Swampy Meadows Research Articles

Grazing weakens the linkages between plants and soil biotic communities in the alpine grassland

Livestock grazing alters the diversity and composition of plants and soil biota in grassland ecosystems. However, whether and how grazing affects plant-soil biota interactions are limited. Here, we performed a field investigation on the Tibetan grasslands to determine the relationships between plant community properties (biomass, diversity and richness) and soil biota (abundance, diversity and composition of bacteria, fungi and nematodes) in the long-term yak grazing and ungrazed plots, and responses of plant-soil biota linkages to grazing in alpine meadows and alpine swampy meadows were compared. The results found that grazing did not cause significant changes in plant community properties but increased the soil water content. Further, grazing weakened plant-soil microbes/nematode relationships in alpine meadows. The bacterial and fungal abundances were correlated with plant belowground biomass and Simpson index in the ungrazed plots of alpine meadows, while the correlation was not significant under grazing. Bacterial composition was correlated with plant richness only in the ungrazed meadows. Plant-soil nematode linkages were more sensitive to grazing than plant-microbes linkages. Grazing decoupled the relationships between the abundances of nematode trophic groups and plant aboveground biomass, richness and Simpson index in alpine meadows, while the decoupling phenomenon is less evident in alpine swampy meadows. The SEM results indicate that grazing altered the plant above- and belowground biomass to affect the soil nematode community, while influenced soil microbes only through alterations of plant belowground biomass. The findings highlight the importance of grazing in influencing the interactions between aboveground plant communities and soil biological communities in Tibetan grasslands.

Біотопи існування та живлення зубра в Національному природному парку Цуманська Пуща (Україна)

The conservation and restoration of the bison (Bison bonasus L.) is one of the fundamental issues of international importance in the Tsumanska Pushcha National Nature Park, Ukraine. The distribution of bison in the territory of the park and adjacent areas is associated with the specific requirements of the species regarding food and protective properties of the terrain. In spring, with the beginning of the growing season, the grass cover is thin and the amount of food is insufficient, so bison prefer swampy biotopes. In March–April, birch–alder and aspen–birch–alder stands provide optimal feeding conditions for the animals. Within the territory of spring distribution of bison, the biotopes they inhabit are represented by wet and fairly fertile sites (types C3 and C4,), as well as moist and fairly infertile pine site (type B3). Biotopes these animals inhabit during the spring–summer period (March–August) cover an area of about 1640 hectares, of which 350 hectares are within the national park, and the rest are part of the territory of the Muravyschensky and Sokyrychivsk forests of the Kivertsi Forestry State Enterprise. The territory of the forest districts is characterised by a mosaic structure of stands, alternating areas of broad-leaved and coniferous species, wetlands and grass glades with good feeding conditions for the animals. The animals have adapted to almost all types of forest biotopes. During the entire growing season, the trophic activity of bison is particulary high in pastures, forest clearings, and swampy meadows adjacent to woodlands. The main bison biotopes are located at a large distance from human settlements and characterised by poorly developed road network, low level of disturbance, and favourable living conditions. The current size of the bison population in the national park is 21 individuals, and the presence of calves and young animals is a sign of favourable conditions and positive population dynamics that may lead to further increase in the future. In order to minimise the impact of negative factors, relevant measures should be implemented to maintain the stability of the subpopulation, to protect the habitats of the animals, and to conduct active educational and informational activities in the park. The technologies of forest felling, harvesting of minor forestry products, and other forestry works must include elements aimed at preventing negative effects on bison.

Propagation strategies of Deyeuxia angustifolia in heterogeneous habitats

Plants utilize different strategies in different environments to maximize population expansion. Understanding plant reproductive strategies in heterogeneous habitats is therefore important for explaining plant ecological adaptability, and for effectively managing and conserving ecosystems. We wanted to explore the reproductive strategy transformation of D. angustifolia in heterogeneous habitats, as well as the environmental factors driving and affecting its reproductive characteristics. To do this we measured the reproductive characteristics of D. angustifolia, as well as the soil physical and chemical properties of these heterogeneous habitats. The density, biomass per unit area, and proportion of aboveground biomass in swampy meadows were significantly higher compared to other habitats. The proportion of rhizome node buds gradually increased from swampy to typical to miscellaneous grass meadows, while the proportion of tillering node buds decreased. The allocation of sexual reproduction within D. angustifolia populations was significantly and positively correlated with plant rhizome biomass and negatively correlated with the number of tillering node buds. The propagation strategies of D. angustifolia in heterogeneous habitats were consistent with CSR theory (Competitor, Stress-tolerator, and Ruderal). The proportions of inflorescence (2.07 ± 0.52%; 1.01 ± 0.15%) and root (23.8 ± 1.5%; 19.6 ± 1.4%) biomass in miscellaneous and typical meadows were high, which tended toward the “Ruderal” adaptation strategy. In swampy meadow, D. angustifolia invested mostly in vegetative growth to produce tiller node buds (14426.67 buds/m2; 46%) and ramets (1327.11 ± 102.10 plants/m2), which is characteristic of the “Competitor” strategy. Swamp D. angustifolia resisted flooding by maintaining a resource balance in its body, and was therefore biased toward the “Stress-tolerator” strategy. Environmental factors accounted for 74.63% of reproductive characteristic variation, in which the interpretative proportions of soil water content, dissolved organic carbon, ammonia nitrogen, and nitrate nitrogen were significant (p < 0.01). When soil water content, dissolved organic carbon, and nitrate nitrogen increased, D. angustifolia tended toward the C strategy; in contrast, when soil water content decreased, amine nitrogen and available phosphorus increased, and D. angustifolia tended toward the R strategy. In a stressful environment, the escape mechanism constitutes an increased rhizome and sexual reproduction investment. In contrast, for suitable habitats, tillering node buds increased in order to expand the population via new plant production, which was the propagation strategy of D. angustifolia in heterogeneous habitats.

A Topographic Perspective on the Propensity for Degradation of Plateau Swampy Meadows in Maduo County, West China

The swampy meadows atop the vast Qinghai–Tibet Plateau in West China fall into alpine, pediment, valley, floodplain, terrace, lacustrine, and riverine types according to their hydro-geomorphic properties. They have suffered degradation to various levels of severity due to climate change and external disturbance. In this paper, we studied the propensity of these types of swampy meadows to degrade from the topographic perspective. Evaluated against four degradation indicators of vegetation, hydrology, soil erosion, and pika (Ochotona curzoniae) damage, degradation severity at 106 swampy meadows representing all types of wetlands was graded to one of four levels, from which the field-based propensity to degrade (PtD) index value was derived. Judged against this index, terrace and alpine swampy meadows are the most prone to degradation while valley, lacustrine, and riverine swampy meadows are the least. The index value of a given swampy meadow type bears a close relationship (R2 = 0.916) with its rate of change during 1990–2013, which confirms the validity of the proposed index in predicting the propensity of swampy meadows to change. The observed differential PtD of different types of swampy meadows is attributed primarily to elevation (R2 = 0.746; p = 0.027) and, secondarily, to surface morphology (R2 = 0.696; p = 0.039). Thus, the elevation at which a swampy meadow is situated is a more important factor to its PtD than its surface morphology. In particular, swampy meadows located at a higher elevation with a convex surface are much more prone to degradation than those at a lower elevation of a concave slope. Such findings can guide the proper management of different types of swampy meadows to achieve sustainable animal husbandry.

Effects of water levels in heterogeneous habitats on sexual reproductive allocation of Deyeuxia angustifolia.

Taking Deyeuxia angustifolia as the research object, a representative plant of wetland in Sanjiang Plain, we analyzed the variations of individual size and biomass among the habitats of swamp wetlands, swampy meadows, typical meadows and miscellaneous grass meadows, and the relationship between reproductive components and plant biomass. We explored the effects of water level on individual biomass and reproductive allocation of D. angustifolia in different types of wetlands. The results showed that plant biomass, height and the characteristics of sexual reproduction significantly decreased with the increases of water level. The reproductive thresholds of D. angustifolia in miscellaneous grass meadow, typical meadow, swampy meadow, and swamp wetland were 0.245, 0.149, 0.148 and 0.157 g, respectively. There was a significantly negative correlation between plant size and reproductive allocation in three habitats except swampy meadow. Compared with individual size, soil water content had a stronger effect on reproductive allocation of D. angustifolia. The different investment between individual size and reproductive allocation in different habitats was the basic condition that contributes to the good ecological adaptability of D. angustifolia.

Meadows and pastures in the agricultural landscapes of the Karelian province of the Middle Taiga zone of the North-West of Russia

In order to take into account the territorial differences of natural and economic conditions, to identify biological and ecological patterns, the agro-landscape and ecological zoning of natural forage lands (NFL) of the North-Western natural and economic region of the Russian Federation has been developed. The Karelian province occupies 23% of the area in the north of the Leningrad region, bordering Karelia and Finland. The Karelian province is located in the western part of the Middle Taiga zone, which is characterized by Eastern European Middle Taiga plains. Most of the area of the province (65%) is covered by forests. Agricultural land occupies only 4% of the total area of the province. Including arable land – 2%, hayfields and pastures – 1% each. The territory of the province is significantly moistened and swampy. Swamps occupy 11% of the area, under water – about 11%. Shrubs occupy 3% of the area of the province, other land – about 6%. The structure of NFL is dominated (53%) by normally moistened dry-grass grasslands on sod-podzolic soils. Fine-grained sweet-scented and finegrained grasslands with a large participation of various grasses are common. The yield of hay is 9–13 c/ha, feed is 70 c/ha. Grass-mixed grass and grass-sedge-mixed grass lowland and swampy meadows on swamp-podzolic soils occupy 44%. Grass stands with the dominance of the sod pike are common. Swampy depressions are occupied by large-seeded grass stands. The yield of hay is 10–15 c/ha, feed is 9–11 c/ha. The ecological state of the province’s landscapes is satisfactory-tense.

Agrolandscapes of the East Sayan Mountain Province of Eastern Siberia and the Far East of Russian

According to the data of the agro-landscape and ecological zoning of Eastern Siberia and the Far East, conducted by the authors, the spatial distribution of biological and ecological patterns in the East Sayan Mountain province was established. The province is located in the Eastern Sayan mountain system within the Southern Taiga zone. Its area is 17022.5 thousand hectares. Mountains occupy 76% of the province’s territory, plains – 24%. In the structure of land forests occupy more than 68% of the area of the province . Other land (mainly rocks and glaciers) occupies 20%. Under water is 3.4% of the area, swamps occupy 2.8%. Shrubs occupy less than 1%, mountain deer pastures – 0.8% of the area of the province. Agricultural land occupies 4.5% of the total area of the province. Including arable land – 0.9%, pastures – 2.6%, hayfields – 1%. The structure of natural forage lands (NFL) is dominated by mountain pastures on mountain soils (76%). The plains and foothills of the province are dominated by dry southern taiga meadows (13%). Floodplain meadows (5%) and swampy meadows (5%) are also represented. The ecological state of the province’s landscapes is good and satisfactory. In particular, NFL – good and satisfactory, forests – good and satisfactory, mountain deer pastures – good. The ecological state of arable land is tense. The established patterns are the necessary information basis for the development and implementation of innovative technologies for sustainable agricultural development, rational nature management and environmental protection in the East Sayan Mountain Province of Eastern Siberia and the Far East.

АНТИКРИЗИСНОЕ УПРАВЛЕНИЕ ПАСТБИЩНЫМИ ТЕРРИТОРИЯМИ КАЗАХСТАНА НА ОСНОВЕ АВТОМАТИЗИРОВАННОЙ ИНФОРМАЦИОННОЙ СИСТЕМЫ

The purpose of the studyis to study the problems of stopping and preventing the process of desertification of pasture lands in Kazakhstan and development of measures for anticrisis management of cattle grazing territories by introducing a model of automated information management system (AIMS). The authors provide data on the considered issue as part of the implementation of the Program on Combating Desertification in the Republic of Kazakhstan for 2005-2015. Based on the analysis of the influence of anthropogenic factors on vegetation and soil surface of deserted zone of the republic, it was revealed that its total area is more than 50 mln ha, which has conditioned the relevance and timeliness of the system of measures aimed to overcome desertification of the republic's pasture lands. The results of the implementation of AIMS are shown on the example of a pilot innovation-active territory of administrative district using the public information system (GIS) and cooperation of agribusiness objects based on Smart technologies. Managing the diversity and differentiation of agricultural landscape determines the stability of its balance, self-restoration of potential and resistance to anthropogenic loads. Therefore, when managing pastures, it is necessary to preserve diversity of biotopes, primarily regeneration centers, swampy meadows and pastures, nodal thickening of biota; avoid uniform agricultural relief to maintain the balance of many biotic and abiotic factors in landscape; strive to create interconnected elements of ecological frame of the area, for which the development of appropriate automated information management system is required.

Meadow Birds at the Waning Traditional Pasture Animal Husbandry

Журнал принимает на русском и английском языках статьи, представляющие результаты научных исследований в различных областях теоретической и прикладной экологии. Приоритет отдается научным статьям, основанным на явно сформулированных гипотезах.

Rare phytobiota of protected areas of Dergachiv and Zolochiv districts of Kharkiv region

The study of the phytobiota of the Dergachiv and Zolochiv districts of the Kharkiv region has proved that there are 15 protected areas and 3 perspective territories for building reserves, which are characterized by significant cenotic and floristic diversity. These are meadow, real and shrub steppes; hollows of oak; real and swampy meadows; coastal water and aquatic vegetation, where 4 rare for Ukrainian vegetative groups (Nymphaeeta albae, Nuphareta luteae, Stipeta capillatae, Stipeta pennatae) and 41 species of plants are protected: 10 species listed in the Red Book of Ukraine (RBU): Adonis vernalis L., Anacamptis palustris (Jacq.) R.M.Bateman, Pridgeon et M.W.Chase, Dactylorhiza incarnata (L.) Soo s.l., D. maculata (L.) Soo s.l., D. majalis (Reichenb.) P.F.Hunt et Summerhayes s.l., Iris furcate M.Bieb., Pulsatilla pratensis (L.) Mill. s.l., Stipa capillata L., S. pennata L., Tulipa quercetorum Klokov et Zoz, and 31 species from the Red List of Kharkiv area (RLK): Actaea spicata L., Aconitum lasiostomum Rchb., Clematis integrifolia L., Gentiana cruciata L., Sanguisorba officinalis L., Thalictrum lucidum L. etc. For each of the surveyed areas lists of rare species and plant groups are given. Phytososological analysis shows the degree of representativeness of the rare phytobiota of the investigated areas and the almost direct correlation between the area of the protected area and the quantitative indices of phytodiversity. The greatest degree of rare phytodiversity has been revealed on the territory of the planned Rogozian landscape reserve of about 2 thousand hectares (4 groups from the Green Book of Ukraine (GBU), 7 species from the RBU, 16 from the RLK); somewhat less in the planned hydrological reserve "Snigivsky" (2 groups from GBU, 1 species from the RBU, 6 from the RLK), in the regional landscape park "Vilkhova balka" (2 species from the RBU, 7 from the RLK), in the “Lychane” botanical reserve (1 group from GBU, 2 species from RBU, 2 from RLK) and in the entomological reserve "Udiansky" (6 species from RLK). In other territories, there are no more than three rare species of plants.

Intermediate lakes of the Chulym and Kargat river valleys and their role in the evolution of the Lake Chany basin

The Chulym and Kargat Rivers flow through chains of saucer-shaped depressions, which are swampy meadows or drainage lakes. In the past, all of them were lakes short-lived in different Holocene periods. These depressions accumulated a significant amount of the Chulym and Kargat runoff and thus influenced the water balance of Lake Chany. Our studies have reconstructed the history of these depressions. A model describing their filling with sediments is proposed. The lacustrine sediments penetrated by boreholes and pits are dated by the radiocarbon method at 6.3-2.0 cal. kyr BP. The data obtained explane the long existence of Lake Chany as a shallow basin and rise in its level at ~2 kyr BP.

Combining bulk sediment OSL and meteoric 10Be fingerprinting techniques to identify gully initiation sites and erosion depths

AbstractDeep erosional gullies dissect landscapes around the world. Existing erosion models focus on predicting where gullies might begin to erode, but identifying where existing gullies were initiated and under what conditions is difficult, especially when historical records are unavailable. Here we outline a new approach for fingerprinting alluvium and tracing it back to its source by combining bulk sediment optically stimulated luminescence (bulk OSL) and meteoric 10Be (10Bem) measurements made on gully‐derived alluvium samples. In doing so, we identify where gully erosion was initiated and infer the conditions under which such erosion occurred. As both 10Bem and bulk OSL data have distinctive depth profiles in different uneroded and depositional settings, we are able to identify the likely incision depths in potential alluvium source areas. We demonstrate our technique at Birchams Creek in the southeastern Australian Tablelands—a well‐studied and recent example of gully incision that exemplifies a regional landscape transition from unchanneled swampy meadow wetlands to gully incision and subsequent wetland burial by post‐European settlement alluvium. We find that such historic alluvium was derived from a shallow erosion of valley fill upstream of former swampy meadows and was deposited down the center of the valley. Incision likely followed catchment deforestation and the introduction of livestock, which overgrazed and congregated in valley bottoms in the early 20th century during a period of drought. As a result, severe gully erosion was likely initiated in localized, compacted, and oversteepened reaches of the valley bottom.

Degradation of frigid swampy meadows on the Qinghai–Tibet Plateau

The frigid swampy meadows of the Qinghai–Tibet Plateau in western China have suffered widespread degradation. The severe degradation of such meadows can lead to the formation of a landscape commonly known as heitutan. Much research has been undertaken to study its triggers, formation mechanism, grading of severity, and rehabilitation. These studies are comprehensively reviewed in this paper. In particular, it attempts to reconcile two divergent theories on heitutan formation by proposing a new model to elucidate the role of a given factor at each stage of degradation. In this model, climate desiccation is the most important in transforming healthy meadow to dry grassland, while rodent attack is the most important in worsening dry grassland to degraded meadow. Overgrazing is the most important factor during the early stages of degradation. Wind and water erosion is important during the final stage, when a large quantity of loose materials has been accumulated by rodent burrowing. Also covered in this paper is how to rehabilitate heitutan to productive use, including the effectiveness of various measures. Finally, this paper identifies the gap in our understanding of swampy meadow degradation and spells out a future research agenda. It is concluded that future research on heitutan will undergo a transformation from descriptive to quantitative. The expected research outcome will inform herders of the appropriate strategies that can be adopted to prevent heitutan formation. This proactive approach will minimize economic loss from swampy meadow degradation and reduce its adverse impact on the environment.

CHEMICAL COMPOSITION OF THE ESSENTIAL OIL OF PYRETHRUM BALSAMITA (L.) WILLD. FROM AZERBAIJAN

Pyrethrum balsamita (L.) Willd. (syn.: Tanacetum balsamita L.) is a wild-growing plant in Azerbaijan. P. balsamita refers to perennial plant which grows up to 25 and 90 cm. The plant is polycarpic, mezophyte. It grows in fragments, forming small clumps. This is a common plant in Azerbaijan, and mainly grows in the northern and central parts of the Minor Caucasus and mountainous part of Nakhchivan AR. It occurs in damp or swampy meadows, along the mountain streams of subalpine to alpine zone. In traditional medicine, the aerial part of P. balsamita is used as an infusion for stomach cramps as a painkiller during budding and flowering. The powder of the flowers is used as anthelmintic. Small amounts of the young leaves, stems, buds at the beginning of budding are added to salads, meat and fish soups, vegetable dishes, and the powder of herbs - in desserts and pastries, as well as other drinks and kvass as a spice. Essential oil of P. balsamita used in perfumery, cosmetic industry and also in food industry. The composition of the essential oil that hydrodistilled from the above ground parts of plant in the end of the budding and in the beginning of the flowering periods were analyzed by GC and GC/MS. The above-ground part of plant contains 0,6% of essential oil, that has brown colour and camphor odour. In total 23 components were identified. T he major compounds of essential oil were camphor (+)- ( 25,29%) and L-borneol (21,84%).

Characteristics of Fasciola hepatica infections in Galba truncatula originating from riverbank populations

Four geographical strains of Galba truncatula living on riverbanks (the first on a sedimentary soil and the other three on an acid soil) were subjected to bimiracidial exposures with Fasciola hepatica to study their aptitude for cercarial shedding and to count metacercariae in snails dissected at day 42 post-exposure. All snails were reared in 14-cm Petri dishes at 24 °C, with the same spring water (60-73 mg/l of Ca²+) and the same diet (grass and lettuce leaves). Metacercariae of F. hepatica were noted in the four populations after a cercarial shedding or after snail dissection. However, in spite of the breeding method used, the characteristics of snail infections varied with the origin of each geographical strain. For example, the shell heights of infected snails at day 42 were close to those found for the corresponding adults in the field (6.8-8.0 mm for the population living on the sedimentary soil, but only 4.6-5.5 mm for another strain originating from the acid soil). This variability may be explained by assuming that the diet of these riverbank G. truncatula would be different from that of snails living in swampy meadows. However, another hypothesis based on the influence of snail habitat on the characteristics of snail life cannot be excluded.

Tepexpan revisited: A multiple proxy of local environmental changes in relation to human occupation from a paleolake shore section in Central Mexico

Building up a scenario of Late Pleistocene–Holocene environmental change and human–landscape interactions in Central Mexico – one of the key areas for the natural and cultural history of America – requires development of local paleoenvironmental reconstructions. We studied the Tepexpan section at the edge of Texcoco a paleolake, near the mouth of Teotihuacan Valley as a multiproxy record of the environmental dynamics at the shore in the Basin of Mexico throughout the period of human occupation. The section is located in an ecotone affected by intensive and variable geomorphic processes and includes lacustrine, fluvial and volcanic sediments as well as paleosols. Our chronological scale is based on 6 AMS 14C dates from pollen concentrates and paleosol organic matter. The lower segment of the section dominated by the lacustrine sediments yielded pollen spectra; in the upper segment the record is based on the pedogenetic characteristics of paleosols. Different proxies agree in demonstrating the general trend (although some reversals are apparent) of decreasing effective moisture since MIS3: it is reflected first in the increase of herbaceous pollen after 27 ka BP, the decrease of lake level, the cessation of lacustrine sedimentation and beginning of marsh soil development at 10 ka BP and finally, the shift from hydromorphic to dryland semiarid pedogenesis in the Late Holocene. We assume that this trend was climatically controlled, whereas the deposition of sedimentary layers enriched with tephra are related to the pulses of volcanic activity; the pedosedimentary features associated with the upper soil are human-induced. Comparing the proposed scheme of environmental change with the archaeological record we propose that the initial settlers, Late Paleolithic hunters, could have utilized the wet swampy meadows which expanded on the Basin bottom as the lake level lowered and provided the niche for large herbivores during the Pleistocene–Holocene transition. Development of agriculture and the network of permanent settlements are believed to be linked to the formation of well drained soils. In the methodological perspective the study shows the potential of ecotones as highly dynamic and sensitive systems that may archive valuable paleoecological records.

Problems in naming and defining the swampy meadow—An Australian perspective

This paper explores the confusing terminology used in the description of a landform characterised by swampy, alluvial valley floors, generally known in Australia as ‘swampy meadows’. Swampy meadows were once common in the Australian landscape. Following the impacts of European settlement, such as clearing, grazing, swamp burning and draining, functionally intact systems have become rare in the contemporary landscape. Detrimental affects on swampy meadows are now increasingly being recognised, leading to a need for their restoration and conservation. Confusion over terminology and definitions, however, has hindered our capacity to understand the complex nature of these systems, and to develop appropriate management strategies and policies to protect and restore them. In particular, a multi-disciplinary understanding of their geomorphic processes, hydrology, and ecological form and function is not catered for in any single definition or characterisation that is useful to policy makers and land managers. The paper discusses the repercussions that unclear swampy meadow nomenclature has on ecological understanding, conservation policy, restoration, and land values. It concludes with the construction of a more precise taxonomic definition of the swampy meadow.

The control of Galba truncatula (Gastropoda: Lymnaeidae) by the terrestrial snail Zonitoides nitidus on acid soils

Abstract Field investigations on the control of Galba truncatula by Zonitoides nitidus were carried out over the past 30 years in the different types of lymnaeid habitats located in central France. When a layer of mowed vegetation was used to cover G. truncatula habitats at the end of June, the introduction of adult Z. nitidus (20/m2) eliminated lymnaeid populations after 2 years of control in habitats located in swampy meadows, around the heads of intermittent springs, in areas trampled by cattle, and along river or pond banks. In the case of wild watercress beds, 3 years were necessary. The best results (elimination of G. truncatula after a single year of control) were obtained using an association of snails (Z. nitidus + Oxychilus draparnaudi), or a mixed control (a first application of 0.1 mg/l CuCl2, followed 3 months later by the introduction of Z. nitidus). Recolonization of treated habitats by G. truncatula coming from downstream populations was noted 3 years following the last application of biological control. Apart from the regular introduction of Z. nitidus in several watercress beds, the use of this snail to control G. truncatula has not become generalized in cattle- and sheep-breeding farms. The reasons for this situation are probably the complexity of applying this control in the field by nonspecialists and the difficulty of selecting the period of snail control at the end of June due to frequent local rainfall at this time.

Using Sediment Budgets to Investigate the Pathogen Flux Through Catchments

We demonstrate a materials budget approach to identify the main source areas and fluxes of pathogens through a landscape by using the flux of fine sediments as a proxyfor pathogens. Sediment budgets were created for three subcatchment tributaries of the Googong Reservoir in south-eastern New South Wales, Australia. Major inputs, sources, stores, and transport zones were estimated using sediment sampling, dam trap efficiency measures, and radionuclide tracing. Particle size analyses were used to quantify the fine-sediment component of the total sediment flux, from which the pathogen flux was inferred by considering the differences between the mobility and transportation of fine sediments and pathogens. Gullies were identified as important sources of fine sediment, and therefore of pathogens, with the pathogen risk compounded when cattle shelter in them during wet periods. The results also indicate that the degree of landscape modification influences both sediment and pathogen mobilization. Farm dams, swampy meadows and glades along drainage paths lower the flux of fine sediment, and therefore pathogens, in this landscape during low-flow periods. However, high-rainfall and high-flow events are likely to transport most of the fine sediment, and therefore pathogen, flux from the Googong landscape to the reservoir. Materials budgets are a repeatable and comparatively low-cost method for investigating the pathogen flux through a landscape.

A field study of natural infections in three freshwater snails with Fasciola hepatica and/or Paramphistomum daubneyi in central France

AbstractNatural infections of three freshwater snails with Fasciola hepatica and/or Paramphistomum daubneyi were studied during two periods in 1996 and 1997 (June–July and September–October) on 18 farms located in the departments of Vienne and Haute Vienne (central France), and known for low prevalences of F. hepatica infections in ruminants. A total of 1573 Lymnaea glabra and 1421 L. truncatula 6 mm high or more were collected in the meadows of 13 farms and dissected under laboratory conditions. Snails with single or concurrent infections of F. hepatica and/or P. daubneyi were found for each Lymnaea species. InL. truncatula, global prevalences of natural infections with F. hepatica (3.8% in June–July, and 3.6% in September–October) were significantly greater than those recorded for P. daubneyi (1.1% and 0.8%, respectively). In L. glabra, global prevalences of F. hepatica infections (0.4% in each investigation period) were significantly lower than those found in L. truncatula, whereas there were no significant differences between prevalences of P. daubneyi infections. A total of 2721 Planorbis leucostoma measuring at least 4 mm in diameter were collected in the meadows of the other five farms on which L. truncatula was absent. In these planorbids, global prevalences of natural infections with F. hepatica were 0.4% in each period of investigation. Contrary to fasciolosis, snail infections with P. daubneyi were not noted on all farms of the Vienne and Haute-Vienne departments. Natural single or concurrent infections with F. hepatica and/or P. daubneyi in L. glabra and a natural infection of P. leucostoma with F. hepatica were found in swampy meadows on acid soil.