Extract from the introduction from the Natural England Publication: Climate Change -Lowland Fens. This document provides a useful summary of the likely changes and impact the changes to the climate will have on the Fens.
The fens are highly sensitive to changes in the quality and quantity of water supply and its seasonal availability. All of these factors are likely to alter significantly under climate change. The direct impacts of changes to precipitation and temperature pose a severe threat to lowland fen habitat and may in many cases be compounded by increasing demand for water leading to increased abstraction. Sea level rise and associated saline intrusion will pose an increasing threat to fen close to the coast.
Fens are wetlands that occur on peat and mineral soils and which can receive water from various sources (groundwater, surface run-off and river flooding, as well as rainfall), unlike bogs, which receive water at their surface only from precipitation. Fens are complex and dynamic systems. They frequently form complex mosaics with a number of associated habitat types, including wet woodland (fen carr), bogs, lowland heathland and lowland meadow.
The character of a fen is largely determined by the landscape setting, and the quantity, quality (in terms of macro-nutrients N, P & K) and chemistry (eg pH) of the water that supplies it. These various factors interact to create an extremely wide range of conditions in which fen vegetation occurs, and result in the development of a very wide range of vegetation types. In order to understand the likely impacts of any external pressure on a fen, it is essential that the ecohydrological function of the individual wetland (ie where the water comes from, how it moves through the site, the chemistry and nutrient status of the water, the nature of the substrate, and vegetation present) is understood. Management is also important, and understanding the influence of historical management as well as current practice is necessary.