Division II.3 Frequency of sampling

Litterfall shall be collected at least monthly and even bi-weekly in periods of heavy litterfall. The samples may be pooled to periodic samples for chemical analyses. In regions with snow and frost in wintertime and in remote areas it may be necessary to let the traps stay over winter in the forest. Litterfall may then be collected once before the winter period and once after snowmelt, as frost limits drainage and litter decomposition.