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GIS Analysis of Spatial Clustering and Temporal Change in Weeds of Grass Seed Crops
- George W. Mueller-Warrant, Gerald W. Whittaker, William C. Young III
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- Journal:
- Weed Science / Volume 56 / Issue 5 / October 2008
- Published online by Cambridge University Press:
- 20 January 2017, pp. 647-669
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Ten years of Oregon Seed Certification Service (OSCS) preharvest field inspections converted from a nonspatial database to a geographic information system (GIS) were analyzed for patterns in spatial distribution of occurrence and severity of the 36 most common weeds of grass seed crops. This was done under the assumptions that those patterns would be primarily consequences of interactions among farming practices, soil properties, and biological traits of the weeds, and that improved understanding of the interactions would benefit the grass seed industry. Kriging, Ripley's K-function, and both Moran's I spatial autocorrelation and Getis-Ord General G high/low clustering using the multiple fixed distance band option all produced roughly similar classifications of weeds possessing strongest and weakest spatial clustering patterns. When Moran's I and General G analyses of maximum weed severity observed within individual fields over the life of stands were conducted using the inverse distance weighting option, however, results were highly sensitive to the presence of a small number of overlapping fields in the 10-yr record. Addition of any offset in the range from 6 to 6,437 m to measured distances between field centroids in inverse distance weighting matrices removed this sensitivity, and produced results closely matching those for the multiple fixed distance band method. Clustering was significant for maximum severity within fields over the 10-yr period for all 43 weeds and in 78% of single-year analyses. The remaining 22% of single-year cases showed random rather than dispersed distribution patterns. In decreasing order, weeds with strongest inverse-distance spatial autocorrelation were German velvetgrass, field bindweed, roughstalk bluegrass, annual bluegrass, orchardgrass, common velvetgrass, Italian ryegrass, Agrostis spp., and perennial ryegrass. Of these nine weeds, distance for peak spatial autocorrelation ranged from 2 km for Agrostis spp. to 34 km for common velvetgrass. Weeds with stronger spatial autocorrelation had greater range between distance of peak spatial autocorrelation and maximum range of significance. Z-scores for General G high/low clustering were substantially lower than corresponding values for Moran's I spatial autocorrelation, although the same two weeds (German velvetgrass and field bindweed) showed strongest clustering using both measures. Simultaneous patterns in Moran's I and General G implied that management practices relatively ineffective in controlling weeds usually played a greater role in causing weeds to cluster than highly effective practices, although both types of practices impacted Italian ryegrass distribution. Distance of peak high/low clustering among perennial weeds was smallest (1 to 3 km) for Canada thistle, field bindweed, Agrostis spp., and western wildcucumber, likely indicating that these weeds occurred in patchy infestations extending across neighboring fields. Although both wild carrot and field bindweed doubled in average severity over the period from 1994 to 2003, wild carrot was the only weed clearly undergoing an increase in spatial autocorrelation. Soil chemical and physical properties and dummy variables for soil type and crop explained small but significant portions of total variance in redundancy and canonical correspondence analysis of weed occurrence and severity. Fitch-Morgoliash tree diagrams and Redundancy Analysis (RDA) and Canonical Correspondence Analysis (CCA) ordinations revealed substantial differences among soil types in weed occurrence and severity. Gi∗ local hot-spot clustering combined with feature class to raster conversion protected grower expectations of confidentiality while describing dominant spatial features of weed distribution patterns in maps released to the public.
Contributors
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- By W. Neil Adger, Jeroen Aerts, Armando Apan, Jessica Ayers, Jon Barnett, Juan F. Barrera, Simon P. J. Batterbury, Linda C. Botterill, Sarah Boulter, Edwin Castellanos, Declan Conway, Gustavo Cruz-Bello, W. Priyan, S. Dias, Markus G. Donat, Stephen Dovers, Thomas E. Downing, Hallie Eakin, C. J. Fotheringham, Andrew W. Garcia, Marisa C. Goulden, Daniela Guitart, John Handmer, Katharine Haynes, Sam S. L. Hettiarachchi, Saleemul Huq, Jiang Tong, David John Karoly, Jon E. Keeley, Diane Keogh, David King, Zbigniew W. Kundzewicz, Timothy M. Kusky, Karine Laaidi, Alain Le Tertre, Gregor C. Leckebusch, Matthew Mason, David M. Mills, Helda Morales, Michael J. Mortimore, Colette Mortreux, Karen O’Brien, Jean Palutikof, Mathilde Pascal, Bimal K. Paul, Munshi K. Rahman, William D. Snook, Su Buda, Alexandra D. Syphard, Melanie Thomas, Madeleine C. Thomson, Uwe Ulbrich, Pier Vellinga, George Walker, Joshua Whittaker
- Edited by Sarah Boulter, Griffith University, Queensland, Jean Palutikof, Griffith University, Queensland, David John Karoly, University of Melbourne, Daniela Guitart, Griffith University, Queensland
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- Book:
- Natural Disasters and Adaptation to Climate Change
- Published online:
- 05 October 2013
- Print publication:
- 14 October 2013, pp ix-xii
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The Santiago Iglesias Case, 1901–1902: Origins of American Trade Union Involvement in Puerto Rico
- William George Whittaker
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- Journal:
- The Americas / Volume 24 / Issue 4 / April 1968
- Published online by Cambridge University Press:
- 11 December 2015, pp. 378-393
- Print publication:
- April 1968
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In November of 1898, Samuel Gompers, president of the American Federation of Labor, lashed out at the expansionists and denied most emphatically that there was “justification for our enforced conquest and annexation ”of the “semi-nude people ”of Puerto Rico, living in a state of “peonage.” At large, the American trade union movement appears to have been caught up in the movement for Cuban independence—both political and economic. Puerto Rico, however, was a different matter. The trade union leadership had shown no special awareness of the island or of conditions prevailing there and, following the American occupation, adopted a strongly anti-imperialist stand. Yet, in February of 1901, the American Federationist (edited by Gompers) warmly applauded the Louisville conventions decision “. . .to organize the 15,000 skilled workers of the island of Puerto Rico on the unshakable basis of the trade union.” By the summer of 1902, trade union opinion had largely reversed itself and fraternal ties between the American Federation of Labor and the Federación Libre of Puerto Rico had been irrevocably forged.