Correspondence
Härdtle, W. (1995) On the theoretical
concept of Potential Natural Vegetation
and proposals for an up-to-date modification. Folia Geobotanica et Phytotaxonomica, 30, 263–276.
Lobo, A., Ibáñez, J.J. & Carrera, C. (1997)
Regional scale hierarchical classification
of temporal series of AVHRR vegetation
index. International Journal of Remote
Sensing, 18, 3167–3193.
Loidi, J. (1999) Preserving biodiversity in
the European Union: the Habitats Directive and its application in Spain. Plant
Biosystems, 133, 99–106.
Loidi, J. (2007) La evolución del paisaje
vegetal del centro-norte de la Penı́nsula
Ibérica a lo largo de la historia. Boletı́n de
la RSBAP, 11, 11–51.
Moravec, J. (1998) Reconstructed natural
versus potential natural vegetation in
vegetation mapping. Applied Vegetation
Science, 1, 173–176.
Rivas-Martı́nez, S. (1987) Mapa de series de
vegetación de España. ICONA Serie Técnica, Madrid.
Rivas-Martı́nez, S. (2007) Mapa de series,
geoseries y geopermaseries de vegetación
de España. Parte I. Itinera Geobotánica,
17, 5–435.
Rivas-Martı́nez, S., Penas, A., Asensi, A.,
Costa, M., Llorens, L., Pérez de Paz, P.L.,
Loidi, J., Dı́az, T.E., Izco, J., Ladero, M.,
Fernández-González, F., Masalles, R. &
Sánchez-Mata, D. (2003) Atlas y manual
de los hábitat de España. Dirección General
de la Conservación de la Naturaleza,
Ministerio de Medio Ambiente, Madrid.
Rodrigues Tarroso, J.P. (2007) Late-Quaternary landscape dynamics in the Iberian
Peninsula and Balearic Islands. Universidade do Porto, Porto.
Tüxen, R. (1956) Die heutige potentielle
natürliche Vegetation als Gegenstand
der Vegetationskartierung. Angewandte
Pflanzensoziologie, 13, 5–55.
Editor: John Lambshead
doi:10.1111/j.1365-2699.2010.02302.x
The power of potential natural
vegetation (and of spatialtemporal scale): a response to
Carrión & Fernández (2009)
ABSTRACT
A commentary by Carrión & Fernández
(Journal of Biogeography, 2009, 36, 2202–
Journal of Biogeography 37, 2209–2215
ª 2010 Blackwell Publishing Ltd
2203) compared Holocene pollen records
with models of potential natural vegetation (PNV) proposed in the phytosociological literature and concluded that the
predicted PNV resulted from anthropogenic disturbance. However, the authors
misinterpreted PNV, leading to two serious flaws in their assumptions: (1) PNV is
not defined as a pre-anthropic or climax
plant community; and (2) PNV is not a
concept restricted to the phytosociological method. Therefore we criticize the
conclusions expressed in the commentary, and we stress the need for an
interdisciplinary approach based on
multi-temporal and multi-spatial scales to
achieve a modern framework for the
study of plant communities.
Keywords Climax concept, ecological
restoration, Holocene vegetation, landscape dynamics, phytosociology, potential natural vegetation, secondary
succession, vegetation classification, vegetation science.
In a commentary regarding Holocene pollen
deposits from the Canary Islands, Carrión &
Fernández (2009) argued that the discovery
of Quercus and Carpinus pollen is noteworthy because Ôthe prevailing concepts of
natural potential vegetation in the study
region imply that the pre-anthropic (mature
phase or climax) vegetationÕ would be an
evergreen forest dominated by species of
Lauraceae. Inferences of pre-anthropic vegetation made by palynologists were also
compared with the potential natural vegetation (PNV; incorrectly quoted in the
commentary as Ônatural potential vegetationÕ) proposed in the phytosociological
literature at a number of sites in the Iberian
Peninsula. The results of the two models
indicated that, in many instances, the
dominant species differed. Therefore they
concluded that the PNV types determined
in previous studies were the result of
anthropogenic disturbance. Consequently,
the authors polemically argued that there is
a bias Ôin the conceptualization of the vegetational dynamicsÕ by Ôtraditional vegetation scienceÕ, and resistance to abandon this
bias Ôhas little to do with scientific evidenceÕ,
in front of Ôa growing body of work questioning
the
floristic-phytosociological
approachÕ. Unfortunately, this line of reasoning is based on two serious misunderstandings regarding the PNV concept.
First and foremost, PNV is not defined by
vegetation scientists as Ôpre-anthropic
(mature phase or climax) vegetationÕ. On
the contrary, PNV is defined as the plant
community that Ôwould become established
if all successional sequences were completed
without interference by man under the
present climatic and edaphic conditions
(including those created by man)Õ (MuellerDombois & Ellenberg, 1974, p. 422; our
emphasis; see also: Westhoff & van der
Maarel, 1973; Ellenberg, 1988; Ricotta et al.,
2002). European landscapes exhibit present
soil conditions that are often dramatically
different from their original state, due to
recent or ancient but irreversible human
disturbance (cf. Dupouey et al., 2002).
Consequently, it is an essential part of the
PNV theory that the potential vegetation of
a site can be very different from the preanthropic vegetation at the same site
(e.g. Mueller-Dombois & Ellenberg, 1974;
Chytrý, 1998; Moravec, 1998; Zerbe, 1998;
Gamisans, 1999). The PNV concept was
introduced (Tüxen, 1956) to express the
present (ÔheutigeÕ) potential of a region or
site as a useful reference to define a target
for restoration ecology and ecological
engineering projects, or for landscape
management purposes (e.g. to forecast and
manage landscape evolution on a time-scale
of a few decades) (Rodwell & Patterson,
1994; Härdtle, 1995; Miyawaki, 1998; Zerbe,
1998; Verheyen et al., 2006; Dostalek et al.,
2007).
It is quite surprising that Carrión &
Fernández (2009) completely ignored the
large body of works addressing and defining
PNV theory. Furthermore, it is perplexing
they assumed that Ôclimax vegetationÕ and
PNV are considered synonyms in vegetation
science. On the contrary, it is well known
that the idea of PNV arose as an outcome of
(and reaction to) the long-lasting debate on
the ÔclimaxÕ concept (Zerbe, 1998; Ricotta
et al., 2002). European vegetation scientists
have questioned the concept of climax for
decades (Mueller-Dombois & Ellenberg,
1974; Chytrý, 1998; Schulze et al., 2005),
and we now acknowledge that vegetation is
not returning to an alleged, past equilibrium, but is adapting continuously to a
changing abiotic environment and biotic
interactions. In addition, the inferred climax
phase requires a long period of succession,
which introduces not only the effects of
long-term climatic changes, but also those
of vegetation-induced soil modifications.
Finally, the climax concept was developed to
study the phytogeography of North America, a continent featuring abiotic homogeneity over large areas, a condition rarely
verified in Europe.
2211
Correspondence
The second fundamental mistake in
Carrión & Fernández (2009) was their
assumption that PNV is a concept exclusive to the phytosociological school (i.e. of
the Braun-Blanquet approach to plant
community entitation, sampling and classification; see e.g. Westhoff & van der
Maarel, 1973). Although originally developed by phytosociologists, the PNV model
does not stem from the assumptions of
phytosociology, nor do the Ôpotential
communitiesÕ need to be defined and
classified through the phytosociological
system. PNV-based models can be usefully
applied even if vegetation is classified on a
purely physiognomic basis (e.g. Liu et al.,
2009).
Furthermore, despite the fact that PNV
arose in a historical context, when succession
had a linear deterministic interpretation, it is
interesting that even in modern ÔchaoticÕ
models of succession, the PNV hypothesis is
supported, as it can be viewed as the strange
attractor where succession trajectories converge (Anand & Orloci, 1997; Ricotta et al.,
2002). Thus the comparison between the
distribution of actual vegetation patterns
and PNV types is presently integrated in the
most current applied ecological research, for
example: to assess the effects of disturbance
on pattern and diversity in landscape ecology
studies (Ricotta et al., 2002; Bajocco et al.,
2010); to study the effectiveness of protected
area networks (Rosati et al., 2008); and to
contribute to habitat monitoring (Mücher
et al., 2009).
As a consequence, the use of PNV concepts is definitely not restricted to a few
Ôacademic refuges [of phytosociology]Õ in
Spain or Italy (Carrión & Fernández, 2009).
PNV-based methods are largely adopted
today in countries where the phytosociological approach is not traditionally applied,
such as the USA and China (e.g. Küchler,
1964; Brohman & Bryant, 2004; Liu et al.,
2009; Zou et al., 2009), and⁄or within disciplines not related to phytosociology,
including forestry and wildlife ecology (e.g.
Lexer et al., 2002; Aubry et al., 2007; Kennedy & Wimberly, 2009; Strand et al.,
2009). Recently, PNV concepts were integrated in major vegetation-mapping projects, based on extensive international
collaboration (Bohn et al., 2004; Walker
et al., 2005).
Therefore it is unclear why any shortcomings in the PNV model (see Zerbe, 1998
for limitations and caveats) should Ôquestion
the floristic-phytosociological approachÕ
and why any flaws of the phytosociological
approach should weaken the usefulness
2212
of the PNV concept. Incidentally, it should
be noted that the conflicts between the
assumptions of the phytosociological
method and the latest views in ecology form
a complex and long-lasting debate (see e.g.
Dengler et al., 2008 and references therein),
which cannot be summarised here, and have
little to do with the issues raised by Carrión
& Fernández (2009).
Furthermore, it is not clear why Carrión
& Fernández (2009) quoted the Willis &
Birks (2006) review to support the claim
that Ôthe palaeoecological literature is full of
overwhelming evidence against [the phytosociological] notions of vegetational
dynamicsÕ. Instead, the need for a multimethod approach to a modern, integrated
framework for the study of plant communities (as advocated by Willis & Birks, 2006)
should be stressed. We believe in a multidisciplinary approach to community ecology, where short-term secondary succession
studied by vegetation scientists and longterm dynamics reconstructed by palynologists are two views of the same process
studied at two different spatial-temporal
scales, both of which should contribute to
the development of a unified, multi-scale
model of vegetation dynamics (Davis et al.,
2005; Willis et al., 2007; Pickett et al., 2009;
Zou et al., 2009).
Emmanuele Farris1, Goffredo
Filibeck2*, Michela Marignani3
and Leonardo Rosati4
1
Dipartimento di Scienze Botaniche,
Ecologiche e Geologiche, Università degli
Studi di Sassari, Via Piandanna 4,
I-07100 Sassari, Italy
2
Dipartimento di Ecologia e Sviluppo
Economico Sostenibile, Università degli
Studi della Tuscia, Largo dellÕUniversità
snc, I-01100 Viterbo, Italy
3
Dipartimento di Biologia Vegetale,
Università degli Studi di Roma
‘‘Sapienza’’, Piazzale Aldo Moro 5,
I-00185 Roma, Italy
4
Dipartimento di Biologia, Difesa e Biotecnologie Agro-forestali, Università degli
Studi della Basilicata, Viale dellÕAteneo
Lucano 10, I-85100 Potenza, Italy
*E-mail: [email protected]
REFERENCES
Anand, M. & Orloci, L. (1997) Chaotic
dynamics in a multispecies community.
Environmental and Ecological Statistics, 4,
337–344.
Aubry, K.B., McKelvey, K.S. & Copeland,
J.P. (2007) Distribution and broadscale
habitat relations of the wolverine in the
contiguous United States. Journal of
Wildlife Management, 71, 2147–2158.
Bajocco, S., Rosati, L. & Ricotta, C. (2010)
Knowing fire incidence through fuel
phenology: a remotely sensed approach.
Ecological Modelling, 221, 59–66.
Bohn, U., Gallub, G., Hettwer, C., Neuhauslova, Z., Raus, T., Schlüter, H. & Weber,
H. (2004) Interactive CD-ROM to the map
of the natural vegetation of Europe. Bundesamt für Naturschutz, Bonn.
Brohman, R. & Bryant, L. (2004) Existing
vegetation classification and mapping technical guide. USDA Forest Service, Washington, DC.
Carrión, J.S. & Fernández, S. (2009) The
survival of the Ônatural potential vegetationÕ concept (or the power of tradition).
Journal of Biogeography, 36, 2202–2203.
Chytrý, M. (1998) Potential replacement
vegetation: an approach to vegetation
mapping of cultural landscapes. Applied
Vegetation Science, 1, 177–188.
Davis, M.A., Pergl, J., Truscott, A.M., Kollmann, J., Bakker, J.P., Domenech, R.,
Prach,
K.,
Prieur-Richard,
A.H.,
Veeneklaas, R.M., Pyšek, P., del Moral,
R., Hobbs, R.J., Collins, S.L., Pickett,
S.T.A. & Reich, P.B. (2005) Vegetation
change: a reunifying concept in plant
ecology. Perspectives in Plant Ecology
Evolution and Systematics, 7, 69–76.
Dengler, J., Chytrý, M. & Ewald, J. (2008)
Phytosociology. Encyclopedia of ecology
(ed. by S.E. Jorgensen and B. Fath),
pp. 2767–2779. Elsevier, Oxford.
Dostalek, J., Weber, M., Matula, S. &
Frantik, T. (2007) Forest stand restoration
in the agricultural landscape: the effect of
different methods of planting establishment. Ecological Engineering, 29, 77–86.
Dupouey, J.L., Dambrine, E., Laffite, J.D. &
Moares, C. (2002) Irreversible impact of
past land use on forest soils and biodiversity. Ecology, 83, 2978–2984.
Ellenberg, H. (1988) Vegetation ecology of
Central Europe, 4th edn. Cambridge University Press, Cambridge.
Gamisans, J. (1999) La végétation de la
Corse. Edisud, Aix-en-Provence.
Härdtle, W. (1995) On the theoretical
concept of the potential natural vegetation and proposals for an up-to-date
modification. Folia Geobotanica Phytotaxonomica, 30, 263–276.
Kennedy, R.S.H. & Wimberly, M.C. (2009)
Historical fire and vegetation dynamics
in dry forests of the interior Pacific
Northwest, USA, and relationships to
northern spotted owl (Strix occidentalis
caurina) habitat conservation. Forest
Ecology and Management, 258, 554–566.
Journal of Biogeography 37, 2209–2215
ª 2010 Blackwell Publishing Ltd
Correspondence
Küchler, A.W. (1964) Potential natural vegetation of the conterminous United States.
Special Publication No. 36, American
Geographical Society, New York.
Lexer, M.J., Honninger, K., Scheifinger, H.,
Matulla, Ch., Groll, N., Kromp-Kolb, H.,
Schadauer, K., Starlinger, F. & Englisch, M.
(2002) The sensitivity of Austrian forests
to scenarios of climatic change: a largescale risk assessment based on a modified
gap model and forest inventory data. Forest
Ecology and Management, 162, 53–72.
Liu, H., Wang, L., Yang, J., Nakagoshi, N.,
Liang, C., Wang, W. & Lv, Y. (2009)
Predictive modeling of the potential natural vegetation pattern in northeast
China. Ecological Research, 24, 1313–1321.
Miyawaki, A. (1998) Restoration of urban
green environments based on the theories
of vegetation ecology. Ecological Engineering, 11, 157–165.
Moravec, J. (1998) Reconstructed natural
versus potential natural vegetation in
vegetation mapping – a discussion of
concepts. Applied Vegetation Science, 1,
173–176.
Mücher, C.A., Hennekens, S.M., Bunce,
R.G.H., Schaminée, J.H.J. & Schaepman,
M.E. (2009) Modelling the spatial distribution of Natura 2000 habitats across
Europe. Landscape and Urban Planning,
92, 148–159.
Mueller-Dombois, D. & Ellenberg, H.
(1974) Aims and methods of vegetation
ecology. John Wiley & Sons, New York.
Pickett, S.T.A., Cadenasso, M.L. & Meiners,
S.J. (2009) Ever since Clements: from
succession to vegetation dynamics and
understanding to intervention. Applied
Vegetation Science, 12, 9–21.
Ricotta, C., Carranza, M.L., Avena, G. &
Blasi, C. (2002) Are potential vegetation
maps a meaningful alternative to neutral
landscape models? Applied Vegetation
Science, 5, 271–275.
Rodwell, J. & Patterson, G. (1994) Creating
new native woodlands. HMSO, London.
Rosati, L., Marignani, M. & Blasi, C. (2008)
A gap analysis comparing Natura 2000 vs
National Protected Area network with
potential natural vegetation. Community
Ecology, 9, 147–154.
Schulze, E.D., Beck, E. & Müller-Hohenstein, K. (2005) Plant ecology. Springer,
Berlin-Heidelberg.
Strand, E.K., Vierling, L.A., Bunting, S.C. &
Gessler, P.E. (2009) Quantifying successional rates in western aspen woodlands:
current conditions, future predictions.
Forest Ecology and Management, 257,
1705–1715.
Tüxen, R. (1956) Die heutige potentielle
natürliche Vegetation als Gegenstand
Journal of Biogeography 37, 2209–2215
ª 2010 Blackwell Publishing Ltd
der Vegetationskartierung. Angewandte
Pflanzensoziologie, 13, 5–42.
Verheyen, K., Fastenaekels, I., Vellend, M.,
De Keersmaeker, L. & Hermy, M. (2006)
Landscape factors and regional differences in recovery rates of herb layer
richness in Flanders (Belgium). Landscape
Ecology, 21, 1109–1118.
Walker, D.A., Raynolds, M.K., Daniëls,
F.J.A., Einarsson, E., Elvebakk, A., Gould,
W.A., Katenin, A.E., Kholod, S.S.,
Markon, C.J., Melnikov, E.S., Moskalenko,
N.G., Talbot, S.S., Yurtsev, B.A. & the
other members of the CAVM Team (2005)
The Circumpolar Arctic vegetation map.
Journal of Vegetation Science, 16, 267–282.
Westhoff, V. & van der Maarel, E. (1973)
The Braun-Blanquet approach. Ordination and classification of communities (ed.
by R.H. Whittaker), pp. 617–726. Handbook of Vegetation Science, Vol. 5. Junk,
The Hague.
Willis, K.J. & Birks, H.J.B. (2006) What is
natural? The need for a long-term perspective in biodiversity conservation.
Science, 314, 1261–1265.
Willis, K.J., Bennett, K.D., Froyd, C. &
Figueroa-Rangel, B. (2007) How can a
knowledge of the past help to conserve
the future? Biodiversity conservation
strategies and the relevance of long-term
ecological studies. Philosophical Transactions of the Royal Society B: Biological
Sciences, 362, 175–186.
Zerbe, S. (1998) Potential natural vegetation: validity and applicability in landscape planning and nature conservation.
Applied Vegetation Science, 1, 165–172.
Zou, S., Cheng, G., Xiao, H., Xu, B. & Feng,
Z. (2009) Holocene natural rhythms of
vegetation and present potential ecology
in the Western Chinese Loess Plateau.
Quaternary International, 194, 55–67.
Editor: John Lambshead
doi:10.1111/j.1365-2699.2010.02323.x
The concepts of potential
natural vegetation (PNV)
and other abstractions (trying
to pick up fish with wet hands)
ABSTRACT
This note follows from an earlier Commentary published in Journal of Biogeography (Carrión & Fernández, 2009, 36,
2202–2203), which provided palaeoecological data, and two replies in the form of
Correspondence (Loidi et al., 2010, 37,
2209–2211; Farris et al., 2010, 37, 2211–
2213). The latter papers attempt to
invalidate the palaeoecological database
as a source of comparison with the maps
of potential vegetation. Here, some of the
different interpretations of the term Ôpotential natural vegetationÕ (PNV), as used
by the floristic phytosociological school,
are discussed. It is suggested that there is a
conceptual impasse that will not have a
solution until a terminological consensus
is reached. This terminology will open
new methodological avenues that will
facilitate the entry of new information
derived from historical biogeography,
palaeoecology, ecology, phylogeography,
and niche and community modelling. One
of the main sources of conflict arises from
the link made between habitats and floristically-determined associations, a confusion that has crucial repercussions in
biological conservation, including in
respect of the EU Habitats Directive.
Keywords Climax concept, conservation,
historical biogeography, palaeoecology,
phytosociology, potential natural vegetation.
This paper is a response to two papers
authored by sixteen phytosociologists from
Spain and Italy. The first, Loidi et al. (2010),
presents what could be seen as the phytosociological schoolÕs consensus position as
already published, for example, by Loidi
(1998) in reaction to Blanco et al. (1997). The
latter, among others (e.g. Spribille & Ceska,
2001), claim that potential natural vegetation
(PNV) has the following weaknesses: (1) the
subjective character of sampling, (2) the
inefficient description of human-disturbed
areas, (3) the lack of regard to the role of
structure in the definition of communities,
(4) the confused system of nomenclature and
the instability of the classification, (5)
impoverished, outdated methodology, (6)
lack of experimental field studies, and (7) a
strong tendency to use ad hoc taxonomy to
name phytosociological taxa.
Loidi et al. (2010) argue that by seeking a
comparison with pristine vegetation, Carrión & Fernández (2009) are using an inexact
interpretation of the concept of potential
natural vegetation (PNV), even though this
comparison is common in applied forestry
(Higgins et al., 2004). In practice, it is difficult to determine which interpretation of
PNV should be adopted given that there are
2213