Effects of thinning and extraction on advance regeneration of Sitka spruce (Dartmoor 2005)
Extensive damage to and mortality of understorey seedlings during overstorey thinning could prevent the use of natural regeneration as a method of restocking. Experiments carried out on three upland conifer sites in Britain assessed the short-term impact of thinning operations on survival and damage to advance regeneration seedlings of different heights. At two sites dominated by Sitka spruce, the number of small-sized (<50 cm) and medium-sized (50 – 200 cm) seedlings lost during harvesting was significantly higher than the number of large seedlings (>200 cm) which tended to be damaged rather than lost. At the Scots pine/Japanese larch site, damage and loss were not related to seedling size. Survival or damage was significantly related to the distance from the nearest extraction rack (striproad). At two of the sites, survival or damage was related to distance to the nearest felled tree stumps. The seedlings in 25 – 30 per cent of the area were lost due to clearing the extraction racks prior to harvesting. In the stand matrix, 40 – 80 per cent of the regeneration survived and was not severely damaged; the remaining regeneration was likely to be suffi cient to restock at all three sites, although distributions were clumped. There were no marked differences between motormanual and harvester felling. See also: Stokes, V., Kerr, G., and Ireland, D. (2009.) Seedling height and the impact of harvesting operations on advance regeneration of conifer species in upland Britain. Forestry. 82 (2): 185-198. (see pdf) Attribution statement: If you use this data you must cite: Stokes, V., Kerr, G., and Ireland, D. (2009.) Seedling height and the impact of harvesting operations on advance regeneration of conifer species in upland Britain. Forestry. 82 (2): 185-198.
dataset
protocol: http
name:
description: Data download
57ebd6a8-08d0-46c6-9253-547c27854df6
eng
http://www.opengis.net/def/crs/EPSG/0/27700
environment
Continuous cover
England
Thinning
environment
science
publication
2010-01-13
research
publication
2010-01-13
damage
publication
2010-01-13
damage assessment
publication
2010-01-13
inventory of forest damage
publication
2010-01-13
-3.893
-3.889
50.638
50.634
2004-09-07
2005-04-11
creation
2005-04-11
revision
2016-01-18
notPlanned
The seedlings on site were assessed before and after harvesting. Where possible the exact same plots were used before and after. Some plots could not be assessed at all. Previously used extraction racks were still apparent. These were designated as permanent racks and cleared with chainsaws prior to harvesting. Where there was no previous rack and access was required, the areas with the lowest regeneration density were used. The spacing between racks was ~ 20 m, although there were some areas where the spacing increased to 30 m. Due to the large tree size, trees were felled with chainsaws using feller selection, i.e. trees were not marked and operators selected trees according to a felling prescription as they worked. Trees were felled towards the racks and then the first one or two timber lengths were cut before processing the remainder of the stem with a CAT-318 excavator base and Logset harvesting head, reducing the need to drag long timber lengths out. The bulk of the top (harvesting residue) was processed in the rack and was used as a brash (slash) mat. The weather had been dry in the preceding weeks but was cold and wet during felling, although not below freezing. The operators were all highly experienced in the harvesting methods used on each site and had many years experience of working in the local site conditions. They were aware that the intention was to utilize the regeneration to restock the site but were not informed that the sites were being used for a harvesting damage study. No special precautions were taken to protect the regeneration in the experiment plots which were marked as discretely as possible. Approximately 70 regeneration assessment plots were laid out across each study area prior to thinning, positioned systematically on a grid. Plots were 2 × 2 m quadrats with the distance between plot centres. Quadrats were aligned north – south and were permanently marked with discrete wooden marker pegs with 5 cm above ground in opposite corners. The distance and bearing from the nearest canopy tree was recorded to aid relocation, and the plot number was painted discretely on the tree. Prior to harvesting, the regeneration in each quadrat was counted by species and it was noted whether they were alive or dead. Seedlings with no green leaf or needle tissues (and for broadleaves, no fresh, healthy buds) were assumed to be dead. For the purposes of this study, all regenerating stems have been termed ‘seedlings ’, recorded on the basis of height as small (<50 cm), medium (50 – 200 cm) or large (>200 cm). Presence or absence of deer browsing damage was also recorded for each seedling. The second assessment took place within 2 months of completion of the thinning. The plots were relocated and number of seedlings by species, height class and whether they were alive or dead was recorded. An assessment of harvesting damage to each seedling was also made using the scale: no damage, low damage (1 - central axis not snapped and likely to recover) and high damage (2 - central axis snapped and unlikely to recover). The number of seedlings lost from each quadrat was calculated by subtracting the number after harvesting from the number before harvesting for each height class. The distance from the centre of each plot to the closest edge of the two nearest extraction racks and to the two nearest recently felled stumps was also recorded. The site is described as: Extensive moorland, Sitka spruce plantation Overstorey: Planted 1922 Sitka spruce, occasional Norway spruce Elevation: 360m above sea level Topography: Gently sloping to the north-west Geological formation: Permian granite Soil: Well drained, humose, gritty, loamy soils. Occasionally with thin iron pan Avery soil classification: 6.12 (podzolic soils: humic brown podzolic soil) Mean annual rainfall: 1622 mm Vegetation: Moss, grasses, Vaccinium, ferns, dense Sitka spruce regeneration
Open format | Comma Separated Values file (CSV)
NA
Contains Forestry Commission information licensed under the Open Government Licence v3.0.
Forest Research must be acknowledged as the source of the data in any subsequent papers/products
Forest Research must be acknowledged as the source of the data in any subsequent papers/products
Forest Research must be acknowledged as the source of the data in any subsequent papers/products
Forestry Commission
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2024-01-17