Rainwater, snow and throughfall collectors

Both the bulk precipitation and throughfall is measured continuously and stemflow manually from 12 trees. Bulk precipitation is measured with two cylindrical tipping bucket collectors installed at the top of the measurement tower above the canopy. Bulk deposition for chemical analysis are collected with two separate collectors made of polyethylene funnels (0.13 m² in area; Plastex Oy, Lohja, Finland) located also in the tower. In the winter, snow fall is collected into circular canisters (0.2 m² in area). The canisters is changed monthly in winter and bi-weekly in summer, or whenever they are getting full. No antimicrobial substances are used in the canisters. There is one throughfall collector at the vicinity of each pit. The collector consists of two V-shaped (60 ° angle), two meter long, 10 cm wide and 10 cm deep stainless steel gutter with the total surface area of 0.4 m². The throughfall runs to a tipping bucket counter and is collected in plastic containers the weight of which is determined after each rain episode and samples for chemical analyses are taken from this container. Stemflow collectors consist of silicon tubing cut in half and attached in a watertight manner around the stem. The water runs into collectors that are weighted and samples for chemical analysis are taken from the collected stemflow.