Hoveton House Plantation ‘Sheet Mulcher’

Hoveton House Estate in Norfolk won the 2017 RFS Excellence in Silviculture Gold Award for the establishment of 12-year-old Stable Field Wood, a 2.9-hectare site with rather remarkable growth rates.

Forestry Journal recently joined a site visit to the plantation and an estate woodland diversification, organised by the RFS East Anglian Division. Carolyne Locher reports.

In the shadow of a Cypress oak (Quercus robur Fastigiata), 50 RFS members and guests gather in the parkland in front of Hoveton House. Members are greeted by RFS East Anglia Division Chairman Thomas Courtauld and introduced to new RFS President Andrew Woods.

Tom Blofeld, author and forest adventure playground entrepreneur, welcomes the group to the Estate, telling us that family fortunes were made from wool sold to the Low Countries for farming ‘underwear’, or as he affectionately calls it, ‘underpants-based wealth’. With these profits, his ancestors… “bought this house in the Bure Valley. The River Bure and Great Broad form a horseshoe shape around the estate. There are no permissive rights of way; there is nowhere to walk to.”

Prior to WW1, the reeds grown across 3,000 acres of marshland in this valley were farmed and harvested for chaff to feed military horses. The alder was used for charcoal. During the war, tanks replaced horses and many marsh men, all servicemen, lost their lives. Unmanaged alder and willow proliferated, forming a ‘carr’ or wet woodland. With virtually no income beyond that from farming, little woodland estate management occurred until the eighties when, under lawyer Sir John Blofeld’s stewardship, Andrew Falcon set about managing Hoveton’s alder carrs in 1993.

Today, woodlands cover 270 hectares of the estate. Wet woodland flood plains, an area of SSSi covered in mostly willow and alder, accounts for 60% of the holdings. Mixed mid-rotation woodlands (P1930–1990) account for 17%, 10% mature and over-mature mixed broadleaf and 13% young woodland (including some P2014) coming up to first thinnings.

Alder is now coppiced (sustainably) on a 25-year rotation for piling poles or firewood, (poles fetching double the price of firewood), as markets arise.

Andrew Falcon worked firstly in Brazil, sourcing legitimate mahogany. Returning to the UK in 1989, he consulted on post-1987 storm clearings before setting up his own contracting and forestry management business, now managing (approximately) 4,500 hectares of mixed woodland in East Anglia. Andrew says, “Since the early 1990s, I have been trying to reinstate alder coppice throughout the broadland; coppicing moribund stools to grow back as vigorous, straight poles for use in river bank pilings. Alder never rots underwater. Our target was to clear 50 hectares. Phytopthora omnivora (water-born) came in, impairing the growth rates, and the market for locally sourced, natural and sustainable materials hasn’t quite taken off.”

Alder stools coppiced at Hoveton in the ’50s have produced oversized poles 6 inches in diameter, 5–6 metres in length, which will be used in the £4.5 million Heritage Lottery-funded restoration project that Hoveton (along with project partners the Environment Agency and Natural England) are involved in.

Natural England’s Reserves Manager for the Broads, Rick Southwood, explains. “Bure Marshes National Nature Reserve contains the most extensive floodplain wet alder woodlands in Western Europe. These assets are prized for their trees and biodiversity. Hoveton Great Broad, 37 hectares of open water, suffered from nutrient enrichment (nitrates and phosphates from agricultural runoff and human sewage), causing algal blooms and vast accumulations of sediment. Phosphorus stripping at sewage plants improved the river water quality. We then had to decide what to do with 56,000 cubic metres of accumulated silt.” Last winter, alder pilings were driven into the fen bottom, holding in place a line of 50-metre-length geo-bags. Sediment is pumped into the bags to form a bund. The area behind will be backfilled to the same height as the adjacent marsh, creating the conditions needed for new fen to grow on top. “The alder tops will rot in 20–30 years. It all looks very promising.”

Walking towards Stable Field Plantation through a mature mixed-broadleaf wood, P1870 oak stems, streaked with the telltale black stripes of AOD, form part of the story of why, in 2004, Sir John asked Andrew to establish five hectares of new woodlands over four sites. Stable Field Wood was planted on ex-arable sandy loam soil. The aim was to produce a final crop of quality hardwood timber: quality chestnut at year 70 and 50 oak trees/ha in year 100+, releasing high volumes of birch firewood in the short term. With Hoveton and Wroxham village expanding in the south-west, rapid growth for screening, amenity and biodiversity, was required.

In the shade provided by 11.5-metre-high sweet chestnut trees, it is not hard to see why the RFS judges marked this wood so highly. Growth rates are off FC yield class charts. Andrew says, “I was asked to design a multi-purpose woodland, with 75% native species: 20% Sweet chestnut, 20% oak, 25% Silver birch, 10% hornbeam, 10% small-leafed lime and 10% mixed woody shrubs as understorey.

Rather than use traditional planting methods, incurring high establishment costs and high losses due to weeds and deer, Andrew used the ‘sheet mulcher’ system, the machinery for which he developed in 2000 to create fast-growing, maintenance-free woodlands. “At first we used 0.5-tonne rolls of cardboard matting, which didn’t work well in wind or rain. I found a new thermodegradable PVC material and Hoveton’s woods were the first to use this new material. The system is a pre-planting treatment, the thermodegradable PVC matting laid down mechanically. At the same pass, it lays a layer of composted green garden waste residue on top. Trees are then planted through the matting in 4-metre-centre rows, planting the matrix at 1.1-metre intervals, giving a stocking density of 2,272 stems per hectare. With establishment maintenance already done, you can go back years later with a pruning saw.

“This spacing was eligible for grant aid under the Woodland Grant Scheme whose wording stated that trees could be ‘evenly distributed across the site,’ maximising the economy per plant. In 2006, the EWGS wording changed. Rows could not be wider than 2.5 m, making the sheet mulcher uneconomical.” Around 50 hectares of new woodlands have been planted using this system. Under the new Countryside Stewardship Scheme, the system is once again eligible for use.

Stable Field Wood’s establishment costs were £1.32 per tree, or £3,000/ha, including supplying and laying the mulch and matting, and trees planted in spiral guards with cane supports. Losses have been minimal as the matting suppresses weeds, provides moisture retention and offers frost protection. There has been no herbicide spraying or fencing. Following early evidence of browsing, the deer have been controlled. Squirrels have damaged an understorey planting at one end of the wood.

Silver birch was used to draw up the crops and the woods’ widely spaced crowns met in year 7. “In year 8, we applied for a felling licence. Birch, 10 m in height with 10 cm+ dbh swamping the oak needed removing.” By year 10, some sweet chestnut had grown 9.5 m high. This year, some pendunculate oaks have grown to 10.5 m with a dbh of 13 cm.

Stable Field Wood exemplifies what Andrew Falcon was aiming for: the rapid growth of species that grow best in this area to achieve a multi-purpose woodland that will produce a good final crop. “A member of the FC said it was the first new plantation that he had inspected that felt like he was walking through a woodland in year 1: ‘I like the atmosphere, the light, and being able to see the trees and manage them accordingly. Often management does not get done because you can’t get into the woods or see the trees’.” Andrew Woods is impressed that from the first intervention, Hoveton made money in the firewood market .

A second wood (P2004) planted using the sheet mulcher system incorporates a different species mix. “The idea was to grow a final crop of ash, interspersed with alder and oak (20%) throughout.” The ash remains untouched because of Chalara. The alder has been cut for poles for the Hoveton Broad Restoration Project. “We sell alder at £150/m3 as opposed to firewood prices. Planting a mixture, if disease strikes, you always have a crop. Our target now is for a final crop of oak. There are many ways we can achieve that.”

The third woodland of four (P2004) was planted in the traditional way and without the use of the sheet mulcher system. Its weedy forest floor has been treated with Roundup and the trees are half the height of those seen in Stable Field Wood.

In 2005, Andrew received a letter from Sir John Blofeld (then aged 75) who wrote, “I would like to say that the planting that you have done at Hoveton looks admirable. I only wish I had a real chance to live long enough to see the trees reach their full glory in years to come.” Sir John has seen the trees and pruned them. Andrew says, “It was one of the nicest letters I have ever received.”

Our afternoon begins with a change of scenery and a completely different use of Hoveton’s woodlands. A raised wooden walkway leads us through a tangled alder carr to BeWILDerwood’s snack shack. The café deck is supported by 60-metre pilings sunk into the marsh below. BeWILDerwood is a 50-acre forest adventure park, conceived by Tom Blofeld, filled with treehouses, zip wires, a broken bridge, a maze, a lake, waterways and colourful characters – whose adventures he has written about in an accompanying series of books. Tom asks, “What do you do when faced with an estate that does not make money? Forestry is an economic matter that made a 0.03% return on value. BeWILDerwood changed this. Children come here and feel as though they could have built it. Consistent branding and standards and being unique are the reasons why it worked.”

In 2012, visitor numbers dropped. Tom said, “With a visitor attraction, the public comes in once. Why should they return, what is different? If the answer is nothing, they won’t return. Our response was to build the ‘Sky Maze’, 7.5 m at its highest point, and to professionalise our management structure.” Last year, visitor numbers grew to 171,000.

The ‘Broken Bridge’, built in a plantation that did make the estate an income, is accessed from entry points anchored around mature sweet chestnut tree stems. “We left a bit of a gap when building around these trees, so as not to restrict bark growth. Then we discovered the struts were throttling the trees. They are growing surprisingly fast, so continued monitoring and management is incredibly important.” Andrew recommends an enrichment planting and a thinning to let more light in.

Opposite the new Sky Maze, built from sustainably sourced timber (as is every structure here), the ‘Den Building’ has caused compaction around the base of the beech trees. Sticks and branches used to build the dens have been leant against the trees, causing ring barking. Some beech has already been removed. The remaining canopies are being monitored. “We are considering decommissioning the Den Building altogether.”

Tom is opening a second forest adventure park at Cholmondeley Castle, in Cheshire. The park itself will comprise 4–5 acres, with 45 acres of backdrop. “Visitor numbers will be restricted to a maximum of 350,000 a year. Otherwise, footfall will kill the wood.”

Aside from income, the biggest gain of BeWILDerwood to Hoveton, and to the forestry sector in general, is that visitors may learn to love woodlands. “The public will not fund woodland if they do not love it and they will not care if it goes. In the face of all these new diseases, we need the public to fund woodlands for future generations. We win awards (Themed Entertainment Association ‘Best Attraction under US$5m budget’, 2009), because we get the public back into a ‘wild’ wood.”