Effects of land use change on dry heathland soil moisture in a changing climate

Conversion of natural and semi-natural systems to agricultural use is one of the largest conservation
challenges of our time. As the world’s population continue to grow at unprecedented rates,
multinational organizations like the United Nations and its subsidiary the Food and Agriculture
Organization call for higher crop production and the expansion of existing agriculture to ensure future
food security, especially in the face of changing climate. However, these efforts will most likely endanger
numerous landscapes of historical and cultural value, including those found in northwest Europe. How
these possible changes in land use may alter the functions of these ecosystems and the associated
services they provide are questions that need to be answered before any policy decisions can be made.

Using a state-of-the-art ecotron facility, we compared soil moisture profiles between an intact dry
heathland system and heathland soils that had been cleared for cereal agriculture, both of which were
subjected to climate conditions projected for the year 2070, in line with the IPCC RCP8.5. After
continuously monitoring moisture changes in the top 1.5 meters of soil for three years, we found that
there are significant differences between the two modes of land use. Soils used for cereal crops were
significantly drier (up to >60%) in the upper 10-20cm than intact heathland soils, and significantly wetter
(up to >500%) at the lowest soil levels (140cm). This redistribution of moisture within the soil column
under different land use schemes can have serious implications for overall ecosystem functioning,
particularly with regard to potentially mitigating heathland soils’ ability to store and capture carbon and
exacerbating detrimental soil-climate feedbacks under agricultural use.