agridat (version 1.5)

ivins.herbs: Percent ground cover of herbage species and nettles.

Description

Percent ground cover of herbage species and nettles.

Usage

data(ivins.herbs)

source

Ivins, JD. (1952). Concerning the Ecology of Urtica Dioica L., Journal of Ecology, 40, 380-382.

Details

On the University of Nottingham farm, 13 different strains and species of herbage plants were sown on about 4 acres in an RCB design. Each grass species was sown together with white clover seed. During establishment of the herbage plants, it became apparent that Urtica dioica (nettle) became established according to the particular herbage plant in each plot. In particular, nettle became established in plots sown with leguminous species and the two grass species. The graminaceous plots had less nettles. The data here are the percentage ground cover of nettle and herbage plants in September 1951. Note, some of the percent ground cover amounts were originally reported as 'trace'. These have been arbitrarily set to 0.1 in this data. lll{ gen species strain G01 lolium perenne Irish perennial ryegrass G02 L. perenne S. 23 perennial ryegrass G03 Dactylis glomerata Danish cocksfoot G04 D. glomerata S. 143 cocksfoot G05 Phleum pratense American timothy G06 P. pratense S. 48 timothy G07 Festuca pratensis S. 215 meadow fescue G08 Poa trivialis Danish rough stalked meadow grass G09 Cynosurus cristatus New Zealand crested dogstail G10 Trifolium pratense Montgomery late red clover G11 Medicago lupulina Commercial black medick G12 Trifolium repens S. 100 white clover G13 Plantago lanceolata Commercial ribwort plantain }

References

Ivins, JD (1950). Weeds in relation to the establishment of the Ley. Grass and Forage Science, 5, 237--242. O'Gorman, T.W. (2001). A comparison of the F-test, Friedman's test, and several aligned rank tests for the analysis of randomized complete blocks, Journal of agricultural, biological, and environmental statistics, 6, 367--378.

Examples

dat <- ivins.herbs

xyplot(herb~nettle|block, dat) # Nettle is primarily established in legumes.

# O'Brien used first 7 species to test gen differences
dat7 <- droplevels(subset(dat, is.element(gen, c('G01','G02','G03','G04','G05','G06','G07'))))
m1 <- lm(herb ~ gen + block, data=dat7)
anova(m1) # gen p-value is .041
friedman.test(herb ~ gen|block, dat7) # gen p-value .056