A comparison of streams in logged and unlogged areas of Great Smoky Mountains National Park

Second order streams draining areas of virgin forest in Great Smoky Mountains National Park, Tennessee and North Carolina, U.S.A., are compared to those which drain forests logged before the establishment of the park in the 1930's. Water quality of two main study streams (one unlogged and one formerly logged) was compared and the unlogged stream had generally higher levels of dissolved solids and lower levels of suspended particulates than the logged stream. Stream channel characteristics were compared on four logged and four unlogged streams. The unlogged streams had over four times more (by volume) of woody debris and 10 times more material in debris dams than the logged streams. Only minor differences in substrate composition were observed. Macroinvertebrate samples from the four logged and four unlogged streams showed that the logged streams contained greater numbers of organisms and more taxa. More detailed sampling on the two main study streams showed similar patterns of more individuals and more taxa in the logged stream, as well as differences in the composition of five functional groups. These differences in invertebrate fauna may be due to differences in quantity and quality of leaf litter inputs, although other explanations are also possible.     

Effects of sewage waste stabilization lagoon effluent on stream invertebrates

The ecological impact of discharge to streams of domestic sewage waste stabilization lagoon effluent was investigated. Benthic invertebrates were compared upstream and downstream of discharges to eight New Zealand streams where effluent dilution ranged from 6- to 484-fold. The percentage of common invertebrate taxa whose density changed significantly (ANOVA, P<0.05) downstream declined in proportion with the log of the effluent dilution (r=-0.87) and increased with downstream increase in benthic respiration (r=0.91) and several intercorrelated indicators of organic enrichment (log biochemical oxygen demand, r=0.91; log suspended solids (SS), r=0.84). However, these changes in invertebrate densities did not always reflect degraded community structure. The nature and direction of changes suggests a subsidy-stress gradient of responses. Increases in SS of > 4 g m^-3 were associated with significant changes in density of > 50 percent of the common taxa and > 50 percent reduction of the densities of the sensitive Ephemeroptera, Plecoptera, and Trichoptera (EPT). However, EPT densities increased by up to 50 percent at lower organic solids loadings. No general relationships were found between relative densities of functional feeding groups and metabolic or water quality variables. These findings confirm that early warning of enrichment stress is more easily seen at the species level than at the functional level.     

A stressed stream ecosystem: macroinvertebrate community integrity and microbial trophic response

A year-long study of a second-order stream in Southwestern Virginia was carried out from 1979–80. One of the objectives of the study was to evaluate the effects of sewage and electroplating plant effluent stress on the trophic response of aquatic invertebrate assemblages and microbial communities in the stream. Quantitative benthic samples were collected periodically at three reference stations and four stressed stations below the outfalls. Invertebrates were counted, identified taxonomically, and classified into functional groups based on their feeding strategies. Ash-free dry weights were obtained for each functional group by date and station, and the number and density of different taxa were calculated as well. Reference stations had diverse invertebrate assemblages; scrapers were well represented and all functional groups were present in reasonably equivalent proportions. Stressed stations were dominated by collector gatherers and filterers to the virtual exclusion of scrapers. The trophic status of the microbial community was determined by suspending artificial substrates in the stream for 1-week periods. The community that colonized the substrates was assayed for ATP and chlorophyll a, and an autotrophy index (AI) was calculated using these values. The autotrophic component of the microbial community was greatest at the reference stations, and the community became primarily heterotrophic below the outfalls. The AI correlated well with the proportion of scrapers. Aquatic invertebrate assemblages and microbial communities responded to stress by changing their trophic structure to fit best the available energy sources. Where heterotrophic microbes dominated, gathering and filtering invertebrates utilized the abundant organic matter. In areas where a mainly autotrophic microbial community existed, scrapers, gatherers, and filterers were all present in balanced proportions.     

On the influence of substrate morphology and surface area on phytofauna

The independent effects and interactions between substrate morphology and substrate surface area on invertebrate density or biomass colonizing artificial plant beds were assessed in a clear-water and a turbid playa lake in Castro County, Texas, USA. Total invertebrate density and biomass were consistently greater on filiform substrates than on laminar substrates with equivalent substrate surface areas. The relationship among treatments (substrates with different morphologies and surface areas) and response (invertebrate density or biomass) was assessed with equally spaced surface areas. Few statistically significant interactions between substrate morphology and surface area were detected, indicating that these factors were mostly independent from each other in their effect on colonizing invertebrates. Although infrequently, when substrate morphology and surface area were not independent, the effects of equally spaced changes in substrate surface area on the rate of change of phytofauna density or biomass per unit of substrate surface area were dependent upon substrate morphology. The absence of three-way interactions indicated that effects of substrate morphology and substrate area on phytofauna density or biomass were independent of environmental conditions outside and inside exclosures. Handling editor: D. Harper     

Short-term decompositional state does not influence use of wood by macroinvertebrates in subtropical, coastal plain streams

Woody debris is an important habitat component, particularly in streams that lack other hard substrates. Research suggests a general relationship between increasing invertebrate density, diversity, and taxa richness with increasing wood decay in lotic systems, with some authors observing invertebrate taxonomic succession as decay proceeds. We designed a field experiment using colonization of known-aged woody debris in two streams to examine patterns in invertebrate colonization, density, diversity, richness, and succession. After aging woody debris 0–6 weeks in laboratory tanks and then placing the debris in the two subtropical, coastal plain streams for five additional weeks, we did not detect any statistical relationship between invertebrate density, diversity, evenness, richness, or life-history pattern with increasing woody debris decay, nor did we detect any relationships between the colonization or abundance of individual taxa and the decompositional state of the wood. In this paper, we propose two non-exclusive explanations for these trends based on opportunistic colonization and evolutionary filtering. Despite the apparent unimportance of decompositional state, woody debris still supported many taxa and remains an important habitat component. Our research further supports the importance of flooding and maintenance of intact riparian and floodplain forests to the woody debris dynamics and macroinvertebrates in coastal plain lotic systems.     

Taxon-specific physico-chemical change points for stream benthic invertebrates

Freshwater organisms face numerous stressors, such as nutrient enrichment, contaminant pollution, sedimentation and alterations in stream hydrology and habitat structure. One of the most significant and widespread stressors in European freshwaters is expected to be water pollution from intensive land use. However, the information on critical threshold concentrations at which taxa decline or increase in frequency and abundance is missing for the large majority of river benthic invertebrate taxa. The main aim was to determine ecological change points for benthic invertebrate taxa at which rapid alterations in species frequency and abundance occur as a consequence of relatively small changes in the environmental gradient. These change points can be interpreted as critical threshold concentrations. A total of 468 river benthic invertebrate taxa and nine physico-chemical variables describing the daytime dissolved oxygen, chloride, nutrient concentrations and organic load were analyzed. We selected 751 river sites from a nationwide range of locations in Germany for this investigation. Depending on the physico-chemical variable, between 20.6% and 48.8% of the total number of tested taxa were assigned with a valid change point. All taxa were assigned to negative or positive response groups depending on the response direction. Except for daytime dissolved oxygen, negative responding taxa are referred to as decreasers and positive responding taxa as increasers, respectively. In total, 25.8–100% of the decreasers’ change points were below (and above in the case of daytime dissolved oxygen) the background values defined as quality criteria for German rivers by the water authorities. This indicates that stricter quality criteria may need to be set to reach the good ecological status according to the European Water Framework Directive. The calculated daytime dissolved oxygen change points were essentially in line with the species saprobic values and taxon-specific change points for physico-chemical variables fit well with the data provided in other international studies. We deliver valuable knowledge about the sensitivities and response schemes of river benthic invertebrate species. This information is especially useful for the development of efficient management and policy tools to predict the likelihood of occurrence of individual species under different levels of anthropogenic impact.     

Use of bioassay-based whole effluent toxicity (WET) tests to predict benthic community response to a complex industrial effluent

Whole effluent toxicity (WET) tests are a usefulmonitoring tool because they provide a rapid andreplicable measure of the potential ecotoxicologicaleffect of effluents. Although WET tests have beenincorporated into toxicity-based effluent limits toprotect receiving systems from adverse effects, fewstudies have attempted to quantitativelyfield-validate laboratory-derived toxicity thresholds.In this study, we examine the ability of WET tests topredict response thresholds of an invertebratecommunity to a paper mill effluent discharged into theNicolet-SW River, Québec, Canada. We quantifiedinvertebrate community structure and density in theriver and detrended for the effects ofphysical/chemical variables. This allowed examinationof direct correlation between invertebrate communitystructure and effluent concentration. There was asignificant decrease in taxonomic richness at aneffluent concentration of 16%, but significantchanges in the density of invertebrates occurredbetween 0% and 2% effluent. This suggests thatalthough most taxa returned to the river downstream ofthe effluent, they did so at lower densities.Calculated field thresholds were compared tolaboratory thresholds for the effluent using chronicWET tests with algae, cladocerans and fish. The WETtests produced a mean MATC of 3.6%. Thus, standardWET tests overestimated response thresholds of theinvertebrate community in the receiving environmentand impacts were observed in areas where no impact wasexpected.     

A comparison of the relative contributions of temporal and spatial variation in the density of drifting invertebrates in a Dorset (U.K.) chalk stream

1. Invertebrate drift is commonly investigated in streams, with the majority of studies focussed on temporal (typically diel) variation. In comparison, few studies have investigated spatial variation in drift and there is little consensus among them. We tested the hypothesis that spatial variation in invertebrate drift is as important as temporal variation. 2. The density of drifting invertebrates in a chalk stream was sampled using an array of nets arranged to determine vertical, lateral and longitudinal variation. Samples were collected at dawn, during the day, at dusk and by night, on four separate monthly occasions. Insecta and Crustacea were analysed separately to identify the effect of differing life history strategies. The density of drifting debris was also recorded, to act as a null model. 3. Time of day and vertical position together explained the majority of the variance in invertebrate drift (79% for Insecta and 97% for Crustacea), with drift densities higher at dusk and night, and nearer the stream bed. Independently, time of day (38%, Insecta; 52%, Crustacea) and vertical position (41%, Insecta; 45%, Crustacea) explained a similar amount of the observed variance. Month explained some of the variance in insect drift (9%) but none for Crustacea. 4. Variation in the density of drifting debris showed little in common with invertebrate drift. There was little variation associated with time of day and only 27% of the observed variation in debris could be explained by the factors investigated here, with month explaining the largest proportion (20%). We suggest the difference in drifting debris and invertebrates provides further evidence for a strong behavioural component in invertebrate drift. 5. Spatial variation in invertebrate drift can be of the same order of magnitude as the much‐described diel temporal variation. The extent of this spatial variation poses problems when attempting to quantify invertebrate drift and we recommend that spatial replication should be incorporated into drift studies.     

Impact of abattoir waste on Woji Creek,Port Harcourt,Nigeria, using physicochemistry and macrozoobenthic diversity indices

The impact of waste discharge from Zoo abattoir, Port Harcourt, on the environmental quality of Woji Creek was studied from April 2001 to March 2002 using physicochemistry and diversity of benthic animals as indicators. Priority physicochemical parameters (total suspended solid, dissolved oxygen and biochemical oxygen demand) indicated high organic enrichment, chiefly due to inputs of bloody effluent. The burning of animal skin with discarded car tyres to produce kpomo, a common local soup component, contributes to the creek's quality alterations. Ironically, diversity of zoobenthos was highest at the area receiving the abattoir effluents compared to areas upstream and downstream from that point. Possible explanations are provided for the inverted diversity trend using the Hutcheson Index, which indicated significant diversities in invertebrate species amongst the three sample sites. The inefficiency of ecosystem quality evaluations using isolated single indices is also discussed.     

Structural and functional responses of sewage microbial communities used for the treatment of a complex mixture of volatile organic compounds (VOCs)

Aims:  The aim of this work was to assess the impact of the applied mass loading on the selection of an efficient microbial community able to degrade a complex mixture of volatile organic compounds (VOCs).
Methods and Results:  Two reactors were used and were supplied with a gaseous effluent containing 11 VOCs with different concentrations. The response of the microflora was monitored as a function of time: biodegradation activity, bacterial density and diversity. The results showed that the applied mass loading seems to have an impact on the functioning and the genetic structure of the bacterial community.
Conclusions:  A high mass loading seems to induce a low efficient functioning in terms of elimination efficiency and a simplification of the genetic structure of the total bacterial community with the apparition of a dominant microflora. A low mass loading seems to favour a better functioning and allows to keep a healthier bacterial diversity.
Significance and Impact of the Study:  In the treatment processes of gaseous effluents, it would be judicious to define the functioning parameters of the process to keep the diversity of important functional bacterial groups. These results provide also useful information about changes in microbial communities following natural or anthropogenic alterations in different ecosystems.     

Assessment of Littoral Benthic Invertebrate Communities at the Land–Water Interface in Lakes Recovering from Severe Acid- and Metal-Damage

Benthic invertebrate communities within confluence sites, or areas of sediment deposition, are shaped by the input of catchment products including coarse woody debris, organic and inorganic particulates, and contaminants, but these sites also appear to be potential “hotspots” where recolonization of severely damaged ecosystems begins. Two species of leaf packs and a sweep netting technique were used to assess benthic invertebrate communities across a gradient of 14 confluence sites in 3 recovering lakes near the copper and nickel smelters in Sudbury, Canada. Environmental variables including delta habitat composition, delta area and length, and composition of deposited materials were used to detect spatial patterns in littoral benthic invertebrate communities. Benthic invertebrate community relationships with water chemistry were also assessed. Partial redundancy analysis (pRDA) showed that all sampling methods detected similar gradients of increasing invertebrate community richness and diversity as area and length of the sediment delta and the surface organic matter abundance increased. Two-way nested ANOVAs showed significant differences (p < .05) in taxa richness and diversity metrics among sites. Of the three methods, the benthic invertebrate community measurements from the birch leaf packs provided the strongest correlations with measures of organic matter inputs or habitat characteristics of the confluence zones. These correlations suggest that tree planting in riparian areas, or organic matter or macrophyte additions to littoral zones, may enhance littoral benthic invertebrate richness and diversity in acid and metal damaged lakes.     

Stressor prioritisation in riverine ecosystems: Which environmental factors shape benthic invertebrate assemblage metrics?

Aquatic ecosystems are amongst the most heavily altered ecosystems and exhibit a disproportional loss of biodiversity. Numerous stressors, such as nutrient enrichment, contaminant pollution, sedimentation and alterations in stream hydrology and habitat structure, account for these losses. Understanding these forces is of utmost importance to prevent riverine ecosystems from further deterioration and to provide helpful insights for restoration practices. In the present study, we analyse the response of biological indicators to a large number of environmental factors. For this, benthic invertebrate assemblages from 83 sites in Germany were described based on 25 metrics from four different metric types. The condition of the sites was described using 27 environmental factors: 13 for water quality, 4 for land use in the catchment and 10 for local scale habitat structure. The relative importance of single environmental predictors or predictor combinations for benthic invertebrate assemblages was analysed with single and multiple linear regression models. The results for the latter models were statistically supported via a bootstrap approach. The models revealed the importance of water quality and catchment-scale land use in explaining benthic invertebrate assemblages; in particular, chloride, oxygen, total organic carbon and the amounts of artificial surfaces and arable land were the most important predictors. Models including solely structural variables such as plan form, bank structures and substrate diversity had lower goodness of fit values than those for other variables. Regarding the four different assemblage metric types, functional metrics had on average lower goodness of fit values than composition/abundance, richness/diversity and sensitivity/tolerance metrics. Among the richness/diversity metrics, however, the model results for the Shannon–Wiener and Simpson diversity indices and evenness were poor. Our results show that catchment-related factors and water quality were of overriding importance in shaping biodiversity patterns and causing species loss. In contrast, structural degradation at a local scale was not the most significant stressor. This finding might explain why structural restoration at a reach scale often yields a low benefit–cost ratio and may be considered to represent inappropriate investment prioritisation.     

Characterization of 18S-ITS1-5.8S rDNA in eleven species in Soleidae: implications for phylogenetic analysis

Wildfire is one of the most important global agents of disturbance affecting terrestrial and riparian vegetation. Post-fire vegetation changes can alter stream resource pathways and cause channel reorganization and sediment-laden debris flows. Yet, little is known about macroinvertebrate community recovery following wildfire and debris flows and how these communities fit into the broader stream community mosaic. We examined the effects of wildfire and debris flows on relative resource availability and macroinvertebrate assemblages at 31 streams in Idaho, USA using a space-for-time study design. Wildfire and debris flows had no apparent effects on resource standing crop. However, macroinvertebrate communities among unburned, burned, and debris flow streams were quite different. Compared to unburned streams, biomass and density were higher at streams which experienced debris flows ~ 10 years post fire, but exhibited the near-complete absence of macroinvertebrates at streams with more recent debris flows. Stream macroinvertebrate communities impacted by debris flows were distinct compared to unburned and burned streams which did not experience debris flows. When found, differences in macroinvertebrate biomass, density, richness, and community structures were largely due to the incidence of debris flows. Debris flows removed the riparian vegetation, slowing its recovery, cascading to affect macroinvertebrate community structure into the long term.     

Environmental impact of heated mining waters on clitellate (Annelida: Clitellata) assemblages

Mining is a relatively highly monitored industry. While chemical pollutants (toxic ions, radionuclides, etc.) have mostly been eliminated from mining waters, other types of environmental pollution (temperature regime alterations, high concentrations of various anions, etc.) can affect benthic invertebrates. In this study, we focused on the effect of mining water effluent on the diversity and density of aquatic Clitellata. Four sampling sites were selected. Three sites in a natural stream (the Nedvědi?ka River, Czech Republic), one upstream and two downstream from the mining effluent, and one site on the mining waters were sampled monthly during 2008–2009. Environmental variables were recorded in and samples were collected from two types of habitats — riffles and pools. The response of clitellate assemblages was evaluated using principal component analysis and generalised estimating equations. The results indicated that the mining effluent caused partial species exchange and had negative effects on clitellate taxa richness and abundance. These responses were specific to both the habitat (riffle/pool) and species sampled. In each of the different taxa studied, we observed one of four typical clitellate responses: (a) elimination of stenotherm species; (b) reduction of clitellate species followed by quick recovery; (c) neutral response; or (d) positive influence. We found that aquatic clitellates, which are considered to be eurytopic with broad ecological valences, are also sensitive to even slight environmental pollution.     

Impacts of an Invasive Non-Native Annual Weed,Impatiens glandulifera,on Above- and Below-Ground Invertebrate Communities in the United Kingdom

Vegetation community composition and the above- and below-ground invertebrate communities are linked intrinsically, though few studies have assessed the impact of non-native plants on both these parts of the community together. We evaluated the differences in the above- (foliage- and ground-dwelling) and below-ground invertebrate communities in nine uninvaded plots and nine plots invaded by the annual invasive species Impatiens glandulifera, in the UK during 2007 and 2008. Over 139,000 invertebrates were identified into distinct taxa and categorised into functional feeding groups. The impact of I. glandulifera on the vegetation and invertebrate community composition was evaluated using multivariate statistics including principal response curves (PRC) and redundancy analysis (RDA). In the foliage-dwelling community, all functional feeding groups were less abundant in the invaded plots, and the species richness of Coleoptera and Heteroptera was significantly reduced. In the ground-dwelling community, herbivores, detritivores, and predators were all significantly less abundant in the invaded plots. In contrast, these functional groups in the below-ground community appeared to be largely unaffected, and even positively associated with the presence of I. glandulifera. Although the cover of I. glandulifera decreased in the invaded plots in the second year of the study, only the below-ground invertebrate community showed a significant response. These results indicate that the above- and below-ground invertebrate communities respond differently to the presence of I. glandulifera, and these community shifts can potentially lead to a habitat less biologically diverse than surrounding native communities; which could have negative impacts on higher trophic levels and ecosystem functioning.     

The relative importance of drift causes for stream insect herbivores across a canopy gradient

A key attribute of riverine food webs is the downstream movement of invertebrates via the water column, or invertebrate drift. Causes of drift include benthic predation, food limitation, and perhaps passive entry, which may occur when invertebrates lose their purchase on stream substrate. However, the relative importance of drift causes is unknown, as is whether the relative importance of drift causes varies across space. Combining observational data on invertebrate herbivore and predator guild densities with in‐stream experiments, we evaluated the relative importance of benthic predation, food limitation, and passive entry as proximate causes of drift for the herbivore guild across the canopy gradient of a montane stream. We found that 1) benthic predation and food limitation were both more important as causes of herbivore drift than passive entry; 2) drift caused by food limitation did not vary with riparian canopy, whereas herbivore density decreased with increasing riparian canopy, and 3) per capita drift increased linearly with increasing density, while per capita drift decreased in a negative hyperbolic fashion with increasing food, indicating that herbivore drift is proportional to herbivore density, and inversely proportional to food. We conclude that invertebrate herbivore drift was overwhelmingly an active process to improve fitness, and that herbivore food did not vary across the canopy gradient, likely because increased herbivory from larger herbivore populations at sunnier sites prevented food from accumulating.     

Amino Acid Requirements and Proteolytic Activity of Streptococcus sanguis

The growth response of Streptococcus sanguis groups 1:A and 1:B in a complete chemically defined medium was not influenced by the oxygen concentration of the growth atmosphere. All of the cultures required cysteine and arginine; tyrosine and branched-chain amino acids were frequently required. Proteolysis of casein, mucin, and the anionic proteins of germfree rat saliva by S. sanguis was demonstrated. Hydrolytic activity toward casein was found in the soluble contents of the cells and in the cellular debris after disruption of the cells, with the soluble fractions exhibiting greater proteolytic activity toward casein. The soluble fractions from S. sanguis did not hydrolyze mucin, but this substrate was hydrolyzed by the cell debris fraction. When the amino acid requirements and proteolytic activity of S. sanguis and S. mutans were compared, these two oral streptococcal species exhibited distinct and characteristic differences.     

Vertical distribution and abundance of invertebrates within the sandy substrate of a low-gradient headwater stream

SUMMARY. 1 The vertical distribution of invertebrates (>0.053 mm) was studied in a sandy-bottomed, first-order stream on the Coastal Plain of Virginia, U.S.A. Invertebrate species composition, abundance and bio-mass were determined monthly over one year at sediment depth intervals of 0–1, 1–5, 5–15,15–30 and 30–40 cm.
2. The subsurface community was numerically dominated by species of Chironomidae, Nematoda and Crustacea, while much of the biomass was due to early instars of several species of Trichoptera.
3. Invertebrate density and biomass decreased significantly with depth in the substrate (ANOVA; P <0.05). Annual mean density decreased from 1,346,844 individuals m⁻³ at the surface to 13,578 individuals m⁻³ at 15–30 cm. Annual mean biomass decreased from 66.30 g m⁻³ at the surface to 0.44 g m⁻³ at 15–30 cm.
4. Dissolved oxygen decreased markedly from the surface to the 5 cm depth in the substrate, anaerobic conditions often occurring below 10 cm. Density and biomass both showed a significant positive relationship with dissolved oxygen concentration (Linear regression; P <0.05).
5. Physical forces were important in structuring the subsurface invertebrate community. Besides low dissolved oxygen concentration, sediment scouring resulting from storm discharge dramatically reduced density and biomass     

Comparison of benthic macroinvertebrate fauna and substratum composition in riffles and pools in the impounded River Elan and the unregulated River Wye, mid-Wales

SUMMARY. The macro-invertebrate fauna and substrate were studied in a riffle and pool from a regulated (Elan) and an unregulated (Wye) river in summer. There were some differences in the substrate particle size distribution of the two rivers and between the riffle and the pool on the Wye. There was more detritus in pools than in riffles in both rivers and generally more in the Elan than the Wye. Deposits on the bed of the Elan were rich in iron and manganese.
On the Wye. there was a greater density of invertebrates in the riffle than in the pool, but species richness was similar. Most species showed some preferences for either the riffle or the pool. The riffle contained a substantial number of Ephemeroptera, Trichoptera, Plecoptera and Simuliidae (52%) whilst the pool was dominated by chironomids (71%). Compared with the Wye, total invertebrate density and species richness were reduced in the Elan. Some species characteristic of riffles were reduced or absent on the Elan. Invertebrate density on the Elan was similar in the riffle and pool; species richness was greater in the riffle. The distribution and abundance of invertebrates is discussed in relation to such environmental factors as water velocity through the substrate and dissolved oxygen supply in interstitial habitats.     

北京市春季天气状况对针叶树叶面颗粒物附着密度的影响

对北京市侧柏、圆柏、油松和云杉冲洗与未冲洗植株春季1个月内叶面颗粒物附着密度进行了观测,并对照逐日气象数据和测试树种叶表面微形态,分析了天气状况对叶面颗粒物附着密度的影响。结果表明,春季降雨、大风、沙尘等天气状况交替出现导致叶面颗粒物附着密度随之变化,大多数时间低于冬季。测试树种叶面部分颗粒物附着牢固,不能被中等强度15 mm降雨冲掉。5~6级大风不会使叶面颗粒物附着密度减少。与本地扬尘相比,外来入侵沙尘可使叶面颗粒物附着密度较大增加。侧柏和圆柏叶表面密集脊状突起间的沟槽可深藏许多颗粒物,且颗粒物固着牢固,不易被降雨和大风去除。油松叶表面光滑、粘性大,易于小颗粒物的附着,但颗粒物容量较低,附着不牢固。云杉气孔周围较宽凹槽利于牢固滞留较大颗粒物,能有效捕获粒径较大的外来沙尘。