Ecological Archives E094-263-A1
Bert Hidding, Jean-Pierre Tremblay, Steeve D. Côté. 2013. A large herbivore triggers alternative successional trajectories in the boreal forest. Ecology 94:2852–2860. http://dx.doi.org/10.1890/12-2015.1
Appendix A. Statistical tables of the effects of immediate and delayed deer exclusion on woody regeneration on Anticosti Island, Quebec, Canada.
Table A1. Response of the tree community to the immediate and delayed exclusion of white-tailed deer on Anticosti Island on stem density (dbh > 1 cm) of all species and of Picea glauca in 2010. Models were fit assuming a Poisson distribution using the lme4 library in R. To correct for overdispersion, an observation level random effect was included. Likelihood ratio tests (LRT) compared models including the variable in question and models without them. A post hoc analysis was performed by merging two factor levels of treatment and contrasting it to the remaining factor, again using LRTs. Post hoc tests are designated by the codes of the only remaining factor level. LogLik denotes the log-likelihood. EXC = original exclosures, CTL = control plots, DEL = delayed exclosures. Significant p values indicated in bold font.
All species |
df |
logLik |
χ2 |
p |
Full model |
8 |
-41.5 |
|
|
Treatment × Distance |
6(2) |
-41.97 |
0.9 |
0.627 |
Treatment |
4(2) |
-52.2 |
20.5 |
<0.001 |
Distance |
5(1) |
-42.28 |
0.6 |
0.427 |
EXC = DEL |
4(1) |
-46.22 |
7.9 |
0.005 |
DEL = CTL |
4(1) |
-44.96 |
5.4 |
0.021 |
EXC = CTL |
4(1) |
-52.31 |
20.0 |
<0.001 |
|
|
|
|
|
Picea glauca |
df |
logLik |
χ2 |
p |
Full model |
8 |
-41.21 |
|
|
Treatment × Distance |
6(2) |
-41.44 |
0.4 |
0.801 |
Treatment |
4(2) |
-46.91 |
10.9 |
0.004 |
Distance |
5(1) |
-43.11 |
3.3 |
0.068 |
EXC = DEL |
4(1) |
-48.11 |
10.0 |
0.002 |
DEL = CTL |
4(1) |
-44.38 |
2.6 |
0.111 |
EXC = CTL |
4(1) |
-44.75 |
3.3 |
0.07 |
Table A2. Analysis of deviance on early and delayed exclusion effects on sapling and seedling densities and mean stem height of tree species over time since herbivore exclusion. Sapling and seedling densities were count variables and were modeled with a Poisson distribution, with forest edge distance as a covariate in lme4 in R. Mean stem height was modeled on transformed data (4√, log- and 2√ respectively) using a heterogeneous error structure in nlme in R. Likelihood ratio tests (LRT) compared models including the variable in question and models without them. Degrees of freedom used in the LRTs are indicated within brackets. Post hoc analyses were performed by merging two treatment factor levels followed by LRTs. EXC = original exclosures, CTL = control plots, DEL = delayed exclosures. Significant p values indicated in bold font.
|
Stem density tall regeneration |
|
Seedling density |
|
Stem height |
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|
|
|
|
|
|
|
|
|
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|
|
|
|
|
Picea glauca |
df |
logLik |
χ2 |
p |
|
df |
logLik |
χ2 |
p |
|
df |
logLik |
χ2 |
p |
Full model |
9 |
-187.93 |
|
|
|
9 |
-157.18 |
|
|
|
11 |
101.53 |
|
|
distance |
8(1) |
-188.29 |
0.7 |
0.391 |
|
8(1) |
-157.75 |
1.1 |
0.285 |
|
|
|
|
|
Treat. × Time |
7(2) |
-192.31 |
8.8 |
0.012 |
|
7(2) |
-161.46 |
8.6 |
0.014 |
|
9(2) |
98.42 |
6.22 |
0.045 |
Treatment |
5(2) |
-197.01 |
9.4 |
0.009 |
|
5(2) |
-170.01 |
17.1 |
<0.001 |
|
7(2) |
64.71 |
67.41 |
<0.001 |
Time |
6(1) |
-199.81 |
15.0 |
<0.001 |
|
6(1) |
-192.43 |
61.9 |
<0.001 |
|
8(1) |
43.36 |
110.12 |
<0.001 |
EXC = DEL |
7(2) |
-196.88 |
17.9 |
<0.001 |
|
7(2) |
-169.4 |
24.4 |
<0.001 |
|
9(2) |
66.72 |
69.61 |
<0.001 |
DEL = CTL |
7(2) |
-191.67 |
7.5 |
0.024 |
|
7(2) |
-166.27 |
18.2 |
<0.001 |
|
9(2) |
72.92 |
57.21 |
<0.001 |
EXC = CTL |
7(2) |
-190.32 |
4.8 |
0.092 |
|
7(2) |
-158.65 |
2.9 |
0.23 |
|
9(2) |
98.28 |
6.49 |
0.039 |
|
|
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|
A. balsamea |
df |
logLik |
χ2 |
p |
|
df |
logLik |
χ2 |
p |
|
df |
logLik |
χ2 |
p |
Full model |
9 |
-101.4 |
|
|
|
9 |
-202.53 |
|
|
|
11 |
-105.84 |
|
|
distance |
8(1) |
-102.32 |
1.9 |
0.173 |
|
8(1) |
-202.55 |
0.0 |
0.848 |
|
|
|
|
|
Treat. × Time |
7(2) |
-113.26 |
23.7 |
<0.001 |
|
7(2) |
-208.42 |
11.8 |
0.003 |
|
9(2) |
-112.38 |
13.1 |
0.001 |
Treatment |
5(2) |
-124.82 |
23.1 |
<0.001 |
|
5(2) |
-224.07 |
31.3 |
<0.001 |
|
7(2) |
-117.98 |
11.2 |
0.004 |
Time |
6(1) |
-136.12 |
45.7 |
<0.001 |
|
6(1) |
-237.47 |
58.1 |
<0.001 |
|
8(1) |
-148.13 |
71.5 |
<0.001 |
EXC = DEL |
7(2) |
-108.99 |
15.2 |
<0.001 |
|
7(2) |
-220.16 |
35.3 |
<0.001 |
|
9(2) |
-105.86 |
0.1 |
0.976 |
DEL = CTL |
7(2) |
-108.84 |
14.9 |
<0.001 |
|
7(2) |
-210.16 |
15.3 |
<0.001 |
|
9(2) |
-114.46 |
17.2 |
<0.001 |
EXC = CTL |
7(2) |
-124.6 |
46.4 |
<0.001 |
|
7(2) |
-213.5 |
21.9 |
<0.001 |
|
9(2) |
-117.58 |
23.5 |
<0.001 |
|
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|
|
|
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|
|
|
B. papyrifera |
df |
logLik |
χ2 |
p |
|
df |
logLik |
χ2 |
p |
|
df |
logLik |
χ2 |
p |
Full model |
9 |
-106.78 |
|
|
|
9 |
-160.7 |
|
|
|
11 |
23.98 |
|
|
distance |
8(1) |
-108.1 |
2.63 |
0.105 |
|
8(1) |
-163.73 |
6.06 |
0.014 |
|
|
|
|
|
Treat. × Time |
7(2) |
-107.02 |
0.47 |
0.791 |
|
7(2) |
-164.03 |
6.66 |
0.036 |
|
9(2) |
-5.54 |
59.05 |
<0.001 |
Treatment |
5(2) |
-135.94 |
57.85 |
<0.001 |
|
5(2) |
-165.8 |
3.55 |
0.169 |
|
7(2) |
-24.04 |
37 |
<0.001 |
Time |
6(1) |
-128 |
41.96 |
<0.001 |
|
6(1) |
-165.52 |
2.98 |
0.084 |
|
8(1) |
-12.52 |
13.95 |
<0.001 |
EXC = DEL |
7(2) |
-107.66 |
1.75 |
0.418 |
|
7(2) |
-162.66 |
3.93 |
0.14 |
|
9(2) |
15.54 |
16.89 |
<0.001 |
DEL = CTL |
7(2) |
-126.59 |
39.61 |
<0.001 |
|
7(2) |
-163.58 |
5.76 |
0.056 |
|
9(2) |
1.41 |
45.15 |
<0.001 |
EXC = CTL |
7(2) |
-134.21 |
54.86 |
<0.001 |
|
7(2) |
-163.74 |
6.08 |
0.048 |
|
9(2) |
-15.11 |
78.19 |
<0.001 |