Impact of lowland forests in England on water resources: Application of the Hydrological Land Use Change (HYLUC) model

Abstract

[1] The U.K. Government's 1995 White Paper on Rural England [Her Majesty's Stationery Office, 1995] proposed a doubling of the area of woodland within England by the year 2045. Questions were later raised concerning the possible impacts on water resources of such a large change in land use. This paper presents results of field study investigations of the water use of grass, heath, oak, and pine vegetation at Clipstone Forest, Nottinghamshire, United Kingdom, which were used to calibrate the water use model HYLUC and derive predictions of the impact of different vegetation types on recharge in this locality. Average annual recharge plus runoff (millimeters) over a 32.5 year period and the uncertainties due to spatial sampling, calculated with the HYLUC model, were 136 ± 11 for the grass site, 122 ± 3 for the heath site, 76 ± 5 for the oak site, and 34 ± 8 and 38 ± 3 for two pine sites. In this region of Britain the long-term recharge beneath pine is approximately one quarter that under grass and essentially only occurs in years of above average rainfall. Oak woodland is also predicted to have a significant impact by reducing recharge plus runoff by almost one half as compared with grassland.

Forests and water—Ensuring forest benefits outweigh water costs

“…Cumulative recharge predicted for grass, heath, oak and pine vegetation at Clipstone, UK, using the locally calibrated HYLUC model, together with cumulative values of measured rainfall and Penman potential transpiration for short grass (right hand scale) (Source:Calder et al, 2003a).…”

Four-year comparison of water contents beneath a grass ley and a deciduous oak wood overlying Triassic sandstone in lowland England

“…Various estimates of recharge between March 1998and March 2002presented by Calder et al (2002 indicate that recharge under oak was between 66% and 86% of that under grass. However, modelling of data from these sites (Calder et al, 2003) suggests that the average annual recharge over a 32.5-year period was 136 mm for the grass site and 76 mm for the oak site, equating to recharge beneath oak being only 55% of that of grass.…”

Towards a research agenda for woodland expansion in Scotland

“…For example, increased woodland habitat may encourage agricultural pests such as the bark beetle or sheep headfly (Bell, 1999;Toivanen et al, 2009). Woodland expansion can also reduce water quality and availability in some instances, and can contribute to the acidification of surface waters through canopy pollutant capture (Calder and Reid, 2003;Calder, 2007;Nisbet, 2014). Forest establishment practices can also increase both nutrient and sediment loads (Marks and Leeks, 1995).…”