High rainfall intensities on slopes produce runoff and erosion, but seeds are also carried down slope into streams by surface wash, causing weed infestation in lower parts of a river system. This interdisciplinary study was performed in the Houay Pano catchment (M-TROPICS/MSEC in Laos), farmed by smallholders and equipped with eight gauging stations. Main findings are: most seeds were exported in running water and only 8% was trapped in eroded soil, 96% of seeds were weeds and grassy seeds were preferentially washed out, hill slope processes were the major contributors to seed dispersal, and wetlands and the riparian areas had only a local effect on dispersal.

The paper was published in the Agriculture, Ecosystems & Environment journal. For paper download please click here (50 days’ free access to the article, available until September 06, 2018).