ECT’s first webinar of 2025 featured Sara Middleton from the University of Oxford speaking about the first eight years of results from the RainDrop drought/enhanced rainfall experiment at Wytham Woods. We invited Jonathan Silvertown, one of ECT’s founding trustees, to tell the story of how RainDrop first came into being.
Despite its name, RainDrop did not just fall from the sky! The ECT began thinking about what the experiment might look like some 10 years before it actually came into existence. ECT was registered as a charity on 1st October 2008, but for three years before that and for some years afterwards, a group of ecologists including myself, Jerry Tallowin (current Chair of Trustees), Bridget Emmett (UKCEH), the late Phil Grime (Sheffield), Mike Morecroft (Natural England) and Robin Buxton (Northmoor Trust) and others met frequently to thrash out the scientific case for long-term experiments. You can read our conclusions in the paper that we published in Trends in Ecology and Evolution in 2010.
Our fundamental contention was (and is) that we need a long-term perspective, informed by experimental manipulation of key environmental drivers in order to see beyond immediate conditions. I came up with the metaphor that without this, we suffer from "environmental myopia", unable to see beyond our noses. That metaphor did not fly, and I now prefer the more positive notion that an LTE is a time machine that enables us to study the past and see into the future. Using this idea, a section of the 2010 paper should have been called "How to design a time machine." Much of that design eventually materialised as RainDrop.
Prototype rainout shelter designed, manufactured and built at the Open University in Milton Keynes in 2014, seen here a year later. It was tested by David Gowing, Kadmiel Maysek and Melanie Stone and funded by a grant from the Patsy Wood Trust.
We spent a great deal of time debating what the next generation of LTEs should look like, and especially what response variables we should focus on. Phil Grime, at the time PI of the Buxton Experiment, one of the earliest climate change experiments anywhere, insisted that we ought to be concerned with biodiversity. I tended to agree with him. Others thought that the carbon cycle should be the main focus. The problem was that the former pointed to an experiment on a skeletal soil such as that at Buxton, while the latter requires a more organic, deeper soil which usually means lower plant diversity. This debate may seem strange now, but at the time we were acutely aware that we did not have the money to start even one new experiment, so it was hard to imagine being able to satisfy everyone.
Construction materials ready for the build of RainDrop at Wytham, April 2016.
In the end, we were pragmatic and went for whatever we could get by way of a site that could provide long-term security. We seriously explored Parsonage Down National Nature Reserve as an experimental site, but its distance from any suitable scientific institution was a problem. Wytham won out because it is owned by the University of Oxford, is accessible to other institutions such as UKCEH at Wallingford and the Open University in Milton Keynes and had already hosted other LTEs. The vegetation at Raindrop is relatively species-rich and the soil is skeletal, but thanks to other sites on the ECT's register, carbon cycling and biogeochemistry feature strongly elsewhere.
ECT's success in creating a UK-wide community and LTE network, means that we probably won't again try to start an experiment in the manner that we initiated RainDrop. With our alliance of partners now ranging from the British Ecological Society to the National Trust and WWF and many others, we can now achieve more by inspiring, facilitating and collaborating. This is an achievement I certainly didn't even dream of back in 2004 when a few of us sat down during a lunch break at a conference in Exeter and decided we needed to start a charity to save our precious few long-term experiments.
