Evaluating the success of upland hay meadow restoration using green hay transfer

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Ruth Starr-Keddle describes her latest research with the North Pennines Area of Outstanding Natural Beauty Partnership to further the knowledge base on upland hay meadows and investigate the success of seed addition of key indicator species for restoring the landscape.

Over the last 50 years there have been substantial declines in botanical diversity of traditionally managed species-rich upland hay meadows (conforming to the UK National Vegetation Classification (NVC) MG3b mesotrophic grassland) and they are now one of the rarest grassland types in the UK.

The widespread disappearance of characteristic meadow plants has been related to intensive spring grazing, earlier cutting times, chemical fertilisers, a move from hay making to silage, re-seeding and loss of meadows to pastures. These ancient meadows have northern-montane species such as wood crane’s-bill (Geranium sylvaticum), Lady’s-mantle (Alchemillaspp), and melancholy thistle (Cirsium heterophyllum) which are late-flowering, longer-lived perennial plants.

As botanical diversity declines, the plant communities shift from MG3b to MG6 meadows. MG6 and MG3b meadows share a number of positive indicator species such as yellow rattle (Rhinanthus minor), ribwort plantain (Plantago lanceolata) and red clover (Trifolium pratense), however MG6 meadows are missing the rarer MG3b plants.

A further shift occurs as the commoner wildflowers disappear due to agricultural intensification: MG7 meadows have a range of grasses with few positive indicators, often found where the meadows are cut for hay earlier, re-seeded or soil fertility is increasing.

The North Pennines Area of Outstanding Natural Beauty (AONB) Partnership’s Hay Time project aimed to improve the knowledge of upland hay meadows and to investigate the success of seed addition of key positive indicator species.

We undertook a landscape-scale restoration programme between 2006 and 2012, harvesting seed from 82 species-rich donor meadows and spreading seed onto 89 receptor meadows (222.82ha).  The receptor meadows have been managed in a traditional way for centuries; they have been in agri-environment schemes from the 1980s with hay-making requirements and chemical fertiliser restrictions.

We harvested seed as green hay, using two types of donors: an MG6 donor (classed as restoration) or using an MG3b donor (classed as enhancement). Great attention was given to the selection of species-rich donors to make sure they would complement the botanical composition of the receptor meadows.  A forage harvester was used to harvest green hay: cutting the vegetation close to the ground, collecting, and then tipping the green hay into the spreader.

The receptor meadows were scarified (by approximately 50%) using a spring-tine harrow, creating lines of exposed soil. The green hay was spread using a conventional muck spreader, following the scarified lines. We monitored the receptor meadows, undertaking a baseline botanical survey before seed addition, and repeating the survey three to five years later. In addition, we also monitored 41 control meadows without seed addition.

Our results show that species-richness, diversity and floristic composition improved in 77 meadows three to five years after seed addition.

18 plant species had an increase in frequency in the receptor meadows with no increase in the control meadows. The most successful were eight positive indicators species such as sweet vernal grass (Anthoxanthum odoratum) and lesser trefoil (Trifolium dubium).However, rarer characteristic MG3b plants such as Lady’s-mantle (Alchemilla spp.) and wood crane’s-bill (G. sylvaticum) showed few signs of establishing.

Our research demonstrates that green hay transfer, harvesting in early to mid-August, is an effective way in shifting the plant communities from a species-poor MG7 meadow to a MG6 meadow community.  In particular, eyebright (Euphrasiaspp.), ribwort plantain (P. lanceolata), yellow rattle (R. minor) and red clover (T. pratense) could be useful target species to assess whether seed addition has been successful, to improve botanical diversity, and to enhance soil and microbial functioning. These annual or fast-growing perennial plants tend to flower in June and set-seed at the same time in mid-July, with numerous seeds in their seed-head.

What is now needed is an effective method to establish characteristic MG3b plants, such as wood crane’s-bill (G. sylvaticum) and melancholy thistle (C. heterophyllum). Lessening spring grazing, extending the shut-up period, easing farmyard manure usage, restricting chemical fertilisers, and more flexible hay cutting times would be desirable, alongside a green hay and plug planting regime to maintain and increase species richness, diversity and positive indicators to further enhance the MG3b upland hay meadow target community into the future.

Read the full article: “Evaluating the success of upland hay meadow restoration in the North Pennines using green hay transfer” in Issue 3:1 of Ecological Solutions and Evidence.

All National Vegetation Classification documents can be found on the JNCC website. The NVC name codes are also available below: