Ecological Archives E088-026-A2

F. Leland Russell, Svata M. Louda, Tatyana A. Rand, and Steven D. Kachman. 2007. Variation in herbivore-mediated indirect effects of an invasive plant on a native plant. Ecology 88:413–423.

Appendix B. ANCOVA results for effects of Rhinocyllus conicus density in the focal musk thistle patch and distance to the focal patch on R. conicus egg load on wavyleaf thistles. Distance × year is included as a random effect. Wavyleaf thistle size, measured as number of flower heads per plant, is the covariate.

Source
Numerator df
Denominator df
F
P
 
 
 
 
 
R. conicus density
1
33.5
5.08
0.0308
Distance
3
10.5
15.07
0.0004
R. conicus density × distance
3
78
1.24
0.2994
Wavyleaf thistle size
1
1033
12.30
0.0005
Size × R. conicus density
1
1033
0.15
0.6987
Size × Distance
3
1029
2.17
0.0904
Size × R. conicus density × distance
3
1021
0.96
0.4116

 

A posteriori comparisons of least square means among treatment levels for R. conicus density and distance using protected least significant differences.

Source
Treatment level
Treatment level
Estimate
Standard Error
df
t value
P
R. conicus density
High
Low
0.2799
0.1210
33.4
2.31
0.0271
Distance
Far
In
-0.7071
0.1314
13.5
-5.38
0.0001
Distance
Far
Mid
-0.0589
0.1325
13.7
-0.45
0.6632
Distance
Far
Near
-0.2675
0.1331
13.8
-2.01
0.0644
Distance
In
Mid
0.6481
0.1151
8.56
5.63
0.0004
Distance
In
Near
0.4396
0.1156
8.69
3.80
0.0045
Distance
Mid
Near
-0.2085
0.1164
8.84
-1.79
0.1073


[Back to E088-026]