Table 7 Overview about the sampling methods applied by the 21 NFIs
From: Harmonisation of stem volume estimates in European National Forest Inventories
Country—NFI | NFI cycle used (years) | Grid size (km × km) | Stratification | Clustering of plots | Plot design | Small tree sampling | Plot number | |
|---|---|---|---|---|---|---|---|---|
Sample plots | Assessments | |||||||
Austria | 2007–2009 | 3.9 × 3.9 | No | Quadratic cluster with four plots | Angle count sampling and circular plots | 1 per cluster | Stem count, 2 dbh-classes, species groups | 9905 |
Belgium | 1994–2008 | 1.0 × 0.5 | No | Single plots | Concentric circular plots | 4 per plot | Stem count, 2 dbh-classes | 9590 |
Czech Republic | 2011–2015 | 2.0 × 2.0 | No | Duplex clusters and single plots | Concentric circular plots | 2 per plot | Measurement, species, h | 14,521 |
Denmark | 2012–2016 | 2.0 × 2.0 | No | Quadratic cluster with four plots | Concentric circular plots | 1 per plot | Stem count, 2 dbh-classes | 6960 |
Estonia | 2009–2013 | 5.0 × 5.0 | No | Quadratic clusters with eight volume plots | Concentric circular plots | 1 per plot | Stem count, 1 dbh-class | 11,200 |
Finland | 2009–2013 | 3.0 × 3.0 to 20.0 × 20.0 | Yes | Cluster shape and plot number depending on regions | Angle count sampling | 1 per plot | Measurement, species, dbh, h | 53,601 |
France | 2009–2013 | 4.5 × 4.5 to 18.0 × 18.0 | Yes | Single plots | Concentric circular plots | 30% of year 2010 | Stem count and measurement, 2 dbh-classes, species, mean height, height | 33,004 |
Germany | 2001–2002 | 2.0 × 2.0 to 4.0 × 4.0 | Yes | Quadratic cluster with four plots | Angle count sampling | 1 per plot | Stem count, 3 dbh-classes | 57,053 |
Hungary | 2010–2014 | 4.0 × 4.0 | No | Quadratic cluster with four plots | Concentric circular plots | 1 per plot | Stem count, 2 height-classes, species, mean diameter at half mean height | 5355 |
Ireland | 2009–2012 | 2.0 × 2.0 | No | Single plots | Concentric circular plots | 1 per plot | Stem count, species, height, dbh | 1633 |
Latvia | 2009–2013 | 4.0 × 4.0 | No | Quadratic cluster with four plots | Concentric circular plots, rectangular plot | 1 per plot | Stem count, species, mean diameter at half mean height | 8721 |
Lithuania | 2010–2014 | 2.0 × 2.0 to 4.0 × 4.0 | Yes | Quadratic cluster with four plots | Concentric circular plots, rectangular plot | 1 per plot | Stem count, 2 height-classes, mean height, mean dbh | 5259 |
Norway | 2010–2014 | 3.0 × 3.0, 3.0 × 9.0, 9.0 × 9.0 | Yes | Single plots | Circular plots | 4 per plot | Stem count, 2 dbh-classes | 12,662 |
Portugal | 2005–2006 | 2.0 × 2.0 | No | Single plots | Circular plot | 5 per plot | Stem count, 2 dbh-classes, mean height | 5446 |
Romania | 2008–2012 | 2.0 × 2.0 and 4.0 × 4.0 | Yes | Quadratic cluster with four plots | Concentric circular plots | 261 plots | Stem count, species | 21,711 |
Serbia | 2004–2006 | 4.0 × 4.0 | No | Quadratic cluster with four plots | Concentric circular plots | 1 per plot | Stem count, species | 5631 |
Slovakia | 2005–2006 | 4.0 × 4.0 | No | Single plots | Concentric circular plots | 1 per plot | Stem count, 7 dbh-classes, species, mean height | 1419 |
Slovenia | 2012 | 4.0 × 4.0 | No | Single plots | Concentric circular plots | 1 per plot | Measurement, dbh, h | 760 |
Spain | 1997–2007 | 1.0 × 1.0 | Yes | Single plots | Concentric circular plots | 1 per plot | Stem count, 2 dbh-classes, species, frequency classes, mean height | 91,922 |
Sweden | 2011–2015 | 3.0 × 3.0 to 20.0 × 20.0 | Yes | Quadratic or rectangular clusters with 4 to 12 plots | Concentric circular plots | 2 per plot | Stem count, 2 dbh-classes, species, dbh, h, height-classes | 31,602 |
Switzerland | 2009–2013 | 1.4 × 1.4 | No | Single plots | Concentric circular plots | 1 per plot | Stem count, 12 dbh-classes, species | 3695 |