Vegetation Monitoring at Lake Vyrnwy

MONITORING THE VEGETATION RESPONSE TO DITCH BLOCKING AND RELATED RESTORATION ACTIVITIES WITHIN BLANKET BOG IN THE BERWYN AND NORTH CLWYD MOUNTAINS SAC, NE WALES.

The project partners are committed to assessing the vegetation response to the ditch-blocking programme to a high standard acceptable for publication in the peer-reviewed literature. Pre-restoration monitoring is regarded as particularly critical given the comment in the recent review by Holden et al (2006, p. 105) that "it is rare to find any data which have been collected for a sufficient length of time before blocking to justify good scientific interpretation of the full effects of blocking". We would expect that vegetation near blocked grips would become more characteristic of blanket bog in favourable condition, and do so increasingly further away from grips in successive years.

 Experimental design

Monitoring data, replicated at local (1 ha) and wider scales (25 ha), will in most cases, be collected before, during and after grip blocking.  Therefore, the design can be viewed as a before-after control-impact (BACI) experiment, although the sub-catchment level treatments will be applied in different years.  LIFE projects allow monitoring after the funding period, and data in year 7 (2012) will be included out-with this contract as an additional before/after sub-catchment comparison, and provide longer-term responses for sub-catchments managed early in the project.

Within each of the sub-catchments, paired treatment and control will be established for the UK-Pop-Net project. These paired areas would each be 1^st order catchments of comparable size (c. 25 ha) containing varying numbers of grips (mean 6, range 3-9) of an average length of 531m. Treatment areas would have grips blocked in winter 2007/08. Control areas will have grips blocked in the final winter of the project, or possibly be retained beyond the life of the project.

Vegetation monitoring protocols

Vegetation monitoring will take place between 1^st June and 31^st July in years two, three and five of the LIFE project (2007, 2008 & 2010). Vegetation species composition, cover and structure will be measured in 1m² quadrats replicated along transects.  Within each sub-catchment, 20 transects will be placed at grips selected at random. Transects will be perpendicular to each grip, and will extend 22 metres to each side.  In addition, 10 transects will be placed at random in areas within each sub-catchment lacking grips. In total, each sub-catchment will have 30 vegetation transects, the exact locations of which will be determined by the LIFE project. Each transect will be permanently marked at the grip and, at each end and locations recorded with adequate accuracy  (e.g. potentially using differential GPS). 

One metre square quadrats will be surveyed at distances of 1-2, 3-4, 8-9, 15-16 and 21-22 metres from each side of the grip edge (or randomly determined location in areas lacking grips), making 10 quadrats in each transect. Surveyors should (at least initially) use stringed quadrats to record cover values and check against each other to ensure consistency (for example by using fixed-point photography). 

For each quadrat record:

1. if heather is mowed,

2. if dam spoil is present

3. the cover of a) bare ground, b) surface water, c) each plant species including mosses and lichens using the DOMIN scale.

4. peat depth to the nearest 5cms using a marked cane.

5. altitude, aspect and slope (LIFE staff will determine these variables using GIS)

6. presence of grazing damage/ No. of sheep dropping clusters

7. presence/ cover of dead heather

8. GPS location

In the centre of each of the four quarters of the quadrat, use a 1.5m bamboo cane marked off at 5cm intervals and with 1cm thick, white tape at 0, 10, 20, 30 and 40cm from one end to record:

1.      The maximum height at which the quadrat strings are supported by vegetation when the quadrat is rested over the vegetation.

2.      The maximum height to the nearest 5cm class of vegetation within 5cm of the cane, rounding down for intermediate measures (i.e. 0 - 4cm record as 0, 5 - 9cm record as 5 etc).  Record separately the maximum height of dwarf shrubs, graminoid leaves, graminoid inflorescences, Juncus spp (i.e. the three common and taller  J. effusus, J. acutifloris, J. conglomeratus) and bracken. 

3.      Structure: Record whether white marks at 0, 10, 20, 30 and 40cm are obscured by vegetation, when holding the cane vertically, at arms length to the front (i.e. the same 4 positions at which height is measured).

The work will need to be done by two surveyors working together at all times for health and safety reasons.

The 5 sub-catchments will be visited in random order each year.

Some flexibility in timing of visits to some areas may be required due to nesting birds. 

Exact transect locations will be selected by the LIFE project and provided to contractors prior to monitoring starting.

Data recording sheets, and the format of the electronic data files must be agreed with the LIFE Project Manager prior to fieldwork commencing.

A separate contract for data analysis will be established in Year 5 of the LIFE project. The data from the vegetation monitoring will be analysed alongside hydrological and parasite data to tests the predictions of the LIFE project. One possible statistical approach is to have catchment and transect as subjects in a repeated measures generalised linear model, with both year and year since treatment as fixed effects (with the year since treatment column should be blank until grips blocked).