Tyfiant Coed Growth Series Research Plots
Click on the plot below to view stand informationClocaenog Forest:
Gwydyr Forest:
Coed y Brennin Forest:
CYB 4
CYB 5
CYB 7
Tyfiant Coed in North Wales
The Tyfiant Coed project is funded by the EAGGF scheme of the Welsh European Funding Office.
In order to gather data for the Tyfiant Coed growth model a network of permanent sample plots is being established. Initially these plots have been concentrated in North Wales close to the University of Wales, Bangor but eventually will extend to Mid and South Wales. So far plots have been established in three forests, Clocaenog, Gwydyr and Coed y Brenin. An additional plot has been established in Artist's Wood in Gwydyr Forest though this does not form part of the core modelling programme. Also several temporary plots have been and will be established to better define relationships to site conditions.
Growth series data
Growth series (or unreal time series) are based on the idea that long assessment periods of a particular stand can be shortened by assessing several stands of similar characteristics but different age, which are usually located in close proximity to each other in order to guarantee uniform site conditions. Because of the generally large clear fell size and the variable site conditions this concept proved rather difficult to apply in North Wales. Nevertheless, most of the experimental plots established by Tyfiant Coed are based on this concept. Figure 1 shows the location of the plots established before and during the first phase of Tyfiant Coed.
Figure 1; Location of growth series plots established by Tyfiant Coed
These plots serve the dual purposes of data collection and demonstration of CCF practice. The stands at CYB 1/2/3 consist of a mixture of Sitka spruce and birch at different ages and are thus closest to the original growth series concept. CLG 1/2/3/4 represent pure Sitka spruce stands at mature age, where the focus lies on testing different silvicultural approaches to natural regeneration. The stands at CLG 6 and GWY 1 can roughly be characterised by mixed conifer/broadleaved understorey under mixed conifer canopy, and ATW 1 represents the rare feature of a single tree selection system with Douglas fir.
Figure 2; Experiment design at Clocaenog growth series plots
Figure 2 shows the design of the thinning experiment at Clocaenog Forest. The whole subcompartment due for thinning was divided into 5 blocks, containing one experimental plot each (except block 5, where no plot has been established yet). Blocks and plots were thinned as follows:
• Block 1: Uniform shelterwood following the FC standard procedure. CLG 1 including a 50 m buffer zone was excluded from this and kept unthinned as a control area.
• Block 2: Uniform shelterwood with focus on releasing groups of advanced regeneration.
• Block 3: Group strip shelterwood, combining concentric coupes around groups of advanced regeneration with a strip shelterwood coupe at the North-Eastern edge of the stand.
• Block 4: Uniform shelterwood with focus on retaining the stability of the overstorey.
• Block 5: Uniform shelterwood with focus on retaining the stability of the overstorey and an option for underplanting.
This intensive type of field work is very expensive and time consuming. Therefore the installation of the growth series present a serious investment in continuous cover forestry and research in mixed forest stands which only pays off if they are maintained as long-term research plots with regular re-measurements.
<<<< Detailed quantitative
descriptions of all plots are given on separate plot pages listed in side
collumn.
Temporary plots
The site dependent aspect of growth modelling requires, by its nature, the sampling of a range of sites much wider than can be covered with the time-consuming establishment of permanent plots. Therefore temporary plots were established for the collection of specific data needed for site dependent growth modelling. The layout of these plots focuses on sampling individual trees but also includes a basic stand survey. A detailed description of the methods used is given in chapter 4.5 of the Tyfiant Coed phase one final report, which can be found in the Publications section of the website. Figure 3 shows the location of temporary plots established during the first phase of Tyfiant Coed.
Figure 3; Location of temporary plots established by Tyfiant Coed
The plots GWY 3/4 were established on FC land, whereas the forests including GFS 1 and BAD 1/2, respectively, are in private ownership. Table 4 gives an overview over the main stand and site characteristics.
Table 4; Characterisation of Sitka spruce temporary plots
