Theory, Examples & Exercises
Data are included in a book Šmilauer & Lepš (2014) in Case study 3, and originally were published by Pyšek & Lepš (1991)
The experiment was focused on diversity and species richness of weed communities in barley fields after application of industrial fertilizers. The experiment was originally established as a part of hydrobiological research, and for practical reasons it was not established using properly randomized design - individual plots are practically pseudoreplications, but for the purpose of this exercise we ignore it.
All together 122 plots of the size 1 m2 were fertilized by three different fertilizers (for the purpose of this study the types of fertilizers are not distinguished), and on each plot species composition of weed community was recorded (with species covers estimated using ordinal scale from 1 to 7). Fertilizing simultaneously influences also growth and cover of barley, and the cover of barley can in turn also influence species composition of weeds; for this reason, the barley cover in the plot was also recorded.
Close to the village Samšín in South Bohemia, elevation 500 m a.s.l. For further details, see Pyšek & Lepš (1991).
Here we are using simplified dataset without distinguishing the types of fertilizers - we distinguish only the dose.
|dose||dose of fertilizer (0 - not fertilized, 1 - 70 g N/ha, 2 - 140 g N/ha)|
|cover||estimated cover of barley [%]|
|NSP||number of weed species in the plot|
|File name||File type||Description|
|fertil.xls||Excel file||Contains species data, environmental data, design of experiment and other information (file from supplementary materials to the book of Šmilauer & Lepš (2014), Case study 3)|
fertil.spe <- read.delim ('https://raw.githubusercontent.com/zdealveindy/anadat-r/master/data/fertil.spe.txt', row.names = 1) fertil.env <- read.delim ('https://raw.githubusercontent.com/zdealveindy/anadat-r/master/data/fertil.env.txt', row.names = 1)