The floristic composition of the understory plays a fundamental role in the long-term conservation of the diversity, structure, and function of mountain cloud forests in the Andes. We evaluated the relationship between the understory tree floristic composition of four types of predefined cloud forests and the canopy structure, the light transmitted to the understory, and the effect of topography. Through multivariate analysis, we found an environmental gradient correlated with light penetration into the understory and a gradient associated with the slope and, to a lesser extent, with the elevation. Then, we identified floristically well-differentiated ecological groups in response to environmental conditions; however, the groups only partially coincided with the understory composition of the predefined forests. We found environmental response species groups such as Roupala obovata and Beilschmiedia sulcata that are indicator species of sites with lower light penetration into the understory but with steeper slopes and higher elevation. In comparison, Clusia multiflora and Zanthoxylum quinduense to be the main indicator species from sites with greater light penetration into the understory and lower slope and elevation. These findings support appropriate species selection when implementing restoration strategies in forest landscape restoration plans.

Ventenata [Ventenata dubia (Leers) Coss.], an invasive winter annual grass, negatively impacts grassland community composition and function in the Pacific Northwest. Ventenata dubia established in Palouse prairie (PP) and canyon grasslands (CG) of northern Idaho/eastern Washington in the mid-1980s to early 1990s. Understanding and comparing patterns of invasion can elucidate future trends as its range expands. We performed surveys in PP (2012 and 2013) and CG (2018) to assess V. dubia abundance. Specifically, we correlated species richness, Shannon diversity, rank abundance, and indicator species with no, low (<12.5%), and high (>12.5%) V. dubia cover. We used nonmetric multidimensional scaling analysis (NMDS) to visualize species similarities and associations with abiotic variables. In both ecoregions, V. dubia was very common, appearing in nearly 60% of 450 plots. When present, V. dubia cover averaged 26% (±2.3 SE) in PP and 19% (±1.8 SE) in CG. Indigenous plant species richness and diversity were lowest in plots with high V. dubia cover. In CG, this relationship held for nonindigenous species; in PP, nonindigenous plant richness and diversity were higher with high V. dubia cover. Ventenata dubia and other winter annual grasses (Bromus spp., medusahead [Taeniatherum caput-medusae (L.) Nevski]) were moderately associated according to the NMDS analysis. Indicator species analysis showed V. dubia was positively associated with nonindigenous winter annual grasses and negatively associated with indigenous low shrub species. Abiotic factors that explained V. dubia abundance included shallow soils and a south to west aspect. Overall, these findings indicate V. dubia can successfully invade both dry and relatively wet plant communities and is more abundant than other invasive annual grasses. We suggest these findings foreshadow what will happen in sagebrush steppe and Great Plains grasslands, regions where V. dubia recently became established.

Thirty-five species of Micarea are recorded for Tasmania. Ten are described as new to science: M. ceracea Coppins & Kantvilas (also known from Victoria and New South Wales), characterized by a thallus containing perlatolic and didymic acids, pallid apothecia and 3(–4)-septate ascospores, 10–21 × 3·5–6 µm; M. cinereopallida Coppins & Kantvilas (also known from Chile), with a granular to coralloid, goniocyst-like thallus containing superlatolic acid, pallid to piebald apothecia and (0–)1-septate ascospores, 8–15 × 2·5–5 µm; M. micromelaena Kantvilas & Coppins, similar to the widespread M. melaena but with markedly smaller, 0–1-septate ascospores, 8–12·5 × 2·5–4 µm; M. oreina Kantvilas & Coppins, characterized by a thallus of globose areoles containing gyrophoric acid, black, subglobose apothecia, and 1-septate ascospores, 11–16·5 × 4·5–6·5 µm; M. pallida Coppins & Kantvilas, similar to M. ceracea but distinguished by the presence of porphyrilic acid and relatively small, 3-septate ascospores, 9·5–15 × 2·5–4 µm; M. prasinastra Coppins & Kantvilas (also known from New Zealand), a member of the M. prasina group with a finely granular-sorediose thallus containing gyrophoric acid, unpigmented apothecia and (0–)1-septate ascospores, 7–11·5 × 1·8–3·5 µm; M. rubiginosa Coppins & Kantvilas (also known from Chile), likewise allied to M. prasina but with apothecia containing Rubella-orange pigment and ascospores 0–1-septate, 9·5–17 × 3·5–5·5 µm; M. sandyana Kantvilas, related to M. ternaria (Nyl.) Vĕzda but differing by smaller ascospores, 7–13·5 × 3·5–6 µm; M. saxicola Coppins & Kantvilas, characterized by a relatively thick, grey-brown, areolate thallus, convex, black apothecia and 0(–1)-septate ascospores, 7–18 × 4·5–7 µm; and M. tubaeformis Coppins & Kantvilas, related to M. flagellispora and with filiform ascospores, 45–100 × 1–2 µm, but differing by containing 2′-O-methylperlatolic acid and having funnel-shaped pycnidia. Ten species of Micarea are reported for Tasmania for the first time: M. almbornii Coppins, M. argopsinosa P. M. McCarthy & Elix, M. byssacea (Th. Fr.) Czarnota et al., M. contexta Hedl., M. farinosa Coppins & Aptroot, M. humilis P. M. McCarthy & Elix, M. incrassata Hedl., M. myriocarpa V. Wirth & Vězda ex Coppins, M. nowakii Czarnota & Coppins and M. pseudocoppinsii Brand et al. Also recorded for the first time for Victoria are M. alabastrites (Nyl.) Coppins and M. cinerea (Schaer.) Hedl. A key to Micarea-like lichens in Tasmania, which includes Micarea itself as well as Brianaria, Psilolechia and Leimonis, is presented. Leimonis erratica (Körb.) R. C. Harris & Lendemer and Brianaria tuberculata (Sommerf.) S. Ekman & M. Svensson are recorded for Tasmania for the first time.

Weed management is a major challenge in organic crop production, and organic farms generally harbor larger weed populations and more diverse communities compared with conventional farms. However, little research has been conducted on the effects of different organic management practices on weed communities and crop yields. In 2014 and 2015, we measured weed community structure and soybean [Glycine max (L.) Merr.] yield in a long-term experiment that compared four organic cropping systems that differed in nutrient inputs, tillage, and weed management intensity: (1) high fertility (HF), (2) low fertility (LF), (3) enhanced weed management (EWM), and (4) reduced tillage (RT). In addition, we created weed-free subplots within each system to assess the impact of weeds on soybean yield. Weed density was greater in the LF and RT systems compared with the EWM system, but weed biomass did not differ among systems. Weed species richness was greater in the RT system compared with the EWM system, and weed community composition differed between RT and other systems. Our results show that differences in weed community structure were primarily related to differences in tillage intensity, rather than nutrient inputs. Soybean yield was lower in the EWM system compared with the HF and RT systems. When averaged across all four cropping systems and both years, soybean yield in weed-free subplots was 10% greater than soybean yield in the ambient weed subplots that received standard management practices for the systems in which they were located. Although weed competition limited soybean yield across all systems, the EWM system, which had the lowest weed density, also had the lowest soybean yield. Future research should aim to overcome such trade-offs between weed control and yield potential, while conserving weed species richness and the ecosystem services associated with increased weed diversity.

Ventenata [Ventenata dubia (Leers) Coss.], an invasive winter annual grass, significantly reduces forage production in grassland systems and displaces species within both perennial- and annual-dominated grasslands within the Inland Northwest. The range of V. dubia is expanding into sagebrush steppe communities, an expansive habitat critical for forage production, wildlife, and recreation. Currently, there is limited knowledge of V. dubia’s distribution and abundance within sagebrush steppe communities. We performed field surveys at 15 locations in sagebrush steppe rangelands in southern Idaho and eastern Oregon to assess where V. dubia occurs, with the aim of providing insight about its niche in this new habitat. Specifically, we evaluated biotic and abiotic factors of the plant community as indicators of V. dubia presence. We also correlated species diversity measures with no, low (<12.5%), and high (>12.5%) V. dubia cover. Though widely distributed throughout the study region, V. dubia only appeared in 45% of the 225 plots, and foliar cover was typically less than 50%. It was primarily found in ephemerally wet microhabitats. Species richness and the Shannon diversity index were lowest in plots with high V. dubia cover. Nonmetric multidimensional scaling analysis revealed that V. dubia and medusahead [Taeniatherum caput-medusae (L.) Nevski] were closely associated. Furthermore, chi-square indicator analysis showed that T. caput-medusae was more prevalent, while mountain big sagebrush [Artemisia tridentata Nutt. spp. vaseyana (Rydb.) Beetle] was less prevalent, in plots containing V. dubia. Abiotic factors that explained variation in V. dubia abundance included rock cover, soil depth, and a north/south aspect. Higher V. dubia cover also correlated with higher clay content and lower phosphorus and potassium concentrations in the soil. We suggest that at this point, detection survey efforts to locate incipient infestations of V. dubia in sagebrush steppe communities should focus on moist areas and sites susceptible to invasion by T. caput-medusae.

The extent and nature of spread of exotic plant species to and within Alaska by shipment of hay and straw was studied. The amounts of hay and straw imported into Alaska and the amounts and types of seed in imported and locally produced hay and straw was determined We purchased alfalfa hay, wheat straw, ryegrass straw, and timothy hay produced in Washington and Oregon (WA–OR) and locally produced straw and hay. The hay and straw were shaken over screens, and the remaining fines were mixed with sterile potting soil and incubated in the greenhouse. Forty-nine plant species were identified from hay and straw, nine of which are ranked as invasive in Alaska, including downy brome, foxtail barley, hare barley, narrowleaf hawksbeard, and quackgrass—a prohibited weed in Alaska. The number of seeds ranged from 0 to 6,205 seeds kg−1, with an average of 585 seeds kg−1, and the number of species ranged from 0 to 12, with an average of 4.2 species per bale. Crop seed comprised a large proportion of the germinated seeds in ryegrass straw, wheat straw, and timothy/brome hay (98, 78, and 62%, respectively), but was less prevalent (ranging from 0 to 38%) in the other three hay and straw crop types. Hay and straw from Alaska contained more total seeds and species than hay and straw from WA-OR, but the difference was not significant when only weed seed was used in the analysis. Alaska-grown timothy/brome hay contained significantly more total seed than alfalfa hay and wheat straw from WA–OR and Alaska-grown barley straw. The grower or distributor of the hay and straw also influenced the number of seeds and species among some crop types. Results of this study document that large numbers of alien plant species are transported by movements of hay and straw into and within Alaska.

We studied the emergence phenology of large and smooth crabgrass in lawn and bare soil environments and identified ornamental plants as phenological indicators that predict the progress of emergence. From 2002 to 2004, we monitored emergence of large and smooth crabgrass in field plots to estimate the dates of first emergence, and 25, 50 and 80% emergence. Each year, we monitored 74 taxa of ornamental plants to determine dates of first and full bloom. We compiled dates of weed emergence and ornamental blooming to create a biological calendar of phenological events for each year, ordered by average cumulative degree days (DD) (January 1 start date, 10 C base temperature). Ornamental plant flowering events that occurred in a regular sequence before crabgrass emergence events were identified as the phenological indicators. We also evaluated DD and rule-based models for predicting crabgrass emergence and optimum time of PRE herbicide application. In general, smooth crabgrass reached each emergence stage earlier than large crabgrass. Differences in emergence between environments were not consistent over years for the two species. There was no consistent pattern in parameters for DD models predicting emergence events for either crabgrass species or environment. For published DD models, the deviation between observed and predicted emergence events ranged from 0 to > 60 d. Published rule-based predictions, though accurate in some cases, were sometimes difficult to implement. The order of ornamental plant blooming and crabgrass emergence events was generally consistent over years (R2 = 0.977). The biological calendar provided useful crabgrass emergence predictions using real-time field-based indicators of sequential biological events that can help managers plan and optimize management strategies.

The compositions of the germinable weed seedbank and aboveground weed communities in a long-term tillage and rotation study were characterized 4, 5, and 6 yr (2002 to 2004) after the adoption of glyphosate-tolerant corn and soybean. Averaged across rotation, mean germinable weed seed density and diversity were greatest in the no-tillage treatment as compared to the minimum- and conventional-tillage treatments. Averaged over tillage, density and diversity were greater in the corn–oat–hay (ryegrass + alfalfa) system as compared to the continuous corn and corn–soybean rotations. Similar trends in density and diversity were observed for the aboveground weed communities. Differences in community composition among treatments were quantified with the use of a multiresponse permutation procedure. Results indicated that the weed seedbank community in a corn–oat–hay rotational system differed from the communities associated with the continuous corn and corn–soybean rotational systems. Weed seedbank communities developing under a no-tillage operation differed from those in minimum- and conventional-tillage scenarios. Compositional differences among the aboveground weed communities were less pronounced in response to tillage and rotation. Indicator species analyses indicated that the number of significant indicator weed species was generally higher for no tillage than minimum or conventional tillage for both the seedbank and the aboveground weed communities. The number of significant indicator species for the seedbank and weed communities was generally greater in the three-crop rotation as compared to the continuous corn and corn–soybean rotations. The trends observed in density, diversity, and community composition after the adoption of glyphosate-tolerant corn and soybeans, and a glyphosate-dominated weed management program, were also observed when soil-applied herbicides were included in the study. We suggest that the switch to a POST-glyphosate protocol did not significantly alter weed communities in the short term in this study.

Late-season field surveys conducted in Indiana from 2003 to 2005 showed that common lambsquarters and giant ragweed plants were present in 11 and 22%, respectively, of randomly sampled soybean fields that also contained glyphosate-resistant horseweed. In the fall of 2005 and 2006, seed from 13 common lambsquarters and 22 giant ragweed populations were collected from previously surveyed fields that had confirmed glyphosate-sensitive or -resistant horseweed. The objective of this study was to determine whether the presence of glyphosate-resistant horseweed was correlated with the presence of common lambsquarters and giant ragweed biotypes with elevated tolerance to glyphosate. Through a series of greenhouse screens, 57% of common lambsquarters and 31% of giant ragweed populations collected from fields that had glyphosate-resistant horseweed expressed elevated levels of glyphosate tolerance. However, elevated tolerance to glyphosate was expressed by 33% of giant ragweed and 100% of common lambsquarters populations collected in fields that had glyphosate-sensitive horseweed. Therefore, under the parameters of this experiment and through different types of analyses, we concluded there was not a strong correlation between the late-season presence of glyphosate-resistant horseweed and common lambsquarters and giant ragweed populations with elevated glyphosate tolerance in the same field. A number of the weed populations expressed significant stunting from exposure to glyphosate, but were able to resume growth. Thus, researchers should evaluate plant regrowth in addition to biomass suppression when making assessments of glyphosate resistance in weed populations through greenhouse and field screening.

Savannas intermingled with gallery forests are dynamic habitats typical in Africa. This study aims to determine if differences in species traits lead to non-overlapping distribution of gallery-forest and savanna species and abrupt transition between gallery forest and savanna. Tree species densities were measured in 375 plots of 1500 m2 covering a total sample area of 56.25 ha along forty 3-km transects located at right angles to a riverbed with gallery forest into surrounding savanna. Location, vegetation type, soil physical properties, erosion and fire occurrence were recorded as site factors. Data analysis included the quantification of co-occurrence patterns, threshold indicator taxa analysis and fuzzy set ordination. The gallery forest–savanna gradient predicted floristic composition of plots with a correlation of 0.595 but its accuracy was locally modified by the occurrence of fire and the physical properties of soil that covered more than 30% of the range of residuals. The distribution of gallery-forest and savanna tree species did not overlap. Along the gallery forest–savanna gradient, savanna species gradually increased in density while gallery-forest species showed a community threshold at 120 m from the river beyond the width of gallery forest. The forest species driving this trend should play an important role in the dynamics of gallery forest–savanna boundaries.

Samples were collected from 10 stations distributed through three sectors in Guanabara Bay during two consecutive years, in order to determine factors that influence the spatial pattern of molluscs and to describe the structure and composition of this community in a eutrophic estuarine system on the Brazilian coast. Although only one species, the gastropod Heleobia australis, comprised 77% of mollusc abundance, 59 species were identified in the bay. In addition to H. australis, three other species were dominant: the gastropod Anachis isabellei and the bivalves Americuna besnardi and Ervilia concentrica. The mollusc communities were significantly influenced by the spatial gradient; the outermost sector has marine conditions, and the other sectors are typically estuarine, leading to differences in the composition and abundance of molluscs. The outermost sector showed the highest diversity, which gradually decreased towards the innermost sector where the dominance of a few opportunistic species is favoured by highly organic mud sediments. Sediment type was strongly correlated with mollusc occurrence in the bay. Guanabara Bay showed two indicator species: the bivalve E. concentrica of the outer sector, and the gastropod H. australis of the intermediate sector. Our results suggest that benthic molluscs in Guanabara Bay show characteristics related to levels of environmental impact. A monitoring programme based on this community is needed to evaluate the effects of human impacts on this community and to monitor changes in its biodiversity in Guanabara Bay.

Prevalence monitoring of avian influenza in wild bird populations is important to estimate risks for the occurrence of potentially zoonotic and economically disastrous outbreaks of highly pathogenic avian influenza virus (AIV) in poultry worldwide. A targeted, cost-effective monitoring method for AIV in wild birds was developed, which is based on monitoring results for AIV in Germany and information on the distribution and abundance of wild bird species in selected habitat types. Spatial data were combined with virological and outbreak data for the period of 1 January 2006 to 31 December 2010. Using Germany as an example, we identified 11 indicator species. By concentrating monitoring efforts on these species in spatially confined locations, we propose a targeted and more cost-effective risk-based AIV monitoring approach that can be adapted universally for the identification of wild bird indicator species worldwide with the perspective of reducing sample sizes (and costs) without impairing the validity of the results.

Two surveys of the lichen and bryophyte flora growing on oak twigs from a Welsh and a Danish locality were compared with additional data on bark pH and % nitrogen in thalli of Hypogymnia physodes. Despite differences in climate and lichen flora, both sites showed a shift in the lichen communities from nitrogen sensitive (nitrophobe) to nitrogen tolerant (nitrophile) species, which was correlated with both increasing bark pH and an increase in total nitrogen in thalli of H. physodes. The floristic survey from Wales was a repetition of a study eight years earlier (Wolseley & Pryor 1999) now showing a loss of nitrophobes in all sites and the appearance of nitrophiles in pasture sites in 2003. This study demonstrates that lichens on twigs can be used as an early warning system to detect a response to changes in land management and nitrogen deposition.

A study of the diversity and distribution of lichens at 10 sites within the Mehao Wildlife Sanctuary in Arunachal Pradesh, India, revealed 177 species, belonging to 71 genera and 35 families. The Sanctuary exhibited almost all the habit and habitat groups of lichens within its climatically heterogenous and altitudinally (400–2700 m) varied landscape. Among the different habitat groups, obligately corticolous lichens were dominant (133 species), followed by facultatively corticolous lichens (occurring on both rock and bark; 25 species), saxicolous lichens (17 species) and terricolous lichens (2 species). The corticolous habitat group was dominated by crustose species while saxicolous and terricolous groups were made up of mostly fruticose species. A substantial number of species (77) occurred at single sites only, and each of the 10 sites supported a distinct lichen assemblage. Altitude and humidity were the putative key factors controlling the diversity and distribution of lichens within the Sanctuary. The mid altitude range 1400–1600 m had the greatest lichen diversity, which showed a unimodal pattern in relation to altitude.

Studies in western Amazonian forests have found that similarities in soil cation concentration and texture explain floristic similarities between sites, when these are measured using trees, pteridophytes or Melastomataceae. However, it is not known to what extent the three plant groups react to the same soil characteristics, because tree studies have almost always been conducted in different areas than studies on the understorey plant groups. We made inventories in 23 sites representing non-inundated rain forests on clayey to loamy soil in three regions of western Amazonia. Significant Mantel correlations between the floristic patterns of trees and pteridophytes were found in all three regions when floristic differences were measured with species presence–absence data. When species abundance data were used, and when the floristic patterns of trees and Melastomataceae were compared, significant correlations were found in one or two regions. Mantel correlations between plant groups were highest in the two regions where the observed variation in soil characteristics was largest. In all regions, the same soil variables emerged with significant Mantel correlations with trees, pteridophytes and Melastomataceae. Soil calcium and magnesium were most frequently retained in the models of multiple regression on distance matrices. On average, soil differences explained 50% of the variation in floristic differences (range = 14–84%), and geographical distances explained 16% (range = 0–64%). Our results demonstrate that beta diversities of the three plant groups are highly correlated, and that much of this congruence is explained by similar reactions to soil variation. These results support the idea that pteridophytes, and to a lesser degree Melastomataceae, can be used as indicators of general floristic and edaphic patterns in Amazonian rain forests. Since understorey plants are much quicker to inventory than trees, this would make it possible to recognize and map floristic patterns over huge areas of lowland Amazonia within a reasonable time.

A key issue in the implementation of the Water Framework Directive is the classification of streams and rivers using biologicalquality parameters and type-specific reference conditions. Four groups of stream types were defined in NE Spain on the basisof 152 diatom samples by means of detrended correspondence analysis and classification techniques. Diatom analysis was restrictedto epilithic taxa, and the sites included gradients ranging from near-natural streams to sites with poor ecological quality.The main gradient shows a clear separation of sites in relation to the degree of human influence: polluted streams (mainly locatedin the lowlands) differ from streams in mountainous areas and in the Pyrenees. A second gradient is related to physiographicalfeatures. Headwater streams can be distinguished by their catchment geology. The type-specific diatom taxa for the streamtypes studied were determined by using indicator species analysis (IndVal). The type-specific taxa from near-natural streams arecoincident with the indicator taxa for high ecological status. Human impact reduced the typological heterogeneity of the diatomcommunity composition. Overall, the diatom communities in NE Spain exhibit a regional distribution pattern that closely correspondswith that observed in river systems elsewhere. Physiographical differences are only evident in undisturbed sites, whilenutrient enrichment and other human disturbances may mask the regional differences in the distribution of diatom communities.

Freshwater habitats of the Italian Alps are largely unexplored and further floristic-ecological surveys are needed to clarify the role of freshwater lichens in these environments. This applies especially to springs, since they seem to be suitable for a relatively high number of aquatic species due to their ecological stability. The present work is focused on springs in an alpine region, and is centered on: (a) floristics of freshwater lichens of the Italian Alps, (b) ecological and morphological information on potential indicator species for calcareous and siliceous springs. The study was carried out in the eastern Italian Alps on 36 perennial springs. Single springs proved to host a surprisingly low number of species, while at regional level the entire pool of investigated springs host a relevant lichen flora representing 45% of the freshwater lichens of the Italian Alps. One species is new to Italy and 3 are new to Trentino-Alto Adige. Biodiversity conservation measures should therefore be planned at regional level, including a whole network of sites in different altitudinal belts and with different substrates. Verrucaria elaeomelaena and V. funckii are the most frequent species on calcareous and siliceous springs respectively. They are suggested as potential indicator species, since they proved to be indicative of the main physical, ecological and hydrochemical features of their habitat. A detailed morphological description of these two species is also provided in order to enhance their identification by environmentalists.

The responses of 32 Hydraenidae and Elmidae species to six chemical parameters - alkalinity, Cl-, SO4 --, COD, NO3 - and total P have been analysed in the Orbigo river basin. The study of the distribution in relation to these factors by means of elaborating their ecological profiles pointed out the indicator species for each one of these parameters, according to their reciprocal species-factor information.