civu.csv

Demographic data for an exotic thistle, Cirsium vulgare, at eight sites in eastern Nebraska. At each site, there were 14 3 m x 1 m plots crossing seven seed density treatments with two herbivory treatment (pesticide application to exclude insect herbivores, water only control). Each plot was divided into 3 1 m x 1 m subplots to facilitate data collection. The experiment was run for three years from 2006-2008.

Realized plant density was quantified by counting seedlings and rosettes at the subplot level. To measure individual-level growth, survival, and reproduction, up to 10 plants were marked in each subplot. We recorded the number of leaves and size of a mid-sized leaf in each year. Survival of marked plants was checked in 2007 and 2008. Flowering was monitored in 2007 only. All mature flowers were bagged and collected, and seed production for each plant was quantified as the number of flower heads times the number of filled seeds in a median-sized flower head.

Columns:
“Start_Dens”: Experimental seed density of entire 3 m2 plot. The seed density of each 1 m2 plot is one-third of this density.
“Herbivory”: Herbivores present (control) treatment (value=0), Herbivores excluded with insecticide (value = 1).
“Replicate”: Site number for sites 1-8
“Plot”: Plots are numbered 1-112. There are two plot numbers missing from study (plots were accidentally destroyed with herbicide).
“Demographic ID#”: Every plant within every plot is numbered 1-30.
“June.actual.density.2006”: Density of seedlings for each 1 m2 plot. This tells you the actual density of seedlings surrounding each plant in each 1 m2 plot in June 2006 which is the beginning of the experiment.
“may.actual.density.2007”: Same as june density but one year later.
“size_t”: size of plants (number of leavesX length of average leaf). You may want to log transform these data prior to analysis. If an NA appears, that means that there is no data for this plant but the plant is still included as a sample because there may be data at size t+1 or flowering. THESE VALUES ARE TOTAL MILLIMETERS (TOTAL LEAFE NUMBER TIMES MILLIMETERS OF AN AVERAGE [=REPRESENTATIVE LENGTH]).
“size_t+1”: size of plants in the next time interval. Size_t versus size_t+1 interval includes plants from 2006-2007 and 2007-2008. If a plant died, then an NA appears in size_t+1. But it is possible that a plant might not have been found at t+1. In this case, an NA is inserted under BOTH size_t+1 and survival_t+1 because we do not know if the plant survived and if so how much did it grow.
“survival_t+1”: survival from time t to t+1 corresponding to each plant. If a plant flowers, they die. In cases where the plant flowered but was apparently alive in t+1, we counted them as dead in t+1. What is likely occurring in these scenarios is another plant (in t+1) was confused for the plant that flowered and died (prior to t+1). Note: plant tags were placed very closed to plants, but because of the high density of thistle in the plots it was sometimes difficult to discern which tags went with which plants.
“Flowering”: 0 = no flowering, 1=flowering. Plants flowered in fall of 2007. This is after the spring census (time 1) and before the next spring census in 2008 (t+1).
“seed production”: We quantified seed production on all flowering plants, if the plant did not flower during the time interval, either because it died or just did not flower, we insert an NA.
“Time intervals”: I indicate the years for the t and t+1 intervals as a reference since I have combined all time intervals together. This will help you if you want to look at year differences.