Weed Search and Control: Theory and Application

The detectability of invasive organisms influences the costs and benefits of alternative control strategies, and the feasibility of eradicating an infestation. Search theory offers a mathematically rigorous framework for defining and measuring detectability, taking account of searcher ability, biological factors and the search environment. To demonstrate the application of search theory to invasive species control, invasive species detectability is incorporated into a population simulation model. The model is applied to a base set of parameter values that represent reasonable values for a hypothetical weed. The analysis shows the effects of detectability and search time on the duration of an eradication program. Furthermore, for a given level of detectability and search time, the analysis shows that the variables with the greatest influence on the duration of the eradication effort are search speed, kill efficiency and seed longevity. A series of Monte Carlo simulations are performed on a set of five scenarios, involving different combinations of plant longevity, seed longevity and plant fecundity. Results of these simulations are presented as probability distributions and allow us to calculate how the probability of eradication will be affected by search strategy.search and control, search theory, weed control, stage matrix, impedance factors, population dynamics, stochastic model, Farm Management,

Time since Introduction, Seed Mass, and Genome Size Predict Successful Invaders among the Cultivated Vascular Plants of Hawaii

Extensive economic and environmental damage has been caused by invasive exotic plant species in many ecosystems worldwide. Many comparative studies have therefore attempted to predict, from biological traits, which species among the pool of naturalized non-natives become invasive. However, few studies have investigated which species establish and/or become pests from the larger pool of introduced species and controlled for time since introduction. Here we present results from a study aimed at quantifying predicting three classes of invasive species cultivated in Hawaii. Of 7,866 ornamental species cultivated in Hawaii between 1840 and 1999, 420 (5.3%) species naturalized, 141 (1.8%) have been classified as weeds, and 39 (0.5%) were listed by the state of Hawaii as noxious. Of the 815 species introduced >80 years ago, 253 (31%) have naturalized, 90 (11%) are classed as weeds, and 22 (3%) as noxious by the state of Hawaii. Using boosted regression trees we classified each group with nearly 90% accuracy, despite incompleteness of data and the low proportion of naturalized or pest species. Key biological predictors were seed mass and highest chromosome number standardized by genus which, when data on residence time was removed, were able to predict all three groups with 76–82% accuracy. We conclude that, when focused on a single region, screening for potential weeds or noxious plants based on a small set of biological traits can be achieved with sufficient accuracy for policy and management purposes

Weed Search and Control: Theory and Application

The detectability of invasive organisms influences the costs and benefits of alternative control strategies, and the feasibility of eradicating an infestation. Search theory offers a mathematically rigorous framework for defining and measuring detectability, taking account of searcher ability, biological factors and the search environment. To demonstrate the application of search theory to invasive species control, invasive species detectability is incorporated into a population simulation model. The model is applied to a base set of parameter values that represent reasonable values for a hypothetical weed. The analysis shows the effects of detectability and search time on the duration of an eradication program. Furthermore, for a given level of detectability and search time, the analysis shows that the variables with the greatest influence on the duration of the eradication effort are search speed, kill efficiency and seed longevity. A series of Monte Carlo simulations are performed on a set of five scenarios, involving different combinations of plant longevity, seed longevity and plant fecundity. Results of these simulations are presented as probability distributions and allow us to calculate how the probability of eradication will be affected by search strategy

Temporada coreogràfica 1984

Programa de la Temporada coreogràfica 1984 que va tenir lloc entre el 9 d'abril i el 5 de maig, en la qual hi van participar el Ballet Reial de Flandes i la London Contemporary Dance Theatre. L'orquestra que els va acompanyar va ser la del Gran Teatre del Liceu, dirigida per F. Terby, i B. Pheloung. El Ballet Reial de Flandes, dirigit per J. Brabants, va interpretar "Les rendez-vous" amb música d'E. Auber i coreografia de F. Ashton, "La Péri" amb coreografia de J. Butler i P. Dukas, "La cathédrale engloutie" amb coreografia i argument de J. Kylian i música de C. Debussy, "Whimsicalities" amb coreografia de N. Christe i música de G. Auric, "Allegro Brillante" amb coreografia de G. Balanchine i música de P. I. Txaikovski, "Symphony in three movements" amb coreografia de N. Christe i música d'I. Stravinsky, "Masque of separation" amb coreografia de R. Cohan i música de B. Alcántara i "Venusberg" amb coreografia d'A. Leclair i música de R. WagnerEl "London Contemporary Dance Theatre", dirigit per R. Cohan, S. Davies i J. Eager, va interpretar "Canso trobar", amb coreografia de C. Bannerman i música de M. Best, realitzada per B. Pheloung, "Agora" de R. Cohan i música de J. S. Bach, "Run like thunder", amb coreografia de T. Jobe i B. Pheloung, "Stabat mater" amb coreografia de R. Cohan i música d'A. Vivaldi, "New Galileo" amb coreografia de S. Davies i música de J. Adams i "Class" amb coreografia de R. Cohan i música de J. Keliehor. També inclou el programa d'un concert de M. Caballé amb M. Zanetti en benefici de la Creu Roja que va tenir lloc el dia 27 d'abril de 1984 i que va incloure àries de V. Bellini, L. Cherubini, G. Pacini, S. Mercadante, G. Rossini, Saint-Saëns, G. Bizet, F. Mompou i E. Toldr