The best start for Headstart: why surveying the whole freshwater landscape matters

This summer, Freshwater Habitats Trust carried out the first surveys for Headstart, a major new Ofwat Water Innovation Fund project. Technical Director Penny Williams explains how the team went about gathering vital data for the project and the importance of the surveys for the future success of Headstart.

Headstart has just completed its first major round of freshwater plant surveys. What has the team been surveying, and why are the surveys taking place now?

It’s been a massively busy summer for me and fellow Freshwater Habitats Trust botanists, Astrid Biddle and David Morris. Headstart’s six demonstration catchments cover almost 300 square km so this has been a huge undertaking. We’ve been walking streams and ditches across these areas and surveying as many ponds and lakes as we can get permission to access.

It’s an unusually intensive approach. We’re aiming for a complete inventory of the wetland plants in each catchment’s different freshwater habitats. That means a lot of exploring, including places that wouldn’t normally feature in a monitoring programme.

These surveys are vital to the success of the whole project. We need to establish what’s there before introducing measures, such as creating new ponds, restoring headwater streams, or carrying out upgrades to wastewater treatment works. Gathering this baseline data means we can detect future changes and decide where the measures could make the greatest difference. Getting access has been a big job in itself, and we’re very grateful to the partners and many landowners who’ve helped make it possible.

We’re also using plants as an indicator of wider freshwater biodiversity. Our research shows that sites that are good for wetland plants tend to be good for other groups, including aquatic invertebrates. Plants won’t tell us everything about those groups, but they give us a useful way to assess biodiversity across a large area.

We can still miss plants, especially in a dry year, so it’s great that we have a second baseline year in 2027 to help fill the gaps. The more complete the inventory, the more confidently we can interpret later changes.

How were the six Headstart catchments chosen, and why was it important to include catchments in a diversity of landscapes and with different pressures?

Headstart needs to demonstrate approaches that can work under a range of conditions. The six demonstration areas therefore bring together different landscapes, freshwater habitats and pressures, including agriculture and wastewater pollution, through partnerships with six water companies.

They are Eye Brook in Leicestershire, Sowley Stream in Hampshire, Upper Leven and The Stell in North Yorkshire, Frilford and Marcham Brook in Oxfordshire, and the River Crane in Dorset. There’s quite a contrast between them, from steep, wooded slopes on the North York Moors to flat, deeply drained farmland and the heathlands of the New Forest.

Each area has a pair of catchments: one where Headstart measures will be introduced, and a control catchment for comparison. That helps distinguish changes associated with the project from wider influences which can create variation in species occurrence, such as a particularly wet or dry year. The range of landscapes will also help show which approaches can be used widely and which need adapting.

It’s been fascinating to see the effects of earlier habitat work too, from the striking richness of plants in lake inflow areas where scrub has been cleared, to the plants colonising interception ponds on the North York Moors. These give us opportunities to learn from work that’s already happened.

And some of the most interesting places are very unassuming. Shallow trackside ditches in the forestry areas supported lovely wetland plants, including Marsh Willowherb and Creeping Forget-me-not. That’s one of the rewards of such thorough surveys: you find things in places you might otherwise walk straight past.

Headstart is interested in the whole freshwater landscape, rather than focusing only on rivers or other larger waterbodies. Why is it important that the surveys include ponds, streams, ditches and other small waters?

Because each can contribute something different. If we leave out ponds or ditches, we miss part of the catchment’s biodiversity, potentially including species that don’t occur anywhere else locally.

Surveying so widely lets us see those contributions. A pond might have only a handful of plant species, but if one occurs nowhere else in the catchment, it adds something important. Equally, several individually rich sites may largely support the same species.

We need that whole-landscape picture to understand where biodiversity is concentrated and which places are particularly important to protect. It also helps Headstart plan how to strengthen the freshwater habitat network, giving species more places to live and opportunities to spread.

Because we’re covering so much of each catchment, we can find pockets of valuable habitat that might be missed by monitoring only a few locations. Sometimes the plant community improves along a particular stretch of stream or ditch, suggesting a local source of cleaner water, such as groundwater entering the channel. Those places could be especially important to protect.

We still need to interpret the patterns alongside other evidence that we collect during the survey, because factors such as shade, drying and habitat management also affect what grows. Combining the plant surveys with water chemistry and other monitoring data will help us understand the pressures and track how habitats respond to the Headstart measures.

These surveys will provide a baseline for Headstart. What does that mean in practice, and how will we use the baseline to measure change over the lifetime of the project?

It’s our starting inventory, before we introduce measures in the catchments. We’re recording where we survey and where species occur so that we can return and look for changes.

The thoroughness is what makes this especially useful. If we’ve searched widely for a plant and haven’t found it, then discover it in a new habitat later, we have stronger evidence of a genuine addition to the catchment. If a plant initially occurs in just one pond and later grows in five, we can show that it has become more widespread, even though the total species count hasn’t changed.

The control catchments – where we make no changes – are also important in their own right. Where we’ve used this approach before, we’ve recorded systematic species losses in a control catchment. That’s a really significant finding: it shows that, without measures to improve the freshwater environment, biodiversity can continue to decline across a whole landscape.

So we need to measure gains against that background. Maintaining existing species could itself be an important achievement if they’re being lost elsewhere. Comparing the Headstart catchments with their controls will help us see both whether we’re adding biodiversity and whether we’re preventing further losses.

Headstart aims to demonstrate approaches that can ultimately be replicated elsewhere in England and Wales. How will monitoring across six very different catchments help us understand what works and where?

Using the same monitoring approach across six different landscapes lets us compare how much biodiversity the measures add and how the results depend on local conditions.

The replication itself also builds confidence. If we see biodiversity gains repeated across several catchments, we can be more confident that the approach has wider potential. Where results differ, we can investigate why and understand what needs adapting.

Combined with costs and the partners’ practical experience, this should give others a clearer basis for deciding what to do in their own catchments and what biodiversity benefits they can reasonably expect.