First observation in the wild:	1885
Invasion stage:	spread
Spatial distribution:	restricted

Reproduction in the wild:	yes
Dispersion potential:	medium
Natural habitats:	high

More on invasiveness: Both in its native and invaded range, Douglas' spirea grows best on loamy and sandy wet soils. It is tolerant to permanently water-logged soils (peat) and widely fluctuating water tables. It occurs mainly in riparian habitats such as swamps, shrub carrs, marshes and bogs. This pioneer species needs full sunlight for optimal growth, flowering and fruiting but may survive under tree canopy. Contrary to other North American Spiraea species, Douglas' spirea may produce fertile seeds under Belgian climatic conditions. They are disseminated at a slow rate by wind in the vicinity of parent shrubs and germinate in areas free of dense plant cover. This shrub has been increasingly observed in the wild in Belgium during the last decade.

Predation / Herbivory:	low
Competition:	high
Disease transmission:	low
Genetic effects:	low

Nutrient cycling:	unknown
Physical alteration:	high
Natural successions:	high
Food web alteration:	low

More on impacts: Douglas' spirea is a fast-growing rhizomatous shrub, propagating clonally. It easily form dense monospecific thickets that can colonise large areas, displace other plant species and dominate communities in wetland areas (probably via allelopathic interactions). It can be invasive in its native range and colonise rapidly clearcut areas. It has been reported to be a serious danger to native plant communities in Belgium. Old dry plant shoots are vulnerable to early ignition and may be the cause of fires.

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