Invader complexes or generalist interactions? Seasonal effects of a disturbance gradient on plants and floral visitors

AGÜERO, JUAN I.; COULIN, CAROLINA; TORRETTA, JUAN P.; GARIBALDI, LUCAS A.

FOREST ECOLOGY AND MANAGEMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2022 vol. 506

0378-1127

Disturbances can facilitate the spread of exotic plants, which establish mutualisms withexotic bees, constituting invader complexes. However, a disturbance-mediatedincrease in flower resources can also promote native floral visitors due to the fact thatplant-pollinator interactions are generalist. We experimentally tested these ideas innorthern Patagonian woodlands. In three sites, we examined the effect of harvestingintensity (HI) (0%, 30%, 50%, 70% of biomass removal) on flower density (exotic:herbs; native: herbs, shrubs, trees) and floral visitor density (exotic: honey bees,bumblebees; native: bees and wasps, hoverflies, other flies, beetles, ants). For fouryears, we made observations throughout the flowering period to test seasonality. HIhad the most substantial positive effect on native herbs, followed by shrubs, and it wasnull on trees. The effects on the floral density of exotic herbs depended on site. HIenhanced the density of exotic bumblebees, native bees and wasps, and hoverflies;but it had no effect on honey bees, and it showed variable effects on the other floral-visitor groups. Although seasonality was relevant, there was no strong interaction withHI. In general, HI enhanced the density of native and exotic floral visitors, which isbetter explained by generalist interactions rather than by invader complexes.