Duchy College: Riparian Tree Planting for Water Quality, Research and Habitat

Planting as Part of a Trial

In total, 1,500 trees were planted at a density of 1,600 trees per hectare.

The species mix included native riparian and wet woodland species such as willow, alder, birch, oak, hazel, hawthorn and rowan. The planting was carried out in randomised patterns rather than straight rows, helping the new woodland feel more natural as it establishes along the wet valley corridor.

All trees were supplied by Duchy College, along with the plastic-free guards being tested as part of the trial. Two different types of biodegradable plastic guards were used, each supported with 60cm hardwood stakes.

Half of the trees were also planted with mycorrhizal fungi inoculant. The trial needed those trees to be clearly identifiable, so we set a randomised plan and marked the relevant stakes with permanent spray marker. This meant the college team could return later and know exactly which trees had received the inoculant and which had not.

That kind of detail matters. If the marking is wrong, or the wrong trees get the wrong treatment, the trial results become less useful. So the team had to keep the planting accurate throughout the week, even as conditions and plans changed on site.

Working Around a Mains Gas Pipe

One of the first jobs was to mark out a mains gas pipe that ran through one half of the planting area.

Working from supplied plans and alongside a college representative, we marked the pipe and set out a 3m exclusion zone on either side. That exclusion zone was required for the project and followed good practice when planting trees near underground services.

No willow was planted near the gas main because of its vigorous root system. Instead, smaller woody shrubs with less aggressive root structures were planted towards the edges of the exclusion zone where appropriate.

This is a good example of why planting near infrastructure needs thought. The right species in the wrong place can create problems later. On this site, the planting design had to work for habitat, research and underground service protection at the same time.

Wet Ground, Steep Edges and Changing Plans

The site had the usual challenges that come with riparian planting: wet ground, steep field edges, awkward access and changing conditions underfoot.

There was also the added challenge of keeping the trial elements organised while the plan adjusted during delivery to meet the changing requirements of the trial. Tree species, guard types, inoculant treatment and gas main constraints all had to be kept clear while the team continued planting efficiently.

This was not a job where the team could simply work through bundles of trees from one end of a field to the other. The details mattered all the way through.