Fig. 2: Histogram of annual GPP trends for 1991–2020 at four grid cells.

Grid cells correspond to the location of core terrestrial sites for four domains in the National Ecological Observatory Network (NEON). See Fig. 1 for the location of the sites. Panels show a D01: Northeast, b D19: Taiga, c D02: Mid-Atlantic, and d D09: Northern Plains sites. The left axis is the frequency distribution for the n = 50 ensemble members, and the black line is the cumulative distribution (right axis). Yellow shading shows members with a statistically significant trend (n = 30 years; p ≤ 0.05), and light blue shading shows non-significant trends. The mean ± standard deviation and the percentage of members with a non-significant (n.s.) trend are provided in the upper left of each panel. Also shown is the 95% confidence interval (red circles) obtained as the range of trends (n = 48) after excluding the smallest and largest trends.