Ad hoc decisions during fieldwork reduce the accuracy and reliability of vegetation maps. A method is proposed to objectify vegetation (thematic aspects) mapping (spatial aspects) for monitoring (temporal aspects). The most accurate and reliable description of the vegetation is a list of all plant species found within a plot. Therefore, the proposed method is an interpolation of a spatially representative sample of permanent plots combined with aerial photo interpretation. The method is objective because surveyors do not have to make decisions during fieldwork based on their personal judgement. Moreover, it is flexible, because the classification and interpolation methods can be adapted to specific views or needs depending on the aim of a study. The method was applied to an area in the north of the Netherlands in 1998. A sampling design with a density of 1 plot/ha was used, and interpolated with a perpendicular bisector. In 2002, the number of plots/ha was doubled. The influence of sample density on the mapping results was studied because it is an important decision to be made before fieldwork. Two plots/ha seem to be sufficient in order to obtain reliable information on patterns of plant species composition and vegetation types of the area, and their change over time. However, in patches where vegetation varies on a very small spatial scale this plot density was insufficient.
Cherrill, A. and C. McClean. 1999. Between-observer variation in the application of a standard method of habitat mapping by environmental consultants in the UK. J. Appl. Ecol. 36:989-1008.
'Between-observer variation in the application of a standard method of habitat mapping by environmental consultants in the UK ' () 36 J. Appl. Ecol. : 989 -1008 .
Curtis, J.T. and R.P. McIntosh. 1951. An upland Forest continuum in the prairie-forest border region of Wisconsin. Ecology 32: 3:476-496.
'An upland Forest continuum in the prairie-forest border region of Wisconsin ' () 32 Ecology : 476 -496 .
De Vlas, J., and J.M. Marquenie. 2003. The Impact of Subsidence and Sea Level Rise in the Wadden Sea: Prediction and Field Verification. NAM, Assen, the Netherlands.
The Impact of Subsidence and Sea Level Rise in the Wadden Sea: Prediction and Field Verification , ().
Dirkse, G.M. 1998. The validity of general purpose flora-based classification of vegetation. PhD thesis, University of Utrecht, the Netherlands.
Droesen, W.J. 1999. Spatial modelling and monitoring of natural landscapes: with cases in the Amsterdam Waterworks Dunes. PhD thesis, Wageningen Agricultural University, the Netherlands.
Ellenberg, H. 1991. Zeigerwerte der Gefäszpflanzen (ohne Rubus). Scripta Geobotanica 18:9-166.
'Zeigerwerte der Gefäszpflanzen (ohne Rubus) ' () 18 Scripta Geobotanica : 9 -166 .
Bakker, J.P. 1979. Vegetation science and nature conservation. In: M.J.A. Werger (ed.), The Study of Vegetation. Junk, Den Haag, the Netherlands.
Vegetation science and nature conservation , ().
Bakker, J.P. and J.C. Ruyter. 1981. Effects of five years of grazing on a salt-marsh vegetation. A study with sequential mapping. Vegetatio 44:81-100.
'Effects of five years of grazing on a salt-marsh vegetation. ' () 44 Vegetatio : 81 -100 .
Bakker, J.P. 1989. Nature Management by Grazing and Cutting. Geobotany 14. Kluwer, Dordrecht, the Netherlands.
Geobotany 14 , ().
Burrough, P.A. 1986. Principals of Geographical Information Systems for Land Resources Assessment. Clarendon, Oxford.
Principals of Geographical Information Systems for Land Resources Assessment , ().
Burrough, P.A. 1987. Spatial aspects of ecological data. In: R.H.G. Jongman, C.J.F. ter Braak and O.F.R. van Tongeren (eds.), Data Analysis in Community and Landscape Ecology. Pudoc, Wageningen, the Netherlands.
Spatial aspects of ecological data , ().
Cain, S.A. 1938. The species-area curve. Amer. Midland Nat. 19:573-581.
'The species-area curve ' () 19 Amer. Midland Nat. : 573 -581 .
Fisher, R, A.S. Corbet and C.B. Williams. 1943. The relation between the number of species and the number of individuals in a random sample from an animal population. J. Animal Ecol. 12:42-58.
'The relation between the number of species and the number of individuals in a random sample from an animal population ' () 12 J. Animal Ecol. : 42 -58 .
Fortin, M., P. Drapeau and P. Legendre. 1989. Spatial autocorrelation and sampling design in plant ecology. Vegetatio 83:209-222.
'Spatial autocorrelation and sampling design in plant ecology ' () 83 Vegetatio : 209 -222 .
Goldsmith, F.B. 1991. Monitoring for Conservation Ecology. Chapman and Hall, London.
Monitoring for Conservation Ecology , ().
Hill, M.O. 1979. TWINSPAN, A FORTRAN program for arranging multivariate data into an ordered two-way table by classification of the individuals and attributes. Cornell University, Ithaca.
TWINSPAN, A FORTRAN program for arranging multivariate data into an ordered two-way table by classification of the individuals and attributes , ().
Huston, M.A. 1994. Biological Diversity; The Coexistence of Species on Changing Landscapes. Cambridge University Press, Cambridge.
Biological Diversity; The Coexistence of Species on Changing Landscapes , ().
Janssen, J.A.M. 2001. Monitoring of salt-marsh vegetation by sequential mapping. PhD thesis, University of Amsterdam.
Kent, M. and P. Coker. 1992. Vegetation Description and Analysis, a Practical Approach. Wiley, Chichester.
Vegetation Description and Analysis, a Practical Approach , ().
Kuechler, A.W. and I.S. Zonneveld. 1988. Vegetation Mapping, Handbook of Vegetation Science, part 10. Kluwer, Dordrecht, the Netherlands.
Vegetation Mapping, Handbook of Vegetation Science, part 10 , ().
Legendre, P. and L. Legendre. 1998. Numerical Ecology. Elsevier, Amsterdam.
Numerical Ecology. , ().
Leps, J. and V. Hadincova. 1992. How reliable are your vegetation analyses? J. Veg. Sci. 3:119-124.
'How reliable are your vegetation analyses ' () 3 J. Veg. Sci : 119 -124 .
Londo, G. 1974. Successive mapping of dune slack vegetation. Vegetatio 29:51-61.
'Successive mapping of dune slack vegetation ' () 29 Vegetatio : 51 -61 .
Marsman B.A. and J.J. De Gruijter. 1986. Quality of soil maps. A comparison of survey methods in a sandy area. Soil Survey Papers, no 15. Soil Survey Institute, Wageningen, the Netherlands.
Quality of soil maps. A comparison of survey methods in a sandy area. Soil Survey Papers, no 15 , ().
Mueller-Dombois, D. and H. Ellenberg. 1974. Aims and Methods of Vegetation Ecology. Wiley, New York.
Aims and Methods of Vegetation Ecology , ().
Nilsson, C. 1992. Increasing the reliability of vegetation analyses by using a team of two investigators. J. Veg. Sci. 3:565.
'Increasing the reliability of vegetation analyses by using a team of two investigators ' () 3 J. Veg. Sci. : 565 .
Oude Voshaar, J.H. 1981. Steekproefmethoden in het onderzoek naar verspreiding van perceelsvormen: oppervlakteschatting van mozaiken via steekproefpunten. IWIS-TNO, Wageningen, the Netherlands.
Steekproefmethoden in het onderzoek naar verspreiding van perceelsvormen: oppervlakteschatting van mozaiken via steekproefpunten , ().
Schaminée, J.H.J., A.H.F. Stortelder and V. Westhoff. 1995. De vegetatie van Nederland. Deel 1. Inleiding tot de plantensociologie - grondslagen, methoden en toepassingen. Opulus, Leiden.
De vegetatie van Nederland. Deel 1. Inleiding tot de plantensociologie - grondslagen, methoden en toepassingen , ().
Schouten M. and M. van Ool. 2003. Werken met waarden bij Staatsbosbeheer. Natuurbehoud als beschavingsnorm. Jaarverslag Staatsbosbeheer 2002.
Smartt, P.F.M. and J.E.A. Grainger. 1974. Sampling for vegetation survey: some aspects of the behaviour of unrestricted, and stratified techniques. J. Biogeogr. 1:193-206.
'Sampling for vegetation survey: some aspects of the behaviour of unrestricted, and stratified techniques ' () 1 J. Biogeogr : 193 -206 .
Tokeshi, M. 1993. Species abundance patterns and community structure. Adv. Ecol. Res. 24:111-186.
'Species abundance patterns and community structure ' () 24 Adv. Ecol. Res : 111 -186 .
Van Holst, A.F. 1990. Bodemkartering en bodemkaarten. In: H. de Bakker and W.P. Locher (eds), Bodemkunde van Nederland. Deel 2, bodemgeografie. Malmberg, Den Bosch, the Netherlands.
Bodemkartering en bodemkaarten , ().
Van der Maarel, E., R Boot, D. van Dorp and J. Rijntjes. 1985. Vegetation succession on the dunes near Oostvoorne, the Netherlands; a comparison of the vegetation in 1959 and 1980. Vegetatio 58:137-187.
'Vegetation succession on the dunes near Oostvoorne, the Netherlands; a comparison of the vegetation in 1959 and 1980 ' () 58 Vegetatio : 137 -187 .
Van Dorp, D., R. Boot and E. van der Maarel. 1985. Vegetation succession on the dunes near Oostvoorne, the Netherlands, since 1934, interpreted from air photographs and vegetation maps. Vegetatio 58:123-136.
'Vegetation succession on the dunes near Oostvoorne, the Netherlands, since 1934, interpreted from air photographs and vegetation maps ' () 58 Vegetatio : 123 -136 .
Van der Meijden, R., 1996. Heukels' Flora van Nederland. Wolters-Noordhoff, Groningen, the Netherlands.
Heukels' Flora van Nederland , ().