Long-term changes in the water quality of rainfall, cloud water and stream water for moorland, forested and clear-felled catchments at Plynlimon, mid-Wales

Reynolds

Hydrol. Earth Syst. Sci.

et al. 2004

Self Cite

At Vyrnwy, in mid-Wales, a study of the hydrogeochemistry of two small spruce forested catchments, one a control and one felled midway through the study, shows a classic picture of rainfall inputs damped by the catchment and stream waters the chemistry of which varies as functions of flow and particularly of the supply of more acidic and aluminium-bearing soil water and of more basic and calcic ground waters from the zone where weathering reactions with the bedrock are high. The ground waters are most alkaline although pH may be depressed due to high dissolved carbon dioxide pressures. Nitrate concentrations increase in the first year after felling and decrease thereafter below those of the control. Water quality changes due to the dominant hydrogeochemical processes show that harvesting raises no significant water quality management issues.

Section: Temporal Patterns For the Streamsmentioning

confidence: 80%

The hydrochemistry of plantation spruce forest catchments with brown earth soils, Vyrnwy in mid-Wales

Reynolds

Hydrol. Earth Syst. Sci.

et al. 2004

Self Cite

“…The information presented in this paper complements other studies of conifer harvesting at Plynlimon and other parts of Wales that deal with felling responses for podzolic soils (Reynolds et al, 1988;Stevens et al, 1988;Neal et al, 1992aNeal et al, ,b, 2003a and brown earth soils (Neal et al, 1997a(Neal et al, , 2003b, thereby infilling information to cover all the major soil types for the region. The data also show that even for catchments with soils that have a high potential for water quality deterioration, the impacts of felling on stream water quality can be minimal.…”

Section: Introductionmentioning

confidence: 60%

“…1b are for the Afon Hafren which is used as a marker to set against the changes observed in the Nant Tanllwyth. Note that the Hafren has been felled progressively through the years but there is little effect on stream water quality (other than perhaps for potassium concentrations) as the phased felling results in runoff from different parts of the catchment that are influenced by the early felling effects as well as the recovery phase (Neal et al, 2003a). The patterns of change observed are as follows.…”

Section: The Main Stem Of the Nant Tanllwythmentioning

confidence: 89%

The water quality of streams draining a plantation forest on gley soils: the Nant Tanllwyth, Plynlimon mid-Wales

Reynolds

Hydrol. Earth Syst. Sci.

et al. 2004

Self Cite

The water quality of the Nant Tanllwyth stream in the Plynlimon region of mid-Wales is related to the key hydrobiogeological controls and the effects of conifer harvesting based on an analysis of rain, cloud, stream and groundwater measurements. The results show the normal patterns of stream water quality response to hydrology. Thus, there is a high damping of atmospheric inputs due to storage in a highly heterogeneous soil and groundwater system. Correspondingly, there is a highly dynamic response for components such as calcium, bicarbonate and aluminium. This response links to the relative inputs of acidic and aluminium-bearing soil waters under high flow conditions and base enriched bicarbonate bearing waters from the groundwater areas under baseflow conditions. The introduction of a deep borehole near the main stem of the river opened up a groundwater flow route to the stream and other parts of the catchment. There were two aspects to this. Firstly, it caused a change to the stream water quality, particularly under baseflow conditions, by increasing the concentrations of calcium and magnesium and by reducing the acidity. The monitoring shows that this change has persisted for over eight years and that there is no sign of reversion to pre-borehole times. Secondly, it caused a change in the groundwater level and chemistry at a borehole on the other side of the river. This feature shows that the fracture system is of hydrogeochemical and hydrogeological complexity. The effects of conifer harvesting are remarkable. At the local scale, felling leads to the expected short term increase in nitrate, ammonium and phosphate from the disturbance of the soil and the reduction in uptake into the vegetation. Correspondingly, there is a reduction in sodium and chloride linked to reduced scavenging of atmospheric inputs from cloud water by the vegetation and also due to increased dilution potential due to reductions in transpiration by the trees. However, within the main stream, virtually no change is observed in stream water quality with felling, except for a decrease rather than an expected increase in nitrate concentration. It seems that the increase in phosphate, for a system that is essentially phosphate limiting, has stimulated biological activity in the stream leading to increased uptake of nitrate and ammonium. However, there is little change in the sodium and chloride in the stream and there are important issues of the representative nature of studying small scale drainage areas. Boreholes, introduced to assess the impacts of the felling programme, show unexpected variations in groundwater chemistry. These variations are associated with the complexity of both flow routing and the chemical reactivity within the groundwater and lower soil zones, rather than changes that can be linked specifically to felling. The implications of the study are discussed in relation to both process understanding and forestry management practices.

“…as has been suggested in the short water cycle theory (Ripl 1995(Ripl , 2003Pokorný 2001;Kravčík et al 2008), the intensively evaporating vegetation retains close circulation of water and energy in the ecosystem (Brom & Pokorný 2009). a transformation of the vegetation cover may lead not only to changes in the water and energy budget of the landscape in question, but also to mineralisation and consequent leaching of nutrients and CO 2 release (Rees & Ribens 1995;neal et al 2001;Procházka et al 2008). Our research has supported the importance of the role of vegetation in the solar energy dissipation and water use, and has contributed to other published results which point to the imperative need of wise management of the landscape in order to improve its functions.…”

Section: : S49-s58mentioning

confidence: 99%

Evaluation of functional properties of various types of vegetation cover using remotely sensed data analysis

Brom¹,

Procházka²,

Rejšková³

2009

Soil & Water Res.

Abstract:The dissipation of solar energy and consequently the formation of the hydrological cycle are largely dependent on the structural and optical characteristics of the land surface. In our study, we selected seven units with different types of vegetation in the Mlýnský and Horský catchments (south-eastern part of the Šumava Mountains, Czech Republic) for the assessment of the differences in their functioning expressed through the surface temperature, humidity, and energy dissipation. For our analyses, we used Landsat 5 TM satellite data from june 25 th , 2008.The results showed that the microclimatic characteristics and energy fluxes varied in different units according to their vegetation characteristics. a cluster analysis of the mean values was used to divide the vegetation units into groups according to their functional characteristics. The mown meadows were characterised by the highest surface temperature and sensible heat flux and the lowest humidity and latent heat flux. On the contrary, the lowest surface temperature and sensible heat flux and the highest humidity and latent heat flux were found in the forest. Our results showed that the climatic and energetic features of the land surface are related to the type of vegetation. We state that the spatial distribution of different vegetation units and the amount of biomass are crucial variables influencing the functioning of the landscape.