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. 2019 Aug 19;116(36):17867–17873. doi: 10.1073/pnas.1819027116

Table 3.

Across all datasets, temporal plant community responses (lnRR richness and composition differences) to global change treatments do not vary by treatment type among single-resource or nonresource manipulations (richness: χ2 = 12.47, degrees of freedom [df] = 11, P = 0.330; composition: χ2 = 9.42, df = 11, P = 0.583), but do vary by treatment category among multifactorial manipulations (richness: χ2 = 21.85, df = 6, P = 0.001; composition: χ2 = 15.78, df = 6, P = 0.015)

Treatment type/category Total possible responses No. of richness responses Proportion significant richness responses No. of composition responses Proportion significant composition responses
Treatment type
 CO2 9 1 0.11 3 0.33
 Drought 23 1 0.04 8 0.35
 Irrigation 28 4 0.14 7 0.25
 Precipitation variability 10 1 0.10 1 0.10
 N 69 15 0.22 24 0.35
 Phosphorus 20 6 0.30 4 0.20
 Other resource 4 0 0.00 0 0.00
 Temperature 16 1 0.06 3 0.19
 Mowing/clipping 16 1 0.06 2 0.13
 Herbivore removal 8 0 0.00 1 0.13
 Plant manipulation 11 1 0.09 1 0.09
 Other nonresource 6 3 0.50 4 0.67
Treatment category
 Single resource 163 28 0.17* 47 0.29*
 Single nonresource 57 6 0.11* 11 0.19*
 Resource × resource 46 12 0.26* 24 0.52
 Nonresource × nonresource 13 2 0.15* 3 0.23*
 Resource × nonresource 70 12 0.17* 21 0.30*
 3+ Resources 41 23 0.56 26 0.63
 No. + resource and nonresource 48 17 0.35 24 0.50
Overall 438 100 0.23 156 0.36

Numbers and proportions are of each treatment type/category that showed a significant temporal response to experimental global change manipulations. Across only long-term (≥10-y) datasets, temporal plant community responses to global change treatments do not vary by treatment type among single-resource or nonresource manipulations (richness: χ2 = 3.36, df = 10, P = 0.972; composition: χ2 = 4.21, df = 10, P = 0.938) or treatment category among multifactorial manipulations (richness: χ2 = 3.01, df = 6, P = 0.808; composition: χ2 = 1.39, df = 6, P = 0.967). Exclusion of treatment types or categories with fewer than 3 replicates did not qualitatively affect the results.

*

Significant differences in the proportion of richness or composition responses compared to results marked by or at P < 0.05 as determined by Fisher’s exact test.

Significant differences in the proportion of richness or composition responses compared to results marked by * or at P < 0.05 as determined by Fisher’s exact test.

Significant differences in the proportion of richness or composition responses compared to results marked by * or at P < 0.05 as determined by Fisher’s exact test.