Pertwood Manor Farm and Visit

A shortage of over-winter stock in part due to the unusually high demand for tree supplies associated with to tree-planting projects caused planting to take place a later than originally intended. However, the planting took place for 10 days starting on the 24th of January 2022.

Tree species were selected to suit the local micro-climate, in order to ensure reliable sequestration of carbon and to and to support wildlife biodiversity. The species mix included White Elm (40%), Norway Maple (10%), Wild service tree (10%), Italian Alder (5%), Beech (10%), Sycamore (10%), Western Red Cedar (5%), Norway Spruce (5%), Hazel (2%), and Hawthorn species (3%). Most of the saplings were sourced from within the UK. The White Elm in particular was included to encourage the success of the white letter hairstreak butterfly, of which species have been declining rapidly.

1.55 hectares of farmland, in three separate lots, were planted with 1715 trees at a stocking density of 1100 whips per hectare (3m spacing). This compares with a calculated estimated requirement for 1.7 hectares to meet the target for carbon sequestration.

The PIU (Pending Issuance Units) was generated and came to the 748 metric tonnes of carbon after 100 years, with a 20% buffer for the chance of fire or disease. A landowner can sell these units as future carbon sequestration, but a WCU (Woodland Carbon Unit), which has already been grown, is more valuable. In this case, however, the carbon units sequestered will remain as Dr Alison Cooke’s own personal lifetime carbon offsetting. Within 100 years of 2022 Dr Alison’s CO20 project will have sequestered enough carbon dioxide from the atmosphere to offset her lifetime of emissions.

A visit to Pertwood Manor Farm was made by Esther Tun on Thursday the 27th of January, the third day of planting, at an approximate total cost of £13,000. Images of the largest of the three allotted areas for Alison’s woodland are below. If interested, there is also a detailed explanation of the planting process.

Details of the planting process:

  • Before planting could take place, it was necessary to remove the maize cover crop (planted to provide shelter for game birds, as the new trees mature these will provide continued cold weather protection). The maize was removed by use of a mechanical topper.
  • The flint bearing soil was well drained but difficult to work. Trees were planted directly without prior soil cultivation. Cultivation would have made planting easier but would have resulted in an increased release of carbon to the atmosphere. To facilitate access for management a ride-way through the middle of the plot was left unplanted.
  • 2-year old bare root whips (~40-60cm overall length) were selected, being ideal for the field conditions. First the stakes go in at 3 metre intervals, then at each one a hole is dug, the tree put in and heeled around with soil for a firm hold. A guard goes on afterwards to protect the tree from browsing damage. 1.5 metre guard protects them from fallow deer and 1.25m wo for roe deer and brown hare protection. Conifer whips, being unpalatable to deer were protected with the smaller guard as were dogwood and spindle shrubs.
  • Some tree species were grouped together, such as the evergreen conifers in clumps of 15 or 20 throughout. These would support a higher yield and provide pockets of warmth for birds; they would also produce more aesthetic green patches amongst the brown of the other trees. Previous clumps of blackthorn were left to retain animal habitats.
  • In spring the sites will require spot spraying to prevent the competition of other plants.
  • Although the trees may take 80 years to reach peak height, within 30 years the canopy should be closed and give the appearance of continuous woodland.