Degree Of Anthropogenic Influence Research Articles

Emisije ugljikovog dioksida (CO2) iz tla tijekom obnove sastojine hrasta lužnjaka (Quercus robur L.) u ljetnom razdoblju

The loss of soil organic carbon stock and increased CO2 emission from soil are induced by various human activities. The aim of this study was to examine whether an anthropogenic influence during the regeneration of a pedunculate oak (Quercus robur L.) stand can affect the increment of CO2 emission from the soil. The research was carried out within three plots, out of which two were exposed to different degrees of anthropogenic influence. The air samples were collected using the soil respiratory chambers and analysed using the gas chromatograph Agilent 8890. Based on the obtained results, soil temperature and moisture as the most dominant drivers of the CO2 emission had different effects on the CO2 flux from soil depending on the intensity of anthropogenic influences and environmental conditions. Within the experimental plot with the significant soil alteration, a reliable positive correlation was detected for the CO2 flux with the soil temperature (r = 0.77, p < 0.05). High significant correlation was observed considering soil moisture (r = 0.85, p < 0.05) in the natural soil where the application of pesticides was conducted. The results showed that both soils that were exposed to the anthropogenic influences had notably higher values of the CO2 flux in comparison to the reference natural soil without anthropogenic impacts.

Microplastics pollution in the intertidal limpet, Nacella magellanica, from Beagle Channel (Argentina)

Microplastics (MPs) have been identified in diverse marine invertebrates; however, there are few studies on limpets. This study aimed to evaluate and compare the presence of MPs in Nacella magellanica among sites of the Beagle Channel with different degree of anthropogenic influence. Intertidal limpets were sampled in three sites: Ushuaia Bay (UB) (inside Ushuaia city), a site with high anthropogenic influence owing to population growth, and fisheries, industrial and port activities; Ensenada Zaratiegui (EZ) and Playa Larga (PL) (west and east of Ushuaia city, respectively), both sites with a certain degree of environmental protection and low anthropogenic influence. MPs were isolated from the whole soft tissue of individuals by oxidative digestions with H2O2 (30%; 1:10 w/v). MPs occurrence was 100% in organisms from UB and EZ, whereas 90% in PL. Limpets from UB showed 10 ± 6.69 MPs/ind and 2.22 ± 0.78 MPs/g ww, while in PL and EZ there were 2.90 ± 2.02 MPs/ind and 0.96 ± 0.94 MPs/g ww; and 5.60 ± 2.59 MPs/ind and 2.41 ± 1.47 MPs/g ww, respectively. Fibres were the most abundant MPs type, followed by fragments and films. Fibres and films were identified as semi-synthetic cellulose and, although the polymer matrix of fragments was masked by copper phthalocyanine, one of them could be identified as polystyrene. As expected, the highest abundance of MPs was found in UB. However, a lower abundance of particles was detected in PL (downstream of UB) than in EZ (upstream of UB). This could be due to the influence of both the main current of the Beagle Channel and fluvial discharges, reducing the buoyancy of MPs. More studies are needed to understand the contribution of regional and local features to the accumulation of MPs in these environments and their interaction with the biota.

Seaside Recreation Ground: A Multi-Proxy Palaeoenvironmental Investigation on the Coastal Edge of the Willingdon Levels, Eastbourne, East Sussex, UK

ABSTRACT The Willingdon Levels hold some of the best-preserved prehistoric archaeological and palaeoenvironmental remains in south-east England. This study aims to characterise the previously unexplored coastal limits of the Willingdon Peat and compare the chronology with known sites. The degree of anthropogenic influence on vegetation cover in prehistory is of significant interest to archaeologists, and this paper aims to strengthen the case for human-induced landscape alteration surrounding the Willingdon Levels in the Bronze Age. Lithological, palynological, entomological, ostracod, foraminifera, diatom and radiocarbon analyses were applied to a sequence of deposits at Seaside Recreation Ground. This paper palaeoenvironmentally reconstructs the coastal edge of the Willingdon wetland and proposes a timing for the main period of peat initiation that occurred across the Levels. A decline in woodland taxa and the presence of cereal pollen allude to human presence in the landscape. The results have contributed to the Willingdon Levels modelling project.

Spatiotemporal variations and relationships of phosphorus, phosphomonoesterases, and bacterial communities in sediments from two Chilean rivers

Rivers are important ecosystem services providers in southern Chile; however, the microbiology of most rivers are understudied. This is particularly true for phosphorus (P) recycling by bacterial activity. Here, we studied the physicochemical properties, P contents, phosphomonoesterase (Pase) activities, and bacterial Pase genes (phoD, phoC, and phoX) in Chilean river sediments (Imperial and Toltén rivers, Chile) collected in sites with less and more degrees of anthropogenic influence during the summer and winter seasons. The richness, diversity, composition, and predicted function of the bacterial communities were addressed, as well as the spatiotemporal relationships among P-associated parameters and bacterial communities. Our results showed spatiotemporal variations, highlighting higher values of the temperature, conductivity, nutrients (C, N, P), Pase activity, and Pase genes in sediments collected in sites more anthropogenized during summer. In contrast, higher richness, diversity, and abundance of total bacteria were found in sediments collected in winter. The phylum Proteobacteria and heterotrophy were the most relatively abundant bacterial taxa and predicted function, respectively. The differentiation among winter and summer sediments was also revealed and the relationships between bacterial community and P-associated parameters were confirmed. Our analysis also highlighted the positive relationship between Pase genes with Gemmataceae, Xanthomonadaceae, and Chitinophagaceae families, and between Pase activity and Po with Chromatiaceae and Desulfobacteraceae families. This study represents an initial investigation aimed to unravel the compositions and relationships of bacterial communities with P recycling in these sediments, which are threatened by anthropogenic activity (e.g., agriculture, industry, cities, etc.). This information may be used in the design of countermeasures to prevent deterioration of Chilean rivers, which are relevant as ecosystem service providers.

Flocking of Foraging Yellow-Billed Choughs Pyrrhocorax Graculus Reflects the Availability of Grasshoppers and the Extent of Human Influence in High Elevation Ecosystems

Mountain ecosystems are subject to many pressures, including changes in land use, rising temperatures and increasing recreational activities. These factors may disrupt food webs, threatening the survival of organisms and, ultimately, ecosystem functioning. However, few studies focus on the trends of different groups joined by trophic links in alpine ecosystems. The Yellow-billed (Alpine) Chough, Pyrrhocorax graculus, a gregarious bird that moves in flocks, is an ideal target species within this framework since it has a grasshopper-based diet during the summer and may attend sites that are heavily developed for recreational activities. We tested therefore whether flock size co-varied with grasshopper abundance along an elevational gradient in two alpine areas subject to different levels of human disturbance. Chough flock size and grasshopper abundance were measured along elevational transects. The median flock size was analysed in relation to grasshopper abundance and biomass, we also conducted negative binomial GLMs to account for effects of period (i.e. from June to mid-August), site and elevation. In both study areas, chough flocks were larger at the elevation where grasshoppers were more abundant. This may indicate the capacity of the species to follow large-scale fluctuations in their key insect prey. On the other hand, the relationship between flock size and grasshopper biomass was positive at a natural site and negative at a tourist site. This suggests that where there is a high level of human influence, other factors, such as the availability of human-provided food, may disturb the natural relationship between choughs and their key prey. Overall, our results indicate that flocking by foraging Yellow-billed Choughs reflects both grasshopper abundance and the degree of anthropogenic influence.—Vallino, C., Caprio, E., Genco, F., Chamberlain, D., Palestrini, C., Roggero, A., Bocca, M. & Rolando, A. (2021). Flocking of foraging Yellow-billed Choughs Pyrrhocorax graculus reflects the availability of grasshoppers and the extent of human influence in high elevation ecosystems. Ardeola, 68: 53-70.

River biofilms adapted to anthropogenic disturbances are more resistant to WWTP inputs.

The sensitivity and spatial recovery of river sediment biofilms along 1km after the input of two wastewater treatment plants (WWTPs) located in two river reaches with different degrees of anthropogenic influence were investigated. First, at the upper reach, we observed an inhibition of some microbial functions (microbial respiration and extracellular enzyme activities) and strong shifts in bacterial community composition (16S rRNA gene), whereas an increase in microbial biomass and activity and less pronounced effect on microbial diversity and community composition were seen at the lower reach. Second, at the lower reach we observed a quick spatial recovery (around 200m downstream of the effluent) as most of the functions and community composition were similar to those from reference sites. On the other hand, bacterial community composition and water quality at the upper reach was still altered 1km from the WWTP effluent. Our results indicate that biofilms in the upstream sites were more sensitive to the effect of WWTPs due to a lower degree of tolerance after a disturbance than communities located in more anthropogenically impacted sites.

Deadwood stocks in south-western European forests: Ecological patterns and large scale assessments

Forest deadwood is a relevant factor in the provision of ecosystem services (forest biodiversity, carbon sequestration, recreational and aesthetic values), but it also influences the risk and impact of forest perturbations. Hence, reliable estimations are urgently need in the lack of detailed information in Mediterranean forests at large scales. In this study we provide, for the first time, national-level estimations for Spain based on the information from the Spanish National Forest Inventory (38,945 plots). In addition, we compare and validate two approaches for estimating deadwood stocks where data is lacking; the first of these being a modelling approach based on stand, climatic and physiographical variables, and the other considers the ratio between deadwood and living biomass. We also examine the different patterns stock across forest types in four biogeographical regions according to a broad-spectrum of species groups and forests with different degrees of anthropogenic influence. The degrees are based on levels of protection and naturalness categories.The modelling approach provides more robust deadwood estimates and better predictive capacity than the ratio approach. Alpine (6.09 Mg.ha−1) and Atlantic (3.53 Mg.ha−1) bioregion forests store significantly higher mean deadwood biomass stocks than Macaronesian and Mediterranean forests. However, the share of deadwood in relation to the total biomass stock is greater in Mediterranean biogeographical region. As regards species groups, the mean deadwood stock of mixed forests doubled the stocks found in conifer and broadleaved dominated forests. We also found significant differences in deadwood biomass stocks between forests with different levels of anthropogenic protection. However, forest types with intensive forest management had contrasting figures for deadwood stock.The mean values obtained at national level according to forest type, bioregion and degree of anthropogenic influence, provide baseline information for carbon accounting as well as for other forest policy planning and management strategies.

Biometric and hematological indices of Mugil curema inhabiting two Neotropical estuaries

The present study aimed to evaluate the biometric and hematological indices in Mugil curema collected in two Neotropical estuaries in the south coast of Brazil, and to investigate if such variables can be influenced by seasonality and degree of anthropogenic influence. Differences between seasons and estuarine systems were observed, where the dissolved oxygen and salinity, together with the historical contamination of the Santos estuarine system (SES), seem to play an important role in the biological response. Fish from the SES presented, in general, high responses of the hematological variables (red and white series) and the hepatosomatic index, relative to those fish from Peruíbe estuarine system (PES), even with the remote contamination present at PES, while no erythrocytic abnormalities or micronucleus were observed in fish collected at SES and PES in both seasons. The present work demonstrated that M. curema collected at SES are experiencing hematological and metabolic perturbations that are not observed in fish collected at PES.

Geochemical Features of Elements Distributions in the Lake Waters of the Arctic Region

Abstract—Data on the water quality and the contents of a large group of elements in small lakes are reported for three regions of the Arctic basin: European Russia (Kola region), Western (Yamal–Nenets district) and Eastern (Norilsk region) Siberia. All studied waters are low-salinity and oligotrophic. The air pollution in the lake waters caused the elevated concentrations of many elements. The waters of the Norilsk and Kola regions are enriched in Ni, Cd, As, Sb and Se owing to the distribution of smoke emissions from copper–nickel smelters over long distances. The petroleum industry leads to increased concentrations of V, Pb, and Mo in water. The degree of anthropogenic influence on the lake waters of the Arctic regions was estimated using the Enrichment Factors (EF). The high values of EF for most part of analyzed elements are explained not only by anthropogenic dispersion of elements, but also by a change in the conditions of element migration and the geochemical features of ore occurrences. The calculations demonstrated the effect of anthropogenic dispersion on the enrichment of Arctic waters by a large group of elements, including toxic ones.

Symbiont-bearing Foraminifera from Reefal Areas: a Case Study from Rio Grande Do Norte (rn, Brazil)

AbstractWe examined the abundances of two species of benthic foraminifera that host algal endosymbionts (SBF) in two sedimentary reefal areas (Pirangi and Maracajaú) of Rio Grande do Norte (RN, Brazil). The original dataset is based on 95 samples collected in winter in 2013 and 2014 by divers or grab samplers, and is compared to other known Brazilian reefs. The tests of Amphistegina gibbosa were conspicuous in sediments associated with coral and coral-rubble substrata, whereas tests of Amphisorus hemprichii were best represented in sediments associated with seagrass. Our studies also have revealed that populations of these species are depauperate near tourism sites in Pirangi, as the area is affected by trampling from tourist activities. In the Maracajaú area, these populations are healthier, except at sites severely affected by tourism. Differences in microhabitats of the two taxa are likely to be associated with the degree of anthropogenic influence on the inner shelf at Pirangi compared to the offshore Maracajaú area.

The vegetation of the cretaceous outcrops of Novhorod-Siverskyi Polesie loess “islands” (Ukraine) and the new locality of Gentiana cruciata L.

The vegetation of the cretaceous outcrops of Novhorod-Siverskyi Polesie loess “islands” is represented by the grasslands communities of the Artemisietea vulgaris Lohmeyer et al. in Tx. ex von Rochow1951, Festuco-Brometea Br.-Bl. et Tx. ex Soo 1947, TrifolioGeranietea sanguinei T. Muller 1962 classes and shrubby phytocoenoses of the Robinietea Jurko ex Hadac et Sofron 1980 class. The structure and composition of the plant communities are influenced by the degree of anthropogenic influence (both in the past and present) on the ecosystems of cretaceous outcrops. The determining anthropogenic factors contributing to the formation of the ruderal communities were chalk mining and gardening. The influence of erosive processes is manifested in the spatial delimitation of plant communities of various syntaxonomic belongings. The anthropogenic successional communities: semiruderal grasslands and herblands of the immoral and subboreal zones of Europe (ConvolvuloAgropyretum repentis Felfoldy (1942) 1943, Poo compressae-Tussilaginetum farfarae R. Tx. 1931) and scrub communities of temperate Europe, represented by the Elytrigio repentisRobinietum Smetana 2002 phytocoenoses typical for Steppe zones, prevail. Semixerothermic communities were found on the steep slopes of the cretaceous outcrops (eastern and southwestern expositions) – early successional stages with a significant amount of the characteristic species of the Festuco-Brometea Br.-Bl. et Tx. ex Soo 1947 class. On the cretaceous outcrops of Novhorod-Siverskyi Polesie loess “islands” the communities of Trifolion medii T. Muller 1962 (meso-subxerophytic fringe phytocoenoses on nutrient-poor but base-rich soils at lower altitudes of temperate Western and Central Europe) is localized on the slopes of the eastern and southeastern parts of the expositions which do not undergo anthropogenic influence and are separated by erosion forms. Such conditions were favorable for preserving the Gentiana cruciata L. relict species in this locality. The population of this species was found in the area of 50 m2 in the Trifolio medii-Agrimonietum Th. Muller 1962 association community and represented by two compact groups of individuals (the area of 0.5 m 2 each) and individual plants. In order to preserve the habitat of this rare species, it is worth creating here a reserve.

Seasonal response of benthic foraminifera to anthropogenic pressure in two stations of the Gulf of Trieste (northern Adriatic Sea, Italy): the marine protected area of Miramare versus the Servola water sewage outfall

A seasonal survey of living benthic foraminifera was performed in 2013 in the Gulf of Trieste (N Adriatic Sea) to compare two marine coastal sites with different degrees of anthropogenic influence. An assessment of ecological quality statuses showed that the station located near the end of an urban pipeline (Ser station), has worse ecological conditions than the site located in a protected marine area (Res station) all year around. Stressed conditions at Ser station were mainly related to high contents of total organic carbon (TOC) and Zn in the bioavailable fraction, which were a limiting factor for the studied foraminiferal communities. Ammonia tepida, Bolivina spp., and Bulimina spp., which characterised this station, were the most tolerant taxa of the studied assemblage. Conversely, Elphidium spp., H. depressula, N. iridea, Quiqueloculina spp., R. nana and Textularia spp., could be considered less tolerant species as they benefitted from the less stressful conditions recorded at Res station, despite slightly higher concentrations of some potentially toxic elements (PTEs), especially Pb, being recorded in this station in comparison to Ser station. Furthermore, foraminiferal assemblages were found to be quite resilient over an annual cycle, being able to recover from a seasonal unbalanced state to a mature one. The beginning of spring and latest summer would be the best period to assess the ecological quality status to avoid any under- or overestimation of the health of the environment.

Valuing the carbon sequestration regulation service by seagrass ecosystems of Palk Bay and Chilika, India

The regulatory ecosystem services in terms of carbon sequestration and storage by Indian seagrass ecosystems were coupled with their monetary values in the context of climate change mitigation in the seagrass meadows of Palk Bay and Chilika Lagoon, two major seagrass ecosystems of India. The results showed that the meadows acted as a net sink of atmospheric CO2; however, they may also act as a minor source of CO2 to the atmosphere depending on the degree of anthropogenic influence. The mean ecosystem productivity ranged between 6.31 and 11.9 kg C ha−1d−1, which is equivalent to the capture of 8.44 and 15.9 Mg CO2 ha−1 year−1. This captured carbon was apportioned primarily in sediments (129 Mg Corg ha−1 in top 1 m soil), which was much higher than the carbon stored as above and below ground biomass (0.20–0.96 Mg Corg ha−1 and 0.30–2.90 Mg Corg ha−1, respectively). The economic valuation of regulatory ecosystem services in the form of C sequestration by an estimated 51,700 ha of total seagrass cover in India was largely dependent on the sequestration rates and the average social cost of carbon. The estimated values ranged between $ 1.02 million and $ 3.65 million per year. In addition, monetary values of the stored carbon in live biomass of Indian seagrass systems ranged between $ 0.45 million and $ 3.89 million, whereas, in the top 1 m soil it ranged between $ 109 million and $ 146 million. Detailed evaluations of various ecosystem functions considering the importance of the local variables may provide a better monetary estimate of these regulatory services.

The stable isotope ecology of Pan in Uganda and beyond.

Stable isotope analysis has long been used to study the dietary ecology of living and fossil primates, and there has been increasing interest in using stable isotopes to study primate habitat use and anthropogenic impacts on non-human primates. Here, we examine the stable carbon and nitrogen isotope compositions of chimpanzees (Pan troglodytes) from seven communities in Uganda across a continuum of habitat structure (closed to more open) and access to anthropogenic resources (no reliance to heavy reliance). In general, the hair δ(13) C, but not δ(15) N, values of these communities vary depending on forest structure and degree of anthropogenic influence. When integrated with previously published hair δ(13) C and δ(15) N values for Pan, it is apparent that modern "savanna" and "forest" Pan form discrete clusters in carbon and nitrogen isotope space, although there are exceptions probably relating to microhabitat specialization. The combined dataset also reveals that Pan δ(13) C values (but not δ(15) N values) are inversely related to rainfall (r(2) = 0.62). We converted Pan hair δ(13) C values to enamel equivalents and made comparisons to the fossil hominoids Sivapithecus sp., Gigantopithecus blacki, Ardipithecus ramidus, and Australopithecus anamensis. The δ(13) C values of the fossil hominins Ar. ramidus and Au. anamensis do not cluster with the δ(13) C values of modern Pan in "forest" habitats, or with fossil hominoids that are believed to have inhabited forests. Am. J. Primatol. 78:1070-1085, 2016. © 2016 Wiley Periodicals, Inc.

Analysis of forest vegetation in Koviljski Rit: Comparison of habitats with varying degrees of anthropogenic influence

Koviljski Rit is located along the left bank of the Danube River, between the villages of Kovilj and Gardinovci. It is a rare example of pristine nature, where the original features of a swamp biotope are preserved. Because of its exceptional natural value, Koviljski Rit, along with the swamp in Petrovaradin, has been under the protection of the Republic of Serbia since 1998, when it was proclaimed a Special Nature Reserve of the first category. Natural vegetation found in Koviljski Rit includes woodlands composed of willow and poplar. The majority of the reserve consists of forest plantations (55.6%), which include habitats influenced by human activities. Based on DCA (Detrended correspondence analysis) of forest vegetation in Koviljski Rit, there is a high degree of similarity between natural populations of white willow and stands of anthropogenic origin. However, in contrast, the same analysis indicates clear differences between natural and artificial poplar stands. Moreover, depending on whether they were planted in temporary or permanent flood plain habitats, significant differences are evident in the floristic structures of Euro-American poplar forests. Ecological conditions in habitats of white and Euro-American poplar (Populus x euroamericana/Dode/ Guinier) communities were found to be more similar with respect to illumination and soil humidity. However, more importantly, the anthropogenic forests recorded the lowest diversity as a result of regular thinning and measures implemented through forest management.

Effects of metal-contaminated soils on the accumulation of heavy metals in gotu kola (Centella asiatica) and the potential health risks: a study in Peninsular Malaysia.

Centella asiatica is a commonly used medicinal plant in Malaysia. As heavy metal accumulation in medicinal plants which are highly consumed by human is a serious issue, thus the assessment of heavy metals in C. asiatica is important for the safety of consumers. In this study, the heavy metal accumulation in C. asiatica and the potential health risks were investigated. Samples of C. asiatica and surface soils were collected from nine different sites around Peninsular Malaysia. The concentration of six heavy metals namely Cd, Cu, Ni, Fe, Pb and Zn were determined by air-acetylene flame atomic absorption spectrophotometer (AAS). The degree of anthropogenic influence was assessed by calculating the enrichment factor (EF) and index of geoaccumulation (Igeo). The heavy metal uptake into the plant was estimated through the calculation of translocation factor (TF), bioconcentration factor (BCF) and correlation study. Estimated daily intakes (EDI) and target hazard quotients (THQ) were used to determine the potential health risk of consuming C. asiatica. The results showed that the overall surface soil was polluted by Cd, Cu and Pb, while the uptake of Zn and Ni by the plants was high. The value of EDI and THQ showed that the potential of Pb toxicity in C. asiatica was high as well. As heavy metal accumulation was confirmed in C. asiatica, daily consumption of the plant derived from polluted sites in Malaysia was not recommended.

Western Mediterranean environmental changes: Evidences from fluvial archives

When dealing with current and past landscape evolution, a key issue addresses responses of geomorphic systems to the large number of influencing variables. Identifying morphodynamic phases and revealing interrelations with specific driving forces are demanding tasks for Quaternary research. In this paper, we present late Pleistocene and Holocene fluvial sedimentation patterns of three Western Mediterranean river catchments, namely Jarama River, Guadalete River and Guadalquivir River that extent along a climatic transect from semi-humid SW-Spain to semi-arid central Spain. These studies are based on extensive fieldwork conducted on 36 exposures and 13 drillings in floodplain positions. Field data is supported by geochemical analyses, while the chronological framework was obtained from the analyses of 70 radiocarbon samples. Results show distinct patterns of fluvial sedimentation as well as soil formation linked to floodplain stability for each river catchment. On regional or catchment scale, pollen stratigraphical correlation and comparison with lacustrine records show that fluvial dynamics have a strong reaction to climatic shifts, with phases of high fragility characterized by catchment erosion and floodplain sedimentation in response to climatic aridification events and phases of climate change in general. The comparison of the examined river systems reveals that periods of supra-regional floodplain sedimentation in several catchments occurred from 8.0 to 7.0, 5.0 to 3.8, 2.2 to 1.5, and around 1.0 as well as 0.4 ka cal. BP, while we found periods of supra-regional soil formation from 13.3 to 12.7, 7.0 to 5.1 (with a short interruption around 6.0 to 5.5 ka), 2.8 to 2.3 ka, 1.4 to 1.2 ka, and 0.8 to 0.5 ka cal. BP. Beside these consistencies we found deviating dynamic patterns that are apparently expressed in terms of differing onset and offset, differing durations, or even the lack of fluvial system response. The main reasons for this can be seen in different regional climate condition and impacts of further influencing factors, or in different levels of sensitivity of the river catchments that may be controlled by initial hydrological conditions, catchment size, or the degree of anthropogenic influence. A larger scale assessment shows that fluvial dynamic patterns are hardly comparable across entire Spain due to strong spatial heterogeneity of physiographic and climatic conditions on the Iberian Peninsula, in particular when areas are influenced by different circulation systems (e.g. regions influenced by the Atlantic Ocean vs. regions influenced by the Mediterranean Sea). However, the consideration of North Atlantic marine records reveals a certain coupling between North Atlantic coolings, atmospheric processes leading to arid climate over large parts of Spain, as well as increased landscape instability including strong fluvial sedimentation activity. Attendant atmospheric conditions are discussed.

Riqueza y composición florística de pteridobiontes en bosque mesófilo de montaña y ambientes asociados en el centro de Veracruz, México

We describe and compare the richness and floristic composition of ferns in natural humid montane forest and disturbed environments associated with different degrees of anthropogenic influence. The study sites were located at the Loma de Santa Rita in the Sierra de Chiconquiaco, central region of Veracruz, Mexico. Furthermore, we made a comparison with other fern inventories from humid montane forests in central Veracruz based on published studies. We established 72 sampling plots of 10×10m each in 6 different environments; natural forest, mature and young secondary forest, shade coffee, Pinus patula plantation, and pasture with remnant trees. We recorded a total of 81 species distributed in 17 families and 36 genera. The results indicate that the natural forest is most species rich, whereas fern diversity decreases with the degree of vegetation disturbance up to 70%. The study highlights the importance of fallows and shade coffee plantations to retain and allow the establishment of many species also found in the forest.

Lead and its isotopic ratios in atmospheric precipitation in the Baikal region and Primorski Krai

Presented are the results from investigating the lead isotopic composition in atmospheric precipitation in the Baikal region and Primorski Krai. It is established that at three stations of the Baikal region, differing in their physical-geographical location and in the degree of anthropogenic influence, the isotopic ratios are similar to those for lead ores of Kazakhstan, the main supplier of lead to Russia. Atmospheric precipitation in Primorski Krai is intermittently influenced by the trans-boundary transport of atmospheric impurities from industrial areas of China.

Aerosol‐cloud relationships in continental shallow cumulus

Aerosol‐cloud relationships are derived from 14 warm continental cumuli cases sampled during the 2006 Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) by the Center for Interdisciplinary Remotely‐Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft. Cloud droplet number concentration is clearly proportional to the subcloud accumulation mode aerosol number concentration. An inverse correlation between cloud top effective radius and subcloud aerosol number concentration is observed when cloud depth variations are accounted for. There are no discernable aerosol effects on cloud droplet spectral dispersion; the averaged spectral relative dispersion is 0.30 ± 0.04. Aerosol‐cloud relationships are also identified from comparison of two isolated cloud cases that occurred under different degrees of anthropogenic influence. Cloud liquid water content, cloud droplet number concentration, and cloud top effective radius exhibit subadiabaticity resulting from entrainment mixing processes. The degree of LWC subadiabaticity is found to increase with cloud depth. Impacts of subadiabaticity on cloud optical properties are assessed. It is estimated that owing to entrainment mixing, cloud LWP, effective radius, and cloud albedo are decreased by 50–85%, 5–35%, and 2–26%, respectively, relative to adiabatic values of a plane‐parallel cloud. The impact of subadiabaticity on cloud albedo is largest for shallow clouds. Results suggest that the effect of entrainment mixing must be accounted for when evaluating the aerosol indirect effect.