7.19 Optional subprogramme VS: Vegetation structure and species cover

Revised in 2010

• 7.19.1 Introduction
• 7.19.2 Methods
• 7.19.2.1 Selection of plots
• 7.19.2.2 Observations
• 7.19.3 Frequency of observation
• 7.19.4 Quality assurance/Quality control
• 7.19.5 Data reporting
• 7.19.6 References

7.19.1 Introduction

The main aim of the VS subprogramme is to follow any major changes in the structure and species composition of whole plant communities of the monitoring site. The data also serves the needs of plant diversity monitoring of trees, shrubs and field and bottom layer species of the entire catchment.

Methods for the estimate of biomass and its chemical elements of the understorey vegetation should be developed to complement the estimate of elements in the tree stands (subprogramme BI).

7.19.2 Methods

7.19.2.1 Selection of plots

Observations are carried out on permanent plots, preferably circular. An area of 100 m2 (radius 5.64 m) makes cover estimates easy (1 m2=1%). The plots could preferably be distributed along transect mapping lines (Figure 5.7) on or near the plots of the BI (Tree bioelements and tree indication) subprogramme, i.e. in a quadratic network, using the same station codes. Soil data may be available for the BI plots and they can be used as explaining variables in the VS subprogramme. Location outside the BI plots is recommended for sensitive vegetation in order to avoid influence by trampling. The centre of the plot is marked permanently for revisits.

If a plot is "impossible" with regard to topography, heterogeneity etc. or if the dominant plant community does not cover 50% or more, it is rejected.

Whatever design that is used, the observed parameters should be representative for the entire catchment. In the new 2010 reporting format, reporting is made at the level of plots and not at the level of plant communities (as in the 1998 format).

7.19.2.2 Observations

Divide the vegetation into tree, shrub, field and bottom layers according to its stratification and life forms. No specific height limits of trees and shrubs can be given, but here is an example:

• tree layer: trees > 5 m
• shrub layer: trees 1-5 m, morphological shrubs >1 m
• field layer: trees and shrubs <1 m, other vascular plants irrespective of height
• bottom layer: bryophytes and lichens

According to this classification a tree species can be present in both tree, shrub and field layers. If desirable the tree layer could be separated into an upper (T1) and a lower (T2) stratum.

Estimate the total cover of each vegetation layer and the cover of each species in each layer for each sample plot. Cover is defined as the area that above-ground living parts of a plant occupy when projected vertically on to the ground (shade when sun is in zenith) (Figure 7.17.2). Normally percentage cover-classes are used. In practice one per cent classes can be applied at the ends of the scale, while in the middle, i. e. round 50%, such fine estimates are practically impossible. However, all values are reported as per cent.

Note that plants growing on divergent surfaces e. g. on rocks and wind thrown objects should not be observed.

7.19.3 Frequency of observation

The survey is repeated after 10-20 years or after major changes, such as heavy management measures, increased grazing, fire, extensive storm felling, avalanche and landslide. The season for the inventory should coincide with maximum development of vegetative and reproductive organs of plants.

7.19.4 Quality assurance/Quality control

The estimate of cover on a 100 m2 large plot is crucial and data do not permit any fine changes to be detected. However, even rough cover figures of separate layers tell much about the vertical stratification and dominance in a community. The observer is advised not to spend too much time trying to find the "true cover", but concentrate on finding and identifying the species. Regarding insignificant species, such as some small hepatics, the observer is, however, warned against perfectionism.

7.19.5 Data reporting

Mandatory parameters

Example files

VS example Excel file
VS example ASCII file

• File identifier SUBPROG states the subprogramme.    
• Station number SCODE identifies the sample plot
• The plant community the sample plot belongs to is reported as MEDIUM. Enclose a separate list of those (full) community names and codes that are used. Note which sociological system has been applied or whether local names and codes have been established. The country code is given as the list name (LISTMED), e.g. SE for a Swedish code list. (List codes will be unified by the Programme Centre and already established Codelists for countries can be obtained from the Programme Centre). (In the old 1998 reporting format MEDIUM was mandatory since a number of sample plots were aggregated to describe the plant communities. The spatial pool (SPOOL) was the number of circular plots in one plant community that constitutes the sample. In the new 2010 version, reporting is done at the level of sample plots.)
• In the new 2010 reporting format spatial pool (SPOOL) it is always 1.
• Plant species are reported as SPECIES, using NCC codes (see Annex 6).
• Layers (T=tree, S=shrub, F=field, B=bottom) are indicated by the parameter codes (PARAM).
• Sampling year and month are given as YYYYMM.
• General information on flags is given in Chapter 4.

7.19.6 References

Cruickshank, M. M. & Tomlinson, R. W., 1996. Application of CORINE land cover methodology to the UK. Some issues raised from Northern Ireland. -Global Ecology and Biogeography Letters 5: 235-248.

van Ek, R. & Draaijers, G.P.J., 1991. Atmospheric Deposition in Relation to Forest Stand Structure. Inst. of Geographical Research, Dept of Physical Geography, Univ. of Utrecht.

Påhlsson, L. (ed.), 1994. Vegetationstyper i Norden (Vegtation types in the Nordic countries). Tema Nord 1994:665. Nordic Council of Ministers. (In Swedish, with introduction and type names in English.)