Past land use at Upper Seeds - modern times

The management history of a parcel of land is often hard to establish; I'm lucky to be working on an estate that has an extensive archive, and which has been the focus of many different ecological surveys over the years.  Past land use has a bearing on current soil characteristics and ecology, and because of this, will influence future development and successional change.

This is particularly important when trying to restore or establish species-rich semi-natural calcareous grasslands, as these are considered to need several decades of appropriate management to begin to approach the diversity and complexity of historical grasslands.In common with many grassland areas across the country, Upper Seeds was ploughed during WW2, and put down to arable.  This may explain in part the apparent consistency of soil depth observed in the rainshelter post holes, as small-scale variation in underlying limestone bedrock topography would be erased through the erosive nature of ploughing. 

The Conservator at Wytham has kindly sent me some aerial photos of the area spanning 20 years from immediately post-war:

1.  Wartime ploughing of grasslands, followed by use as pasture

Upper Seeds, 1953

Upper Seeds, 1946

2.  Under arable crops from 1960 to 1982:

Upper Seeds, 1960

Upper Seeds, 1968

The field wasn't managed between 1982 and 1984, from when it was deer-grazed only.  From November 2006, it has been sheep pasture, with Spring/Summer and Autumn grazing, with occasional use of a forage harvester to remove and prevent the encroachment of scrub, especially hawthorn, which is still present as small bushes and low-growing seedlings.  From now on, it will be mown as for hay, twice yearly.

Mowing as management for a UK calcareous grassland

Using mowing as a management strategy for Upper Seeds is a compromise driven primarily by issues around having grazing animals in fields with permanent structures and equipment (the rainshelters and irrigation systems).  Ideally, I'd have grazed it, as this is mostly how we manage calcareous grassland in the UK; in continental Europe, there is wider use of hay cropping, so there is justification for this as a management technique for this habitat.  The problems with having sheep on site include congregation around rainshelter legs, with nutrient addition and trampling in these locations; chewing, rubbing against and other damage of the pipes and upstanding elements of the irrigation.  The effect of mowing will be different to that of grazing, as grazing is continual low-level foraging, and selective, whereas mowing is indistriminate, biannual and less good for invertabrates.  Certainly in the 11 years that the sheep grazing and scrub removal has been carried out, Upper Seeds has moved on a long way from being a species-impoverished grassland, and I'm happy to receive comments and advice on how to better replicate grazing over Upper Seeds, as this is a more real-world scenario. 
 

Ready for first cut

It's been a very busy and full few weeks, during which I've had the chance to really get acquainted with the site in some depth.  On the hardware side, we've now got all ten rainshelters up, and just await the first cut before we can install the irrigation system that will carry the intercepted precipitation to the supplemented plots. 

Rainshelters in the sun

Before that can happen, baseline vegetation surveys had to be done - this comprised 100 metre-square quadrats, so I've been busy recording the species present, and their percentage cover, and taking a  biomass harvest from each quadrat location.  I've started sorting the biomass harvests into 6 categories: graminoids (grasses, sedges), legumes, non-leguminous forbs, woody species, bryophytes, and litter; once dried, this will give me an indication of productivity in each group.  This data will form the baseline reference against which all my subsequent surveys will be compared, so it's been important to get it right - grass ID continues to prove time-consuming, but I'd like to think I'm getting better, at least at some species; this is in no small part due to an excellent training day with Dominic Price of the Species Recovery Trust (http://www.speciesrecoverytrust.org.uk/), whose enthusiasm and knowledge kept us all going through a day of incessant rain - no mean feat!

I have grown to love the chalk grassland plant species over the last few years' surveying, and it's a pleasure to see some of them here on the limestone at Wytham, along with some familiar Lepidopteran faces in the guise of Marbled White and Common Blue butterflies.

Marbled Whites in the sun

This plant species assemblage makes for a very colourful sward, with pinks (Red Clover, Common Centaury, Pyramidal Orchids), purples (Self-heal, Field scabious, Common Vetch), whites (White Clover, Hedge Bedstraw, Common Mouse-ear, Fairy Flax) and yellows (Smooth Hawk's-beard, Perforate St. John's Wort, Bird's-foot Trefoil, Black Medick, Mouse-ear Hawkweed).  As the season has progressed, I've been interested to see more species coming into evidence and flowering, and by Friday last week, it looked very different to the low green grass-dominated sward it had been.

There's plenty of non-plant interest, too; the invertebrate community is rich and fascinating, and really warrants a page all of its own.  Similarly the bird life - there's long-tailed tits flitting about in the remaining scrub and woodland edge, a pair of kestrels regularly hunt over the hillside, and buzzards cruise by over the nearby woods.  In places, the flowering heads of grasses and Wild Parsnip is now shoulder-high to me, and providing shelter for a number of roe deer (including fawns) that up and run if I get too close.  The southern side of the field has been claimed by a male pheasant, who regularly makes me jump with his clattering call and accompanying rattle of feathers.  As I have just taken my final biomass harvest for this round, the field will now be mown, and will look very different next week to how it was when I left on Thursday:

Upper Seeds up to my knees (and beyond, in places!)