Habitat heterogeneity enables spatial and temporal coexistence of native and invasive macrophytes in shallow lake landscapes

Macrophyte invasive alien species (IAS) fitness is often hypothesised to be associated with beneficial environmental conditions (environmental matching) or species-poor communities. However, positive correlations between macrophyte IAS abundance and native plant richness can also arise, due habitat heterogeneity (defined here as variation in abiotic biotic over space time). We analysed survey palaeoecological data for macrophytes satellite lakes along the Upper Lough Erne (ULE) system (Northern Ireland, UK), covering a gradient of eutrophication connectivity partition how conditions, diversity explained Elodea canadensis, widely distributed non-native Europe. E. canadensis positively correlated at both within- between-lake scales indicating coexistence time. was more prolific highly connected macrophyte-rich lakes, but sparser eutrophic-isolated ones. Partial boosted regression trees revealed that abundances water clarity (negatively), (positively), cover (negatively) whereas diverse-connected beta (both negatively) related most greatly abundance. Dense unfavourable thus appear confer invasibility resistance sufficient mask any single effect biodiversity matching controlling Therefore, shallow lake landscapes, variously enables reducing often-described homogenisation effects macrophytes.