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Invasive plants alter community structure, threatening ecosystem function and biodiversity, but little information is available on whether invasive species richness responds to environmental conditions in the same way that richness of native plants does. We surveyed submerged and floating-leaved plants in 99 Connecticut (northeast USA) lakes and ponds, collecting quantitative data on abundance and frequency. We used multiple linear and logistic regression to determine which environmental conditions were correlated with species richness of invasive and native plants. Independent variables included lake area, maximum depth, pH, alkalinity, conductivity, phosphorus concentration, productivity, and dominance (the proportional abundance of the most abundant and frequently found species), plus two estimates of human activity. Species richness of both native and invasive richness was correlated with alkalinity and human activity. Native richness also increased with water clarity, lake area, and productivity; invasive species richness also rose with pH. We found no evidence that richness of one group affected richness of the other. We also investigated patterns of dominance and found that native plants were as likely to become dominant as invasive species. Dominance occurred overwhelmingly in shallow lakes with high productivity. Key words: abiotic conditions, biodiversity, community structure, dominance, lakes, macrophyte. Les plantes envahissantes modifient la structure des communautes en menacant les fonctions des ecosystemes et leur biodiversite, mais on connait peu de chose a savoir si la richesse en especes envahissantes reagit aux conditions du milieu de la meme facon que la richesse en plantes indigenes. Les auteurs ont suivi les plantes submergees et a feuilles flottantes dans 99 lacs et etang du nord-est des Etats-Unis, en reunissant les donnees d'abondance et de frequence. Ils ont utilise la regression lineaire multiple et logistique pour determiner quelles conditions environnementales montrent une correlation avec les richesses en especes des plantes envahissantes et indigenes. Les variables independantes comprennent la surface des lacs, la profondeur maximum, le pH, l'alcalinite, la conductivite, la teneur en phosphore, la productivite et la dominance (l' abondance proportionnelle des especes les plus frequentes et les plus abondantes), ainsi que deux valeurs estimees pour l'activite humaine. La richesse en especes indigenes aussi bien qu'en especes envahissantes montre une correlation avec l'alcalinite et l'activite humaine. La richesse en especes indigenes augmente egalement avec la clarte de l'eau, la surface du lac et la productivite; la richesse en especes adventices augmente aussi avec le pH. On ne percoit aucune preuve que la richesse d'un groupe affecte la richesse de l'autre. Les auteurs ont egalement examine le patron de la dominance pour constater que les plantes indigenes ont autant de chance de devenir dominantes que les especes envahissantes. On retrouve la dominance surtout dans les lacs peu profonds a forte productivite. Mots-cles : conditions abiotiques, biodiversite, structure des communautes, dominance, lacs, macrophytes. [Traduit par la Redaction], Introduction Invasive plants are an economic and ecological problem in many aquatic systems (Pimentel et al. 2005). They can dominate lakes, interfering with recreation and reducing real estate values (Bergstrom [...]

1. The structure of biological communities reflects the influence of both local environmental conditions and processes such as dispersal that create patterns in species’ distribution across a region. 2. We extend explicit tests of the relative importance of local environmental conditions and regional spatial processes to aquatic plants, a group traditionally thought to be little limited by dispersal. We used partial canonical correspondence analysis and partial Mantel tests to analyse data from 98 lakes and ponds across Connecticut (northeastern United States). 3. We found that aquatic plant community structure reflects the influence of local conditions (pH, conductivity, water clarity, lake area, maximum depth) as well as regional processes. 4. Only 27% of variation in a presence/absence matrix was explained by environmental conditions and spatial processes such as dispersal. Of the total explained, 45% was related to environmental conditions and 40% to spatial processes. 5. Jaccard similarity declined with Euclidean distance between lakes, even after accounting for the increasing difference in environmental conditions, suggesting that dispersal limitation may influence community composition in the region. 6. The distribution of distances among lakes where species occurred was associated with dispersal-related functional traits, providing additional evidence that dispersal ability varies among species in ways that affect community composition. 7. Although environmental and spatial variables explained a significant amount of variation in community structure, a substantial amount of stochasticity also affects these communities, probably associated with unpredictable colonisation and persistence of the plants. [ABSTRACT FROM AUTHOR]

Presents a study that determined the effects of container media with biosolid composts on the growth of ornamental plants. Measurement of the chemical media properties; Effect of container media with biosolid composts on the growth of flowering annual plants and herbaceous perennial plants; Impact of biosolid composts on the growth of woody ornamental shrubs.

Biosolids compost is used in media to grow potted plants. Nitrogen (N) in media leachate may contribute to nitrate (NO3‐N) contamination of surface or ground water. Addition of sawdust to potting media containing biosolids compost will increase the carbon (C) to nitrogen ratio and could prevent N leaching without adversely affecting plant growth. A control medium containing 0% sawdust (v/v), 30% perlite, 50% municipal biosolids compost, and 20% sand was modified to contain either 10, 20, or 30% (v/v) fresh hardwood sawdust. The sawdust replaced either 1/3, 2/3, or all of the perlite in the control medium. Slow release fertilizer, slow plus quick release fertilizer, or no fertilizer was added to each of the four media to determine how the sawdust affected fertilizer needs. Coreopsis (Coreopsis grandiflora L.) and Rudbeckia (Rudbeckia hirta L. ’Goldstrum') were grown in pots for five months. Leachate was tested for NO3‐N and ammonium N (NH4‐N). Increasing amounts of sawdust produced no differences in growth of Coreopsis and few differences in the growth of Rudbeckia. The addition of slow or slow plus quick release fertilizer had little effect on the growth of Coreopsis and a greater effect on the growth of Rudbeckia. Sawdust and fertilizer had no effect on the leaching of N. Nitrogen leached primarily as NH4‐N during the first four weeks of the experiment. [ABSTRACT FROM PUBLISHER]

Deficiencies in soil zinc (Zn) may limit yield of corn (Zea mays L.) in parts of the northeastern United States. Because phosphorus (P) fertilizer is usually applied in excess of what is removed by the crop, buildup of P could reduce the plant availability of Zn. This study examines the effects of P and Zn fertilizer on yield of corn and levels of P and Zn in soil and tissue. Compared to corn that received no P or Zn, the yield of grain increased in three years when 66 kg/ha P + 0 kg/ha Zn and 66 kg/ha P + 15 kg/ha Zn was applied. When corn was fertilized with 0 kg/ha P + 15 kg/ha Zn, grain yield increased in one year. Similarly, an increase in grain yield occurred in only one year in plots fertilized with 66 kg/ha P + 15 kg/ha Zn compared to 66 kg/ha P + 0 kg/ha Zn. Increases in grain yields ranged between 5 and 22 percent for plots receiving P alone and P plus Zn, and between 5 and 10 percent for plots fertilized with Zn alone. Silage yields followed the same trends as the grain yields except they were less pronounced. Tissue and soil analyses showed significant increases in Zn in plots fertilized with Zn but little increases in P in plots fertilized with P. Zinc reductions in tissue because of P fertilizer was minimal. [ABSTRACT FROM PUBLISHER]

This article documents the addition of 205 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Bagassa guianensis, Bulweria bulwerii, Camelus bactrianus, Chaenogobius annularis, Creontiades dilutus, Diachasmimorpha tryoni, Dioscorea alata, Euhrychiopsis lecontei, Gmelina arborea, Haliotis discus hannai, Hirtella physophora, Melanaphis sacchari, Munida isos, Thaumastocoris peregrinus and Tuberolachnus salignus. These loci were cross-tested on the following species: Halobaena caerulea, Procellaria aequinoctialis, Oceanodroma monteiroi, Camelus ferus, Creontiades pacificus, Dioscorea rotundata, Dioscorea praehensilis, Dioscorea abyssinica, Dioscorea nummularia, Dioscorea transversa, Dioscorea esculenta, Dioscorea pentaphylla, Dioscorea trifida, Hirtella bicornis, Hirtella glandulosa, Licania alba, Licania canescens, Licania membranaceae, Couepia guianensis and 7 undescribed Thaumastocoris species. [ABSTRACT FROM AUTHOR]