The first Swiss national forest inventory (NFI) was conducted as a systematic survey on a 1x1 km grid, and since the aim from the start was to establish a permanent inventory system, all 10675 accessible plots were  permanently marked. Aerial photography was used in the first Swiss NFI for the estimation of forest area.
The 2nd NFI will be a combined inventory, using terrestrial assessments as well as aerial photographs. Two-phase sampling for stratification will be integrated into sampling with partial replacement (SPR).
The emphasis of this paper is on the statistical design and the estimation procedures. The data flow and the  integration of the photo interpretation data into data-base system and the analysis software will be presented.