Kinver Edge Summer Woodland Survey

Introduction

Despite it being “that wet Thursday” which will be known as the storm of 2012 in years to come, volunteers on the summer working holiday at Kinver Edge took a day to survey selected parts of the woodland. The data contributes towards the point centred quarter technique which can be used to give densities of trees, and conversely the average area occupied by an individual tree.

Whilst measuring distances of trees from randomly selected points, volunteers also recorded the species and the DBH (diameter at breast height): allowing analysis of what trees make up the sample areas, and also – based on relative size – the age distribution.

The resulting numbers can be input to produce a series of graphs and charts which then need further interpretation.

Flaws

There are a number of flaws which must be considered, for both the recording and interpretation.

• Tree identification skills: misidentification of trees will affect the results of species based analysis.
• Randomness of sample points: although points were selected at random, samplers may choose to avoid the tallest dampest vegetation on a particularly miserable day, and instead select a more favourable location. 
• Size: although it may be possible to record the more obvious new growth and saplings, it is highly probable that many of the youngest trees are overlooked. They could be low enough to be hidden by vegetation, or appear as field layer annuals.

Sample areas

Two areas were chosen based on a subjective view of the differences in species composition, and geographically distant. Effectively, these were a representation of the north and south landscapes. In each area, four sample plots were recorded: the northern area plots were bound by paths, allowing results to be tied to measurably sized plots; the southern section was not, and was truly plotless.

For an idea of how representative the sample areas are in relation to the overall size, using the National Trust’s GIS mapping system, the wooded area of Kinver Edge is around 91 hectares. The total sample plot size of the northern sample plots is around 1.7ha; so around 1.9%

Individual plot analysis

The following are a few of the more interesting results:

i)                    Oak plantation.

Plot number 5 in the south of the site has been managed for several years with the intention of producing a crop of oak in the future. The species composition may only appear 36% oak, but the distribution of DBH shows that the majority of the remaining 64% are less than 5cm. Evidence on the ground shows this to be coppice re-growth, including re-growth of oak. The larger oaks in the 50-54.9cm and 85-89.9cm range are likely to be a known line of historic oaks close to the sample area, which do not reflect the nature of the plot.

ii)                  Oak dominant.

Sample 2 lies in the northern section of the site. The plot is dominated by oak, with rowan forming the second most recorded species. Using the data for DBH analysis, shows oak and rowan forming the understorey to an oak dominated canopy.

Large plot results.

Compiling the eight sets of data into two sets based on northern and southern areas increases the overall sample area date size:

i)                    Northern sector.

Based upon 168 records.

Species contribution:

So oak is dominant, which is not necessarily a surprise. Maybe rowan being the next most common species is more of a surprise. It is known from evidence on the ground that aspen is present in the north of the site and due to the suckering nature of the tree has come to dominate a particular area: yet it isn’t recorded here. We could consider it’s presence as localised, whilst what was recorded is a more general picture.

DBH distribution:

Plotting the results of just the three main species (oak 44%; rowan 14%; birch 13%), so as to avoid the graph becoming too messy.

Tree density:

Based on the 168 records, it is calculated that there are 637 trees per hectare, each tree occupying a space of 15.7 square metres.

ii)                    Southern sector.

Species contribution:

So again, oak is the dominant species with birch and rowan forming the secondary species. These results are based on amended data as there is some question about whether the species have been identified correctly in the field. As such, half the species composition data is made up of sample plot 5, which is being managed for oak timber production as discussed above.

DBH distribution:

Again just plotting the three main species (oak 48%; birch 17%; rowan 13%). This shows a large amount of young growth, but in many ways is skewed by sample plot 5 – the oak plantation.

Tree density:

Although the details of species and DBH has had to be amended owing to suspected recorder error, the tree density results are still valid. So based upon 156 records it is calculated that there are 343 trees per hectare, each tree occupying a space of 29.1 square metres.

Conclusions

Historic map evidence shows that Kinver Edge’s northern portion was population by trees before the southern portion. Tree density analysis, and DBH distribution does support this to some degree on the ground. Graphs could be interpreted as showing the southern samples are still recruiting a larger number of young trees than in the north, although coppice re-growth in the plantation will affect the results.

 

The relatively localised sampling method for a comparatively large area is inadequate, and the raw data does show a few repeating measurements as the same tree is recorded. As with the example of the localised aspen dominated area, known blocks of homogenous DBH birch and large samples of sycamore on steeper slopes are not reflected in the final results. Returning to record these will be useful evidence for future management planning.  

Thanks

Thanks has to go out to the working holiday volunteers who managed to pick up the survey technique and tree identification in less than an hour, and undertook the work in horrendous weather conditions.

Access all areas......on-going

Volunteers at the foot of Nags Hill, St Kenelm's Pass, half
way through removing an old stile.

Over the next year, volunteers at the Clent Hills will be working to replace what few stiles there are across the site with more accessible kissing gates. Although this can be a costly exercise, improving access for visitors is central to the National Trust’s strategy, locally and nationally – whether that’s through physically improving these entry points, upgrading signage, or reviewing our downloadable walks.



The new kissing gate completed.



Downloadable PDF files, are available from: http://www.nationaltrust.org.uk/clent-hills/things-to-see-and-do/

These are good introductions for two walks and one horse ride at the Clent Hills; and we’re pleased to be working with local cyclists to develop an entry level cycle ride for the Clent Hills which will be available for free from the National Trust website.

New Pool Fencing on the Clent Hills



The area prior to fencing.



As part of a scheme to give aquatic and marginal vegetation a chance to grow over the next few years, a block of temporary fencing has been erected at New Pool.

We're aware that the pool is popular with both dogs and horses, but it also has some biological interest. During the installation of the fence, we undertook some sampling for aquatic animals; so we can monitor how vegetation recovery benefits the overall diversity of the habitat. 

Slingpool Spring.

Marsh Marigold - a large Buttercup, of sorts.

Prior to the recent rain and winds at the end of April, it was possible to walk out onto the "reedbed" that is Slingpool Dam, and still have dry feet in even the most inappropriate footwear – i.e. canvas trainers. Things are a little wetter at the moment, and a healthy squish emanates from underfoot in certain places.

The Wild Garlic, or Ramsons Allium ursinum, can be spotted beneath the Common Alder Alnus glutinosa upstream, and the Marsh Marigold, also known as Kingcup Caltha palustris has popped up in few places among the young Common Reed Phragmites australis, and the Himalayan Balsam Impatiens glandulifera.

Skunk Cabbage at Slingpool, among young Common
Reed, Nettles, and young Himalayan Balsam

The domination of this final species has already been covered elsewhere in this blog, but a recently discovered invader to Slingpool is the Western Skunk Cabbage Lysichiton americanus from North America. With less than six individuals found at the site, digging them up now should prevent us having problems in the future.

Clent Hill's Wet Flushes

Over the winter period, volunteers and students from Bournville College have been undertaking woodland management operations in selected areas to improve opportunities for wildflowers. Across Clent, Adam’s, and Walton Hills, seasonal flushes emerge in a number of small valleys, varying soil moisture levels, creating a series of niche habitats and in some cases, mini streams of flowing water.

Opposite Leaved Golden Saxifrage

Historically, grazing on the hills is likely to have decreased the opportunities for these areas to develop as willow and birch woodlands; and livestock trampling would’ve created an amount of mud where fresh seeds could germinate. Today, we need to physically intervene in order that wildflowers have an opportunity to flourish. Cuckoo Flower or Ladies Smock, Opposite Leaved Golden Saxifrage, along with species of sedge and fern will all benefit from the temporary reduction of tree cover: the presence of nectar being an additional resource for invertebrates.

Where possible, timber resulting from the operations will be sold as firewood to raise funds to support the work on the Hills.

These areas now will be left to re-grow and provide future nesting habitat for birds. In the meantime, we will identify adjacent areas where wildflowers are suffering from shading and schedule further work. Thereby managing a diverse range of habitats within a confined area to maximise opportunities for a range of wildlife.

Another Lost Boundary at Kinver Edge

As part of routine maintenance, BT dispatched a company of tree surgeons recently to remove obstructions around and between two telegraph poles on Kingsford Lane.

After a few phone calls, and a meeting on-site, we agreed the best course of action was to remove to ground level the young oaks which were growing up through the line. This would prevent the need for further maintenance in the short term. It was agreed also to merely reduce the height of some of the hawthorn which was causing an obstruction.

Stepping back from the area of work, there is an obvious line of hawthorn which would’ve once formed a hedged field boundary.

There are the remains of hedgerows in other places at the site, now swamped by young tree growth. Elsewhere, the remains of stone walls are now lost to the same process of ecological succession.

To conserve this remaining hedgerow as a testament to Kinver’s pastoral history, and to create an added ecological niche, we will look to managing this relic hedge over the next few years.

Trees at Kinver Edge part two: Small numbers of large ones.

The last blog gave some musings on the large number of small trees at the site…..

Larger trees with spreading crowns are uncommon at Kinver
Edge, and extreme branches of oak have a tendancy to die-back
when faced with competition. 

Kinver Edge’s sandy patch off Compton Road has a good, if rather young example, of pendunculate oak Quercus robur. In the open, the tree has been able to develop a spreading crown and pay attention to girth; rather than a desperate fight for height and light. Such trees – having generous crowns, and a notable girth – are relative rarities at Kinver Edge, owing to the former pastoral use of the site.

Diameter at breast height (DBH) can be used
to calculate ages of trees.

An investigation, working with volunteers, is planned for 2012 to map the locations of many trees of significant girth: the DBH, or diameter at breast height. From these results it may be possible to see certain trends in location, especially when coupled with other archaeological evidence. There are at least two obvious former hedgerows, one of holly Ilex aquifolium and one of crab apple Malus sylvestris, marking former field edges but now consumed by secondary growth in the absence of grazing livestock. With both cases the surrounding ground levels also support the hypothesis, and historic map evidence lends further weight.

 

Maybe our more significance oaks were left to provide shade for livestock within the, allegedly, stone walled fields: producing a random distribution? Or maybe they grew up to survive the now disappeared hedgerows: showing more obvious lines? Either way, they are present, although it is a case of can’t see the trees for the wood.

A mysterious line of laid crabapple runs parallel to a wide
linear depression. Maybe a former track?

Some of Kinver Edge's larger oaks line a
public footpath off Kingsford Lane.