When trying to improve plant diversity at St Nicks, we have three main techniques. One is through management alone, second is starting afresh with bare soil, and the third is by sowing into existing habitat. On the meadow and other habitats at St Nicks we do all three methods.
Just managing our habitats correctly through scything and removing the cuttings at the right time of year will lead to a year on year improvement, ensuring the soil nutrients remain low so plants can thrive and spread naturally. But this is a slow process especially with a relatively new site like St Nicks without established diverse seed banks in the soil. This is definitely the preferred method when possible.
2. Sowing into bare soil
Some areas of St Nicks have very little plant diversity, dominated by coarse grasses, probably due to previous poor management. Here, one option would be to over manage the area for a period of time to strip nutrients from the soil. But this means more scything in early summer when we are already busy battling Himalayan Balsam. A quicker but more labour intensive solution which can be done anytime of the year (though autumn – early spring is best) is to strip off the turf and nutrient-rich top soil before sowing into the exposed nutrient-poor sub soil. This can mean a lot of digging and barrowing as the top soil is often a few inches’ deep at a minimum. Another method which achieves the same outcome is inversion. Instead of removing the top soil, we dig out squares of soil and simply turn them upside down to expose the subsoil and bury the top soil. This less messy method is fast becoming a favourite with our volunteers.
3. Sowing into existing vegetation
The third method is by scarifying existing habitat to open up space in the soil. Scarifying involves using metal rakes to go back and forth repeatedly to expose at least 50% soil compared to vegetation. Seeds need good contact with soil to germinate so if the soil cannot be seen as it’s dominated by grass or moss, plants are unlikely to be able to spread naturally by seed alone. By doing this we are also removing dead grass, moss and thatch which again makes more space for seeds and new plant growth. We use this method for areas which contain some nice species (enough that we wouldn’t want to start again) but in small numbers or limited diversity (so management alone would take a long time to make a big difference).
A quick note on seeds: We still buy seeds in from reputable sources such as Emorsgate or Boston Seeds. But we are slowly moving away from this by collecting seeds ourselves from St Nicks and the various other sites we are involved with. This is of course cheaper and greener than buying in but requires some plant ID knowledge. It is always best get permission from landowners before doing this on conservation areas like St Nicks, especially if you are looking to collect a lot! But there are plenty of other public spaces and grass verges to collect from. Grow wild have produced a guide on doing this. Thanks to funding from Two Ridings Bettys Trees For Life Fund, we’re able to work on collecting and sowing seeds in this way.
These methods are about improving plant diversity but there is definitely a place for unmanaged areas too. Across the nature reserve we always leave at least 20% of the total grassland unmown to provide overwinter cover for insects and small mammals. Eventually these areas would scrub over through natural succession so to prevent this we rotate the areas we leave each year.
Post written by Natural Habitats Manager, Jonathan Dent. If you’d like to support St Nicks conservation efforts, please consider making a donation. Thank you.