Biology Reference
In-Depth Information
Experimental Design
To compare abundance of the study species inside and outside the fenced en-
closures, temporary transects (0.5 × 8 m) were established within and outside
of each fenced area. For each species, the total number of individuals along the
transects were counted. For Rosa and Lathyrus, two transects on either side of the
fence were counted. Phlox was counted in four transects inside the fence and four
outside. Rhus transects were established at fenced areas in 2 different fields. Two
transects on either side of the fences were counted in each field.
To measure the effects of different levels of defoliation, individuals of each
species within the exclosures were randomly selected and tagged. Initial height
and number of leaves were recorded. Ten individuals of each species (except Rosa,
which only had enough for 8 individuals for each treatment level) were randomly
assigned to one of the following treatments: 1) control, no simulated herbivory,
2) 20 % of all leaves removed, 3) 40 % of all leaves removed, 4) 60 % of all
leaves removed, 5) 80 % of all leaves removed, 6) 100 % of all leaves removed,
or 7) meristem + natural leaf removal (called the meristem removal hereafter).
This treatment was designed to simulate deer and rabbit browsing in which the
entire top of a plant is often removed. Meristems, leaves and flower buds were all
removed from the top of the plant and left at the bottom of the plant. The mass
of the leaves removed by the meristem removal was determined and converted to
the percent of the plant's total leaf biomass.
Removed leaves were dried at 55 degrees C for one week and then weighed.
Following the initial damage treatment, the sites were visited twice a week. Flow-
ers were counted on multiple visits. Seeds were collected and dried, and then
weighed to give the total mass of all the seeds collected per individual plant. Mesh
bags were placed over Phlox flowers because seeds are small and fall off when they
ripen. No such bags were needed for Rosa or Rhus, both of which have large
seeds, which are retained on the parent plant.
statistics
All statistical analysis was performed on SPSS 10.0 for Windows. One-way ANO-
VAs were used to determine the effect of the enclosures on the abundance of the
individual species. Type III GLM analysis was used to test for differences between
areas within and outside the enclosure, with abundance as the dependent variable
and species, enclosure, and their interaction as the independent variables.
Total leaf biomass was calculated for each plant since larger plants generally
produce more biomass and larger and/or more seeds than smaller plants. Using
