The UK Environmental Change Network: Rothamsted Research

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Rothamsted and the ECN

The Rothamsted Estate encompasses an area of 330 ha, with the majority of the land being under arable farming practices. There is also woodland, grassland and more recently energy crops e.g. short rotation coppice willow and miscanthus grass. This means with a varied ecosystem the whole estate is regarded as the Targeted Sample Site (TSS). The majority of the ECN protocols (see Table 1.) are mainly centred on the Park Grass long-term grassland experiment with its history of botanical and ecological monitoring going back 150 years. The numerous measurement protocols are covered by two site managers at Rothamsted.

Table 1. ECN Protocols carried out at Rothamsted.

Physical and Chemical Measurements Contact:	Biological Measurements Contact:
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 Chemistry - 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 (purple asterisk) has increased and is now approximately 1^oC 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.

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 is downloaded remotely and is used to form part of a unique dataset complimenting the daily datasets available through e-RA. This data is graphed on an hourly basis showing weekly, monthly and yearly data. The yearly data is graphed against the 30 year mean (1981-2010*), based on measurements made at the Rothamsted Meteorological Station, with the variability of the mean being shown using +/- one standard deviation. Data from the automated weather stations at Rothamsted and the other eleven terrestrial sites is available from the ECN Data Centre.

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 (1981 to 2010). (REVISED 01/01/2011 previously 1971-2000).

* The thirty year mean (1981 to 2010) for rainfall should be used only for guidance. This is due to the fact that rainfall measured at the Rothamsted Met Station is by an aerodynamic tipping bucket rain gauge (ARG100) situated within a turf wall. The ECN AWS uses a cylindrical style tipping bucket rain gauge (Didcot) and it is has been found that the ARG100 captures up to 10% more rain water than the Didcot.

(Data shown in the AWS data graphs are 'Raw data' i.e. no corrections have been applied. Graphs have been produced using GenStat Fifteenth Edition version 15.1.0.8035 (64-bit edition))

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 Station and we at Rothamsted have supplemented these samplers with other sets of NO₂ samplers around the farm.

The annual mean NO₂-N data, from 1994 to 2011, measured at the Rothamsted Met Station show that concentrations have declined by approximately fifty percent since the establishment of the ECN in 1993. This decline is mainly due to the Government legislation on abating emissions from motor vehicles, industrial sources and the production of more efficient domestic heating systems. However, since 2008 concentration levels seem to have plateaued at 6.4 µg.m^-3.

Surface Water Chemistry

River Ver

The River Ver is a chalk stream that flows, for approximately twenty four kilometres, 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 section of the Ver that is monitored 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. Abstraction still occurs further down the Ver valley near to St. Albans.

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). The halting of water extraction from the aquifer due to the Buncefield disaster in December 2005 has also been a contributing factor. In late 2010 the river once more ceased to flow after below average rainfall during 2009 and 2010.

Update (02/01/2013) : After a very wet year in 2012, the wettest on record, the river has once again started flowing upstream of the Redbourn by-pass (A5183).

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 using light traps 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 since 2004. 2009 saw the monitoring of frog spawn switch to a new pond on the estate where hopefully tadpoles and froglets won't be eaten by newts.

Rabbit monitoring continues and a healthy population lives on the estate, with the occurrence of Myxomatosis very low at the moment.

Fine grain vegetation monitoring is carried out by Dr Phil Wilson at all sites every 5 years.

 

 

 

Time Lapse Videos

Park Grass
Plot 3, Section d :	Plot 09, Section d :	Plot 14, Section d :
2009	2009	2009
2010	2010	2010
2011	2011	2011
2012	2012	2012
2013	2013	2013

Geescroft Wilderness	Knott Wood	River Ver
2009	2009	2009
2010	2010	2010
2011	2011	2011
2012	2012	2012
2013	2013	2013

Video Archive

Press Releases

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

15th October 2012 - Declines in ground beetle biodiversity found in UK

 

 

 

For comments or enquiries relating to these webpages contact Tony Scott () or to find out more about the ECN visit http://www.ecn.ac.uk

All text and images copyright Rothamsted Research 2012

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