Explanation of experimental design used in the first experimental run.

Contrast Key: (1) Local matching at within-species scale: leaf packs containing leaves from one local vs. non-locally growing red alder tree. (2) High vs. low diversity within species: leaf packs containing 12 leaves from 1 red alder tree vs. 2 leaves from each of 6 red alder trees. (3) High vs. low species diversity: leaf packs containing leaves from either multiple alder or multiple hemlock vs. mixtures of alder/ hemlock. (4) Contrasting multiple alder vs. multiple hemlock mixed individual packs. (5) Contrasting hemlock/alder vs. alder/ vine maple/ bigleaf maple mixed species packs. (6) Local matching at between species scale: leaf packs contain species that match vs. mismatch those growing in the adjacent riparian forest.Numbers in the contrast columns indicate the contrast coefficients (0, 1, -1, etc.), which were assigned to sum to zero. Bolded and italicized fonts indicate the levels within each contrast comparison as described in the contrast key.