Table 3:

Estimated pollen production for trees surveyed in randomly selected and representative plots (the i-Tree Eco census, described in the methods section) and for a street tree database within Ann Arbor, Michigan. Descriptive statistics for tree size and number are provided for each dataset; for the i-Tree Eco total city-wide pollen estimates are calculated by scaling the area surveyed (0.08 km²) to the area of the city (72.08 km²). Total pollen estimates for three species are scaled according to their sex ratio (indicated by “*”; sex ratios are provided in SI 7).

Taxon	Representative plot-based census				Street tree database				Pollen production estimate for a 20 cm DBH tree (in billions)
	Number of trees	Mean DBH (cm)	Pollen/ mean tree (in billions)	Total pollen production in Ann Arbor (in trillions)	Number of trees	Mean DBH (cm)	Pollen/ mean tree (in billions)	Total pollen produced by street trees in Ann Arbor (in trillions)
Acer negundo	63	15.3	5.1	454	127	29.3	17.4	3.1	8.4
Acer platanoides	46	16.1	1.7	83	5,289	34.0	3.5	21.5	2.0
Acer rubrum	41	18.5	2.9	15*	3,053	17.2	2.7	1.2*	3.2
Acer saccharinum	19	52.1	5.7	136	1,818	58.0	6.4	14.7	3.4
Betula papyrifera	4	15.3	15.4	69	17	17.5	18.6	0.4	22.9
Gleditsia triacanthos	11	27.0	34.4	491	3,649	30.5	45.0	210.9	17.5
Juglans nigra	47	19.8	18.6	959	740	48.1	54.6	47.0	18.7
Morus alba	13	8.3	256.8	1,814*	130	26.1	344.5	37.9*	486.0
Platanus × acerifolia	4	32.2	87.8	453	1,886	33.0	92.0	247.3	34.8
Populus deltoides	5	27.1	35.6	88*	206	50.0	47.0	6.6*	33.8
Quercus palustris	3	35.3	46.9	180	177	31.2	39.9	8.7	25.3
Quercus rubra	78	28.9	63.9	5,929	1,264	22.8	53.4	87.6	49.4
Ulmus americana	161	11.6	11.6	1,824	776	24.6	14.4	41.2	13.1
All focal species	495	18.9	-	12,495	19,132	32.3	-	728.1	-
All non-focal species	1,377	15.0	-	-	38,406	20.9	-	-	-
All trees	1,872	16.0	-	-	52,896	25.0	-	-	-