1990 - 1991 r-7=: fl r r if a

Institute of \*\\\,`\:.;; Terrestrial "q7 Ecology Natural Environment Research Council Foreword

Environmental issues continue to grow in importance both nationally and internationally These issues, whether local, regional or global, must be addressed on the basis of sound and up to date scientific knowledge NERC's Terrestnal and Freshwater Sciences Directorate provides a focus for fundamental and apphed research in land use and the development of natural resources, the maintenance of environmental quality and the pnnciples which underline management and conservation

Much of llus research is interdisciplinary and demands the wide range of expertise in NERC establishments and higher education mstitutions The Directorate's m-house capability comprises the Institute of Freshwater Ecology the Institute of Hydrology the Institute of Terrestrial Ecology the Institute of Virology and Environmental Microbiology the Unit of Comparative Plant Ecology (Sheffield University), the Interdisciplinary Research Centre for Population Biology (Imperial College, London), the Unit of Behavioural Ecology (Oxford University) and the Water Resource Systems Research Unit (Newcastle-upon-Tyne University)

The Institute of Terrestnal Ecology continues to provide the major national resource of expertise in ecology and related subjects Its research in areas as diverse as air pollution effects and vertebrate population biology has an international reputation This Report shows the wide range of skills of ITE staff and how essential the research is to the environmental quality and management of the land surface both in the UK and overseas

Dr P B Tinker Director of Terrestrial and Freshwater Sciences Natural Environment Research Council

Front Cover Illustration Salt maish erosion - photographer R Scott Report of the Institute of Terrestrial Ecology 1990/91

Natural Environment Research Council CONTENTS - Science reports 2

Environmental pollution 31 Critical loads for soils 31 Dry deposition of sulphur dioxide in the United Kingdom 34 The exchange of trace nitrogen gases between terrestrial ecosystems and the atmosphere 37 Overview of the transfer of radiosilver within the environment 41

Population ecology 44 Predation of juvenile salmon by red-breasted mergansers 44 Recovery of a sparrowhawk population in relation to a decline in pesticide contamination 46 Recolonisation of disturbed heathland by reptiles and amphibians 48 Genetic determination of caste in the red ant 50

Community ecology 52 Effects of ending livestock grazing on upland vegetation 52 Tablefit and the identification of British vegetation types 54 Nitrogen fertilisers on old peat grasslands 56 British weevil fauna 58

Scientific Services 61 Analytical chemistry group 61 Inductively coupled plasma mass spectrometer 62 Future applications of radar remote sensing in terrestrial ecology 63

Reminder Printing Co Ltd , Ulverston (Cumbria) and Lancaster, England Environmental pollution

The Institute's programme of research on trace nitrogen gases describes an since been developed in a series of on environmental pollution includes ambitious mult-natonal study on one workshops sponsored by the Nordic work on radionuclides, acidic site, winch aimed to compare the Council of Ministers and the United atmosphenc pollutants and trace gases, different methods Improved Nations Economic Commission for pesticides and herbicides, and trace information on the net fluxes to the Europe (UN-ECE) (Nilsson 1986) These metals It also encompasses deposition atmosphere of the radiatvely active workshops have considered the processes, the transfer of pollutants gases is essential for the development definition, calculation and mapping of within terrestrial ecosystems, and of policy to control greenhouse gas cntical loads (Bull 1991, Nilsson & impacts on terrestrial organisms and emissions Grennfelt 1988) The UN-ECE communities An increasing proportion currently sponsoring the production of of the research is directly related to, The research on radionuclides critical load maps for Europe, and has and provides support for, the continues to be dominated by work on produced a mapping handbook development of Government policy the Chernobyl fallout, with the main (Sverdrup, de Vnes & Hendncksen Thus, the work on critical loads emphasis on the cycling of caesium in 1990), ITE Monks Wood is acting as the reported in one of the following papers the acid, organic soils of the uplands co-ordinating centre for UK inputs to this is providing the basis for the UK input to and its transfer to grazing animals exercise the cntical load map of soils for Europe, However, the Chemobyl fallout winch will be used in negotiating future contained other radionuclides winch The concept provides a means of sulphur dioxide (SOO emission control are of great scientific interest, and quantifying the sensitivity of ecosystems protocols The Institute is also involved which could form an important part of to pollutants Critical load maps show in the Department of Environment fallout from accidents involving other the location of the sensitive systems programme of work to develop cntical reactor types The paper on When these maps are overlain with loads for UK vegetation commumtes radiosilver reports work on one such pollutant deposition data, they allow ITE Monks Wood acts as the co- radionuchde Other radionuchdes areas to be identified where the critical ordination centre for producing critical the fallout close to the site of the load is exceeded Further, given load maps for soils, vegetation and Chernobyl reactors were also more suitable models, they can be used to surface waters, linking the UK work with important than caesium, staff of the determine by how much emissions must the west European centre in Bilthoven Radioecology Group are currently be reduced to prevent damage, or to developing a programme of work protect specified systems Critical load maps for soils, vegetation with Russian and CEC scientists winch or surface waters can be overlain with will involve some of these other In determining a critical load, the first data on current inputs of atmosphenc radionuclides stage is to define the target receptor pollutants to identify those areas where system, eg soils or surface waters present deposition exceeds the critical Ideally, a biological indicator should be load Clearly, such an exercise identified as the critical load receptor, requires the best available data on eg tree roots in forest soils or brown current levels of deposition The work Critical loads for soils trout (Salmo trutta) in surface waters A on SO, deposition, described in a (This work is funded by the Department of the chemical limit may then be determined, following paper, is part of a broad Environment, and forms part of the activities of programme of work on deposition its Critical Loads Advisory Group) processes winch is providing improved Table 4 Some chemical cntena suggested for use in setting cntical loads (alter Sverdrup estimates of acidic pollutants being et al A critical load can be defined as the 1990) deposited across the UK maximum load of a pollutant, or pollutants, winch will not cause long- Cntical chemical The main thrust of ITE research on trace term damage to an ecosystem, or to value for forest gases has changed recently, and some specified element of that Cntena rooting zone increased emphasis is being given to ecosystem pH E-layer >pH 4 0 nitrogen species and rachatively active B-layer >pH 4 4 gases The emphasis on deposition has The critical load concept was developed Alkalinity >-300 REq1-1 also been replaced by consideration of in Canada during the early 1980s, where Total aluminium <4 0 mg I-, fluxes to and from terrestrial surfaces it was used in negotiations with the Labile aluminium <2 0 mg ri Several approaches are available for United States concerning reduction of Ca/A1 molar ratio >1 0 the study of such fluxes, and the paper trans-national pollution The concept has NH /K molar ratio <5

31 beyond which the biological indicator Table 6. Factors causing a decrease or increase in loads of acidity for soils will suffer 'damage'. The critical load (after Nilsson & Grennfelt 1988) is calculated to ensure that this Factor Decrease Increase chemical limit is not transgressed. In practice, there is no general Precipitation High Deciduous forest agreement on a satisfactory biological Vegetation Coniferous forest Deciduous forest indicator for use in determining critical Elevation/slope High Low loads for soils, but a number of Soil texture Coarse—sandy Fine chemical limits have been suggested Soil drainage Free Impeded for forest soils (Table 4), and used in Soil/Eill depth Shallow Thick Low High calculating critical loads, with some of Soil sulphate adsorption capacity Base cation deposition Low High these proposed chemical limits, a biological indicator is implicit.

Several rnethods of calculation have been proposed, and they can be divided into two broad groups - those using some type of mass balance calculation, and those using process, or mechanistically based, dynamic models, eg MAGIC, RAINS. In calculating critical loads for acidity, both approaches determine the balance between sources and sinks of acidity. The biogeochemical mass balance approach suggested in the Critical loads for acidity UNÆCE mapping handbook uses the (kEq H+ ha-1 yr1) following equation:

CL (acidity) 4 BC., — BC„— ANCL- 2 NH,„ 0.2 1\iLOTU

where BC 01 = base cation release by 0.5 weathering; BC TL = acidity resulting from base cation uptake; ANC L = ANC 1.0 limit (alkalinity) x water flux; NH41) = ammonium input by deposition; and 2.0 Nrani = total N uptake by vegetation. 4.0

Table 5 Mineralogical classificaUon &sad matebals and critical loads for C0 -50 cm) in each class (after Nilsson & Grennfelt 1988)

Critical load Minerals controlling (kmol

km -2yr-1) aass weathering

5 Quartz <20 K-feldspar

4 Muscovke 20-50 PI iioclase Biotke

3 Biotite Amphibole (<5%)

2 Pyroxene 100-200 Epidote Olivine ,• . )

1 Carbonates >200 Figure 27 Critical loads f o r acidity of GB soils

32 The derivation of the ecpaation is detailed in the mapping handbook (Sverdrup et al. 1990). Base cation release by weathering is the main sink for aciclity as protons are consumed, exchanged for base cations during the weathering process. The net uptake of base cations and ammonium nitrogen by plants is, however, a potential source of acidity, as protons are released from plant roots Exceedance of acidity into the soil solution to balance the uptake of the bases. The mass balance (kEq 1-14- ha-1 yr-1) approach only provides the critical load under equilibrium conditions. More dynamic models facilitate the exploration Not exceeded of time-dependent processes which may influence critical loads. 0.0-0.2

0.2-0.5

0.5-1.0 Critical loads are currently being calculated for several sites in GB, using >1.0 both the mass balance and dynamic modelling approaches. Because only a few sites have all the required input data for the equations or models, a less rigorous approach has been adopted to produce a provisional critical load map for British soils, for use in the early phases of the UN-ECE European mapping exercise.

The provisional map is based upon principles and proposals developed at two workshops, held in 1986 and 1988. The first workshop suggested that critical loads for soils should be set to prevent chemical changes which would lead to long-term harmful effects to the soil/plant system (Nilsson 1986). It also suggested that such chemical changes could be prevented, if acid inputs did not exceed internal (within the soil) alkalinity production, essentially the production of base cations by mineral weathering. The main factor determining the rates of weathering in soils is soil mineralogy. The 1988 Figure 28. Areas where critical loads for acidity of soils are exceeded workshop, at Skokloster in Sweden, divided soil materials into five classes, defined on the basis of their dominant units could then be assigned a critical weatherable minerals (Nilsson & of critical load is used which is at the load. If this allocation were possible, it Grennfelt 1988). Critical loads were lower limit of the values suggested for then assigned to these classes, the given soil material class; if an would provide a relatively rapid method for producing a critical load map for according to the amount of acidity which 'increase' factor applies, then the upper British soils. The approach was first would be neutralised by base cation value is used. tested in two exploratory studies, one in production, by weathering from the north-west Wales and one in northern relevant minerals (Table 5). The critical Given the excellent soil maps and load for a given soil could also be accompanying data bases available for England. In both cases, the relevant adjusted, within the range of values GB, it was felt that sufficient information 1:250 000 soil map produced by the Soil suggested for each class of soil material, might be available for map units on Survey and Land Research Centre by applying modifying factors (Table 6). existing, published, maps to be allocated (SSLRC) was used as the base map. The Thus, if one of the 'decrease' factors to one of the soil material classes defined map units are soil associations, which applies, eg high precipitation, the value at the Skokloster workshop; the map comprise a mosaic of different soil

33 series The associations were allocated 10 km square cells, on the basis of the gas dissolves in water in the to one of the soil matenal classes on the dominant critical load class in the 100 atmosphere before reaching the basis of the mineralogy of the dominant, 1 km squares with the 10 km unit surface For atmospheric sulphur most widespread, soil series dioxide (S02), dry deposition The map shows that soils with small represents the major input in the The results from these trial studies were critical loads dominate in the uplands of south and east of the country where encouraging, but indicated that the western and northern Britain These ambient SO2 concentrations are definitions of the soil matenal classes areas are underlain by rocks which often largest Even in the high rainfall proposed at Skokloster would need contain relatively few weatherable areas of the north and west where modifying for GB conditions The minerals, shallow soils are also common wet deposition dominates, the dry classes were originally defined using Soils with large critical loads dominate in deposition inputs are still important primary minerals commonly found in southern and eastern Britain In these and contribute between 10% and relatively young soils, developed on areas, the soils are often derived from 40% of the total input material denved from igneous and sedimentary rocks, glacial debris or metamorphic rocks, whereas many soils alluvium, and generally contain relatively Unlike wet deposition, dry in GB are denved from sedimentary abundant weatherable minerals deposition is difficult to measure in rocks and are nch in micas and the field and measurement secondary clay minerals Such factors The provisional critical load map has procedures require expensive had to be taken into account when been combined with data on current equipment which, in general, is not allocating the soil associations on the GB pollutant deposition to produce an suitable for long-term momtonng maps to a soil material class exceedance map This map suggests To estimate inputs to the country, it that the critical loads are currently has therefore been necessary to The tnal study in northern England also being exceeded in significant areas of understand the processes which showed the important influence of land Wales, northern England, and Scotland control dry deposition, and to model management on the ability of soils to Reductions in the deposition of sulphur the inputs on a regional scale neutralise acidic deposition (Langan & of up to 80% would be needed to Hornung 1991) In particular, it protect all the soils of GB The process of dry deposition may demonstrated that the allocation of soils be divided into three stages to a soil material class, and hence the M Hornung assignment of a cntical load, should be In the atmosphere, molecules of modified to allow for the effect of liming gas are transported down to the the addition of lime effectively increases References immediate vicinity of absorbing the critical load surfaces (leaves, stems, Bull, K.R. 1991 The critical loads/levels building materials, soil and The approach used in these exploratory approach to gaseous pollutant emission water) by wind eddies studies has now been extended, with control Environmental Pollution, 69, 105-123 (turbulent diffusion) The rate of modifications based on the results of the Langan, S.J. & Hornung, M. 1991 An turbulent diffusion is above studies, to the whole of Great application, and review of the critical load determined by the wind speed Bntam, in a co-operative exercise with concept to the soils of northern England and by the roughness of the the SSLRC, the Macaulay Land Use Environmental Pollution In press ground Wind passing over an Research Institute, and the University of aerodynamically rough surface, Aberdeen (Figure 27) In practice, the Nilsson, J., ed 1986 Critical loads for such as a forest or an urban Stockholm Nordic national critical load map uses a 1 km sulphur and nitrogen area, will induce a much larger Council of Ministers grid, each grid cell was first categonsed rate of turbulent diffusion than according to the dominant soil wind passing over a smooth Nilsson, J. & Grennfelt, P , eds. 1988 association in the 1 km square The Cntical loads for sulphur and nitrogen report surface, like a grass field or associations were then allocated to a soil of a workshop held at Skokloster, Sweden 19- open water matenal class, using the properties of 24 March 1988 Copenhagen Nordic Council the dominant soil series in the of Ministers Close to an absorbing surface, association, chiefly mineralogy and the physical properties of the texture Where the dominant land use in Sverdrup, H., de Vries, W. & gas become much more any 1 km square was arable, or intensive Hendricksen, A. 1990 Mapping cntical important Transport through grassland agriculture, the association loads Copenhagen Nordic Council of the layer of air closest to the was moved to the next lower soil Ministers surface (the viscous boundary matenal class, ie the critical load was layer) is by molecular diffusion, increased to allow for possible impacts and therefore is dependent on of liming The Skokloster approach molecular weight Rates of molecular diffusion are several could not be applied to peat soils Dry deposition of Instead, associations dominated by peat orders of magnitude smaller soils were categorised and assigned a sulphur dioxide in the than rates of turbulent diffusion cntical load using an approach United Kingdom a few metres above the ground developed at the University of Aberdeen, based upon the results of The direct absorption of a pollutant in At the surface, the chemical leaching experiments The map shown gas by terrestrial surfaces is known properties of the gas become in Figure 28 has been derived by as dry deposition, to distingwsh this very important For vegetation, aggregating the 1 km squares into input from wet deposition where the the gas may react on the leaf

34 Atmosphere rba Turbulent diffusion ------• ---0—Vw—o Stomata across boundary layer Canopy I .. _Nvv—o Leaf 1 / \ surfaces ro Molecular diffusion —0.--,\M-0 Surface o OD water / N across viscous sublayer Soil Soil

Figure 29, Deposition pathway of gases and small particles to vegetation and the resistance analogy used to descnbe the process

surface, or it may diffuse Table 7 Land use categones used for the SOs dry deposition model through open stomata and then either dissolve in water or react chemically with other internal leaf components Likewise, for soil, open water or building matenals, the rate of reaction or sorption at these surfaces has a major influence on rates of deposition *Arable, grassland and hill vegetation all show a seasonal dependence on canopy height and leaf area index, monthly values are used, taken from the literature in the ranges shown These three stages in the deposition process are generally quantified using a resistance analogy, in which The uptake of SO2has been show that, in most cases, the the flow of pollutant gases or measured for a range of vegetation, stomatal resistance for water vapour particles is considered as analogous including grass, wheat and pine loss can be used to deduce rates of to the flow of electrical current (Pmusspp ) forest, and over various SO2uptake by vegetation Because through a network of resistances soil types These measurements bulk canopy stomatal conductance (Figure 29)

The two atmosphenc resistances, for the free atmosphere (ram) and for the viscous boundary layer (rbg), may be estimated from the wind speed and — 21 Mar the roughness length of the surface . • • • • . . - • •21 Jun (Thom 1975) The surface t: 0 625 . • ..... 1‘. .*Ir.": 7 .'4' \,, • . — —21 Sep resistance has so far been °. .e.. --- 21 Dec E determined by measurement In c.) practice, the total resistance to dry >. 05 deposition is determined by 3 measuring the flux to the ground, cn / the atmosphenc resistances (ram and c> 0 375 rbg) are estimated directly from wind 0 / .= and temperature velocity profiles, / ... .„.... •••• ••• and then a bulk surface resistance .•••• es §.e. 025 .... •••• ...... — ..-. (re) can be calculated The stomatal ci component of re may be calculated from porometry measurements or 0 0500 1000 1500 2000 2500 from bulk canopy resistance to Time (h) water loss using micro- meteorological methods (Monteith & Unsworth 1990) Figure 30 Daily cycle in deposition velocity of sulphur dioxide to forest

35 •

The atmospheric resistances (ram and rb9) are calculated from the roughness of the vegetation and the average wind speed, assuming a logarithmic wind profile in the atmosphere close to the earth's surface. For each vegetation type, the physiological processes controlling gas uptake by stomata are modelled using mod fied 'big leaf methods (Monteith & Deposition Unsworth 1990; Hicks et al, 1987), and (gS rn-2 yr-1) the surface resistance is determined from the leaf area, air temperature >2.0 and solar radiation, Stomatal opening n 1.0-2.0 characteristics and leaf (external) 0.5-1.0 surface uptake are quantified from published data for a range of species. 0.25-0.5 The computed deposition velocities 0.125-0.25 for each vegetation type are then used to estimate the overall >0.125 deposition rate, using an SO2 concentration field in which interpolated rural values are replaced by the average of urban and suburban measurements in those 20 lcn squares where the latter data were available.

Figure 30 shows the hourly variation in deposition velocity for SO2 on to one of the land uses (forest) computed for four days in the year. The pronounced effect of day length on stomatal opening is clear, but also the very small increase in deposition velocity in December is partly due to the temperatures being close to the threshold for stomatal opening and so causing stomatal closure. The small decline in deposition velocity at mid- day on 21 June is the result of water stress on plants, and is a commonly observed property of plant canopies.

The dry deposition of SO2 to the UK computed using this model is shown in Figure 31. The largest values occur in the industrial Midlands of England with annual inputs of approximately 3 Figure 31, Dty deposition of sulphur in the UK g S r1C1-2. The overall pattern in dry deposition closely follows that of ambient SO2 concentration. These can be approximated for plant meteorological variables, and a values for dry deposition of SO2 are canopies from available radiation model of plant surface resistance to considerably smaller than those and temperature data, we can model estimate rates of deposition to five estimated earlier (ROAR 1987), SO2 uptake over a wide variety of major land uses. The land within because of smaller SO2 concentrations vegetated surfaces for extrapolation each 20 km x 20 kTri grid square is and a reduction in deposition to the countryside of the United classified into arable, grassland, hill velocities. It appears that earlier diy Kingdom (Fowler 1984). vegetation, forest or urban, using ITE land use data. Vegetation height deposition estimates were significantly overestimated. The approach recently adopted for and leaf area index were estimated estimating regional dry deposition for each day (Table 7) and used with inputs of SO2 in the UK uses a the ambient SO2 concentration, wind An important area of uncertainty in the combination of land use and speed, air temperature, and solar dry deposition of SO2 is the influence topographic data, averaged radiation data. of ammonia on rates of leaf surface

36 -

SO2 uptake. There is growing evidence from recent field studies that large ambient ammonia concentrations increase the rate of SO2 deposition. In practice, this would increase the amounts of sulphur deposited in the areas with large ammonia concentrations, but the magnitude of the effect is as yet unknown.

D Fowler and R I Smith

References

Fowler, D. 1984. Transfer to terrestrial surfaces. Philosophical Transactions of the Royal Society of London, B, 305, 281-297.

Hicks, B.B., Ealdocchi, D.D., Meyers, T.P., Hosker, R.P. & Matt, D.R. 1987. A preliminary multiple resistance routine for driving dry Plate 13. Some of the eguiPment installed at the experimental site at Halvergate marshes, Norfolk deposition velocities from measured guantrates. Water, Air and Soil Pollution, 36, 311-330,

Monteith, J.L. & Unsworth, M.H. deposited on vegetation and emitted measurements provides an insight 1990. Principles of environmental physics. by vegetation, but in very different to the effect of land use on the 2nd ed. London: Arnold. surface conditions. atmospheric composition for those sites leaking reactive nitrogen to the United Kingdom Review Group on Numerous measurements of the atmosphere. Where inputs of Acid Rain (RGAR). 1987. Acid exchange of one or two of the above nitrogen exceed outputs - which is deposition in the United Kihgdom 1981- nitrogen-containing gases have been almost invariably true for semi- 1985. Stevenage: Warren Spring made in field conditions. However, natural ecosystems in the UK as a Laboratory, a knowledge of the net exchange of consequence of pollution, the biological effects of the deposited Thom, A.S. 1975. Momentum, mass and reactive nitrogen species (ie all heat exchange of plant communities. In: gases excepting N2) is much more nitrogen may be examined in terms Vegetation and the atmosphere, edited by valuable. Such a set of of the net inputs. J.L. Monteith, 57-110, London: Academic.

500

Rn 400 G - y- C 300 -9-- LE The nitrogen-containing trace atmospheric gases exhibit three contrasting types of exchange with vegetation and soil, Reactive pollutant gases such as nitric acid (HNO3) and peroxyacetyl nitrate 100 (PAN) are deposited on vegetation, water and soil, and, for unmanaged ecosystems (eg moorland), represent a source of nitrogen for plant nutrition. Nitric oxide (NO) -100 and nitrous oxide (N20) are emitted 0 300 600 900 1200 1500 1800 2100 2400 by soil following microbial Time (GMT) production. Gaseous ammonia (NH3) and nitrogen dioxide (NO2) have both been observed to be Figure 32, Halvergate radiation balance, 18 September 1989

37 installed at the site, including eddy correlation sensors for determining 250 atmospheric turbulence, fast- response gas analysers placed on the tower, profile anemometers and 200 o TNO temperature sensors on the smaller ITE masts, and the mobile laboratories x IFU belonging to each group 150 + UMIST x HYDRA A radiant energy budget for a typical 7 E 100 day during the campaign, 18 September, is shown in Figure 33 From this sort of information, it is 50 possible to determine not only the partitioning of energy and the value of various exchange coefficients, but v 'V 0 also the bulk stomatal resistance of x vo 00 0 0 0';k7 the canopy The provision of basic 0 xxx plant physiological information is -50 x invaluable for studies of trace gases 00 00 04 48 09 36 14 24 19:12 00.00 which are frequently emitted or absorbed by plants via the stomata Time (GMT)

Figure 33 Halvergate sensible heat flux , 19 September 1989 One of the most important features of the Halvergate experiment was the extensive measurement of At some sites, therefore, we need to dioxide (SO2), between the micrometeorological variables by a study the full range of gases atmosphere and the land surface range of methods, which provided exchanged in order to quantify the valuable opportunities to contribution which each gas makes to The site consisted of unfertilised intercompare fluxes of basic the net exchange, and to investigate pasture (drained marshland) 2 m quantities (sensible and latent heat, the processes controlling fluxes above sea level, from which cattle had and momentum) Such an exercise been removed a short time before the enables a detailed analysis of energy Measurements of the exchange of beginning of the exPeriment A large budgets and of the behaviour of the trace gas species between natural array of equipment was set up by the crop surfaces and the atmosphere have various groups in order to measure been conducted at ITE for several gas concentrations and various micro- One of the intercompansons possible years, and recently the work has meteorological parameters Plate 13 was that of sensible (or convective) been expanded to include shows some of the equipment heat flux An example from 19 collaborative experiments with other European research groups The most recent joint experimental campaign occurred in September 1989 at the 50 Halvergate marshes in east Norfolk Groups from the UKCrrEEdinburgh, -.-- NO (grad) Atomic Energy Authonty Environment ao -.- ITE (grad) and Technology, University of -w- S (box) Manchester Institute of Science and -8- IFU (box) Technology, University of Essex), and 30 -e- IFE (EC) the Continent (Netherlands 7(0 Organisation for Applied Scientific Research, Institut fur Atmosphansche 1 2° Umweltforschung, Germany, z University of Stockholm, Sweden) F 10 participated in the three-week campaign, which was co-ordinated bylTE 0

The objectives of the experiment were to determine the exchange of -10 trace gas species, such as mtnc oxide 00 00 0448 09 36 14 24 19 12 00 00 (NO), nitrogen dioxide (NO2), nitric lime (GMT) acid (HNO3), nitrous oxide (1\120), ammonia (NI-13),peroxyacetyl nitrate (PAN), ozone (03) and sulphur Figure 34 Halvergate NO fluxes, 19 September 1989

38 when stomata were closed, the fluxes were small, and increased as the stomata opened during the day, as 30 the stomata closed again during the afternoon and evening, the fluxes declined Minimum canopy 25 resistances in the order of 100 s m-1 were calculated, a value typical of an CO 20 unstressed grass canopy

Interpretation of the results is 15 comphcated by rapid chemical reactions which affect these three gas species NO and 03 react rapidly to 0 produce NO2, whilst NO2 in the presence of ultraviolet light (contained in dayhght) is rapidly 5 photolysed to NO Analysis is in progress, but, for most of the 0 experimental penod, the corrections 00 00 04 48 0916 14:24 19:12 00 00 to fluxes of 03 for the effects of Time (GMT) chemical conversion in the lowest 3 m above the surface (where measurements were made) were a Figure 35 Halvergate NO flux, 15 September 1989 small fraction of the flux (Hargreaves et al 1991) This is a consequence of the relatively small ambient NO September is shown in Figure 33 soil temperature on this day was concentrations at this site Despite the use of three different insufficient to produce any techniques by five different groups, detectable variation in emission rate Ammonia was emitted from the site the agreement between the different Ozone and nitrogen dioxide were with net fluxes in the order of 100 ng systems is excellent when the both shown to deposit to the canopy nr2 s-1 These large emissions were physical separation of equipment at maximum rates in the middle of caused by the recent presence of along a 150 m cross-wmd transect the day These deposition cattle on the field, and the magnitude considered processes were shown to be of the emissions declined during the controlled by stomata, indicating that the pathway for the exchange of experimental penod as soil ammomum status declined Sulphur Similar mtercompansons were these two gas species is via the possible when considering the trace stomatal cavity During the night dioxide is normally deposited to gas fluxes, and Figure 34 illustrates mtnc oxide fluxes deterrruned by four groups using three techniques Some of the measurement systems measured the fluxes over areas as small as 1 m2, whilst others made 0 integrated measurements extending to a scale of lalometres Despite this variation in scale, the fluxes agree -10 rather well with the exception of one data point, all groups detected emission of NO at rates up to 40 ng nr2 s-1 (Note that the convention for trace gas exchange is that emission of a gas has a positive sign convention and deposition a negative one )

-40 Results obtained by ITE on one other day (15 September) are included in Figures 35 and 36 Again, these results indicate an upward NO flux -50 of 10-15 ng nr2 s-1 The source of 00 00 04:48 0916 14 24 1912 00 00 the gas is microbial mtnfication lime (GMT) Although soil temperature plays an important role in the rate at which nitrification occurs, the variation in Figure 36 Halvergate NO2 flux, 15 September 1989

39 NH3 SO2 Ambient concentration (2 rn) 4 3 pg m-3 (63 ppb) 4.511g rn-3 (1 6 ppb)

Net flux 100 ng rn-2 s-1 60 ng rn-2 s-1

5.88 p.mol rn-2 s-1 0.94 p.mol rn-2 S-1 11 Emission Deposition F01 stomata 46712 ng rn-2 s-1 i NH3 e • Fc2 cuticle

41 48 ng rn-2 S-1

16 og...% It .1.ttkg ft/01 14414.0011( . (•1434,•60,....46,2414.,:i.I.I.:(..,4;2414.

Figure 37 Interactions of NH3and SO2 surface/atmosphere exchange, measured over grassland at Halvergate, Norfolk

vegetation via the stomata, but, in Vegetation has been shown to be a used to gauge the magnitude and the presence of large quantities of perfect sink for nitric acid (Dollard, direction of average summer fluxes ammonia, a significant proportion is Jones & Davies 1991), and this was for the whole range of trace deposited to leaf surfaces (Fowler, confirmed at the Halvergate site nitrogen-containing gases The Duyzer & Baldocchi 1991) There Deposition fluxes of PAN were estimated budget (Figure 38) shows was clear evidence of this 'co- generally very small, and made no a significant net loss of nitrogen (40 deposition' of NH3 and SO2 at the significant contribution to the total kg ha-1), mainly as NH3 and N20 but site, as surnmansed in Figure 37 nitrogen budget of the site including NO The inputs of Nitrous oxide was also emitted, at nitrogen as PAN, NO2 and HNO3 are rates of around 50 ng m-2 s-i, Although these measurements were small by comparison Scaling up to probably as a result of nitnficaton or concentrated on a four-week the growing season is, of course, a denitnfication intensive study, the data may be speculative process, and more

Nitrogen Nrtnc oxide dioxide Nitric acid Nitrous oxide Ammonia 30 10 10 50 130

Typical summer gas fluxes Atmosphere (ng rn-2 s-1) I 1

Vegetation

.-..**. .; .' Soil / i,. ..w • •• • Net loss April-October - 40 kg N ha-1

Figure 38 Halvergate nitrogen budget

40 precise estimates of individual fluxes using process-based models are necessary to reduce the uncertainties. However, for this site, the scaling up process provides a valuable guide to the gases which determine both the net direction and magnitude of the nitrogen exchange.

K J Hargreaves and D Fowler

References

Dollard, G.J., Jones, B.M.R. & Davies, T.D. 1991. Measurements of gaseous hydrogen peroxide and PAN in rural southern England. Atmospheric Environment. In press.

Fowler, D., Duyzer, J.H. & Baldocchi, D. 1991. Inputs of trace gases. particles and cloud droplets to terrestrial surfaces. Philosophical Transactions of the Royal Society of Edinburgh. In press. Plate 14. Study sheep ih uplands of west Cumbria

Hargreaves, K.J., Fowler, D., Storeton-West, R.L. & Duyzer, j.H. 1991. The exchange of nitric oxide, amount in western Europe. show a 400-fold variation in the plant/ nitrogen dioxide and ozone between However, during the analyses of soil concentration ratio in a single pasture and the atmosphere. sheep tissues (Plate 14), we found plant species. Data on the Environmental Pollution. In press. that, apart from radiocaesium and metabolism of silver by animals radiosilver (11tmAg) (physical mostly relate to the study of argyria half-life = 250 days) was routinely (the deposition of silver in the skin detected in the liver. Although only a and various body organs resulting in minor constituent of the fallout (Table a blue/grey pigmentation) in humans 8), the activity concentration of following industrial exposure, and ill'Ag in the liver of sheep was more commonly to the medical use sometimes as high as that of 13405 of silver. These results are of limited (This work was partly funded by the (Beresford 1989a). value in understanding the Ministry of Agriculture, Fisheries and behaviour of radiosilver released Food and Nuclear Electric, and into the environment. No studies had conducted in collaboration with the been conducted on silver uptake and Macaulay Land Use Research Institute) Data on the behaviour of silver in the metabolism by food-producing environment are sparse. Although animals. Recommended values for the factors influencing the behaviour the transfer of u1'11Ag to ruminants for of silver in soils are fairly well use in predictive models were based understood, results for its uptake on limited and diverse data. It was The accident on the 26 April 1986 at and translocation by vegetation can even unclear which organs would the Chernobyl nuclear power concentrate ilomAg. A small research complex in the Soviet Ukraine programme was, therefore, initiated released large amounts of Table 8. Gamma-analysis of a vegetation at ITE Merlewood to study the sample collected on 6 May 1986 from an upland radioactivity into the atmosphere. transfer of radiosilver within the site in west Cumbria High levels of fallout were deposited environment. throughout Europe, and enhanced levels of activity were detected in the northern hemisphere.

The prime cause of concern Studies on the transfer of silver to following the accident was the need vegetation agreed with previous to identify potential pathways to man suggestions that silver is more of the most radiologically significant mobile in soils with a low pH. For nuclides present — the radiocaesium organic soils with a low pH, as found isotopes '31Cs and f3ICs and iodine in the uplands of west Cumbria, a as 'II. Radiostrontium and actinides plant/soil transfer ratio (expressed as (eg plutonium and americium) were a ratio of concentrations) of more not deposited in any significant than two is estimated. This figure is

41 higher than some earlier results would have suggested Given the 1000 % limited nature of the data available, — —— — Cs muscle % - - Cs liver further studies on factors affecting % \ Ag liver the transfer of deposited radiosilver I 800 1 to vegetation are required, t 1 especially in relation to semi-natural % ecosystems because they are more 1 likely to receive high levels of fallout 600 % in future nuclear incidents, often u_ x 7 % have low pH soils, and they provide 0) \ a potentially important pathway for 0 transfer of radioactivity to man via co 400 grazing ruminants Additional studies mvestigatmg the behaviour of silver in soil types typical of those 200 close to nuclear installations would „ also be useful .,...... _ - The transfer of liomAg to o 20 40 60 80 100 120 animals Time (d) The liver was found to be the most important organ when considering Figure 39 A companson of the changes in radiocaesium (134Cs+137Cs)activity concentration in the hver and muscle of a '1000 Bg kg-1 sheep' with changes in the 111)mAgactivity concentration in the transfer of immAgto grazing the hver when the sheep is removed from contaminated to uncontaminated pasture (the curve for animals, both because of a high 11omAg takes account of physical decay of the isotope) uptake from the blood and a long biological half-life Advised equMbnum transfer coefficients* were placed on the movement and represents a 'worst case' example denved from this work for ilomAgto slaughter of sheep at 8914 farms in Applying a value of 87 5 days the hver of sheep are in the order of the UK in 1986, where 134Cs+137Cs (measured in a metabolism cage 5-10 d kg-1 and 1-3 d kg-1 for lambs levels in the muscle exceeded 1000 study) for the biological half-life (Tioo) of 1 — and ewes respectively However, Bq kg-1 fresh weight (FW) Sheep 1omAy in the hver and rates of loss this value may decrease if ilomAgis from the restricted areas with over for radiocaesium from sheep incorporated into plant tissues 1000 Bq kg-1 FW were allowed to calculated by the model, we can leave the areas, but were grazed on compare changes in the activity Transfer parameters denved for less contaminated lowland pastures concentration of radiocaesium in muscle suggest that previously to allow their radiocaesium activity to muscle and hver with that of immAgin advised values given in the literature decrease before entry into the the hver for a '1000 Bq kg-Isheep' were overestimates In contrast to foodcham after it has been transferred from radiocaesium, muscle is unlikely to contaminated to uncontaminated be important when considering the Using a model of the behaviour of pastures (Figure 39) Because of its transfer of radiosilver to grazing radiocaesium in sheep developed longer T1/2b, the l mmAgactivity in the animals, as it has a transfer jointly with the University of hver exceeds that of radiocaesium coefficient about four orders of Nottingham (Galer et al 1990), the after ten days After about 35 days, magnitude lower than that of the radiocaesium activity in the hver of a the activity concentration of 1lOmAg in hver The only tissue other than the sheep with 1000 Bq kg-1 FW in its the hver is greater than that of hver which was found to have muscle can be calculated Using a radiocaesium in muscle We can, detectable levels of ImmAgfollowing 134CS/ 137CS ratio for radiocaesium in therefore, predict that the immAg the Chernobyl accident was the Chernobyl fallout in the UK of 0 53 activity concentration in the hver for brain (Beresford et al 1990) and a ratio of such an animal, at the time of i10mA—/g ii7Cs in the hver of sheep slaughter, could be higher than that of To illustrate the potential importance soon after Chernobyl of 0 67, the other artificial radionuchdes in any _ 110m — of i 10mAy in the hver soon after a Ay activity concentration in the other tissue radioactive deposition, we hver can be estimated (Figure 39) A considered the situation in the ratio for bomAg/137Csof 0 67 was the An alternative and potentially upland areas of the UK following the highest value found during the work important route for the transfer of Chernobyl accident Restrictions conducted, and, therefore, probably "Om Ay —to man is through cattle

*The transfer coefficient (Ft) is commonly used to describe the transfer of radionuchdes from feed to animal tissues or milk It is represented by the equation Ff = Activity concentration of ''°"'Ag in a tissue (13qkg-1 fresh weight) Daily intake of ll'Ag (Eq d-1)

42 Table 9 Predicted activity concentrations of the soil surface, Kanyar et al (1990) lioinAg in vanous environmental components state that milk will provide the around a Hunganan PWR nuclear power station largest contribution to the radiation (Kanyar et al 1990) dose caused by 1 lornAg Despite its Estimated apparent importance, there are no Environmental activity rehable estimates of the transfer of component concentration radiosilver to milk (rnBq kg-1) N A Beresford Soil rooting zone 21 Hay (dry) 34 Cow milk 12 References Cow hver 115 Beef 037 Beresford, N.A. 1989a Field Leafy vegetables 35 observations of Ag-110m, originating from Root vegetables 15 the Chernobyl accident, in west Cumbnan Grain 43 vegetation and soil samples Journal of Radiological Protection, 9, 281-283

Beresford, N.A. 1989b The transfer of Ag-110m to sheep tissues Science of the Cows' milk is known to be an Total Environment, 85, 81-90 important source of some radionuchdes to man, and perhaps Beresford, N.A. , Barnett, C.L., Howard, the most senous gap in our current B.J., Poskitt, J. & Dighton, J. 1990 understandmg of the environmental Vegetation and soil survey in Cumbna to behaviour of radiosilver is the lack of validate the aenal survey of 1988 (NERC contract report to Ministry of Agnculture, data on its transfer from feed to cow Fishenes and Food ) Grange-over-Sands milk The importance of this Institute of Terrestnal Ecology parameter is illustrated by recent results from Hungarian scientists Galer, A.M., Crout, N.M.J., Beresford, N.A & Howard, B.J. 1990 Increasing levels of llomAg are being Modelling radio-caesium transfer in discharged from Hungarian nuclear upland ecosystems In 1st International reactors (Hoang et a) 1990, Kanyar, Conference on the Biological and Fulop & Kerekes 1990) In 1989, the Radioecological Aspects of the Consequences of the Accident at airborne release of ilomAg from one Chernobyl Atomic Station, 264 Moscow Hungarian PWR was 2 GBq, Academy of Sciences of the USSR compared with less than 50 MBq for cobalt (aa soco), 13i/ and 137Cs Hoang, T.S., Szerbin, P., Stur, D. & combined The increase in the Korosi, F. 1990 Uptake of Ag-110m by discharges of immAg (0 74 GBq were PIS= satwum In Proceedings of discharged in 1988) may be due to Conference on Radioecology, 124 Kosice the bomposition of the stainless steel [RANT reactor tank Kanyar, B., Fulop, N. & Kerekes, A. 1990 Modelling of the 116)inAg transport in Kanyar et al (1990) have attempted the terrestnal foodchain and dose to model the behaviour of liomAg in assessment around the nuclear power the terrestrial foodcham around the station in Hungary Presented at Biomovs, power plant in order to conduct a Stockholm, Sweden, 7-11 October 1990 dose assessment, and the model parameters include ITE data for the transfer to the hver of grazing animals (Beresford 1989b) Table 9 shows the ilomAg activity concentrations estimated by the model for a number of environmental components

Cow hver is predicted to have the highest activity concentrations of l wmAg, as would be expected from our results for sheep However, milk is estimated to be the food product with the second highest immAg activity concentration Additionally, apart from the radiation dose from

43 Population ecology

Research in this programme is concerned mainly with dispersal, while salmon harvest, but an attempt to model concerned with understanding what the ant studies are designed to unravel such impact (Shearer et a/ 1987) was determines the distnbution and some of the complexities of ant societies disadvantaged by a lack of precise data abundance of wild plants and animals The present study (1987-90) was The distnbution of any organism is commissioned by the Scottish Office constrained to a large extent by the Agriculture and Fishenes Department to distribution of its habitat, but within that remedy this situation by quantifying the habitat numbers may be influenced by Predation of juvenile population of mergansers on the North the supply of food and other resources, salmon by red-breasted Esk and estimating the numbers of or by the pressure from natural enemies, mergansers salmon they eat such as predators and parasites (This work is being funded by the Scottish Current research covers all these Office Agnculture and Fisheries Department) Population aspects on one species or another, with detailed studies on plant/herbivore, Red-breasted mergansers (Mergus Mergansers came into freshwater in predator/prey and host/parasite serrator) are highly speciallsed ducks April, their numbers peaked at the end interactions which feed mainly on small fish and of April or in May, and fell thereafter crustaceans In Bntam, they spend the (Figure 40) Many birds were in pairs One research area of particular interest winter at the coast but move inland to when first recorded, but they did not at the present time concerns the breed, some to standing waters, but breed until late spring, females laying fragmentation of habitats arising from many to the lower reaches of nvers eggs in May and beginning incubation in human activities, which leads to the where they eat young salmon (Salmo late May and in June Most ducklings increasing isolation of populations New salar) On the nver North Esk in eastern hatched in July and fledged in research is concerned with the genetic Scotland, mergansers are abundant September, rapidly dispersing soon consequences of such isolation, and with during May when juvenile salmon after the role of dispersal in ensuring the (smolts) are migrating downstream to persistence of isolated populations the sea Studies of these fish involve Drakes abandoned incubating females, Another new area concerns the fitting them with external fin tags, many leaving the nver in June and apphcation of molecular genetics of which have been recovered from the congregating to moult on the sea nearby techniques to measure the degree of stomachs of mergansers shot under in July and August Few mergansers genetic differentiation between licence It has been suggested that were seen on the nver from late October populations, and the rates of gene flow these ducks could consume so many through to mid-February through populations Knowledge of the smolts as to significantly reduce the latter is helpful in predicting the rates of numbers of adult salmon returning to The numbers of mergansers along the spread of genetically engineered home waters and thus reduce the whole nver (Table 10) vaned features Such knowledge is likely to be increasingly required in future as genetically engineered organisms are released into natural environments A third area of new activity concerns an 20 assessment of the effects of climate tn • change • :5 •• • -510 • • • • The projects described illustrate a cross- ci • z • • • • section of long-established work The • •• research on ducks forms part of an •• • 0 attempt to assess the impact of these AM J • J • A S ON DJ FM A M birds on fish stocks in Scottish nvers, 1987 1988 while the work on sparrowhawks Month (Accipiter msus) describes the recovery in a population following reductions in the use of harmful pesticides to which Figure 40 Seasonal trends in the number of red-breasted mergansers seen on a sample of these birds are unusually sensitive The freshwater sections of the nver North Esk, eastern Scotland The sohd circles gwe weekly counts work on amphibia and reptiles is and the line connects five-week running means

44 Table 10 Annual estimates of the numbers of red-breasted mergansers on the nver North Esk and (large invertebrates and tiny fish) in moulting offshore, 1987-90 shallow pools, enhancing the foraging of small ducklings, and so their survival

Diet

Merganser diet was estimated from the boney remains of fish in stomachs (Feltham & Marqiuss 1989, Feltham 1990), of adults ducks shot in April, May and June, and of ducklings shot in August

At least six species of small fish were eaten by ducklings Salmon were only a minor part (<5% of mass) of the stomach contents, which were dominated by stickleback (Gasterosteus aculeatus) and *57 mergansers were counted on 60 km of nver in 1987 The numbers of birds on the remaining gadoids in ducklings from near the nver 25 km were estimated using the relationship between density and elevation (Figure 41) mouth, and by small trout (Salmo trutta) in ducklings from 20 km further upstream enormously from year to year in April, week of hatching, and the numbers but were reasonably constant in mid- surviving to complete growth were In spring, adult mergansers also took a May just pnor to breeding Such greatest when nver flow was very low vanety of fish species, including trout, stability in breeding numbers was for the main penod of hatch (Table 11) eel (Anguilla anguilla), brook lamprey unexpected, for between 12 and 31 High flows may physically disrupt (Lampetra plamen), stickleback, minnow ducks were shot in April each year as broods so that ducklings become lost (Phoxmus phoxmus), sandeel part of a licensed cull by fishery and die through lack of brooding (Ammodytes sp ), goby (Goblus sp ), managers Either the shot birds were Alternatively, low flows concentrate prey flounder (Platichthys Ilesus) and transients, passing through in April, or they were local breeders that were quickly replaced within the subsequent Table 11 The annual vanation in the production of fledged young red-breasted mergansers on weeks If this were the case, the late the North Esk, in relation to nver flow, measured (in cumecs) at Loge Mill (data supplied by the spring population of about 75-80 Tay River Punflcation Board) mergansers (29-32 pairs) could have been the upper limit that the nver could support in those years

The numbers of almost fully grown ducklings vaned from year to year (Table 10) Most ducklmgs died within a *Mean (+SE) daily discharge during the period of hatch (12 June-5th August)

stoneloach (Noemacheilus barbatulus), 20 but generally 50-66% of the fish found in stomachs were juvenile salmon Judging from their size, most of these salmon • were small 'resident' fish (parr), few of them were over 9 cm in length and therefore, potentially, smolts Such larger fish occurred mainly in ducks shot • in April, almost none were present in ducks shot in June This seasonal decrease in the average size of salmon 5 • • • consumed resulted in a large decrease • in the proportion by mass of salmon in the overall diet, from 60% in April, to 29% in May, and 15% in June 0 0 50 100 150 200 250 300 350 Predation of salmon in relation to Height (m ad) their abundance

Figure 41 The distnbution of red-breasted mergansers on the nver North Esk, eastern Scotland, with Mergansers did not take salmon smolts respect to elevation Data are from a mid-May census of the whole nver m 1988 Points denote in direct proportion to their abundance in counts of mergansers within 5 kin sections of the nver the nver First, most smolts consumed

45 by ducks were much smaller thanof mortality? These questionschemicals require were known to have average size, not because ducksintensive could work on duck foragingcaused ecology, a decline in the population in not consume large fish - occasionallyincluding some small experimentsthe late 1950s, HEOD McreasMg the they took quite large trout -removing but ducks and/or removingmortality fish in ofa adults and DDE causing apparently because small =ohscontrolled were situation, whilst eggshellsimultaneously thinning and breakage, easier to catch than larger onesmeasuring which parr populations. thereby reducing the breeding rate can swim faster. Second, most smolt- (Newton 1986). Sparrowhawks sized salmon were taken by ducksM Man:piss in and M J Feltham* accumulated these pesticide April, at the start of the smolt(*University migration; of Stirling) residues from the bodies of small fewer were taken during the peak of birds which formed their prey (Plate the migration in May when thousands 15). Sparrowhawks found dead in more were present. Third, fewerReferencAs eastern England over the period smolNsized fish were taken in 1987 1963-90 showed a significant Feltham, M.J. 1990. The diet of red- reduction in HEOD levels in their (12%) and 1990 (19%) than in breasted1988 mergansers (Alergus serrator) during (34%) and 1989 (39%), despite larger livers from around 1975, and a the smolt run in northeast Scotland; the reduction in DDE levels from around numbers of smolts migrating inimportance those of salmon (Salmo salar) smolts and years (199 000 in 1987 and 175parr. 000 Journal in ofZoology, 222„ 285-292. 1980 (Figure 42). The decline in 1990, compared with 141 000 in 1989 - HEOD contamination was especially D A Dunkley, unpublished information).Feltham, M.J. & Marquiss, M. 1989. The marked, and followed a major use of first vertebrae in separating, and reduction in the agricultural use of A further apparent anomaly wasestimating that the size of t out (Salmo trutta) and aldrin and dieldrin, both of which salmon (Satno salar) in bone remains. Journal were withdrawn at that hme from breeding mergansers in May wereofZoology, 219, 113-122. most abundant on the lower sections use on autumn-sown cereal grains. From then on, increasing numbers of (Figure 41), where the river Shearer,was wide W.M., Cook, R.M., Dunkley, and slow-flowing. Salmon parrD.A., were Maclean, J.C. & Shelton, R.G.J. sparrowhawks were seen in the the major prey at this time of1987. year, A modal toyet assess the effect ofpredation region, and increasing numbers of parr densities and biomass wereby sawbill ducks on the salmon stock of the river carcases were received for study greatest at higher elevationsNorth in Esk. Scottish Fisheries research report (Figure 42). The start of Me narrower, fast-flowing river no.sections 37. population recovery was associated where ducks were scarce. One more closely with the reduction in explanation could be that duck HEOD contamination than with the abundance was related to prey reduction in DDE. availability rather than to prey abundance. Salmon parr could have tf_hllielle,A more detailed study of the been easier to catch on the lower river population recovery was made in a sections where the bottom substrate 200 km2 area centred on was finer, less cobbled, with perhaps Rockingham Forest in the north-east less 'cover' and fewer refugesThis for study fish. describes Me recoveryof Northamptonshire, in where Me numbers of sparrowhawk sparrowhawks were last known to (Acc)pitar nisus)in eastern England,have nested about 1960. In 1979 a associated with a reduction insearch of most of the woodland in contamination from organochlorinethe Rockingham area revealed three It is theoretically possible to model the new nestsbut no old nests impact of merganser predationpesticide on residues, namely HEOD (derived from aldrin and dieldrin)remaining from previous years. salmon harvest, but the process has Hence, 1979 was probably the first become quite complicated, We andnow DDE (derived from DDT). These know that, at least on the North Esk, mergansers take far fewer smolts than was previously thought, but large numbers of parr. They selectively prey on fish of certain size classes and living in particular places, so an 'impact' model needs to incorporate intricate population dynamics, including the probability of survival of fish of different sizes living in different places. Moreover, we need to know whether the removal of fish results in the enhanced survival, or growth, of those that remain, and whether merganser predation on saknon is additive or compensatory to other sources of mortality. In other words, if we release fish from merganser predation, what proportion will be lost by a Plate 15. Sparrowhavvk at nest. These hawks nest ih woodland and hunt Ihe small birds that occur 117 corresponding increase in otherwoods causes and farmland

46 year of renewed nestmg in the area, following increased sightings in the 100 —Carcases 38 region as a whole Over the next 11 years, when all the woodland was DDE searched annually, nest numbers 50 HEOD 34 increased progressively from 17 in 1980 to 96 in 1990 (Figure 43), a 30 mean growth rate of 20% per year By 1990, some areas of vacant habitat still remained, malang further 26 o increase seem likely (Wylhe & 0.) Newton 1991)

" CD Over the years 1980-88, based on a capture/recapture procedure, the

18 CD- • annual survivorship of breeders was estimated at 76±SE 6% for males and 74±SE 4% for females (sex 141 difference was not significant) This survivorship was high compared to that in two areas from which 10 estimates had previously been 0.50 obtained for females of 65±SE 3% 0 40 and 62±SE 3% respectively (Wylhe 6 0 30 & Newton 1991) These figures thus 0 20 indicated that, during 1980-88, 2 mortality in the Rocicingham area was no longer greatly enhanced by <0 10 pesticide contamination 1960 1965 1970 1975 1980 1985 1990

Year Over the years of increase, breeding success in Rockingham Figure 42 Numbers of sparrowhawk carcases received from eastern England, 1963-90, gradually improved from an together with trends in the levels of DDE and HEOD found in their hvers For both chemicals, hnes show 5-year moving geometnc means The increasing numbers of carcases received for average of about 1 8 young per study reflected the recovery of the sparrowhawk population in the region clutch in 1980 to an average of 2 9 in

•...•....•„.•••...•••

1980 1985 1990 1980 1985 1990 1980 1985 1990 Year

Figure 43 Trends in organochlonne levels, sparrowhawk nest numbers, and breeding success , Rockingham Forest,1979-90 Organochlonne levels (HEOD and DDE) were measured in addled eggs, and are expressed as pg g-1 wet weight

47 The general conclusion was that the II 1.4 30 recovery of the sparrowhawk population was mainly dependent on • declining HEOD contamination, with a resulting improvement in survival Z,c 1 3 20 z • In the earlier years of increase, breeding success was still • depressed by DDE, but it improved €10 during the 1980s, as DDE •• • • • contamination declined The study 0 • • • • provided a good example of a • recovery in a wild animal population 1.1 0 after a decline in environmental 5 10 20 5 10 20 pollution 90 4 I Newton and I Wyllie •

• • References

• Newton, I. 1986 The sparrowhawk Calton Poyser

Wyllie, I. & Newton, I. 1991 Demography of an increasing population of sparrowhawks Accipiter nisus Journal of 30 1 Animal Ecology In press 5 10 20 5 10 20 DDElevels Figure 44 Relationships between annual mean DDE level (log scale) in addled eggs (pg g-1 wet weight) and (imean shell thickness mdex (measured as shell weight (mg shell length-1 x breadth Recolonisation of (mm)), (n) % of clutches which failed through egg breakage, (m) % of clutches which hatched, and disturbed heathland by (iv) mean number of young per clutch Significance of correlations (i, DDE vs shell mdex, reptiles and amphibians r = —0 968, P<0 001, (n) DDE vs % clutches broken, r = 0906, P<0 001, (iv) DDE vs mean number young per clutch, r = —0 804, P<0 01 (This work was partly funded by British Petroleum)

1990 (Figure 44) This improvement negative) (Figure 44) These The oil extracted from the Dorset was due mainly to events at the egg findings were consistent with the oilfields is pumped to the oil refinery on stage to increases in the proposed causal chain of events, Southampton Water along a pipeline proportions of nests in which eggs beginning with reduced DDT use, that was laid in 1988 At certain hatched, and in the proportions of and leading to reduced DDE locations in Dorset, the route of the eggs per nest which hatched contamination of the birds, reduced pipeline (22 m wide) crossed areas of Throughout, some eggs were shell thinning and egg breakage, heathland that were the known habitat of broken, while others failed to hatch improved hatching success, and all six species of endemic Bntsh after being incubated full term Most increased productivity reptiles, including the two rarest — the of the latter were light in weight, smooth snake (Coronella austnaca) having lost excess moisture through During the study penod, HEOD (Plate 16) and sand lizard (Lacerta agths) a thinned shell Under a binocular levels in unhatched eggs also (Plate 17) microscope, faint hair-line cracks declined slightly (Figure 43) The were often visible in the otherwise mean annual HEOD levels showed a At one site in Wareham forest, the intact shells negative relationship with hatching pipeline route effectively bisected an success and overall breeding area of both wet and dry heath and, as a Over the same penod, DDE levels in success (young per clutch), but result, gave an opportunity for studying unhatched eggs from the area these relationships disappeared in a (i) how quickly the reptiles that continued to dechne (as in carcases multiple regression analysis, after inhabited the heathland either side of in the 1980s, Figure 42) Using the allowing for the effects of DDE the pipeline route would recolornse the annual means, significant Over the years, PCB levels showed disturbed area, and (n) whether the correlations emerged between the no significant trend and no disturbed and exposed area of the geometnc mean DDE level and the relationship with any aspect of pipeline would act as an effective mean shell index (negative), the breeding success Hence, DDE was bamer preventing reptiles crossing percentage of clutches that were the only chemical of those examined from one side to the other In order to broken (positive), the percentage of which was firmly implicated in answer these questions, we needed to clutches (or eggs) that hatched breeding failure, a result consistent know the clitnbution and relative (negative), and the mean with earlier findings for this species abundance of the reptiles on the productivity (young per nest, elsewhere in Bntam (Newton 1986) undisturbed heathland either side of the

4 8 determined each autumn, using a modified Braun-Blanquet scale, where 1 represents over 10% vegetation cover, 2 10-25%, 3 26-50%, 4 51-75%, and 5 over 75%.

During the two years following the laying of the pipeline, neither the percentage vegetation cover nor the species composition of the undisturbed heath changed significantly (Table 12). On the pipeline route, however, the proportion of bare ground per quadrat decreased between 1989 and 1990, whilst the percentage cover of heathland plants, principally heather (Calluna vulgaris) and dwarf furze (tflex minor), increased. This increased cover Plate 16. Adult smooth snake on heathland in Wareham Forest

pipeline route. Also, the recolonisation of the disturbed area by heathland plants was monitored, as vegetation cover was considered an important factor in determining when the disturbed area would be suitable for reptiles.

To date, the distribution and relative abundance of reptiles found on the pipeline route and on equivalent widths of heathland adjacent and parallel to it have been estimated each year between May and September, using a grid of 150 corrugated steel tins (refuges) covering a total area of about 2.5 hectares, The vegetation cover, height and species composition of 42 quadrats from both the pipeline route and the adjacent heathland were Plate 17. Basking male sand bzard at the Arne G Well site

Table 12. Vegetation composition and cover. Mean values de ved from a modified Braun-Blanquet was also reflected in the height of the scale (heathland PI-28; pipeline Ne 14) vegetation, which changed from 2-9 cm in 1989 to 5-30 cm in 1990. Excluding the trees, the vegetation height on the undisturbed heathland was 22-95 cm.

After compensating for the differences in the number of site visits each year, the number of sightings of all reptiles, except the sand lizard and common lizard (Lacerta vivapara), increased on the heathland adjacent to the pipeline route between 1989 and 1990. The most striking increases were seen in the numbers of smooth snakes, grass snakes (Natrix natrix) and slow worms (Anguis fragilis) (Table 13), No common toads (Bufo bufo) were found on the heathland in either year.

49 Table 13. Reptile and amphibian sightings. Mean number of sightings per site visit and total number Both queens and sterile workers are of sightihgs (1W) per year (25 site visits made in 1989, four in 1990) produced from fertilised diploid eggs and, therefore, the mechanisms which control the caste of ant (queen or worker) into which a diploid egg develops are the key to understanding the stability of polygynous colonies. Most studies of both monogynous and polygynous ants, and other social Hymenoptera, have favoured an environmental, rather than a genetic, control of caste (Brian 1979). Indeed, in a recent review of caste determination in the ants, Holldobler and Wilson (1990) state that '. „ allelic differences almost On the pipeline route, there was a total of Gemetl©. cdie:te-gminavdoo.1 never separate the female castes of a colony, even to the extent of slightly 19 sightings of just two herpetofauna ag:calrvle G3 Ithe Real 16151) species, the sand lizard and the common biasing individuals to develop into one caste as opposed to another'. In toad, during 1989. In 1990, the total A major unresolved question in the red ant (Myrmica rubra), however, increased to 58 sightings of four species social biology is the occurrence of we have evidence for a genetic — the sand lizard, smooth snake, grass multi-queened (polygynous) ant determination of caste: heterozygosity snake, and common toad. In both colonies. Many ant species are at a queen-determining locus favours years, the highest proportion of organised into nests where several queen as opposed to worker sightings was of common toads. queens seemingly co-operate in production, and may act as a buffer Haapanen (1974) described site the production of reproductives against the evolution of parasitic tenacity in the behaviour of the (queens and males) and the sterile behaviour, so stabilising the structure common toad, and the high figures female workers that care for them. of polygynous colonies. recorded were almost certainly One way in which a queen could multiple observations of a few increase her fitness is to behave Ants from three populations in Dorset individuals. parasitically by producing only were examined for a polymorphism reproductives and no workers. in the enzyme malate dehydrogenase All the sightings of hatchling sand These queens would rely on the (MDH), detected by electrophoresis lizards (five) during 1990 were on the workers produced by other on iso-electric focusing gels, which pipeline route, as were five of the 28 queens in the colony to tend their separate proteins with different iso- adult female sightings, suggesting that reproductives. If a gene arose that electric points (pI). Three the exposed sandy areas of the route promoted this behaviour, it would phenotypes were detected (Plate 18): may have been used as sites for egg spread rapidly and destabilise 'fast' (F), 'slow' (S) and 'fast/slow' (FS). laying. colony structure as the ratio of These are assumed to represent, queens to workers increased. To respectively, two homozygotes for The distribution of reptiles in the explain the polygynous habit, alleles coding for MDH polypeptide heathland adjacent to the pipeline route therefore, we need to understand subunits with different electrophoretic and sightings of some herpetofauna why parasitism does not appear to mobilities, and the heterozygote species on the route indicate that it did have evolved. not form a barrier to the movements of containing both alleles. Table 14 shows the frequency of these sand lizards, smooth snakes, grass Hamilton (1972) suggested that snakes, or common toads. It is also parasitism may be suppressed interesting to note that the increase in because the members of a colony numbers of both species and total are very closely related. Queens sightings coincided with the increase in would then not increase their vegetation height and cover between fitness by becoming parasitic; it 1989 and 1990. would be in their own interests to co-operate in maximising the The monitoring of the recolonisation of output of their colony because they the pipeline route in Wareham forest share many genes with other will continue during 1991. members. Several studies have shown, however, that levels of C J Reading relatedness in polygynous ant colonies are no higher than Plate 18. Malate dehydrogenase phenotypes ih relatedness between nests. As the red ant, from a nest at Kimmaridge, showing polygyny in ants is a widespread Reference the association of heterozygosity with caste. and apparently stable Lanes 1-6 are workers and all are homozygotes, Haapanen, A. 1974. Site tenacity of the phenomenon, either genetic or either for the fast allele (lanes 3, 4 and 6) or the common toad, Bufo bufo (L.). Annales Zoologici behavioural counter-strategies to slow allele (lanes 1,2 and 5). Lanes 7-12 are Fennici, 11, 251-252. parasitism must have evolved. queens and all are heterozygotes, except lane 8

50 Table 14 The distr2bution of malate offspring of any of the three dehydrogenase phenotypes in different genotypes in a two-allele system castes of the red ant from populations in (On average, gwen equal allele Dorset The number of heterozygous queens is that expected from the frequencies of the frequencies and random mating, SS, fast and slow alleles, whereas the workers FS and FF genotypes all produce show a significant deficiency of heterozygotes and homozygotes heterozygotes In the social insects, males are equal proportions ) The constant haploid and so no heterozygotes should be potential for the evolution of detected Occasionally, diploid males are parasitism through genetic queen produced, however, as revealed by the determination perhaps accounts for sobtary male heterozygote found in the the apparent redundancy Encombe population (CP Chapman's Pool, EN Encombe, KM Kimmendge m=males, represented by the multiplicity of w=workers, q=queens) other caste control mechanisms, such as the manipulation of diet and the biting of larvae by adult workers, observed in Mynnrca species

The fact that a ubiquitous unspecialised species such as the red ant exhibits a degree of genetic caste determination could mean that these mechanisms in the social Hymenoptera have been underestimated It would seem that environmental rather than genetic controls are better suited to the 'fine tuning' of colony output in response to environmental fluctuations This conclusion may, however, simply be a reflection of the lack of suitable genetic markers with which to detect genetic control of caste (enzyme polymorphisms being phenotypes The striking aspect of rather rare in the social insects), and the results is that there are almost no further genetic controls may be heterozygous workers (2 out of 288), revealed as the techniques for but there are heterozygous queens detecting genetic polymorphisms, (16 out of 82) The deficiency of such as DNA fingerprinting, become heterozygotes in the workers can be more sensitive explained if the MDH alleles are markers linked to a queen- A F Raybould and B Pearson determining locus If larvae are heterozygotes at this locus, then References they can only develop into queens, whereas homozygotes at this locus Brian, M.V. 1979 Caste differentiation can develop into queens or workers and division of labour In Social insects, This effect appears to be associated edited by H R Herman, vol 1,121-222 with heterozygosity at a single locus, London Academic Press or group of loci, linked to MDH, rather than with heterozygosity Hamilton, W.D. 1972 Altruism and general, as previous studies of related phenomena, mainly in social insects esterase variation in these red ant Annual Review of Ecology and Systematics, 3, 193-232 populations have revealed no association of caste with Holldobler, B. & Wilson, E.O. 1990 electrophoretic phenotype (eg The ants Berlin Springer Pearson & Child 1980) Pearson, B. & Child, A.R. 1980 The Queen determination through distnbution of an esterase polymorphism heterozygosity can be seen as a in macrogynes and microgynes of mechanism that prevents parasitism Mynmca rubra Latnelle Evolution, 34, 105-109 in polygynous nests where the relatedness of queens is low The reason is that a queen-determining mechanism based on heterozygosity does not confer an advantage on the

51 Community ecology

Research on community ecology in vegetation illustrates the complex be considered unsightly by most ITE, and other parts of NERC, aims to nature of plant succession and the visitors understand the complex factors and difficulty involved in making reliable processes affecting interacting predictions from existing Therefore, during 1990, ITE made a populations of plants and animals laiowledge The vegetation of Great study of upland vegetation protected The work combines long-term field Britain is currently being reclassified, from domestic livestock in order to be studies of communities with and Tablefit is an elegant and useful able to forecast what plant communities manipulative experiments and model which enables us to classify would develop if stocking ceased over mathematical modelling vegetation types automatically and wide areas Vegetation protected from reliably The work on mtrogen grazing is at present scarce, but with An area of increasing concern is the examines the effects of increasing help from bodies such as the Forestry effect of changing land use on fertiliser levels on the species Commission, the Nature Conservancy assemblages of organisms In richness of grasslands and the Council, the National Parks and the particular, the marked changes in interaction between mtrogen and soil National Trusts we collected data from agriculture in recent years have moisture, whilst the study on weevils 74 sites prompted investigations into is aiming to improve the methods of modelling the environmental identification and to collate data on The sites were broadly of two types, consequences of set-aside and farm their distribution and ecology, with tracts and exclosures Tracts were woodlands, and the effects of grazing special reference to endangered or areas that had become inaccessible or pressure on plant successions notable species unavailable to livestock because of such Whereas previous emphasis has events as afforestation or reservoir been given to the effects of construction, they mostly lacked increased grazing, there is now Effects of ending livestock 'control' areas, ie similar ground still considerable interest in the effects of grazing on upland being grazed Exclosures were reduced pressures, particularly in vegetation typically small areas (c 1000 m2) within the uplands where numbers of hill grazed uplands, 'controls' were more sheep are likely to decline Coupled (This work was funded by the Department of often available, although sometimes the with these studies of impacts on plant the Environment) whole of a feature of interest, such as a successions are those concerned limestone outcrop, had been protected with herbivore ecology, especially Bntish uplands have long been used for (Plate 19) the interactions between species free-range grazing by domestic For example, in many Scottish hill livestock At present sheep are the For each site, we determined how long areas, a reduction in sheep numbers most numerous species, but in past there had been protection from large is likely to be compensated for by years cattle, horses, goats and even herbivores, and we recorded increases in the distribution and geese were depastured on hill ground vegetation composition and height We abundance of red deer (Cervus These grazing pressures have modified checked for any colomsing shrubs or elaphus) The ways in which the plant communities, making swards trees, for death of dominant plant herbivores such as sheep and deer shorter and curtailing regeneration of species, and for evidence of former select plant species and the different shrubs and trees, so that vistas have burning foraging strategies they adopt are remained open two areas of current study under the A most noticeable finding was the Joint Agriculture and Environment Large changes in the grazing of uplands variation in compositional trends In Programme The results of these are now likely There is pressure to general, heather (Calluna vulgans) and other projects will enable us to reduce the sizeable subsidies paid to increased in cover, as expected, but at develop more reliable models for farmers for sheep and cattle put to the some sites with control plots there was predicting the consequences of hill, the aim is to lower agricultural less heather in the protected than in the changes in grazing pressure on plant surpluses and prevent unfavourable grazed vegetation (Figure 45) At 19 succession changes in vegetation from sites, heather had 1-25% cover in the overstoclang However, there is also grazed control so the initial cover was The projects described in this Report concern that reducing subsidies may assumed to be low, only at 11 sites show the breadth of 1TE's work on cause livestock to be withdrawn (class B sites) was there a substantial community ecology The research completely from some upland tracts, increase in cover in the protected area on grazing reductions on upland and that the resultng 'wilderness' will For the other eight sites (class A), we

52 moorland from which domestic livestock had been withdrawn were often being utilised by red and roe deer (Cervus elaphus and Capreolus capreolus), especially in Scotland. Deer densities were usually much lower than the typical stockings of sheep and cattle, but, even so, the impact on preferred food species, especially shrubs and trees, could have important consequences.

Colonisation by trees and shrubs was found to have occurred at over 50% of the sites visited. However, often only a few scattered individual bushes were observed, and regeneration was considered prolific at less than 10% of the sites. Several factors were reducing or preventing colonisation, including (i) a lack of seed sources, (ii) lack of niches for establishment, (iii) grazing by Plate 19. Spread of heather and tall grass inside a 31-year-old exclosure at a limestone outcrop at deer or small mammals (hares, rabbits), Inchnadamph NNR, Sutherland and (iv) exposure and waterlogging

believe the spread of heather was being Table 15. Characteristics of upland vegetation from which domestic livestock have been withdravm prevented by the dense growth of grasses and by a failure of seedlings to Increased utilisation by red and roe deer (Genius elaphus and Capreolus capreolus) become established. In one exclosure where trends had been closely Colonisation by trees and shrubs, eg birch (Betula spp.), Scots pine (Pious sylvestns). rowan (Sorbus aucupana) monitored over 30 years, the few ericoid plants initially present had Reduction in cover of grasses, sedges and rushes due to spread of heather and other ericoids grown into full-sized bushes which then Increased height of vegetation degenerated, heather taking 20 years to Greater proportions of dead herbage and dead plants visible in swards become extinct, and bell-heather (Erica Spread of lichens, eg Cladonta Impexa, especially where plant growth is restricted by altitude or ciherea) 12 years. wet soils Decline in number of vascular plants in areas of 1-10 m.2 Other features of protected vegetat on Increased flowering of taller-growing herbs are listed in Table 15. Tracts of

which checked sapling growth. On some such sites, there were many dead or moribund small trees. Figure 45 gives an example of variable colonisation !Class B • caused by the scattered positions of • seed sources. • • • The graminoids which thrived on • protection from grazing were mainly • taller-growing species, such as tufted 1 • • • • hair-grass (Descharnpsia cespitosa), wavy hair-grass (D. Ilexuosa) and red • fescue (Festuca rubra). Species reduced • • in cover (Table 15) included common bent-grass (Agrostis capillaris) , sheep's fescue (Festuca ovina) and heath rush • —1Class A (Juncus squarrosus). Some acidic 0 grasslands were found to have been 0 50 100 surprisingly resilient to change, eg Calluna cover in grazed vegetation (%) swards dominated by cotton-grass (Eriophorurn vagihaturn) and mat-grass (Nardus stricta). Possible reasons could Figure 45. Response of heather to protection from grazing. The solid line links positions with equal be the long lifespan of individual clones, cover in protected and control vegetations: classes of response discussed in the text are marked and the relatively large above-ground

53 standing crops which allow few mches for grouse shooting, more frequent experiments with controlled levels of for incoming species to establish burning will be necessary to provide stockang and for long-term observations Again, there was considerable young nutritious heather to provide information on the timescale variability in the observed trends, which of the successions This knowledge is we consider to be a result of the There are several benefits from the necessary for the proper management of vanable incidence of the many cessation of livestock grazing, upland vegetation, and may be used for controlling factors, and, for small particularly for conservation Some the setting of policy prescnptons for exclosures, of chance occurrences At attractive herbs which at present rarely Environmentally Sensitive Areas, the Moor House National Nature flower because of grazing can produce Hentage Areas, National Parks, and Reserve (NNR), for example, two fine displays of blooms, and the late- Nature Reserves exclosures at similar altitude on similar summer purple of lightly grazed soil had cotton-grass dominant initially, heather-dominant vegetation is widely D Welch and R H Marrs one we categorised as a class A site in admired Plants such as lichens, dwarf Figure 45, the other as class B, heather birch (Betula nana) and many tall herbs having spread markedly will spread Also, diversity will increase in larger units of area, our finding of a The increases in height of vegetation, decline in species nchness applied to Tablefit and the the flowering of taller-growing herbs, small quadrats (Table 15), but in larger identification of British and the proportion of dead matenal tracts divergent trends can produce a vegetation types present in the swards (Table 15) are all more vaned mosaic Thus, parts of an (Thiswork was partly funded by the Nature a direct result of herbage no longer upland may be colonised by trees and Conservancy Council) being eaten in large amounts There is scrub (Figure 46), most of the area will also an effect of changes in composition, support dwarf-shrub heath, while Environmental consultants, nature more productive tall-growing species patches of grassland will remain on rock conservation managers, field naturallsts replacing shorter species If herbage is outcrops, on shallow soils, and where and many others require a common not eaten, it will inevitably decay sooner herbivores concentrate language to talk about habitats in the or later In a low-stature, long-lived natural world At the broadest scale, woody plant like heather, the dead Our sites were widely spread from ecologists and biogeographers assign shoots and branches steadily south-west England to northern ecosystems to biomes, such as tundra, accumulate m situ, and at several sites Scotland, and covered a range of tropical savanna, and coolltemperate 10% of the total plant cover was altitude and soil types It is apparent broadleaved forest At a local scale, estimated to be dead heather This that many different successional and particularly in a man-modified accumulation has implications for pathways can occur and that there is landscape such as that of Europe, a management there is a greater fire risk, considerable regional variation The more precise terminology is required and, if moorlands are being managed study has highlighted the need for Numerous attempts have been made to construct such a terminology for Britain and nearby parts of Europe, mostly Rowan based on the classification of *Birch indicates roughly 20 trees vegetation In central Europe, a system of Latin names for vegetation types has been developed, comparable to the Lmnaean system of binomial nomenclature However, vegetation and habitat are not the same similar 4 0 m o Aberarder vegetation can grow in different 467 m habitats, and histoncal differences such as past cultivation can produce quite New deer fence • different vegetation in a basically similar habitat Because of this fact and 4R6 m because some habitats have no • vegetation, a recent enumeration for 400 Loch Laggan the CORINE programme (Co-ordmated 333 m Environmental Information in the 467 m European Community) is using both New 0 1 physical and vegetational features to plantation • km charactense habitat types (Devillers, Devillers-Terschuren & Ledant 1991)

s <10 m Standard vegetation types distance between saplings c130 m In Bntam, we use Tansley's (1939) classic descnptron of natural and semi- Figure 46 Zonation of tree colonisation at Creag MeagaidhlVNR, Inverness-shire, in a block of natural vegetation His account is now moorland ungrazed by sheep or deer since 1986 Most saplings are birch out-of-date, and is being superseded

54 by a series of volumes entitled British diagnostic expert system for Table 16. Species, fisted in descending plant communities, which contain full identifying British vegetation types. order of abundance„ visidle in the foreground of the photograph of Monks descriptions and tables of vegetation Not only does it identify the type Wood NNR; the canopy tree, field maple, is according to the British system, but a types (Rodwell 1991). The vegetation mamly as stems types recognised by Roclwell have cross-reference is provided, so that been used widely by the Nature the CORINE (European Community) Englishname Scientificname Conservancy Council and are likely to type is also identified. become a national standard. Fieldmaple Acer campestre- Bluebell Hyacinthoides non-scripla There are several problems in using a Hazel Corylus avellana standard set of vegetation types, of Dog's rnercury Mercurial]: perennis Bramble Rubus fruticosus which the most serious is the time As an example of the use of Tablefft, taken to become familiar with the we consider the vegetation in the system. An ecologist or an photograph of Monks Wood (Plate of the woodland type better than that of environmental consultant will often 20). In the foreground of this picture, any subcommunity, the reason is the want a quick and definite answer to five species can be seen (Table 16). incomplete species •st, taken merely the question What type of vegetation This short list of species cannot be from a photograph, is this?' , and will be deterred from regarded as a complete enumeration using a system of classification if for the sfte, but Tablefit can still give The two most likely subcommunities to access is slow or the answer an indication of the likely vegetation fit the picture from the incomplete uncertain. type if the species are entered in information available are the primrose/ descending order of abundance. ground ivy (Primula vulgaris/Glechoma hederacea) subcommunity and the From the input data, Tablefit identifies common ivy (Hedera helix) the vegetation as belonging to the subcommunity. In fact, the first of these Tablefit is a FORTRAN computer broad European (CORINE) type 'Non- possibilities is correct; Monks Wood has program designed to make an alluvial ashwood'. Although no ash abundant ground ivy (not, however, automatic diagnosis of vegetation trees (Fraxinus excelsior) are visible in visible in the picture) and almost no types. It has been written with British the picture, they are abundant in common ivy. It formerly had abundant plant communities in mindbut can Monks Wood. Indeed, in the absence primroses: but these have now been equally be applied to vegetation of recent felling. they would probably eliminated by deer grazing. anywhere in the world. The program be the dominant tree species. Thus, measures goodness-oEfit between the identification is not far-fetched. In Tablefit has been tested on a wide observed vegetation and descriptions the system of British plant communities, variety of vegetation and generally of standard types in an association the stand falls clearly into the ash/ performs well. Where a complete table. A prototype of Tablefit has maple/dog's mercury (Fraxinus species list is available, the program can already been published (Hill 1989). excelsior/Acer campestre/Mercurialis be relied on to give the right answer, The program has now been enhanced perennis) woodland. According to provided that the vegetation to provide a fully operational Tablefit, it fits the generic description corresponds to a type included in British plant communities, The user requires no special training, oniy an ability to identify plants. Reliable, automatic identification of plant communities has become a reality.

M 0 Hill

References

Devillers, P., Devillers-Terschuren, J. & Ledant, J.P. 1991. Habitats of the Einiopean Community. (CORINE biotopestechnHal handbook 2.) Brussels. Commission ofthe European Communities.

Hill, M.O. 1989. Computerizedmatching of releves and associakontables. vv-ith an applicationto theBritish National Vegetation Classification. Vegetal:Hs 83, 187-194.

Rodwell, J.S., ed. 1991. British plant commuMbes. Vol. 1. Woodlands and sallib. Cambridge: Cambridge UniyersifyPress.

Pia te fl 0. vegetatMn in Monks Wood NNR; Tablefit can be used to identify the vegetation Tansley, A.G. 1939. The BiMsh islands and type to whiCh the woodland belongs, using little more information than a list ofthe species visible their vegetation. Cambridge: Cambridge in the foreground UniversityPress.

55 Nitrogen fertilisers on Table 17 Simpson's index of plant diversity (7) for nitrogen ferthser treatments at Tadham old peat grasslands Moor, Somerset, in 1986, 1987, 1988, 1989 and 1990 (This work was funded by the Simpson's index I = I —E p12 1=1 Department of the Environment, the Ministry of Agriculture, Fishenes and Nitrogen fertiliser applied (kg ha-i) F value and Food and the Nature Conservancy I 0 25 50 100 200 Significance Council, and conducted in co- operation with the AFRC Institute for 1986 0 930 0 918 0 934 0 929 0 924 0 855 Grassland and Environmental NS Research (IGER)) 1987 0 941 0 931 0 935 0 918 0 918 3 405 The area of unimproved grassland in P<10% lowland Britain has greatly diminished since 1945 (Fuller 1987) Grassland 1988 0 928 0 915 0 911 0 908 0 868 9 144 has been improved through the use of P<0 5% herbicides and fertilisers, and by 1989 0 939 0 930 0 912 0 901 0 868 32 447 reseeding with productive varieties of P<<0 1% grasses and legumes Much alarm has been expressed about the impact of 1990 0 942 0 942 0 912 0 920 0 900 5 640 these activities on the flora of old P<2 5% grasslands The designation of Environmentally Sensitive Areas (ESA) as zones for management sympathetic restnctions upon farmers regardmg amount removed in the hay cut, but to conservation interests, and the the use of fertilisers and other means neither nutnent was applied to the scheduling of Sites of Special Scientific of intensification There was concern control plots Interest (SSSI) under the Wildlife and among the farming community that the Countryside Act (1981) placed levels fixed for allowable use of fertiliser should be realistic and compatible with economically viable production — 0 kg ha-1 -- 25 kg ha-1 The different interests of — 50 kg ha-1 conservationists and agriculturalists 26 -- 100 kg ha-1 found a focus on the Somerset Levels and Moors ESA, where a spirit of 24 — 200 kg ha-1 compromise led to a study being commissioned in 1986 at Tadham 22 Moor, near Wedmore ITE and IGER began an experiment into the effects 20 of nitrogen fertilisers on the botanical composition and agncultural production of old grasslands on peat soils Data were collected from 1986 to 1990, providing valuable 14 comparison with the Park Grass k Experiment at Rothamsted (Brenchley & Warnngton 1958, Thurston 1969) Five treatments of nitrogen fertiliser (0, 25, 50, 100 and 200 kg ha-i) were applied annually, each replicated three times The botanical composition in all plots was recorded in May each year, using 1 m2 quadrats, and over 140 species were recorded in the five years in which the experiment has been running The abundance of 35 species has been sigmficantly affected by the fertihser 1986 1987 1988 1989 1990 1987 1988 1989 1990 treatment in at least one year After the 1986 Year quadrats had been recorded, the Year fields were cut for hay in early July, and bullocks were grazed until October Phosphorus and potassium Figure 47 Mean number of species per fertilisers were applied annually at Figure 48 Mean percentage cover of quadrat for each treatment levels calculated to replace the perennial rye-grass in each treatment

56 The most marked effects of related (Figure 49). Species are increasing fertiliser levels have been distributed in response to water table, on the species richness of the from upper left (those preferring drier grassland, expressed either in terms sites) to lower right (those normally of the number of species per quadrat occurring in wetter 22).sites, Plate (Figure 47) or as Simpson's diversity These species are also distributed index (Table 17). Both measures along an axis of increasing fertiliser reflect a more species-poor sward in application, from upper right (species later years in those plots receiving growing mainly in control plots) to the higher levels of nitrogen fertiliser lower left (species with high (100 kg ha-- and m200). Thiskg ha percentage cover in plots receiving change reflects increased 100 kg ha-' or 200t of kg nitrogen ha- percentage cover of grasses. fertiliser). Those species most particularly perennial rye-grass abundant in the fertilised plots (rye- (Loll= perenne) and Yorkshire fog grass, Yorkshire fog, common sorrel (Holcus lanatus), in a much taller (Rurnex acetosa), etc) are also absent sward (Figure 48), where many low- or at low population levels in the growing herbs — buttercups wetter plots. (Ranunculus spp.). clovers (Trifoliurn spp.), self-heal (Prunella vulgaris) — and mosses have significantly declined. Not only does the composition of the grassland change, but also the production of flowersPlate 22. Marsh by marigold (Caltha palustris) many of the most attractive species — widespreadof in wet places, but increasingly rare in meadows. An old wet meadows. Both marsh plumeexample of the species of wetter sites thistle (Crrsrurn dissecturn) (Plate 21) and ragged robin (Lychms flos-cuculi) have almost ceased to flower microtopography.in plots This variation and receiving high levels of nitrogenthe proximity to drainage channels fertiliser, where once they wereaffect the water table in the plots. The abundant, and in 1990 only floweredanalytical technique Canoco (ter Braak frequently in the plots which1988) received was used to ordinate species no fertiliser. with respect to (i) the level of nitrogen fertiliser applied, and (ii) the position of Fertiliser application is notthe the water only table. factor affecting the distribution of plants in the plots at TadharnAn Moor.example of the ordination produced Although the land appears flat,from there the 1989 data demonstrates how is considerable variation in soil moisture and nitrogen are inter-

Plate 23. Southern marsh orchid pactylorhiza majalisssp.praetermissa)widespread, — but decreasing because of drainage. One of 14 species whose populations are being monitored in great detail at Tadham Moor

By 1990, no species which had been common at Tadham in 1986 had been eliminated, although many had declined in cover and frequency in the quadrats (Plate 23). The long-term effect of fertiliser application, demonstrated on mineral soils at the Park Grass experiment, will be studied on the peat soils of Somerset. The rate at which intensively fertilised peat grassland reverts to its original composition, when nitrogen is no longer applied, is also being investigated by ITN and IGER in a second phase of the Tadham Moor experiment. This joint approach will Plate 21. Marsh plume thistle — typical of mferble, wet peaty meadows and local in Britain. It has provide both the farmer and ceased to flower in plots receiving high levels of fertiliser conservationist with information about the

57 Centaurea nigra Dry Achrilea milefollum Low N

Agrostis capillans Arrhenatherum elattus

Chstum arvense

Tnlohum Out:gum Depth of water table estuca rubra Hydrocotyle vulgans Carex ntgra Cynosurus cOstatus Cathengon cuspidatum Trffoktan repens Carex disticha Ftanunculus repens Juncus effusus Eleochans palustns Anthoxanthum odoratum Cardamine pratensis Rumex acetosa Glycena fluttans Holcus lanatus Juncus intlexus Lohum perenne Bromus hordeaceus Bromus racemosus

High N Wet

Figure 49 Results of a Canoco ordination where species are plotted in relation to environmental vanables (nitrogen & depth to water table)

levels of nitrogen fertiliser which may be British weevil fauna done Weevils are also important in the applied to species-nch grassland without context of conservation, as the group any adverse effect It will also provide In ecology generally, and more especially contains many rare and interesting evidence on the rate at which previously in community ecology, the accurate species Weevils contribute fertilised grassland will gain species and discrimination and naming of species are considerably to biological cliversity revert to a community of conservation extremely important Failure to recognise both the tropics and temperate regions interest the existence of several species in an Over 600 species of Curculionoidea have investigation, or to determine them been recorded from the Bnlish Isles The J 0 Mountford correctly, can lead to erroneous last monograph and major taxonomic conclusions It is particularly important treatise on the group is by Fowler (1891) for commissioned research, eg in nature Although the literature contains much References conservation and environmental impact scattered information, a modem assessments, that the identification of treatment is urgently required Braak, C.I.F. ter 1988 CANOCO —a species is accurate Background FORTRAN program for canonical Moreover, British work has tended to information on the biology and ignore, and has been overtaken by, community ordination by (partial) distribution of species is also desirable for (detrended) (canonical) correspondence major advances in this family in analysis (version 2 1) (Technical report ecological studies, especially in the case continental Europe LWA-88-02 ) Wagerungen Agncultural of invertebrate animals Such information Mathematics Group has been accumulated over many years in Bntam and, although it can be of mixed The work undertaken in IIE is not a major Brenchley, W.E. & Warrington, K quality, its existence has often proved subproject, but one which is suitable for 1958 The park grass plots at Rothamsted useful as a basis for ecological studies irregular, part-time work, and which 1856-1949 Harpenden Rothamsted attempts to capitalise on a long-standing Experimental Station The term 'weevil' is applied to beetles of interest of the subproject leader It has four main aims Fuller, R.M. 1987 The changing extent the superfamily Curculionoidea, though and conservation interest of lowland the Anthnbidae and the Scolytidae grasslands in England and Wales a (ambrosia and bark beetles) and to establish a better basis for review of grassland surveys 1930-84 Platypodidae are sometimes excluded the identification of species by Biological Conservation, 40, 281-300 The superfamily is the largest, in terms of providing up-to-date species, in the animal kingdom With dichotomous keys and accounts Thurston, J.M 1969 The effects of extremely few exceptions, all species are of additions to the Bnlish fauna, liming and fertihsers on the botanical phytophagous and they include many to accumulate distribution composition of permanent grassland, and records for later incorporation on the yield of hay In Ecological aspects well-known pests, such as the cotton boll of the mineral nutrition of plants, edited by weevil (Anthonomus grandis), on which a into designated Biological I H Ronson Oxford Blackwell Scientific great deal of scientific work has been Records Centre schemes,

58 in to improve knowledge of biology, particularly the range of foodplants utilised (thus linking into the Phytophagous Insects Data Bank), iv to provide information on Red Data Book and National Notable species

The provision of identification keys has been a major activity Following the publication of illustrated keys to the 'orthocerous' groups (Figure 50) (Moms 1990), work is well advanced on the text for a handbook to the adelognathous (broad-nosed) species Some preparation for subsequent handbooks, three of which will be needed to complete the senes, has also been done In the course of this work, species not previously recorded from the Bntish Isles have been detected Preliminary accounts of the • occurrence of Rhynchaenus pseudostigma and Pelenomus zumph • have been published, and more substantial papers are in preparation, as are checklists which incorporate the results of recent continental research In the past, erroneous records have been common, and several corrections have been made to the Bntish list (eg Moms 1989)

The amateur contribution to studies of British weevils is substantial, and two semi-popular accounts of the group have been written for the guidance of new and inexperienced workers (Moms 1991a,b)

A formal distribution recordmg scheme covers only a small proportion of the Bntish weevils Records are being accumulated in expectation of a comprehensive scheme or schemes being established soon Southern England is much Figure 50 A typical orthocerous (straight-antenna'ed) weevil (Apion (Pirapion) atratulum), male ncher in species than northern Scotland, and weevils have considerable potential for studying the biological characteristics The oviposits later than D dejeam impacts of global change The spread discovery that Apron waltom is a larval Several other instances of phenology of Ceutorhynchus picitarsis is one feeder in stems of its host, horse-shoe affecting the feeding of both adults example of a response to land use vetch (1-hppocrepis comosa), has been and larvae are being explored change, this was a scarce and published, but not followed up in any uncommon species until recently, but detail Comparative studies of The phenomenon of 'skating' on the its range and abundance have Dorytomus species feeding on aspen water surface, a locomotory feature increased considerably as the result of (Populus trernula) showed that D of several semi-aquatic species, has widespread growing of oilseed rape tortnx (Plate 24) lays eggs been investigated in outline The The species is now a pest of the crop predominantly in male catkin buds in behaviour seems to be an adaptation throughout eastern England autumn, whereas D dejeani (Plate 25) for avoiding adverse effects of oviposits mainly in female cafians wetting, and includes a series of Some progress has been made in very early spring D affmrs, a rare 'righting' movements for appropnate identifying foodplants and determining species, also uses female catkins, but orientation on the water surface

59 particular taxonomic group will always be ancillary to studies of processes and problem solving, there should be room for such work in a broadly based institute.

M C Morris

References

Fowler, W.W. 1891. Coleoptera of the British Island. London: Reeve & Co.

Morris, M.G. 1989. The identity of four unique specimens of Cymnetron Schoenherr (Col., Curculionidae). Entomologist's Monthly Magazine, 125, 25- 30.

Morris, M.G. 1990. Orthocerous weevils. Coleoptera Curculionoidea (Nemonychidae, Anthribidae, Urodontidae, Attelabidae and Apionidae). Plate 24, Dorytomus tortrix, a weevil which feeds as a larva mainly in the male catldns of aspen Handbooks for the Identification of British Insects, 5 (16), 1-108.

Morris, M.G. 1991a. Weev4s, In the Bgtish Red Data Book (Shirt situated for their investigation. These (Naturalists' Handbooks series.) 1987), 22 species of Curculionoidea species, together with butterflies, Richmond: Richmond RubEshing. are listed as endangered, 11 as Orthoptera, spiders and other -vulnerable and 49 as rare (categories species of conservation importance, Morris, M.G. 199 lb. Weevils. In: The 2 and 3 respectively), about 14% of will be considered by the Rare coleoplorist's handbook, (Revised ed.) London: Amateur Entomologist's Society. the total British fauna. Of particular Invertebrates Research Group importance are the five British recently established at ITE Shirt, D.B., ed. 1987. British Red Data species of Cathormiocerus, because Furzebrook. Some attention will also Books: 2. Insects. Peterborough: Nature of their very limited European range, be given to National Notable species, Conservancy Council. and a large proportion of our species information on which has been of Bagous, a relict group also provided for the Nature Conservancy uncommon on the Continent. Most of Council's review of Coleoptera. the Red Data Book weevils occur in southern England, and Dorset is well Although ecological work based on a

Plate 25. Dory-tomus dejeani„ congener of D. tortrix, which feeds as a larva predominantly in female catlens of aspen

60 Scientific services

The scientific services are a lynch-pm Analytical chemistry group used to ensure optimum operating of all research programmes within the conditions for automated instruments, and Terrestrial and Freshwater Sciences The chemistry group at ITE Merlewood to carry out essential data processing, Directorate (T1-SD) of the Natural provides an analytical facility for ITE without compromising sample Environment Research Council research and, increasingly, for other throughput (NERC), and of ITE m particular The institutes and universities as contract provision, on site, of these speciahsed demands increase After over 30 years' Erratic mains electricity supplies initially services, staffed by personnel who involvement in ecological research, it is caused some problems with the newer have a positive interest in the clear that the analysts have been faced computer-controlled instruments, and ecological stuches of the research with contrasting challenges In the small interruptions invariably proved scientists they support, is probably the formative years, interest was 'fatal' The installation of an main advantage that an institute concentrated on analytical methods uninterruptable power supply with scientist has over a university applicable to a wide range of material sufficient capacity to supply all the researcher Recognition of the This work formed the basis of the book instruments has removed this problem, importance of these services has Chemical analysis in ecological matenals, and 'down-time' is now mmimal mcreased considerably over the last edited by S E Allen, published by few years, and the remodelling of the Blackwell Scientific, and recently updated The computing arrangements for data TFSD scientific services programme is (1989) Latterly, applied research effort processing in the laboratory are being another step, providing a direct link has centred on evaluating mechanisms of developed The essential hardware and through to senior management so that nutnent and pollution movement This most of the additional software are now the services receive their fair share of type of research generates high numbers operational Final interfacing of diminishing resources of aqueous samples, and has required instrument output data with the report- improvements in automation and stnct generating package installed on the The scientific services programme standardisation of methodology Station's mainframe area represents the hbranes, is now being implemented The group analytical chemistry laboratories, is collaborating with NERC Computer Services local statistical support/biometncs, Automation support to develop the necessary computing, data centres, electrical and software, which should be available early mechanical instrument workshops, The recent injection of capital into in 1991-92 photography and graphics support, analytical facilities, particularly and special research facilities such as automation and computing, has glasshouses Many of these services significantly increased the efficiency of Analytical procedures have a very high standing in their own the analytical service The inductively nght, the analytical laboratones within coupled plasma optical emission The routine procedures used in the ITE being prime examples The new spectrometer (ICP-OES), continuous flow laboratory are constantly being reviewed services programme is positively analysers, and ion chromatograph now and monitored Investigations during the encouraging the development of links operate routinely, unattended, on year have resulted in improvements to between service groups of the same overnight runs This development has several methods discipline based at different TFSD resulted in an increase in sample sites Some of the early moves along throughput of 60% over the last two Matrix interferences in the determination this road have resulted in closer ties years Nevertheless, although about of sodium and potassium at low levels by between widely dispersed sites, with 100 000 individual determinations are ICP-OES have been identified, exchanges of both knowledge and carried out annually, current demand still particularly in low ionic strength samples equipment, improving the utilisation of exceeds supply, and pnonty for contract such as environmental waters The expensive hardware and making small research means that requests for analysis conditions for maximum sensitivity when units of specialist slalls available for in connection with Science Budget setting up the instrument with single- wider use projects remain largely unfulfilled element standards have been shown to produce significant enhancements for The following articles give examples of The high level of automation, combined these elements when applied to real significant developments made in with the overnight unattended operation, samples Interference can be minimised some of the ITE service sectors has also allowed more efficient use of staff by using multi-element standards, and by However, they represent only a very time and resources for routine rigorous control of instrument operating small part of the total output operations Normal working hours can be parameters Those affecting the position

61 in the plasma from which the emission During 1990-91, BCR required to meet the growing demands on the spectrum is measured, such as excitation certification for trace elements of a service to cover a wider variety of coil height and auxiliary argon flow, are sample of white clover (Tnfohum repens) pesticides and pollutants and also to most important The necessary containing elevated levels of selenium achieve ever greater sensitivity procedural modifications to overcome Along with over 20 other laboratories Thus, gas liquid chromatography the interference have been implemented throughout Europe, the analytical and high-performance liquid This work is being written up, and will be chemistry group at ITE Merlewood chromatography are used routinely submitted for publication in the near analysed the sample for selenium, for detecting many pesticides and future arsenic and molybdenum ICP-OES rodentcides, while atomic proved successful for the measurement, absorption spectrophotometry has Only small amounts of phosphate are in direct mode for molybdenum, and via been used to determine toxic found in most British forest ecosystems, hydride generation for arsenic and elements such as lead, mercury and and research attention has been directed selenium Many laboratones cadmium to the organic-bound phosphorus (P) expenenced difficulty with selenium, The analytical approach has been to even at elevated levels, because acid It became clear from customer oxidise the organic matenal in solution digestion in open vessels was subject to requests during the early 1980s that and then determine the total phosphate, losses of volatile fractions The white there was need for a technique to but initially we found that, at 20 ppb P or clover standard will be made available detect and measure a wide range of lower, the colonmetric method is subject by the BCR in due course, and work is elements in very small samples to senous interferences because of now commencing on a standard for Available techniques were reviewed matrix effects from acid digestion rainwater by an Analysts Working Group in reagents and disturbances to the flow NERC, and it was decided that the dynamics within the measurement cell There is increasing pressure within inductively coupled plasma mass Losses may also occur dunng the scientific research for international spectrometer (ICP-MS) could best digestion stage Control of the acid standardisation of methodology and meet the requirements ICP-MS can concentration and care in the digestion comparability between studies and give simultaneous measurements of proved necessary, but the addition of a laboratones Agencies have been set up major, minor and trace elements modified flow cell was the cntical factor in to monitor performance and to issue important in animal and plant developing a reliable method formal licences to laboratories by physiology down to sub-nanogram assigning accreditation For analytical levels (10-9g) It is also particularly Ligrun estimation by routine procedures laboratories, this accreditation is useful in measuring elements that are is very time-consuming, it suffers from achieved by important in ecological and poor precision and has a limited range of toxicological studies application Two empirical methods i using validated methodology, based on the acid detergent fibre u checking methods with certified The development of the ICP-MS for treatment have been evaluated using leaf reference matenals (such as those enwronmental research was litter residues from decomposition mentioned above), supported by NERC, and the experiments From the literature, the m systematic quality control commercially available VG plasma oxidation procedure using permanganate procedures (fully implemented), quad is based on an instrument built to destroy the ligmfied residues iv well-documented laboratory at the University of Surrey by Drs appeared promising and straightforward management procedures Gray and Date In late 1990, an ICP/ However, we found incomplete and Work has begun to seek accreditation MS facihty was commissioned at unreliable recovery was obtained from through the National Measurement Monks Wood, and three areas of complex litter and woody plant matenal Accreditation Service, and the necessary work have already demonstrated its An alternative treatment of the fibre documentation is being compiled The value residue using sulphuric acid to destroy laboratory plans to seek certification for The first is in studies on animal the cellulose yielded precise values for a common water analysis procedures, and metabolism It is well lmown that wide range of matenal, and this is now for trace element procedures and soil toxic elements, such as lead, being tested more extensively and vegetation analysis cadmium and mercury, exert at least some of their harmful effects in farm Quality assurance J A Parkinson and A P Rowland animals and humans by disrupting Legislation, legal procedures and normal biochemical pathways This contract research are increasing the knowledge needs to be extended to requirement for formal procedures of Inductively coupled plasma studies on wildlife A co-operative quality assurance Part of the assurance mass spectrometer project has now started with scheme is the traceability of analytical Birkbeck College, University of results to those of samples with certified The analytical section at ITE Monks London, and the University of Oxford values, and the CEC Bureau of Reference Wood was set up in 1961 within the to detect adverse environmental (BCR) has a range of available material Toxic Chemicals and Wildlife Section impacts on wildlife A range of There is a need to extend this range, and of the Nature Conservancy to analytical techniques is being used, laboratories of international repute are measure residues of organo-chlonne in which ICP-MS is playing a major invited to analyse material in msecticides in birds and other part These techniques are collaboration, in order to obtain certified animals The range of analytical sufficiently sensitive and values equipment has gradually increased comprehensive that it should prove

62 possible to work almost exclusively Another approach to studying magnetic spectrum One alternative with samples of blood, unne or pollution in birds and mammals makes means of remote sensing is radar, in feather samples This non- use of naturally occurring stable which a pulse of microwave radiation destructive approach to isotopes Lead, for example, has four (wavelengths of 1 mm to 1 m) ecotoxicology and wildlife health stable isotopes, three of which are transmitted towards a target, and the considerably extends the range of radiogenic, 206pb, 207pb and 208pb 'echo' received by the sensor (Figure 52) species and problems that can be The ratios of these lead isotopes to studied It may also provide early each other and to 204Pb vary with Spatial definition within the radar warnings of significant impacts on geological age, and can readily be image is achieved by recording not wildlife, arising either from pollution measured by ICP-MS The sources of only the strength of the return pulse or from natural processes, such as lead can therefore have different lead but also the time penod between disease isotope ratios, and this variation can transmission and reception Modem provide a 'fingerprint' which enables radar systems, known as synthetic us to distinguish different sources of aperture radar (SAR), use lead pollution Figure 51 shows the sophisticated doppler processing to results for lead fishing weights, attain spatial resolution comparable to Tissue of mute swan vegetation and the hver tissue of a that of visible and mfra-red sensors, eg mute swan (Cygnus olor) 20-30 m from an orbiting platform However, in marked contrast to visible The third application of ICP-MS and infra-red systems, radar imaging Pb described is in an ecological study of of the earth surface can operate Pb insect dispersal with the University of largely irrespective of atmosphenc Cambndge This project is tracking conditions, through hazy and cloudy the movement of phytophagous skies, and even hght rain The time of Pb insects under field conditions, using day is no problem either, as the source elements as markers Particular host of the radiation is the radar itself plants are 'labelled' during their growth by irrigating them with The strength of the radar return, or solutions containing barium, strontium, 'backscattered' signal, depends on the II Lead fishing weights rubidium, europium and dysprosium dielectric and geometnc properties of Preliminary tests have yielded positive the target Hence, radar remote responses from insects that are known sensing can provide information to have fed on these plants, while relating to moisture conditions, surface Pb negative results were obtained from roughness, and volumetric structure, Pb other samples of insects ICP-MS therefore, radar is able to monitor provides a unique analytical tool for directly terrestnal features, such as soil such research moisture content and snow depth, Pb which visible and mfra-red systems There is a vast range of potential cannot sample types and contamination levels, and a need for stringent quality The 1990s are a very important penod control Reference matenals include in the development of radar remote iii Vegetation Pb insects, hedgehog spines, hver, sensing applications, as there is to be a feathers and eggs Analyses of these significant increase in the supply of matenals will be validated SAR data from space Previous independently by other laboratones satellite radar missions have Pb comprised the short-hved Seasat M C French satellite of the late 1970s and short- duration space shuttle missions By Pb contrast, this decade will see the Pb launch of seven civil satellites carrying Future applications of SAR sensors (Figure 53) These 200 202 204 206 208 210 212 radar remote sensing in satellites will provide world-wide and terrestrial ecology long-term sets of SAR data, enabling Mass units thorough assessment of satellite SAR sensing and major advances in Figure 51 ICP-MS analysis of (i) tissue from Considerable advances have been made application However, considerable a mute swan which died of lead poisomng, in the mapping and measurement of experimental and methodological (u) lead fishing weights removed from the terrestnal ecosystems using satellite research and development are gizzard, and (m) vegetation sampled along required in the processing and the nver bank The lead isotope ratio (207lpb / remote sensing ITE's Environmental 'Pb) shows that death was caused by lead Information Centre (EIC) at Monks Wood interpretation of such data for poisoning following the ingestion of the lead has made important contributions (Fuller, terrestrial ecology before this fishing weights, and not from the vegetation Jones & Wyatt 1990) Most current technique attains the current which most probably denved the lead applications use sensors that operate in the operational status of some other contamination from motor vehicle exhausts visible and mfra-red regions of the electro- remote sensing methods

63 mature crop, the principal source of the backscattenng Research suggests that backscatter from the ground received by the ERS-1 SAR, operating at a single wavelength of Radar Flightdirection 56 cm, will be blocked by many vegetation types which have a high water content Conversely, the 23 cm wavelength radar of the JERS-1 SAR will be little impeded by such r•-• Pulsefrom radar vegetation, providing greater potential for the monitoring of soil Targetfeaturel r- -- Returnpulse to radar moisture and also the subcanopy ••• • • • structures of forested areas At the shortest wavelengths, ie less than approximately 3 cm, there is little sensitivity to soil moisture where vegetation is present, the backscatter is dominated by the ath scattering of the radiation within the uppermost portions of the cover At these wavelengths, many geometric properties of vegetation canopies, such as leaf and flower-head size, Figure 52 Principles of an imaging radar system shape and position, influence the backscatter, and short wavelength International research efforts into European Space Agency and JRC microwave data therefore have high terrestrial applications of radar over joint developments include the potential as a source of information the last two decades have used data European Radar Cross Section on these charactenstics Seasonal from ground-based scatterometers Database (EURACS), which brings vanations in the data, and the plant and aircraft-borne SAR These efforts together sources of SAR and ground water content, have enabled have concentrated upon radar's reference data in order to improve demonstration of short wavelength potential for estimating soil moisture the understanding of microwave SAR use for mapping crop types content, and mapping agncultural backscatter from different surfaces (Foody et al 1989) crop types, and forest and snow (Churchill & Sieber 1988) characteristics The CEC Joint Current research within the EIC, Research Centre (JRC) has co- The radar wavelength influences the collaboration with the British ordinated numerous aircraft degree of radiation penetration into National Space Centre's Remote campaigns, with repeated use of the target, and, therefore, for a multi- Sensing Application Development several sites in East Anglia layer target, such as a forest or Unit (RSADU),is investigating the

1991 1992 1993 1994 1995 1996 1997 1998 1999 SatelliteSAR missions

ALMAZ / USSR

MI 00 ERS-1 / EuropeanSpace Agency

IMIO• JERS-1 / Japan

• • • SIR-C / NASA SpaceShuttle

ERS-2 / EuropeanSpace Agency

RADARSAT / Canada

EOS SAR / NASAEarth Observation System

Figure 53 Satellite radar remote sensing for the 1990s

64 use of SAR for forest inventory Environmental Research (TIGER) Satellite polarimetric SAR will through the monitoring of species programme, will monitor commence in the mid- to late-1990s composition, tree bole sizes and regenerative tropical forest in West with the Earth Observation System biomass (Baker & Mitchell 1991). Africa, using data from the JERS-1. (EOS) programme. However, This project (which will contribute to polarimetric data from the NASA EURACS) is using data from the The wavelength-dependent airborne SAR, such as obtained from Thetford Forest in Norfolk that were response can be augmented by the the 1989 and 1991 flights over East sensed by the multi-wavelength polarimetric aspects of radar remote Anglia, enable polarisation signatures NASA airborne SAR in August 1989. sensing. Through selective to be determined under experimental The greater global coverage of transmission and selective reception conditions, Initial polarimetric analysis satellite SAR will enable extension of of either horizontally or vertically of the 1989 Thetford data (Plate 26) has this work to other forest types. One polarised radiation, the differential provided a strong basis for further such development, in conjunction radiation scattering mechanisms of developments in mapping and with ITE Edinburgh and as part of terrestrial targets provide an monitoring forests and other the Terrestrial Initiative in Global additional interpretive dimension. ecosystems.

MAESTRO-1 UK forestry test site Thetford, Norfolk 16 August 1989 Radar wavelength colour composites: 68.0 cm response in red 24.0 cm response in green 5.6 cm response in blue

Polarisation combinations:

Horizontal transmit I Vertical transmit Horizontal receive Vertical receive

Horizontal transmit I Vertical receive I

(courtesy of Dr J R Baker, RASDU)

Plate 26. Analysis of multi-polarisation, multi-wavelength SAR image data

65 Much development of the use of radar data within the UK to date has concentrated upon areas of relatively level terrain Future research needs to include assessment of SAR within upland areas, in which more complex topography can introduce artefacts into the data geometry Land relief is particularly significant to SAR forestry applications in the UK, and also to the relatively under- developed potential of SAR within other semi-natural ecosystems, SAR airborne campaign flights this summer at Llyn Bnanne in central Wales will go some way in redressing the balance More generally, the synergisms between radar and other remote sensing techniques require further research, so that applications make the greatest use of their relative strengths At the same time, opportumties for applying the unique feature responses and the systemic benefits of radar remote sensing continue to be pursued

G B Groom

References

Baker, J.R. & Mitchell, P.L. 1991 The UK element of the Maestro-1 SAR campaign International Journal of Remote Sensing Inpress

Churchill, P.N. & Sieber, A.J. 1988 EURACS a European Radar Cross Section Database In Proceedings of IGARSS'88 Symposium, Edinburgh, Scotland, 1988, 29-31 (ESA SP-284 )

Foody, G M., Curran, P.J., Groom, G.B. & Munro, D.C. 1989 Multi- temporal airborne synthetic aperture radar data for crop classification Geocarto International, 3, 19-30

Fuller, R.M., Jones, A.R & Wyatt, B.K. 1990 Remote sensing for ecological research problems and possible solutions In Remote sensing for operational applications technical contents of the I 5th Annual Conference of the Remote Sensing Society, 1989, compiled by E C Barrett & K A Brown, 155-164 Reading Remote Sensing Society

66 ISBN: 1 85531 052 X For further information please contact:

Institute of Terrestrial Ecology (North) Bush Estate Penicuik Midlothian EH26 OQB Telephone: (031)4454343/6

Institute of Terrestrial Ecology (South) Monks Wood Experimental Station Abbots Ripton Huntingdon PE17 2LS Telephone: (04873) 381/8

Natural Environment Research Council £8.00 net