Relationship between vegetation and environmental conditions in the northern Pantanal of Mato Grosso, Brazil

This paper analyses the relationship between the distribution of tropical floodplain vegetation and environmental factors such as the soil types, their physical‐chemical properties and inundation dynamics in the northern Pantanal of Mato Grosso, Brazil. Fifty‐four soil profiles of the four principal geomorphologic units of the lowland were classified into twenty‐one units of the FAO‐UNESCO system and related to eight vegetation formations. Under the deciduous and semideciduous woodland and forest formations on flood free riverbanks and relict dunes Arenosols, Solonetz and Alisols dominate. Inundation forests grow on a large variety of soil groupings such as Alisols, Solonetz, Fluvisols, Gleysols and Cambisols, mainly on fluvial deposits. Under the grassland formations of periodically flooded spreadings and depressions Planosols, Acrisols, Alisols, Fluvisols, Arenosols and Cambisols were cored, while Gleysols are common on swamps bearing Thalia geniculata or Cyperus giganteus. Canonical Correspondence Analysis was applied to study the influence of monitored environmental factors on spatial distribution of vegetation formations. Water regime and soil texture were found to define the grassland‐forest boundaries as well as the transition between different grassland formations and between seasonal as well as evergreen forests.     

The effects of vegetation types and microhabitats on carabid beetle community composition in cool temperate Japan

The effects of vegetation types and environmental factors on carabid beetle (Coleoptera: Carabidae) communities were studied. Carabid beetles were collected using pitfall traps (total 2844 trapping days) and seven microenvironmental factors were measured in four vegetation types: grassland, natural evergreen coniferous forest (Pinus densiflora), deciduous broad-leaved natural forest (Quercus crispula, Betula platyphylla, Alnus japonica, or Fagus crenata), and deciduous coniferous plantation (Larix kaempferi) in cool temperate Japan. These four vegetation types provided a novel comparison between natural forests and plantations because the vast majority of related studies have investigated only deciduous broad-leaved natural forests and evergreen coniferous plantations. PERMANOVA indicated that vegetation types affected carabid community composition. Ordination plots showed that community composition differed greatly between grassland and forest vegetation types, but that community composition in the plantation forest overlapped with that of natural forest types. Characteristics differentiating the grassland included a high proportion of winged species and a low mean carabid body weight. Among the examined environmental factors, litter depth, soil water content, and depth of the soil A-horizon had large effects on carabid communities. These results suggest that the effect of afforestation on carabid communities in cool temperate Japan might be insignificant compared with the effects of cover types (deciduous vs. evergreen) and microenvironmental factors.     

Different factors affect the local distribution,persistence and spread of alien tree species in floodplain forests

Floodplain forests are characterized by high and increasing levels of invasions by plant species, but the factors that drive their spread are insufficiently understood. Using data from 708 plots surveyed twice (1998, 2008) supplemented with further data (management, stand age, distance to dispersal corridors, type of ecosystems invaded) we analyzed the factors which shape the local distribution, growth, persistence and spread of three invasive alien tree species (Acer negundo, Ailanthus altissima, Robinia pseudoacacia) in the National Park Donau-Auen in Austria. Using Generalized Linear Models (GLMs), we found that the distribution of the study species per plot is contingent on stand age (R. pseudoacacia), type of floodplain forest (A. negundo, A. altissima) and distance to the next water body (A. negundo). For all study species, colonization of new plots between both surveys is driven by short distance spread from already established invasion foci. Moreover, recipient habitats (softwood vs. hardwood floodplain forests) modify invasion success in species-specific ways. The probability of occurrence and colonization of plots located in softwood floodplain forests is higher for A. negundo, whereas A. altissima more frequently colonizes hardwood floodplain forests. Persistence of R. pseudoacacia decreases with stand age, whereas its growth rate is significantly higher in plots located in zones where management is allowed than in those which are not managed. Persistence and growth of the other two study species were not related to any explanatory variables analyzed. The on-going spread of the study species in the National Park Donau-Auen suggests that their local distribution is in disequilibrium, i.e. not all suitable habitat patches have yet been colonized. This implies that increased management efforts are necessary to reverse the spread of alien tree species in the study area and to maintain the high conservation value of this iconic area which protects one of the largest floodplain forests in Europe.     

Epiphytic lichen synusiae and functional trait groups in boreo‐nemoral deciduous forests are influenced by host tree and environmental factors

Deciduous forests with temperate broad‐leaved tree species are particularily important in terms of biodiversity and its protection, but are threatened habitats in northern Europe. Using multivariate analyses we studied the effect of forest site type, environmental variables and host tree properties on epiphytic lichen synusiae as well as on the composition of species‐specific functional traits. Epiphytic lichens were examined on Acer platanoides, Fraxinus excelsior, Quercus robur, Tilia cordata, Ulmus glabra and U. laevis in two types of forests: Humulus‐type floodplain forests and Lunaria‐type boreo‐nemoral forests on the talus slopes of limestone escarpment (klint forests). Klint forests located near the seashore were under greater maritime influence compared to floodplain forests located in inland Estonia which experience stronger air temperature contrasts. In addition to stand level and climatic variables, tree level factors (bark pH, trunk circumference and cover of bryophytes) considerably affected the species composition of the lichen synusiae. Overall, 137 lichen species were recorded, including 14 red‐listed species characteristic of deciduous trees. We defined 13 lichen societies and showed their preference to forests of a specific site type and/or host tree properties. In forests of both types, most of the epiphytic lichens were crustose, and had apothecia as the fruit bodies and chlorococcoid algae as the photobiont. However, the proportion of lichens with a foliose or fruticose growth form, as well as the proportion of lichens with vegatative diaspores, were higher in floodplain forests. In klint forests with a stronger influence from the wind, crustose species completely dominated, while species with vegetative diaspores were rare and most species dispersed sexually. Lichens with Trentepohlia as the photobiont were characteristic of these forests, and lichens with lirellate ascomata were prevailing, indicating the great uniqueness of the kint forests for epiphytic lichens in the boreo‐nemoral region.     

Syntaxonomy of vegetation of the Svyatoi Nos peninsula, Lake Baikal 2. Forests and krummholz in comparison with other regions of northern Buryatia

Using the Braun-Blanquet approach, 7 plant communities of forests and 3 communities of krummholz were distinguished on the Svyatoi Nos Peninsula on the eastern coast of Lake Baikal. Dominant species of these communities areAbies sibirica, Larix sibirica, Pinus sibirica, P. sylvestris, P. pumila andBetula divaricata. The data from Svyatoi Nos were combined with all the available data from the northern part of the Republic of Buryatia (289 relevés) and classified into 23 communities. These have been assigned to the following alliances:Aconito rubicundi-Abietion sibiricae—floodplain forests with tall forbs and the relict occurrence of a few nemoral species,Pino sibiricae-Laricion sibiricae—mesic forests with (sub-Atlantic) boreal species and abundant mosses,Vaccinio-Pinion pumilae—krummholz communities of NE Asian distribution,Cladonio stellaris-Laricion gmelinii—Larix gmelinii dominated open forests on permafrosts with NE Asian distribution, andHieracio umbellati-Pinion sylvestris—xeric forests with southern Siberian species. Phytogeographical affinities of these alliances are discussed and a system of high-ranked syntaxa (orders, classes) is proposed for the northern Buryatian forests and krummholz.     

Seasonal flooding decreases fruit-feeding butterfly species dominance and increases spatial turnover in floodplain forests of central Amazonia

The seasonal flood pulse in Amazonia can be considered a primary driver of community structure in floodplain environments. Although this natural periodic disturbance is part of the landscape dynamics, the seasonal inundation presents a considerable challenge to organisms that inhabit floodplain forests. The present study investigated the effect of seasonal flooding on fruit-feeding butterfly assemblages in different forest types and strata in central Amazonia. We sampled fruit-feeding butterflies in the canopy and the understory using baited traps in adjacent upland (unflooded forests—terra firme), white and blackwater floodplain forests (várzea and igapó, respectively) during the low- and high-water seasons. Butterfly abundance decreased in the high-water season, especially of dominant species in várzea, but the number of species was similar between seasons in the three forest types. Species composition differed between strata in all forest types. However, the flood pulse only affected butterfly assemblages in várzea forest. The β-diversity components also differed only in várzea. Species replacement (turnover) dominated the spatial β-diversity in igapó and terra firme in both seasons and várzea in the high-water season. Nonetheless, nestedness was relatively higher in várzea forests during the low-water season, mainly due to the effect of dominant species. These results emphasize the importance of seasonal flooding to structure butterfly assemblages in floodplain forests and reveal the idiosyncrasy of butterfly community responses to flooding in different forest types. Our results also suggest that any major and rapid changes to the hydrological regime could severely affect floodplain communities adapted to this natural seasonal hydrological cycle, threatening the existence of these unique environments.     

Wood growth of Tabebuia barbata (E. Mey.) Sandwith (Bignoniaceae) and Vatairea guianensis Aubl. (Fabaceae) in Central Amazonian black-water (igapó) and white-water (várzea) floodplain forests

Tree growth is a fundamental indicator for conservation plans of Amazonian floodplain forests. In this study we use dendrochronology to analyze wood growth patterns of Tabebuia barbata and Vatairea guianensis, two tree species occurring in nutrient-rich white-water (várzea, Mamirauá Sustainable Development Reserve, MSDR) and nutrient-poor black-water (igapó, Amanã Sustainable Development Reserve, ASDR) floodplain forests of Central Amazonia. From 20 trees per species and floodplain system (total of 80 trees) growing under a similar flooding regime with a mean inundation height of about 4 m we measured diameter at breast height (dbh). We sampled two cores per tree with an increment corer at the height of dbh to determine wood density (WD), tree age and mean radial increment (MRI) rates. The wood samples were macroscopically analyzed. Both tree species show distinct annual tree rings characterized by marginal parenchyma tissues. MRI was measured by a digital measuring device and WD was determined by the ratio dry mass/fresh volume. MRI of both tree species was significantly higher in the várzea than in the igapó, which can be traced back to the contrasting nutrient status. WD showed no difference comparing both floodplain forest types. Tree ages of a species for the same diameter are more than twofold higher in the igapó than in the várzea. To insure a sustainable harvest, felling cycles in these forests should be adjusted according to rates of growth.     

The Influence of Habitat,Season, and Detectability on Abundance Estimates across an Amazonian Parrot Assemblage

The Amazon basin holds very high parrot species richness but almost nothing is known of parrot population densities in the region or how these vary between species, habitats, sites, and seasons. Such data are becoming important as humans impact on increasing areas of the region. Seventeen parrot species were surveyed using a line transect distance sampling method over 3 yr in floodplain and terra firme forests at two sites in the Tambopata region of southeast Peru. Density estimates for most species were in the range of 3.3–7.8/km², with Brotogeris cyanoptera and Amazona farinosa reaching densities of 22 and 23/km² in floodplain forest during the dry season. Parrot densities were higher in floodplain forest than in terra firme forest at both sites. The parrot communities of terra firme forests were similar across sites and seasons, but those in floodplain forests differed widely across sites and across seasons. Upper canopy birds are notoriously difficult to survey. We introduce a procedure to correct for the likely violation of the assumption that all birds on the transect line are detected (distance sampling assumption g(0) = 1). We correct g(0) based on calling rates of birds using a cue‐counting technique. Multipliers for g(0) differ across species and site, but not season. This method yielded density estimates on average 22 percent higher (6–40% higher in individual species) than those from the standard method.     

Relationships of hydrology and life-history strategies on the spatio-temporal habitat utilisation of fish in European temperate river floodplains

Floodplain inundation is considered as crucial for the recruitment of fish in lowland rivers, by either providing suitable spawning areas as well as breeding habitats for young-of-the-year fish (YOY), as well as for supporting species that exhibit different life history-strategies in order to be differently adapted to long term discharge patterns. Fish communities in a set of 38 waterbodies on the Lower Rhine floodplain, representing different long-term frequencies of inundation and differently affected by seasonal inundations, were sampled by means of electro fishing (point abundance sampling, total n = 42,701 points) over a four-year period in order to identify species-specific and life-history strategy related patterns of spatio-temporal floodplain habitat utilisation. For 18 species (total catch: n = 107,150), typically occurring in European lowland rivers and representing different ecological guilds, different responses towards seasonal inundations were found. YOY of most species closely associated to the periodic strategy (e.g., Abramis brama, Aspius aspius, Blicca bjoerkna) were highly abundant in frequently inundated waterbodies, provided these were subject to inundations occurring in spring and early summer and coincided with temperatures required for spawning. However, recruitment in these species was impaired or failed when no inundations in this time frame occurred, although adults were present. In contrast, most species associated to the opportunistic strategy (e.g., Gasterosteus aculeatus, Pseudorasbora parva, Leucaspius delineatus) had highest recruitment in waterbodies unaffected by inundations in this time frame, which had detrimental effects on these predominantly small sized species. Spatio-temporal floodplain habitat utilisation of YOY fish (most rheophilic species as well as eurytopics) is suggested to be size-related, since most fast growing periodic strategists left the floodplain at given connectivity at latest in winter and were then absent in the subsequent year. Smaller YOY fishes and all opportunistic species either remained in more isolated waterbodies, or dispersed from there across the floodplain to some degree during extensive winter floods. These findings suggest adaptations to the long-term hydrograph of large river systems, with flood-related recruitment patterns predominantly occurring in periodic strategists and low-flow recruitment strategies in opportunistic strategists and stagnophilic species. The results of this study point to the significance of hydrological transversal floodplain gradients that provide diverse communities and population maintenance of different life-history strategies, evidencing that fish communities within the floodplain act as indicators for the hydrological conditions.     

Little evidence for niche partitioning among ectomycorrhizal fungi on spruce seedlings planted in decayed wood versus mineral soil microsites

Ectomycorrhizal fungal (EMF) communities vary among microhabitats, supporting a dominant role for deterministic processes in EMF community assemblage. EMF communities also differ between forest and clearcut environments, responding to this disturbance in a directional manner over time by returning to the species composition of the original forest. Accordingly, we examined EMF community composition on roots of spruce seedlings planted in three different microhabitats in forest and clearcut plots: decayed wood, mineral soil adjacent to downed wood, or control mineral soil, to determine the effect of retained downed wood on EMF communities over the medium and long term. If downed and decayed wood provide refuge habitat distinct from that of mineral soil, we would expect EMF communities on seedlings in woody habitats in clearcuts to be similar to those on seedlings planted in the adjacent forest. As expected, we found EMF species richness to be higher in forests than clearcuts (P ≤ 0.01), even though soil nutrient status did not differ greatly between the two plot types (P ≥ 0.05). Communities on forest seedlings were dominated by Tylospora spp., whereas those in clearcuts were dominated by Amphinema byssoides and Thelephora terrestris. Surprisingly, while substrate conditions varied among microsites (P ≤ 0.03), especially between decayed wood and mineral soil, EMF communities were not distinctly different among microhabitats. Our data suggest that niche partitioning by substrate does not occur among EMF species on very young seedlings in high elevation spruce-fir forests. Further, dispersal limitations shape EMF community assembly in clearcuts in these forests.     

Black alder swamps on forested peatlands in Latvia

The black alder (Alnus glutinosa (L.)Gaertn.) stands occupy 2.5% of the forest area in Latvia. The majority of its communities lie on peatlands; they have been studied in the whole of latvia using the Braun-Blanquet approach. One hundred and fifty alder dominated relevés selected from 334 forest areas have been analysed. Three associations (Carici elongatae-Alnetum, Sphagno squarrosi-Alnetum, andCircaeo-Alnetum), one with four subassociations have been recognized; these belong to the Eurosiberian alder swamps (cl.Alnetea glutinosae) and the European broad-leaved forests (cl.Querco-Fagetea). The phytosociological structure, distribution in Latvia and floristic features of these communities are reported. Results are compared with similar communities in the Baltic Sea states and neighbouring countries.     

The role of native forest plantations in the conservation of Neotropical birds: the case of the Andean alder

The gradual increase in reforested areas worldwide, as a strategy for mitigating native forest loss, has stressed the need of assessing their real value as habitat for native species. Forest plantations, particularly those based on native species, could be valuable for conservation purposes, especially in heavily fragmented and disturbed ecosystems. We evaluated the value of a monoculture of a native tree species, the Andean alder (Alnus acuminata), for the conservation of avifauna in the Central Andes region, which is considered a bird species diversity hotspot but also suffers from high anthropogenic disturbance levels. Our results suggest that alder plantations are valuable for conservation from three points of view: (1) they have similar or greater bird species richness and abundance than secondary native forests; (2) low community similarities are found between this type of forest compared to secondary forest stands (with 27 species exclusive to alder plantations); and (3) three near threatened species (Odontophorus hyperythrus, Eriocnemis derbyi, and Cyanolyca viridicyanus). Further, 27 out of the 85 species found at the alder plantations were of least concern but showing decreasing population trends. While forest plantations do not replace native forests, they offer habitat for many bird species, some of them being of conservation concern (i.e., included in an IUCN threat category) or with decreasing populations. Hence establishing native species plantations among native forest remnants – especially in heavily fragmented landscapes – could have a positive effect in the conservation of threatened avifauna.     

Per capita community-level effects of an invasive grass, Microstegium vimineum, on vegetation in mesic forests in northern Mississippi (USA)

Quantifying per capita impacts of invasive species on resident communities requires integrating regression analyses with experiments under natural conditions. Using multivariate and univariate approaches, I regressed the abundance of 105 resident species of groundcover plants and tree seedlings against the abundance and height of an invasive grass, Microstegium vimineum, within 117 plots in four mesic floodplain forests in Mississippi (USA). Microstegium vimineum was most productive (i.e., tallest and most abundant) in canopy gaps in floodplains, and a significant amount of variation in resident species composition was directly explained by canopy gaps and stand age. The relatively small (but statistically significant) percentage of variation in resident species composition (1.8%) explained by M. vimineum in the multivariate analysis was attributable to significant relationships with a few common species. Most of these were negative relationships with shady mesic forest indicators. Most positive relationships were with infrequent disturbance indicators and with species with growth phenologies that differed from that of M. vimineum. Results of field competition experiments with the three most common species to show significant relationships with M. vimineum revealed asymmetric competitive effects of M. vimineum on Chasmanthium laxum and positive responses of Quercus alba seedlings and Leersia virginica adults to the removal of M. vimineum in one growing season. Results of this study suggest that negative per capita community-level effects of M. vimineum are likely to be greater in shady forests than in open floodplain forests due to the relative paucity of vulnerable species in the latter.     

Heterotrophic flagellate biodiversity and community structure in freshwater streams

The species diversity and community structure of heterotrophic flagellates in watercourses from different geographical regions were investigated. Forty-one species have been identified. The species diversity of cercomonads, kinetoplastids, choanoflagellates, and flagellates is the highest. Bodo saltans, B. designis and Goniomonas truncata are the most common species. Planktonic communities in different streams are most similar in terms of species composition. The highest similarity within benthic cenoses was noted between geographically distant communities. Communities of heterotrophic flagellates seem to be highly heterogenous systems; species distribution depends mainly on the type of habitat and not on geographical factors.     

Fish Communities in Central Amazonian White- and Blackwater Floodplains

In Amazonian floodplains, the flood cycle of the river is becoming the dominant seasonal factor, and fish communities are found to fluctuate greatly over the year. During inundation, fish migrate into floodplain forests to feed on fruits and seeds, in an area more than 300000km² in size. To document patterns of species diversity, distribution, abundance and temporal dynamics and in order to describe the ecological importance of the inundated forest, floodplain fish were captured using variously sized gill nets in white and black water areas inside and outside the floodplain forests during low, rising, high and falling water level in 1990 and 1991. Dominance varies to some extent in white water between floodplain forest (0.06) and open water (0.11) while it is unchanged in black water (0.04). Black water fish communities were more diverse. Most abundant among white water fish were Liposarcus pardalis, Pygocentrus nattereri, and Pellona flavipinnis, for example, or Plagioscion squamsissimus, Serrasalmus rhombeus, and Serrasalmus manueli in black water. Among the most abundant white water fish, Colossoma macropomum, Mylossoma duriventre and Osteoglossum bicirrhosum occurred almost exclusively in inundated forests. Of the black water species there were a large number of species which were captured only in inundated forest, such as Geophagus cf. altifrons, Hoplias malabaricus, Osteoglossum bicirrhosum and Uaru amphiacanthoides. Catches varied with sample site, water level and direction of water level change. The average CPUE in white and black water was 190 and 41g fishm^–2 and day, respectively, with maximum yields at low water and minimum yields at high water. Comparing rising and falling water levels, a significantly higher quantity of fishes was captured at falling water level. In black water, fish catches from the floodplain forest exceeded the open water catch by 183 to 550%, depending on season. Differences in respect of white water are smaller (106–281%). Fish communities in the area under investigation seem to be stochastically assembled, with significant differences between white and black water only. Many fishes move into the floodplain forest not only to feed but probably also for other reasons – to seek shelter, for example.     

Fire and local factors shape ectomycorrhizal fungal communities associated with Pinus ponderosa in mountains of the Madrean Sky Island Archipelago

With a warming and drying climate, coniferous forests worldwide are increasingly threatened by wildfires. We examined how fire impacts ectomycorrhizal (EM) fungi associated with Pinus ponderosa, an important tree species in western North America. In the biodiverse Madrean Sky Islands, P. ponderosa forests exist on insular mountains separated by arid lands. How do EM fungi in these isolated ranges respond to fire, and can data from individual ranges predict community shifts after fire at a regional scale? By comparing areas in two ranges that experienced moderate fires 12–16 y earlier, and proximate areas in each range without recent fire, we reveal pervasive effects on diversity and composition of EM communities more than a decade after moderate fires occurred. Post-fire differences in EM communities in different ranges highlight the challenge of predicting fungal community shifts in these isolated forests, despite similarities of climate, plant communities, and fire severity.     

Dominant Pollen Types Recovered From commercial Louisiana honeys

Microscopical pollen analyses of 54 commercial honey samples collected from the major beekeeping areas of Louisiana during 1967–68 showed six dominant pollen types (a dominant type considered as one contributing over 45% of the total grains counted per sample and denoting a unifloral honey). The dominant pollen types and the “ bee plant ” species associated with each pollen type are identified and described. The pollen types are illustrated with light photomicrographs. The pollen types are in order of importance:Trifolium repens, white clover;Rubus spp., blackberry and/or dewberry;Berchemia scandens, rattan vine;Salix spp., willow; Asteraceae, Sunflower family; and Sapiumsebiferum,Chinese tallow tree. White clover and willow were the largest unifloral honey producers in a region including the floodplain and delta of the Mississippi River, and the floodplain of the Red River (the most productive beekeeping area of Louisiana); blackberry and/or dewberry were most significant in the longleaf pine flat woods and mixed hardwoods in the uplands section on the east side of the Mississippi River; rattan vine was most important in west-central Louisiana in an area consisting originally of pine-oak-hickory uplands and longleaf pine flat woods; white clover appeared most important in the prairie region of southwest Louisiana.     

Communities of uropodine mites (Acari: Mesostigmata) in selected oak-hornbeam forests of the Wielkopolska region (Poland)

Pristine oak-hornbeam forests are among the richest flora and fauna environments in Poland. The agricultural development of the Wielkopolska region has led to the replacement of forest area with farmland. Consequently, the oak-hornbeam forests became fragmented, resulting in the isolation of local arthropod populations. The aim of this study was to compare the communities of uropodine mites in selected parts of a forest, differing in stand age and composition, physical soil condition and degree of anthropogenic pressure. Species composition of mite communities in a forest near Duszniki (West Poland), transformed by humans, was compared with the mite species composition observed in three nature reserves in its close vicinity. The analyses showed that Trachytes aegrota and Olodiscus minima constitute more than 50% of all communities in each type of tree stand. Diversity in Uropodina communities was higher in older tree stands, as well as in protected areas. Some species, such as Uroobovella pulchella, Uroobovella pyriformis and Dinychus woelkei, are related to specific microhabitats (e.g., they inhabit only dead wood) but there are also ubiquitous species, occurring in all types of environment, e.g., Oodinychus ovalis. Species like Oodinychus karawaiewi and Dinychura cordieri indicate a high degree of forest disturbance. Presence of such species as Trachytes lamda, Cilliba rafalskii, Cilliba cassideasimilis and Trematurella elegans points at high naturalness of soil in oak-hornbeam forests. These species have been found in old (>100 years old) tree stands, where Uropodina communities were also the richest.     

A comparison of fungal endophytic community diversity in tree leaves of rural and urban temperate forests of Kanto district,eastern Japan

To clarify the effects of forest fragmentation and a change in tree species composition following urbanization on endophytic fungal communities, we isolated fungal endophytes from the foliage of nine tree species in suburban (Kashiwa City, Chiba) and rural (Mt. Wagakuni, Ibaraki; Mt. Takao, Tokyo) forests and compared the fungal communities between sites and host tree species. Host specificity was evaluated using the index of host specificity (Si), and the number of isolated species, total isolation frequency, and the diversity index were calculated. From just one to several host-specific species were recognized in all host tree species at all sites. The total isolation frequency of all fungal species on Quercus myrsinaefolia, Quercus serrata, and Chamaecyparis obtusa and the total isolation frequency of host-specific species on Q. myrsinaefolia, Q. serrata, and Eurya japonica were significantly lower in Kashiwa than in the rural forests. The similarity indices (nonmetric multidimensional scaling (NMS) and C_MH) of endophytic communities among different tree species were higher in Kashiwa, as many tree species shared the same fungal species in the suburban forest. Endophytic fungi with a broad host range were grouped into four clusters suggesting their preference for conifer/broadleaves and evergreen/deciduous trees. Forest fragmentation and isolation by urbanization have been shown to cause the decline of host-specific fungal species and a decrease in β diversity of endophytic communities, i.e., endophytic communities associated with tree leaves in suburban forests were found to be depauperate.     

Invasiveness Does Not Predict Impact: Response of Native Land Snail Communities to Plant Invasions in Riparian Habitats

Studies of plant invasions rarely address impacts on molluscs. By comparing pairs of invaded and corresponding uninvaded plots in 96 sites in floodplain forests, we examined effects of four invasive alien plants (Impatiens glandulifera, Fallopia japonica, F. sachalinensis, and F.×bohemica) in the Czech Republic on communities of land snails. The richness and abundance of living land snail species were recorded separately for all species, rare species listed on the national Red List, and small species with shell size below 5 mm. The significant impacts ranged from 16–48% reduction in snail species numbers, and 29–90% reduction in abundance. Small species were especially prone to reduction in species richness by all four invasive plant taxa. Rare snails were also negatively impacted by all plant invaders, both in terms of species richness or abundance. Overall, the impacts on snails were invader-specific, differing among plant taxa. The strong effect of I. glandulifera could be related to the post-invasion decrease in abundance of tall nitrophilous native plant species that are a nutrient-rich food source for snails in riparian habitats. Fallopia sachalinensis had the strongest negative impact of the three knotweeds, which reflects differences in their canopy structure, microhabitat humidity and litter decomposition. The ranking of Fallopia taxa according to the strength of impacts on snail communities differs from ranking by their invasiveness, known from previous studies. This indicates that invasiveness does not simply translate to impacts of invasion and needs to be borne in mind by conservation and management authorities.