Table 6.

Trends for total deposition (WDEP+DDEP, units of kg N ha⁻¹ yr⁻¹ for nitrogen deposition including TNO₃, NH_X and TIN, and kg S ha⁻¹ yr⁻¹ for TSO₄) over the ten ecoregions. The bolded values indicate trends that are statistically significant with the P value less than 0.05 for the Student’s t test.

ID	Regions Name	TNO3	NHX	TIN	TSO4
5	Northern Forests	−0.087	0.016	−0.071	−0.23
6	Northwestern Forested Mountains	−0.013	0.011	−0.002	−0.021
7	Marine West Coast Forest	−0.018	0.002	−0.017	−0.053
8	Eastern Temperate Forests	−0.15	0.034	−0.12	−0.51
9	Great Plains	−0.041	0.044	0.003	−0.082
10	North American Deserts	−0.016	0.008	−0.008	−0.023
11	Mediterranean California	−0.051	0.013	−0.038	−0.013
12	Southern Semi-arid Highlands	−0.014	0.002	−0.012	−0.074
13	Temperate Sierras	−0.016	0.009	−0.006	−0.054
15	Tropical Wet Forests	−0.026	0.041	0.015	−0.055