Hazardous tree inspection for TPO

NWS Aborist Jim Allitt recently advised on the management of a substantial oak tree subject to a Tree Preservation Order and within the Broads National Park.

Our client, Mr Coleman, had concerns over the extent of deadwood in the canopy, especially where it was close to his and a neighbouring property, but as also keen to retain it as a beautiful feature of his home.

Mr Coleman asked NWS to determine the condition of the tree and make future management recommendations. The tree was surveyed to look at issues such as weak unions or forks, cavities, and especially any defects hidden higher in the canopy.

Hazard tree feature – Branch failure

Sometimes hazards are obvious but subtler hazards may go unnoticed and mechanical failure may occur without specialist management.

Under the Occupiers’ Liability Act (1957 and 1984) the ‘occupier of the land’ where the tree is rooted has a duty of care to ‘take reasonable steps to prevent or minimise the risk of personal injury or damage to property’, both for visitors to the occupiers land (1057) and other persons (1984). The law is quite complicated.

To avoid or deal with risks while retaining the tree, a reasonable and balanced approach to future management requirements is needed, with a full understanding of calculated risk involved. In this case, NWS suggested a 2m, crown reduction and to clear larger deadwood from the canopy so that ‘sailing’ from the wind stressed the branch unions less.

Aerial tree inspection by Jim

Since the tree was protected, the works had to be agreed with the local planning authority, the Broads Authority. NWS’s successful application demonstrated that the works retained the screening the tree provided but were also necessary to reduce the risk the tree posed to the adjacent house and property.

Suction solution for no-cut root route

In June 2017, Anglian Water began work on a pipeline renewal scheme at Belstead Water Tower, Ipswich. Trenching 1.2m deep by 0.5m wide was required to allow pipe-laying, but the only route out of the compound was in the Root Protection Area (RPA) of large oak, an important group of TPO trees.

Norfolk Wildlife Services worked with Anglian Water and Conroys to create an Arboricultural Method Statement [AMS].   An innovative solution  practical  technology –  a suction excavator [Conroy Vac Ex] – to prevent need to cut roots with ground protection techniques to protect tree roots of the protected trees from vehicle damage.

The suction excavator removes the soil around the roots, eliminating the need to cut through them in order to create the trench.  Major roots were left intact which means the trees ability to take up water and nutrients was not compromised.  Exposed roots were wrapped with wet hessian to prevent desiccation.  The pipe was then laid underneath the routes and the trench was then backfilled with the original soil, minimising disruption to the trees’ water supply in a period of dry weather.

Ground protection techniques help prevent compaction of the soil around the tree roots

 

Work begins on suction excavation of trench around tree roots using Conroy Vac Ex

Work with Conroy Vac Ex suction excavator continues on open trench and tree roots

 

Wet hessian bags were wrapped around the roots to avoid desiccation.

 

Pipe laying commences

 

 

 

Into The Woods: Low impact glamping at Moat Island

The site when developed will have 19 ‘glamping’ pitches as well as a communal kitchen area set within a woodland setting around a medieval moat which inspired the name ‘Moat Island Glamping’

The future Moat Island Glamping site

For the client, the sylvan setting of the trees were at the heart of the project as part of the core character of the site. For them connecting the ‘glampers’ with nature while conserving and enhancing that environment was key to success.

Working with the landscape architect Barnaby Baker and site manager Lewis Ennals, Jim, our arboriculturist gave both technical advice and inspiration as to what low impact glamping looked like. Essential when designing and constructing pitches amongst the surrounding trees and woodland. Accurate plotting of potential constraints using CAD software achieved a precise and technical solution.

New planting areas will provide both screening and wildlife interest and are all native species. Careful coppice rotation will also be introduced to provide a distinctive structure to the woodland and to allow an ever varied change in light levels, fully integrating the site into the woods.

 

Invertebrate survey successes for Cley Marshes

coastal lagoon

Ben Christie sampling lagoonal invertebrates

FOLLOW-UP SURVEY ON TRUST’S NEW COASTAL LAND REVEALS IMPORTANT INVERTEBRATES

Our follow-up survey on Norfolk Wildlife Trust’s new marsh at Cley has found five invertebrate species of conservation importance, including lagoon sand shrimp Gammarus insensibilis (legally protected) and mud snail Ecrobia ventrosa.

The Trust commissioned a specialist baseline study on their new land at Cley Marshes when they purchased it in 2014. This was surveying the plants and invertebrates in the site’s ditches, dykes and scrapes.

Since then, the Trust has carried out extensive work on the marsh to convert it from wildfowling ponds to a nature reserve and wanted to repeat the surveys. The plan was to compare with the 2014 baseline and identify any changes resulting from the work.

Twelve sample ditches and lagoons sites from the 2014 survey were re-surveyed for aquatic invertebrates, following the same methodology. For each, we took two dip-net samples to collect a crosssection of the aquatic invertebrates in the water: one in underwater vegetation near the shore; and one reaching out into the depths of the open water.

Ben Christie, our invert specialist said: “By first grouping inverts into taxonomic orders and then using specialist microscope keys for identification, we were able to efficiently identify the specialist communities for every sample site. This allowed both a direct comparison of communities in 2014 and 17, but also showed distributions for five invertebrate species of conservation importance.

“Norfolk Wildlife Trust can now fully assess the benefits of their management on invertebrates as well as the birds and other wildlife who are dependent on them in the food chain.”

 

 

Mitigating for great crested newts

Since starting great crested newt surveys in mid-March 2015, about 20% of the 75 ponds surveyed across Norfolk contained newts. For these sites, their development may now require a “European Protected Species Mitigation” ( EPSM ) licence, granted by Natural England after planning permission is given.

Lemonade and great crested newts

Bottle Trap

Bottle trap used in great crested newt surveys

We devise the mitigation strategy for clients based on where and how many newts are present.

To estimate numbers, we make six nocturnal counts via netting, with “bottle traps” (1.5 litre lemonade bottles) and spotlights. This indication of population size is used to devise a proportional strategy, ensuring that your development does not adversely affect newt populations.

Compensatory habitat

The EPSM licence needs to provide “compensatory habitat” at least equal in extent to that lost by development.  Newt habitats include scrub, grassland and woodland, but also often brown field areas, especially near old gravel or brick pits.  Ideas to think about when designing “compensatory habitat” are:

  • Restoring existing ponds to make them more suitable for great crested newts by clearing out shading scrub or desilting.
  • Creating brand new ponds: often also an attractive landscape feature (but no fish please and balancing lagoons aren’t suitable!)
  • Making wildflower meadows: good foraging habitat for newts plus an attractive feature managed well;
  • Planting woodland belts and hedgerows makes excellent shaded habitat for newts with leaf litter and logs, plus good for site landscaping, and corridors for newts to travel along to safely get from one area to another.

The bucket stage

If work cannot avoid impacting great crested newts, the development will need fencing off and trapping out with “pitfall traps” (buckets) to capture them and move them to safety.   Trapping normally takes place in autumn or early spring as it requires both suitably wet weather, but reasonable temperatures for the newt activity.

The number of nights trapping depends on the population, varying between 30 and 90 nights with additional needs where breeding ponds are removed.  If the fencing fails during building, then retrapping may be required, so investment in a decent spec fence is worth some thought. Generally you will need to keep the perimeter up from start to finish.

To create the compensatory habitat for a site near Dereham, we cleared ornamental shrubs and seeded the bare banks with wetland wildflowers around an existing pond, creating excellent refuges and invertebrates to hunt. Enclaves of wildflowers and trees were connected via thick hedgerows running around the boundary of the development, linking to hedges and ponds in the landscape.  Post development, the 2015 recount of newts showed numbers of breeding newts have remained consistent at 85, and that the mitigation had been successful.

Creating a bespoke boudoir for bats

As part of the re-development of a small brownfield site within Norwich, NWS were commissioned by RGW Portugal Ltd to undertake bat surveys of two small buildings. One of these was found to support low numbers of brown long-eared bats Plecotus auritus and soprano pipistrelles Pipistrellus pygmaeus, which were using the building for roosting in summer. The buildings needed to be demolished in order to create space for two new residential homes, and so NWS prepared a European Protected Species Mitigation licence for bats which was granted by Natural England.

Brown long-eared bat captured during demolition work

Brown long-eared bat captured during demolition work

NWS licensed ecologists supervised the demolition of the buildings in August, removing a roosting brown long-eared bat which was found along the central ridge beam and relocating this within a bat box which had been placed on a mature oak tree in adjacent woodland.

RGW Portugal Ltd were keen for an environmentally sensitive development and had included bike stores within the design to encourage the use of green transport. These features provided the perfect opportunity to create a bespoke bat loft for both species of bats to use. The loft was constructed above the bike stores, using a lined and tiled pitched roof to generate warm internal temperatures. Two carefully-placed bat access points were installed along the ridge and at both gable ends, allowing a number of entry points whilst reducing potential for light ingress and draughts. The ridge beam was formed using rough-sawn timber to create a suitable surface for bats to cling to, and bat batons were also installed along the inner walls to provide additional perching points.

The last features of the bat loft have just been installed this winter and NWS are hopeful to see use of this loft by bats when they return to roost in April.

 

Getting stuck in the mud at Cley

With support from members, business and the Heritage Lottery Fund, Norfolk Wildlife Trust acquired 60 hectares of land at NWT Cley Marshes in 2014. Norfolk Wildlife Services carried out baseline studies of the plants and invertebrates with particular focus on the impacts of the January 2014 flooding on the site’s ecology.

We decided to get stuck into the project (literally) to survey the saline lagoons and freshwater dykes across the site for aquatic plants such as Phragmites australis, and aquatic invertebrates such as the water boatman Arctocorisa garmari.  Initial results showed that an increased proportion of the open water on the site was unsurprisingly either brackish or saline. The effect on invertebrate species was evident during surveying as several groups were under-represented such as dragonflies.

In early summer 2015, we will survey the terrestrial invertebrates when they are most active. Some of the terrestrial invertebrates sought for include the Red Data Book ground beetle Pogonus luridipennis, or more commonly found cross spider Araneus diadematus.  Invertebrates like these are key indicators of the habitat quality and conditions present.

NWS will be running a workshop in September next year, looking at how the invertebrate population at Cley supports birds such as bittern, avocet and godwit. Check our website for more details on this “Bittern’s Breakfast and Avocets Lunch” event.

New winter homes for great crested newts

Since 2000, NWS has worked on development sites that support great crested newts, and in 2014 successfully assisted Saffron Housing in obtaining a European Protected Species Mitigation (EPSM) licence for this species on a residential development in South Norfolk. Nationally great crested newts have suffered huge declines and so are protected by European and UK law. Norfolk is one of the species’ strongholds, with greatest numbers of breeding ponds found on heavy clay soils.

With great crested newts present in ponds around the area and using the grassland on site to move between these, the EPSM licence was required during construction to protect these amphibians and provide compensatory habitat.

NWS staff supervised the installation of “newt exclusion fencing” and carried out pitfall trapping to remove newts from harm’s way. Great crested newts only use ponds for breeding and spend the rest of the year on land. The team focussed the compensatory habitat on features suitable for use during this “terrestrial phase” and supervised the creation of what was dubbed “Newt Nirvana” by the developer:  a wildflower grassland with hedgerows and scrub.

A key feature was the creation of three earth and stone mounds, which newts will use

This hibernacula has a rubble/log base to provide crevices for overwintering newts

This hibernacula has a rubble/log base to provide crevices for overwintering newts and is covered with turf to create stable temperatures through winter

during winter, called hibernacula. Great crested newts hibernate when winter temperatures drop below 5oC, normally from October or November. They typically hibernate underneath logs, within mammal burrow or tree roots, and even in building foundations. The hibernacula on site were designed to provide a number of sheltered crevices using logs and rubble, topped with turf to prevent exposure, whilst also ensuring newts were safe from flooding. Here the newts can remain protected until they emerge in late February or March to begin breeding in ponds.

£50,000 pond restoration at Downham Market nature reserve

Norfolk Wildlife Services has been advising the King’s Lynn and West Norfolk Borough Council on a £50,000 pond restoration project at the Willows Nature Reserve in Downham Market.

The Willows Nature Reserve County Wildlife Site is a fantastic area, adjacent to the pond restoration project area, with thick stands of common reed and bulrush. In 2007, water vole presence within the reedbed was discovered, showing the importance of this small site to fenland wildlife.

Working closely with the Borough Council, we have arrived at a plan, which will restore the pond by removing build up of silt, but not impact on existing wildlife such as reedbeds and water voles. The Fen Group, who have worked with us on a number of other projects, will be undertaking the desilting work under our method statement.  Further drainage work and pipework repairs in the nature reserve will also bring in rainwater and surface water from the reed bed and regulate the new levels within the pond.

Silt will often build up within old ponds and may require removal mechanically. However the silt needs a considerable area to put it in, meaning that area will be buried under nutrient rich slops. As such it needs to be made sure in pond restoration, that in restoring one habitat another isn’t destroyed. In this case, we were able to find an ideal location for a temporary bund to allow the silt to settle out.

Work has commenced and we look forward to seeing the results this summer with abundant fish and invertebrates.

You can read more about it on LynnNews.co.uk

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Invasive Non-Native Species – Japanese Knotweed – successful control

Our team are trained to recognise Invasive Non-Native Species [ also called INNS ]  on survey sites and advise on issues with their control.

One of the most pernicious, we encounter is Japanese Knotweed, which is an Asian species originating as a garden escape, spread via root fragments of its rhizomes, often from fly tipping or contaminated topsoil. Once established the underground rhizomes, Continue reading