique was used to measure the loading of large woody debris in a 1.8 km reach of the Thomson River, Victoria (catchment area of 3540 km²). A debris census (measuring every item present) was done over 0.775 km of this reach. The transect technique over-estimated the actual loading revealed by the census. The loading of debris 0.01 m in diameter for the total 1.8 km reach was 0.0172 m³ m^–2, which is higher than that measured in many headwater streams in other parts of the world. The volume loading of debris measured from low level aerial photographs was only 4.8% of the value estimated by the line-intersect technique. The line-intersect estimates were biased due to non-random orientation of debris in the stream (causing estimated errors of +8% for volume loading and +16% for surface area loading). It is recommended that to avoid this problem, when using the line-intersect transect technique in lowland rivers, each line should comprise at least two obliquely-angled transects across the channel. The mean item of debris (0.1 m in diameter) had a trunk basal diameter of 0.45 m, a length of 7.4 m, and volume of 0.7 m³. The riparian trees and the in-channel debris were of similar dimensions. The debris tended to be close to the bed and banks and was oriented downstream by the flow at a median angle of 27°. Because of this orientation, most debris had a small projected cross-sectional area, with the median value being only 1 m². Thus, the blockage ratio (proportion of projected area of debris to channel cross-sectional area) was also low, ranging from 0.0002 to 0.1, with a median value of 0.004. The average item of debris, which occupied only 0.4% of the cross-section, would have minimal influence on banktop flow hydraulics, but the largest items, which occupied around 10%, could be significant. Judicious re-introduction of debris into previously cleared rivers is unlikely to result in a large loss of conveyance, or a detectable increase in flooding frequency.     

Influence of woody debris on nutrient retention in catastrophically disturbed streams

The role of woody debris in nutrient cycling was investigated in two catastrophically disturbed streams in the Pacific Northwest that had been subjected to large inputs of wood. One study site in each catchment had all woody debris removed (take section), while the debris in the other study site was left intact (leave section). Nitrate, phosphate and chloride (a conservative tracer) were released in each section and nutrient retention was monitored at downstream stations. Phosphate was removed from solution more than nitrate, probably due to the high N : P ratio in the stream water. However, there were no major differences in nutrient retention between the take and leave sections. In contrast, experiments in recirculating chambers showed that woody debris and cobbles exhibited higher nitrate and phosphate uptake per unit surface area than sand/gravel or fine particulate organic matter. The high uptake rates of woody debris and cobbles may be related to their suitability for colonization by heterotrophic microorganisms and algae. Wood may not influence nutrient retention significantly at the reach level because of its low surface area relative to other substrates. However, wood may be very important at small spatial scales because of its high uptake activity.