Method
Seed traps are placed on the soil or water surface to estimate the density per unit time of seed arriving on that surface. The traps are sometimes placed vertically or at a slope but there is no benefit in doing this and it does not give a correct estimate of seed rain per unit area of the soil surface. Sticky traps comprise a sticky surface of known area applied to the ground, which traps all seeds that come into contact with it. The sticky substance should be non-drying and not toxic to the seeds if they are to be germinated or tested for viability. There are several permanently sticky petroleum-based substances that can be used, most commonly substances used to trap insect pests (available from horticultural suppliers). These are semi-liquid and can be smeared or aerosol-sprayed onto the trap surface. The surface used can be anything waterproof that can hold the sticky substance, for instance a pane of glass or polythene wrapped around wood or plastic. Sticky cards developed to trap flying insect pests can also be used without modification. To be