Quantifying the ecosystem service of non‐native weed seed predation in traditional terraced paddy fields

Abstract

AbstractWeed seed predation is an important ecosystem service in paddy areas. To conserve and sustainably utilize this service, it is necessary to quantify the seed predation and reveal the relative contributions of seed predators. In this study, we quantified the extent of postdispersal seed predation of Lolium multiflorum Lam., a non‐native invasive grass weed, on levees of terraced paddy fields located in a traditional cultural landscape (satoyama landscape) of Japan. We investigated the temporal variability in seed predation of L. multiflorum during summer after the seed shed, and estimated the total seed loss due to predation on the levees of terraced paddy fields for 2 years. Furthermore, the relative contribution of invertebrates and vertebrates to the seed predation was estimated based on exclosures. The total seed loss due to predation during 4 months (from late June to late October) was consistently high (>99%) in both years (the maximum proportion of seed predation per 2 weeks = 80.0–86.7%). The seed predators were likely to be mainly invertebrates such as crickets and ground beetles. This study revealed that the seed predation intensity was consistently high and can be an important depletion factor for the seedbanks of weeds such as L. multiflorum on the levees of terraced paddy fields. The high intensity of seed predation by invertebrates might suppress the invasion and population expansion of L. multiflorum on the levees of terraced paddy fields.