ECOFACT Volume 1 Introduction and Approach - Centre for Ecology ...

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ecological behaviour of the plant was different from its environmental demands. For instance, species such as heather (Calluna vulgaris), when cultivated alone, grows well in soils with a higher pH than those in which it grows in the wild, where it is confined to the more acid soils through competition with other species. The values have been recalibrated for British conditions (Hill et al. in prep) and are on the following scales: Light Moisture pH Fertility Continentality 1 (shaded) – 9 (open) 1 (dry) – 12 (wet) 1 (acid) – 9 (basic) 1 (infertile) – 9 (fertile) 1 (least continental) – 9 (most continental) The average Ellenberg scores for each CVS class have been ranked and divided into three percentile bands: low score (0.1–33.3%); medium (33.4–66.6); and high score (66.7–100%). Thus it is possible to see at a glance how the CVS classes compare with each other. In order to allocate vegetation plots (quadrats or relevèes) to the existing hierarchical classification, a binary decision tree was constructed. At each node of the tree a decision method was implemented, appropriate to the classification being emulated. The decisions were based on a partition of multidimensional species-space. The resulting decision tree produced a deterministic result, allocating each vegetation plot to a single vegetation class. It should be emphasised that this procedure gives a precise allocation of each individual plot to the appropriate class of the CVS, based on the entire information available on the species content of that plot. This structure has been implemented as a software package running under Microsoft Windows. So far this package has been made available on request for testing, and has performed well. This package enables a user to classify sample plots for a variety of objectives. The classification has also been incorporated into MAVIS (Modular Analysis of Vegetation and Interpretation System), a package currently being tested which provides ready access to the vegetation analysis procedures of CVS, NVC, CSR and Ellenberg values. This software allows the user to enter species lists for vegetation units either interactively or in batch mode from a data file. Once a vegetation unit or units have been allocated to a class or classes, the software allows the user to determine their positions on the three main vegetation gradients in Great Britain, as determined from the CVS. The CVS allocation software provides a means of sorting the different assemblages, using the whole list of species present. The major exception is saltmarsh, which was excluded from the analysis as it was represented by only 38 plots and is not robustly described within the range of CVS classes. The five most frequently recorded species were common saltmarsh-grass (Puccinellia maritima), sea plantain (Plantago maritima), annual sea-blite (Suaeda maritima), sea aster (Aster tripolium) and Spartina spp., but others such as glasswort (Salicornia spp.) may be locally important. However, if exceptional plots are being observed, eg amongst scrub on sea cliffs, and/or if plots are being examined out of season, then users should be aware that problems could arise in the allocation. Tests have been done, eg on limestone pavements, where no plots were placed in the random survey, and the system assigned the list of species to an appropriate group. It is difficult to provide statistical rules that are easy to apply in order to verify whether a class is appropriate, and judgement must be involved in applying the above guidelines. In critical studies appropriate statistical analyses should be carried out in order to confirm intuitive interpretation.
Vegetation class 1 AGGREGATE CLASS I CROPS/WEEDS Almost weedfree wheat/ other crops Total number of plots Landscape association Plot types Arable Marginal upland Pastural Upland Boundary Hedge Roadside Streamside Main Habitat Description Associated features Soils Land cover Occurrence (%) 45 40 35 30 25 20 15 10 5 0 0 1 2 3 4 5 6 7 8 9 10 106 % 84 0 16 0 % 1 1 1 0 97 0 This class occurs almost exclusively in fields on cultivated soils. It is quite common and has wheat as the main cover. It is very poor in plants with no one characteristic species. This class is found mainly in the core cereal landscapes of East Anglia but may also be present elsewhere in the lowlands. 0 Disturbed 1 Terrestrial raw 2 Raw gley 3 Lithomorphic 4 Pelosols 5Brown 6 Podzolic 7 Surface water gley 8 Groundwater gley 9 Man-made 10 Peat Distribution Occurrence (%) 120 100 80 60 40 20 0 1 2 3 4 5 6 7 8 9 10 11 12 Mapscale approx: 1:11,000,000 Key units Area 000’s km 0 kilometres 500 –2 Length 000’s km 1 Crops 2 Fertile grassland 3 Infertile grassland 4 Grass mosaic/bracken 5 Moorland grass 6 Tall grassland/herb 7 Bog 8 Woodland 9 Heath and screes 10 Water and wetland 11 Maritime vegetation 12 Communications/urban Main Boundary Area 7.36 SE 0.97 Length 1.09 SE 1.09
Page 1 and 2: Introduction and Approach: Introduc
Page 3 and 4: Field recording Programme: The vege
Page 5 and 6: Figure 1. Distribution of the 100 v
Page 7 and 8: The Countryside Vegetation System:
Page 9 and 10: soils oleraceus 3 Woods, tall grass
Page 11 and 12: The radar diagrams will enable user
Page 13 and 14: Illustrations of each aggregate cla
Page 15 and 16: This photograph of the upland woode
Page 17 and 18: Illustrations of CVS characteristic
Page 19: software. Extreme coastal plots are
Page 22 and 23: marginal uplands also have AC III a
Page 26 and 27: Floristic characteristics Species n
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Floristic characteristics Species n
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