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Modeling invasive alien plant species in river systems: Interaction with native ecosystem engineers and effects on hydro‐morphodynamic processes
Author(s) -
van Oorschot M.,
Kleinhans M. G.,
Geerling G. W.,
Egger G.,
Leuven R. S. E. W.,
Middelkoop H.
Publication year - 2017
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1002/2017wr020854
Subject(s) - propagule pressure , invasive species , introduced species , riparian zone , propagule , ecology , native plant , vegetation (pathology) , floodplain , ecosystem , colonization , environmental science , ecosystem engineer , competition (biology) , biology , biological dispersal , habitat , medicine , population , demography , pathology , sociology
Invasive alien plant species negatively impact native plant communities by out‐competing species or changing abiotic and biotic conditions in their introduced range. River systems are especially vulnerable to biological invasions, because waterways can function as invasion corridors. Understanding interactions of invasive and native species and their combined effects on river dynamics is essential for developing cost‐effective management strategies. However, numerical models for simulating long‐term effects of these processes are lacking. This paper investigates how an invasive alien plant species affects native riparian vegetation and hydro‐morphodynamics. A morphodynamic model has been coupled to a dynamic vegetation model that predicts establishment, growth and mortality of riparian trees. We introduced an invasive alien species with life‐history traits based on Japanese Knotweed ( Fallopia japonica ), and investigated effects of low‐ and high propagule pressure on invasion speed, native vegetation and hydro‐morphodynamic processes. Results show that high propagule pressure leads to a decline in native species cover due to competition and the creation of unfavorable native colonization sites. With low propagule pressure the invader facilitates native seedling survival by creating favorable hydro‐morphodynamic conditions at colonization sites. With high invader abundance, water levels are raised and sediment transport is reduced during the growing season. In winter, when the above‐ground invader biomass is gone, results are reversed and the floodplain is more prone to erosion. Invasion effects thus depend on seasonal above‐ and below ground dynamic vegetation properties and persistence of the invader, on the characteristics of native species it replaces, and the combined interactions with hydro‐morphodynamics.