Fixed species sets gave no clear change in ozone and moisture slopes of plant injury in four eastern US samples in 1994-2010

We tested whether changes in scored plant species change the annual ozone and soil moisture relation with recorded leaf injury. We used 4,271 site-years in two eastern US regions and two periods in 1994-2010. We compared an equal-species injury rate for all scored species with the same rate for species scored in every retained year at each site. The four paired product-slope changes were +0.97, +0.36, -2.78 and -0.13 injury percentage points per 10 ppm-h ozone per moisture SD. All four 95 percent intervals included zero. Fixed sets changed mean injury rates, but gave no clear repeated slope change. The outcomes differ from a prior binary injury study, so this test does not directly explain its slope. Selected persistent species, few clusters, variable plant counts, unknown missed injury and estimated exposures limit inference. One smaller sensitivity fit gave a negative variance estimate. Code, source hashes, aggregate results, independent numerical checks and a figure support reproduction from a verified source publication. Source records remain outside this package.

ozone · soil moisture · plant injury · observation bias · species composition · regional replication · null result