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.