Bryophytes display allelopathic interactions with tree species in native forest ecosystems

Abstract

Bryophytes are widespread in terrestrial ecosystems but little is known about their influence on vascular species. Water‐soluble leachates (0%, 1%, 5%, 10% concentration) derived from 18 species of bryophytes (mosses 11 species; liverworts 7 species) were tested on the germination and seedling growth ofLactuca sativaand two common treesMelicytus ramiflorus(Violaceae) andFuchsia excorticata(Onagraceae) in southern New Zealand forests. Bryophyte water soluble extracts (BWSE) have minor impact on seed germination ofLactuca, stimulatory effects on radical growth at low (1%) concentrations and inhibitory effects at higher concentrations (5–10%). ForMelicytusthe BWSE had variable effects, with evidence of strong stimulatory (Dendrohypopterygium filiculiforme) and inhibitory (Lepidozia concinna) effects on germination, but generally inhibited radical growth. BWSE at all test concentrations consistently inhibit both germination and seedling radicle growth inFuchsia. The toxicity effect of water‐soluble leachates varies significantly between bryophyte species but not consistently between mosses and liverworts. Bryophyte species exhibiting strongest inhibition effects under control conditions were associated with significantly reduced densities of broadleaved tree seedlings in forest ecosystems. Our results demonstrate that some bryophyte species via allelopathic interactions can inhibit seedling establishment and growth of forest trees. This mechanism provides an additional factor constraining the spatial distribution of the regeneration niche in forest communities.