
The UK Environmental Change Network (ECN)
The ECN was launched in 1992 as the UK's long-term environmental monitoring programme to study key physical, chemical and biological variables to help understand the impact of environmental changes on the various UK ecosystems. Consisting of a network of 12 terrestrial sites and 44 freshwater sites data measurements are being regularly collected, stored, analysed and interpreted to identify trends within the range of ecosystems covered by these sites. The network is supported by 14 UK government departments/agencies and 7 research organisations. The ECN project at Rothamsted is sponsored by the Biotechnology and Biological Sciences Research Council (BBSRC)

Rothamsted and the ECN

With its range of long-term experiments, covering a variety of ecological conditions, Rothamsted is seen as a suitable monitoring site for the ECN. The whole of the Rothamsted Farm is regarded as the Targeted Sample Site (TSS) and because of this there are two site managers covering the numerous measurement protocols.

Table 1. shows the range of measurements made. These are mainly centred on the Park Grass long-term grassland experiment with its history of botanical and ecological monitoring going back 150 years.

Table 1. ECN Protocols carried out at Rothamsted.

Physical and Chemical Measurements	Biological Measurements
Physical Measurements	Vegetation Measurements
Manual Meteorological Recording Automatic Weather Station	Vegetation Survey

Chemical Measurements	Insect Measurements
Precipitation Chemistry Atmospheric Chemistry - Diffusion Tubes Soil Solution Chemistry Soil Analysis Surface Water Discharge - The River Ver	Moths Butterflies Spittle Bugs Ground Beetles Spiders (new)
	Animal Measurements
	Frog Spawn Common Bird Census Rabbits Bats

Climate

Long-term meteorological observations can be used to identify changes and trends in climate that may have a positive or negative impact on the environment.

Scientists at Rothamsted have been observing aspects of the weather on a daily basis since 1853, when the first measurement of rainfall was recorded. Until 2004 these data were recorded manually. These meteorological records are kept electronically in the electronic Rothamsted Archive (e-RA).

Using the Rothamsted long-term datasets the above graph shows that over the last 15 years (1991 to 2005) the annual mean air temperature (light blue asterisk) has increased and is now approximately 1°C higher than the long-term mean (1878 to 1990). This rise is more evident when you look at the 5 year means (dark blue diamonds). To see whether the annual mean air temperature has increased or decreased since 2005 then Click here or on the chart of Annual Mean Air Temperature.

For monthly weather summaries from 2001 onwards Click here.

For the highest and lowest recorded monthly and yearly mean values since records began at Rothamsted Click here

As part of the ECN protocols a modern automated weather station (AWS) was established at all participating sites to collect the same weather variables on an hourly basis (Greenwich Mean Time). Such records have been continuously collected since 1993. Here at Rothamsted the hourly data collected by our AWS form part of a unique dataset complimenting the daily datasets available through e-RA.

Annual Mean Temperature - Click to Enlarge

Weather Variables Measured by the ECN Automatic Weather Station at Rothamsted

The automatic weather station collects data on the hour and is downloaded remotely two minutes later.

Click on weekly, monthly or yearly to obtain up-to-date graphics (updated five minutes past the hour) of current data (blue line or purple line) for the respective weather variables.

Weekly and monthly graphs show the average or total value for the previous hour. Yearly graphs show daily data (average or total) based on collection times (shown in brackets e.g. (09:00 GMT)) as specified by the UK Met. Office. They also show the thirty year mean (1971 to 2000, red line) with +/- standard deviation (light grey), which represents the variability of the data used to calculate the thirty year mean.

Why use a 30 year mean?

The following extract was taken from the Met Office web-pages explaining why the long-term mean is averaged over a period of thirty years - "The World Meteorological Organization (WMO) requires the calculation of averages for consecutive periods of 30 years, with the latest covering the 1961-1990 period. However, many WMO members, including the UK, update their averages at the completion of each decade. Thirty years was chosen as a period long enough to eliminate year-to-year variations." Therefore, unless stated, we use the current thirty year mean (1971 to 2000).

Data shown are 'Raw data' i.e. no corrections have been applied. Graphs have been produced using GenStat - Twelfth Edition version 12.1.0.3338

Today's weather (00:00 to 00:00 GMT), up to the hour:-

    Mean Air Temperature (last hour - red column; maximum for day - orange pointer; minimum for day - blue pointer).
    Mean Soil Temperature (last hour - red column; maximum for day - orange pointer; minimum for day - blue pointer).
    Total Rainfall (hourly and total - blue column).
    Wind Variables (last hour - closed circle; previous hour - open circle)
    Relative Humidity.

Mean Dry Bulb Temperature (Air), ^oC:- Weekly; Monthly ; Yearly (09:00 GMT)

Daily Maximum and Minimum Air Temperatures (based on dry bulb thermometer), ^oC:- Weekly; Monthly; Yearly

Mean Soil Temperature at 10cm under bare soil, ^oC:- Weekly; Monthly; Yearly (09:00 GMT)

Mean Soil Temperature at 30cm under grass, ^oC:- Weekly; Monthly; Yearly (09:00 GMT)

Mean Solar Radiation, W/m²:- Weekly; Monthly; Yearly (00:00 to 24:00 GMT)

Total Rainfall, mm :- Weekly; Monthly; Yearly (09:00 to 09:00 GMT)

Mean Wind Speed (m/s) and Direction (°) at 2m above ground:- Weekly; Monthly

Weekly and Monthly :- The most recent and penultimate wind speed and direction records are indicated in purple and blue, respectively. Earlier records are displayed using open circles. Data points are the average wind speed for a given direction (averaged) over a one-hour period. The x- and y- axes represent wind direction and the distance of each point from the origin represents wind speed (concentric rings denote the wind speed intervals, m/s).

Mean Wind Speed (m/s) and Direction (°) at 2m above ground:- Yearly (09:00 GMT)

Yearly:- Wind data are summarised on a rose diagram showing the distribution of winds according to their speed (m/s) and direction. Wind records are grouped by direction into 22.5° circular segments each with radius (length) corresponding to the number of wind records in the segment (expressed as a percentage of the 365 daily observations represented). Wind speeds are categorised according to the 'Key' (lower right-hand scale) and the proportion of all records of each speed occurring within each segment are denoted using the appropriate colours.

Other variables recorded by the ECN AWSs, but not shown, are Wet Bulb Temperature (°C), Albedo Sky (W/m²) and Ground (W/m²), Net Radiation (W/m²), Leaf Wetness duration (minutes), Soil Moisture (%v/v) and Relative Humidity (%).

Conversions: Use this link to convert temperature (°C to °F), rainfall (mm to inches) and wind speed (m/s to mph)

Atmospheric Chemistry

Nitrogen Dioxide (NO₂)

The major sources of NO₂ are from motor vehicles, domestic central heating, power generation, heating plants and industrial processes. The concentrations tend to fluctuate through the year with higher levels during the winter months when the combustion of fossil fuels is increased. These high concentrations of NO₂ have been found to be harmful to ecosystems.

Rothamsted has high levels of NO₂ due to being close to Harpenden, the larger conurbations of Luton and St. Albans, and M1 motorway. With high levels of atmospheric N we are interested in the effects of N inputs to our long-term studies. With this in mind the ECN have a set of passive NO₂ samplers situated at the Met Site and we at Rothamsted have supplemented these samplers with other sets of NO₂ samplers around the farm with 4 sets located around Park Grass, one of which is situated near to the Redbourn Lane (B487).

Mean Monthly Data from Park Grass (1993 to 2005) show that concentrations near to the B487 are much higher than further into Park Grass (see above figure). The seasonal trend of higher concentrations in winter are also evident, although next to the road this trend isn't so obvious.

Surface Water Chemistry

River Ver

The River Ver is a chalk stream that flows, for approximately 12 miles, from Kensworth Lynch, Bedfordshire to near Bricket Wood, Hertfordshire where it joins the River Colne. Chalk streams and rivers are globally very rare supporting plants and wildlife that depend on these unique ecosystems. Prior to 1993 the Ver had been dry for many years due to groundwater abstraction from the underlying aquifer further up the valley. Pressure groups like the Ver Valley Society managed to halt this abstraction and the river once again started to flow, if only periodically.

Weekly samples of the water (when flowing) started in June 1994 to determine the influences and effects of climate, agriculture, urban areas and industry on the quality of the water. Our sampling area is north of Redbourn where it passes through Rothamsted land. The stretch of river that we monitor is classified as a winterbourne where flow is dependent on rainfall, mainly during winter and early spring, replenishing the groundwater levels.

In recent years changes in climate and reduction of rainfall during the winter months has seen this stretch of the river only flowing when the water-table is high enough. Since December 2004 the river hasn't flowed due to a consecutive run of very dry winters. However with total rainfall of 657.6 mm from August 2006 to February 2007 (except for September 2006), which is in excess of the 30-year mean (+218.3 mm), the water table rose sufficiently enough for the river to once more flow again at the beginning of March 2007 (see Time Lapse Video).

River Update (03/02/2010) - With the river Ver flowing we have seen aquatic plants, that had been dormant during the drought years, come alive and populate the river.

The river at the end of September 2009 was all but a trickle. Precipitation in the form of rain and snow during November, December 2009 and January 2010 has been sufficient to once again raise the water table enough to allow increase flow. The cold snap also caused the aquatic plants to die back.

Biological Measurements
The ECN at Rothamsted is now in its fifteenth season of collecting data and quite a lot has happened since 1992. The two large surveys, the Common Bird Census (CBC) and the Common Butterfly Survey (CBS) have seen some change as well as some exciting records. The CBC has undergone both a name change and an alteration in procedure. The survey is now called The Breeding Bird Survey (BBS) and this only requires two visits in a season an early one in April and a late visit in July as opposed to twelve visits. Data is collected by walking two parallel transects and identifying species within twenty five, fifty and one hundred metres distance from the walking line and is carried out over five consecutive two hundred metre mini transects on each larger transect this gives ten data sets per visit. In 2007 Red Kite were observed over the estate for the very first time. Numbers of Starling, House Sparrow and Song Thrush appear to be increasing slightly although nationally they are in decline.
The CBS is made over a two-mile, twelve-section, transect which remains unchanged, apart from the localised cropping regime each year. Small Copper, Small Heath and The Wall butterfly have not been observed for a considerable time, this appears to follow the national trend in decline. On a high note, over the last three seasons Marbled Whites have been observed on the survey and in 2006, on a single day's count, fifteen individuals were recorded on five different sections of the transect which would seem to indicate that a colony may well have become established on the estate. Moth populations continue to be monitored on a daily basis and provide valuable data for both the ECN and the Rothamsted Insect Survey (RIS).
Tipulid numbers were initially monitored by taking soil cores and extracting the larvae. This technique has yielded very low numbers. It was noticed at Rothamsted that the light-traps used to monitor moth populations were also catching adult Tipulids in considerable numbers and so it was suggested that this might be a better way to monitor them. This has been looked at over the last two years and a greatly improved data set has been collected. The protocol will, therefore, be altered to use light-trap catches to collect the data. Spittle-bug nymphs and adults continue to be monitored in the mixed sward on the Rothamsted TSS however, over the last two seasons, heavy rains have affected nymph numbers in June and very hot summer weather in August has affected adult numbers.
Carabid beetles continue to be monitored in pitfall-traps and in 2006 it was decided to start looking at spider populations from the same samples. This is a fairly easy method to catch them although in the Rothamsted grassland site on Park Grass extremely high numbers of Lycosidae are being caught. Frog spawn monitoring has halted temporarily due to the appearance, in the monitoring pond, of two pairs of Great-Crested Newts that have fed on the tadpoles. As a result, no adult frogs or spawn have been recorded for the last three years. Rabbit monitoring continues and a healthy population lives on the estate, with the occurrence of Myxomatosis very low at the moment. Finally, fine grain vegetation monitoring is now being carried out by Dr Phil Wilson on all sites and he will be back this year (2007) to carry on the good work.

Press Releases:

6th November 2009 - Soils, butterflies and beetles respond to changing pressures on the UK environment

For comments relating to this webpage contact Tony Scott (tony.scott@bbsrc.ac.uk) or to find out more about the ECN visit http://www.ecn.ac.uk

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The UK Environmental Change Network (ECN)