Fig. 1. The Häme and Kainuu study sites (rectangles) and two subareas within them. The regions of Finland. Digital map data: contains data from the National Land Survey of Finland general map 1:4.5 M 06/2015 and municipal division 1:4.5 M 01/2018.
| Table 1. The multi-source national forest inventories (MS-NFI) used, the measurement years of the training data and the mean (x̄) and the standard deviation (sd) of the mean volume maps on intersecting forestry land (FRYL) masks of the MS-NFIs on the two study sites. | |||||||
| MS-NFI | Reference | Häme c | Kainuu d | ||||
| Tr. data years | x̄ | sd | Tr. data years | x̄ | sd | ||
| m3 ha–1 | m3 ha–1 | m3 ha–1 | m3 ha–1 | ||||
| MS-NFI-8 | (Tomppo et al. 1998) | 1994 | 144.3 | 77.7 | 1990, 1992 | 56.5 | 55.6 |
| MS-NFI-9 | (Tomppo et al. 2008) | 1996–1999 | 147.0 | 78.7 | 1996, 2000–2002 | 67.0 | 55.8 |
| MS-NFI-2002 | (Mäkisara et al. 2001) | 1996–1999 a | 148.2 | 82.9 | |||
| MS-NFI-2005 | (Tomppo et al. 2009) | 1996–1999 a, 2004–2005 a | 151.7 | 80.5 | 1996 a, 2000–2002 a, 2004–2005 a | 74.4 | 54.1 |
| MS-NFI-2007 | (Tomppo et al. 2012) | 2005–2008 | 141.6 | 81.6 | 2005–2008 | 73.9 | 56.5 |
| MS-NFI-2009 | (Tomppo et al. 2013) | 2006–2010 b | 151.2 | 83.5 | 2006–2010 b | 76.2 | 54.6 |
| MS-NFI-2011 | (Tomppo et al. 2013) | 2007–2011 b | 157.5 | 84.1 | 2007–2011 b | 84.3 | 60.0 |
| MS-NFI-2013 | (Mäkisara et al. 2016) | 2009–2013 b | 163.6 | 85.3 | 2009–2013 b | 86.6 | 59.8 |
| MS-NFI-2015 | (Mäkisara et al. 2019) | 2012–2016 b | 161.7 | 96.3 | 2012–2016 b | 86.1 | 60.2 |
| MS-NFI-2017 | (Forest resource maps and municipal statistics 2020) | 2013–2017 b | 162.1 | 97.0 | 2013–2017 b | 88.8 | 66.0 |
| a Field plots computationally updated to the date of the satellite image data. b Field plots computationally updated to 31 July of the MS-NFI year. c The area of the intersecting FRYL masks was 1 394 908 ha. d The area of the intersecting FRYL masks was 2 541 772 ha. | |||||||
| Table 2. The proportion of units with a significant (p < 0.05) trend from the contextual Mann-Kendall test statistic and the proportion of positive S statistic in the case of significant trend. MS-NFI time series 1994–2017 (n = 10) of thematic maps at the Häme study site and 1992–2017 (n = 9) at the Kainuu study site. The mean volume, mean volumes of pine and spruce, proportion of broadleaved tree species of the mean volume and the stand age are listed variables for both sites. | |||||
| Site | Variable | 16 × 16 m2 a | 240 × 240 m2 | 1200 × 1200 m2 | 12 000 × 12 000 m2 |
| p % (of which S positive %) | |||||
| Häme | Volume (m3 ha–1) | 30.8 (81) | 51.4 (97) | 46.3 (98) | 76.1 (100) |
| pine (m3 ha–1) | 31.1 (86) | 32.5 (96) | 50.0 (100) | ||
| spruce (m3 ha–1) | 29.9 (83) | 26.3 (63) | 37.7 (44) | ||
| Prop. of broadl. spp. % | 32.0 (68) | 49.4 (95) | 79.0 (100) | ||
| Stand age (y) | 24.4 (47) | 36.2 (5) | 65.2 (0) | ||
| Kainuu | Volume (m3 ha–1) | 36.7 (92) | 66.0 (99) | 82.0 (100) | 99.5 (100) |
| pine (m3 ha–1) | 62.0 (98) | 76.5 (100) | 98.1 (100) | ||
| spruce (m3 ha–1) | 32.2 (94) | 27.7 (99) | 38.3 (100) | ||
| Prop. of broadl. spp. % | 13.7 (13) | 11.0 (11) | 4.9 (0) | ||
| Stand age (y) | 29.7 (90) | 19.7 (89) | 9.7 (100) | ||
| a Results cover a subarea of the study site (Fig. 1). | |||||
| Table 3. The proportion of units with significant trend, given multiple testing corrected p-values (pmulti < 0.05), from the Contextual Mann-Kendall test statistic and the proportion of positive S statistic in the case of significant trend. MS-NFI time series 1994–2017 (n = 10) of thematic maps at the Häme study site and time series 1992–2017 (n = 9) at the Kainuu study site. The mean volume, mean volumes of pine and spruce, the proportion of broadleaved tree species of the mean volume and the stand age are listed variables for both sites. | |||||
| Site | Variable | 16 × 16 m2 a | 240 × 240 m2 | 1200 × 1200 m2 | 12 000 × 12 000 m2 |
| pmulti % (of which S positive %) | |||||
| Häme | Volume (m3 ha–1) | 0 | 39.8 (98) | 26.2 (99) | 72.5 (100) |
| pine (m3 ha–1) | 0 | 0 | 37.0 (100) | ||
| spruce (m3 ha–1) | 0 | 0 | 10.1 (36) | ||
| Prop. of broadl. spp. % | 0 | 33.3 (99) | 75.4 (100) | ||
| Stand age (y) | 0 | 0 | 49.3 (0) | ||
| Kainuu | Volume (m3 ha–1) | 0 | 59.6 (99) | 79.6 (100) | 99.5 (100) |
| pine (m3 ha–1) | 54.0 (99) | 72.0 (100) | 98.1 (100) | ||
| spruce (m3 ha–1) | 0 | 0 | 6.8 (100) | ||
| Prop. of broadl. spp. % | 0 | 0 | 0 | ||
| Stand age (y) | 0 | 0 | 0 | ||
| a Results cover a subarea of the study site (Fig. 1). | |||||
Fig. 2. A random sample of 10 units from a subset of units with significant trend (pmulti < 0.05) from the contextual Mann-Kendall test applied to time series of multi-source NFI mean volume thematic maps at the Häme study site dated 1994–2017. 240 × 240 m2 units and positive S statistic (a), 240 × 240 m2 units and negative S statistic (b), 1200 × 1200 m2 units and positive S statistic (c), 1200 × 1200 m2 units and negative S statistic (d), 12 000 × 12 000 m2 units and positive S statistic (e), mean volume of spruce, 12 000 × 12 000 m2 units and negative S statistic, 9 units (f).
Fig. 3. Contextual Mann-Kendall test to ten multi-source national forest inventory (MS-NFI) mean volume thematic maps, dated 1994–2017, for a subset of Häme test area. The Z statistic for 16 × 16 m2 units (a), 240 × 240 m2 units (b), and 1200 × 1200 m2 units (c). Threshold classification of regeneration cutting areas is shown using the difference between mean volume estimates of growing stock in MS-NFI-8 and MS-NFI-2017 in grey.
Fig. 4. Contextual Mann-Kendall (CMK) test to ten multi-source national forest inventory (MS-NFI) mean volume thematic maps 1994–2017 at the Häme study site. 1200 × 1200 m2 units and the Z statistic (a), areas with significant trend (pmulti < 0.05) (b), 12 000 × 12 000 m2 units and the Z statistic (c), pmulti < 0.05 (d). CMK test to 9 MS-NFI mean volume thematic maps 1992–2017 at the Kainuu study site. 1200 m units and the Z statistic and a subarea marked (e), pmulti < 0.05 (f). Digital map data: contains data from the National Land Survey of Finland municipal division 1:4.5 M 01/2018. View larger in new window/tab.