Ecological Archives A021-001-A4

Deborah K. Letourneau, Inge Armbrecht, Beatriz Salguero Rivera, James Montoya Lerma, Elizabeth Jiménez Carmona, Martha Constanza Daza, Selene Escobar, Víctor Galindo, Catalina Gutiérrez, Sebastián Duque López, Jessica López Mejía, Aleyda Maritza Acosta Rangel, Janine Herrera Rangel, Leonardo Rivera, Carlos Arturo Saavedra, Alba Marina Torres, and Aldemar Reyes Trujillo. 2011. Does plant diversity benefit agroecosystems? A synthetic review. Ecological Applications 21:9–21.

Appendix D (TABLE D1). We used mean Hedge's d values for the experiments that coincided (indicated in bold type) with those presented in Table 1 of Poveda et al. (2008): herbivores by species, natural enemies or mortality by natural enemies, and yield, including crop damage. Mean Hedge´s d values from the 45 articles ranged from -9.06 to 2.37, with only two zero values. Because taking various “near-zero” values as zero did not radically change the overall level of agreement with the outcome counts of Poveda et al. (2008) we simply used an absolute zero value as zero as did Halaj and Wise (2001). Whereas Poveda et al. (2008) reported contradictory effects with a question mark because test outcomes were sometimes significantly positive and other times significantly negative, in our analysis, a mean Hedge's d value was calculated for all tests (+, -, o). However, if the values making up the mean were noticeably negative and positive and the mean value close to zero, then we considered our value in agreement with a mixed outcome (designated as “?”). Finally, to arrive at direct estimate of how much of the time our analysis components were in agreement, we summed the proportion of coincident outcomes per study in the articles included in both reviews.

  Counts –
Poveda et al. 2008
Mean of Hedge's d values –
Meta-analysis
Proportion
Article Number Herbivore Enemy Yield Herbivore Enemy Yield in Common
2 -     -2.11     1
4   o     -0.16   0
5   o   0.00     0
6   +     2.63   1
7 -     -1.65      1
8 -,+ -.o - [-0.24][-0.23]     0.5
11 - +   -0.25 0.38   1
12 ? +   -1.86     1
14 ?,+ ?.+   0.32 0.92   1
16 -     -1.57     1
17 -     -2.56     1
18 o ?   -0.02 0.08   0.5
19 ? + o 0.33     1
20 o o   0.17 -0.06   0
21 -,o  +       -1.09 0
22 -,o o o [-10.46][-34.61] -0.07 -0.42 0.5
25 o +.o   0.05 [0.80][0.35]   0.33
26 - -.+ - -0.72     1
27 - ?   0.02 -0.50   0.5
28  ? ?.o   -2.88 0.00   1
29 +  +   -0.18 1.76   0.5
32 +     -12.77     0
33     + -1.49     0
34     + -3.60   3.08 1
36 ?     0.66     1
37  o ?.+.o     [0.27][0.72][13]   0.66
39 - +   -0.49 0.99   1
40    +.o     [26.89][0.52]   0.5
44 -   + -0.44     1
45 +,o o ? [2,16][-2,21] 1.09   0.33
46   +   -1.31     0
48   +     1.53   1
50 -   + -1.20     1
51 -   - -9.06     1
52 - + o -1.28     1
53 - + o -2.78 1.52 -3.48 0.66
54 - + + -4.50 14.95 1.59 1
55 - + - 2.37 0.30   0.5
56 ? ? ? -0.35 0.19 -2.82 1
57 o     -0.40 -0.21   0
58 o     -0.46     0
59 o     -0.47     0
60 - + + -2.46 0.27 -1.99 0.66
61    ?     0.90   1
62 -   - -0.61 -0.05 -0.33 1
62 +   - -0.90     0
            % Agreement 41

LITERATURE CITED

Halaj, J., and D. H. Wise. 2001. Terrestrial trophic cascades: How much do they trickle? American Naturalist 157:262–281.

Poveda, K., M. I. Gomez, and E. Martinez. 2008. Diversification practices: their effect on pest regulation and production. Revista Colombiana De Entomologia 34:131–144.


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