HABITAT CONSERVATION STATUS: PROPOSED DEFINITIONS AND CONCEPTS FOR ASSESSMENT
AT THE NATURA 2000 SITE LEVEL
by Lise MACIEJEWSKI1, Fanny LEPAREUR1, Déborah VIRY2, Farid BENSETTITI1, Renaud PUISSAUVE2 & Julien
TOUROULT1
1 Muséum
national d’Histoire naturelle, Service du Patrimoine Naturel, CP41, 36 rue Geoffroy Saint-Hilaire. F-75005 Paris. E-mails:
[email protected] (auteur référent), [email protected], [email protected], [email protected]
2 Muséum national d’Histoire naturelle, Service du Patrimoine Naturel, 4, avenue du Petit Château. F-91800 Brunoy. E-mails: [email protected],
[email protected]
Original title : Etat de conservation des habitats : propositions de définitions et de concepts pour l’évaluation à
l’échelle d’un site Natura 2000
In : Revue d’Ecologie (Terre et Vie), Vol. 71 (1), 2016 : 3-20
Translation: European topic center on Biological diversity
SHORT SUMMARY: Assessing the conservation status of habitats is now a key part in the management plan of protected areas. The transposal
of the Habitats-Fauna-Flora directive (92/43/CEE) (Habitats directive) in French law provides a regulatory frame for assessing the conservation
status of habitat at a Natura 2000 site level. French Museum of Natural History (MNHN) has been asked to develop methods for Natura 2000
managers in order to standardize evaluations. Focusing on the concept of habitat and its evaluation, we propose definitions in order to fill
some identified gaps and precise the concept of conservation status assessment. The need for habitat classification system is mentioned, as
well as the advantages and the limits of this tool. Considering the habitat as a complex system under the general systems theories, its
conservation status means the status of its components, but also of their interactions among them and with the environment. Assessing the
conservation status implies the assessment of the structure, composition and functions of a habitat, which are interdependent. With the need
for evaluation comes the need of making choices, which implies to define the « optimal selected state » as a long-term aim, and the « chosen
favourable status » as an operational target for managers. These choices are enlightened by scientific evidences in a socio-economic and
cultural context bounded by the Habitats directive. We discuss the impact of the habitat’s dynamics and succession on the establishment of
the different conservation status. Finally, some key methodological choices are discussed, especially the role of species in the assessment of
habitat and the connections between evaluation and management.
EXECUTIVE SUMMARY:
A CONCEPT FROM CONSERVATION SCIENCE: FROM AWARENESS TO ACTION
CONSERVATION BIOLOGY ON THE INTERNATIONAL SCENE
The foundations of the concept of conservation status are to be found in the emergence in the 1980s of a branch
of ecology: conservation biology. This discipline developed in response to an alarming situation, linked to the
development of human activities and now considered as the sixth mass extinction.
Conservation biology is a crisis discipline (Soulé 1985) which should evolve from being a science that records
disasters to a science of action (Barbault, 2008), giving new impetus to nature conservation policies. Its conceptual
and methodological framework (Soulé 1985) allows the development of tools for the implementation of nature
protection. As an applied science, conservation biology is necessarily associated with economic and social
considerations.
Nature conservation was developed initially in terms of species preservation. Faced with the homogenization of
ecosystems and landscapes due to human omnipresence, conservationists have developed a more integrated
vision of nature. The concept of ‘habitat’ has proved to be a useful tool to integrate functionality and covering
many species, their relationships between each other and with their environment.
In Europe, the European Directive 92/43 / EEC on the Conservation of natural habitats and of wild fauna and flora
(the Habitats Directive) sets the framework for the European Union's policies on nature conservation. It gives the
common objective for the Member States ‘to ensure the maintenance or restoration, at favourable conservation
status, of the natural habitats and species of wild fauna and flora of Community interest’ (Art. 2). The conservation
status of a habitat is defined it as ‘the effect of all the influences acting on a natural habitat as well as its typical
species that may affect its long-term natural distribution, its structure and functions as well as the long-term
survival of its typical species.’
However, this definition is not operational for use at site level, which is the most relevant level for the
implementation of operational objectives for habitat conservation. Indeed, it applies to a biogeographical scale
but remains vague and general. Conservation status has become an essential element for management documents
for protected areas and as part of environmental assessment procedures.
The Habitat Directive’s transposition into French law has kept the term ‘conservation status’ in the technical
language for nature conservation. In this context, proposals of definitions and concepts are needed to contribute
to discussions about the tools proposed for assessing the conservation status of habitats of Community interest.
ASSESSING CONSERVATION STATUS: A KEY CONCEPT REMAINS TO CLARIFY
In order to help Natura 2000 site managers, the French Ministry of Ecology asked the French National Museum of
Natural History (MNHN) to develop standardized methods for evaluating the conservation status of habitats at the
site-level. Since 2009, several guides have been published by the MNHN by major habitat groups using a common
conceptual and methodological framework: forest habitats, coastal dunes, lagoons, wetlands and aquatic habitats,
grasslands and Mediterranean temporary ponds.
It seemed useful to clarify our understanding of the concepts as a contribution to the debate. Indeed, the terms
and concepts used have multiple meanings and different interpretations are possible, and are only clear when
explained. Our bibliographical review highlighted that there were few references on the subject in scientific
journals and publications are mostly from the grey literature, often treating the subject without defining the
concepts or terms used. This paper aims to expose our interpretation of the concepts related to the state of
conservation of the habitat and its evaluation. It is based on an exchange of ideas with partners from various
disciplines of conservation science (researchers, naturalists, managers and policy makers).
THE OBJECT OF THE EVALUATION: THE HABITAT TYPE AND ITS CONSERVATION STATUS
IMPORTANCE OF THE TYPOLOGY AND THE DEFINITION OF THE SUBJECT
Nature conservation policies require a precise definition of the subjects. For the Habitats Directive, these objects
are species and habitats of community interest. The concepts of species and their limits are regularly revised via
taxonomical research and the evolution of systematic concepts. The definitions of habitats are even more difficult
to grasp. Though, as for species names, habitat names are the gateway to all their ecological, biological and nonbiological attributes: distribution, mapping (habitat polygons), ecology, functions, management, regulation, etc.
Without clear consensus, our understanding of the term ‘typology’ is a systematic approach which, according to
the context and purpose, leads to the definition of a set of types in order to facilitate the analysis, classification and
study of complex realities. The typology is not an end in itself, it is a way to synthesize and organize objects in a
field of study, to simplify a complex reality to facilitate our understanding by creating and naming entities (types)
and adopting a common vocabulary. The aim is to move from a continuous system (e.g. a colour gradient) to a
discrete system (a paint colour swatch). This simplification requires making choices that have important
consequences. These depend on the context, the objective and its construction. When choices are made
deliberately, the consequences and limitations of a typology can be accepted.
Our study only focuses on the Annex I habitats and does not concern species or habitat for species.
THE CONCEPT OF HABITAT
Although definitions of habitat vary considerably in the ecological literature, Boullet (2003), based on Yapp (1922),
underlined three essential principles:
- a geographical space, so with a spatial reality;
- a set of environmental parameters involving physicochemical (abiotic factors) and biotic factors affecting this
geographical area;
- a spatiotemporal organization and a multiscale approach to the concept of habitat.
However, due to its integrative properties, vegetation can be considered as a proxy for habitats for terrestrial
systems (Rameau et al. 2000). This statement helps avoiding semantic confusion between the concepts of habitat
and vegetation while recognizing the role of phytosociology in the characterization of terrestrial habitats. For
marine habitats, habitat determination also includes species communities (cortège) including fauna (Pérès &
Picard, 1964). This point allows the differentiation between the definition of an object and its determination
criteria (as the difference between the definition of a species and species recognition criteria).
The Habitat Directive defines a natural habitat as a ‘terrestrial or aquatic area distinguished by geographic, abiotic
and biotic features, whether entirely natural or semi-natural’. This definition focuses on the first two principles of
the concept of the habitat. However, the third principle remains vague. Indeed, in the Interpretation Manual of
European Union Habitats - EUR28, the scale of habitat description (spatial, temporal and typological) is not
constant nor always specified. For example, in the case of riparian forests, different habitats can be described from
the pioneer phase to the mature phase (e.g. ‘3220 Alpine rivers and the herbaceous vegetation along their banks’
, ‘3230 Alpine rivers and their ligneous vegetation with Myricaria germanica’ and ‘3240 Alpine rivers and their
ligneous vegetation with Salix elaeagnos’). On the other hand, for ‘9120 Luzulo-Fagetum beech forests’, we can
consider that all stages are included in the description of the habitat. There are other types of issues, for example
how to define a favourable conservation status for the habitat ‘7120 Degraded raised bogs still capable of natural
regeneration’. These inconsistencies make it difficult to elaborate a common methodological approach for the
evaluation of the conservation status of all habitats of community interest. However, in order to ensure coherence,
we still sought to establish a common approach for all major habitat types.
Noss (1990) states that the term ‘ecosystem’ includes abiotic and biotic community aspects of the environment,
as well as exchanges between these compartments. We can rely on the idea that a habitat is an ecosystem with
the addition of a geographical dimension precise and descriptive, with mappable boundaries, interactions and
exchanges sometimes exceeding its borders. For practical use in conservation policies (legal aspects, evaluation
and management), this ecosystem must be spatially defined and identifiable on the ground: this is the interest of
a habitat positioned within a typology and accompanied by a description allowing its identification.
DEFINITION OF THE CONSERVATION STATUS FOR HABITAT
Ecosystems are complex systems, to which the general systems theory can be applied. This includes the concept
of emergence; which explains that new global properties emerge from a set of interactions in addition to the
properties of its components (Von Bertalanffy, 1993). In other words, a system composed of a set of related
elements and their interactions is a whole that cannot be reduced to the sum of the parts. Modification or variation
of any element of the system can affect the entire system (Le Moigne, 1977). In order to assess the conservation
status of a habitat, we need to evaluate its components, but also the interactions between its components and the
environment.
The composition of a habitat is the diversity of elements from which it is formed, including species. The structure
of a habitat is its physical organization, that is the arrangement of its elements (e.g. the horizontal and vertical
components of a forest). The structure and the composition of a habitat are its biotic characteristics while its
environment constitutes its abiotic characteristics (e.g. soil, geomorphology, macro and micro-climate). The
ecological functions depend on their interactions, i.e. all biological processes that occur naturally in the ecosystem
and which are the results from the interaction between all these compartments: flux of energy and matter,
exchanges (e.g. decomposition of dead wood) (Maltby et al., 1996; Costanza et al., 1997). A dynamic equilibrium
can occur between the different components, as an ecosystem’s composition, structure and functions are
interdependent (Noss, 1990).
The conservation status of a habitat becomes favourable when these elements (composition, structure and
functions) contribute to the survival of the habitat over time and its stability or expansion in space (within the
limits defined in the typology at a given level).
In terms of flora and fauna composition, one habitat type (as defined in the Interpretation Manual EUR 28) can
vary depending on climatic, bio-geographical, geomorphological, edaphic or historical factors. However, for the
same habitat type, the processes (natural or anthropogenic) and the functions that interact with the species
composition and habitat structure are the same regardless of the environmental context. For example algal
communities on subtidal rock have a different composition in the Basque country and in Brittany but perform the
same function of primary production. At the level of an EU Directive, functions are common to all individual habitat
types while the structure and the composition can vary.
However, it is often difficult to directly evaluate the functions. As part of the composition and the structure of a
habitat reflect these functions, they can be used as indicators. For example the presence of dung beetles in agropastoral habitats is an indicator of the organic matter cycle. For that reason we will try to assess the common
functions of a habitat type by defining indicators of composition or structure. These indicators should take into
account the regional context (e.g. a list of dung beetles by biogeographical region) or constant features (e.g.
degradation indicators).
We schematize the conservation status as a gradient from unfavourable conditions to favourable conditions (Fig.
1).
Figure 1. Gradient of conservation status
It is possible to establish a link between resilience and conservation status. The concept of resilience can be
defined by these four basic points (Holling, 1973; Walker et al. 2004):
- The variation range (or latitude), i.e. the maximal change a system can endure before losing its ability to return
to its initial state;
- the resistance to interference, i.e. the difficulty for a system to change;
- the precarity which is the distance between the current state of the system and the irreversible degradation
threshold;
- the panarchy [a term describing evolving hierarchical systems with multiple interrelated elements], as there are
interactions between the levels of organization, the resilience of a system at one level will depend on the
influences at lower and upper levels.
An improvement in the conservation status results in a reduction of precarity. The amplitude of variation and the
resistance to interference are intrinsic characteristics of a habitat type. Walker et al. (2004) present a
multidimensional view of the dynamics of a system. Globally, resilience represents the situation of a system
regarding other possible states.
ASSESSING CONSERVATION STATUS OF A HABITAT
EVALUATION: QUANTIFICATION AND VALUE JUDGMENT
A difficulty comes from the term ‘evaluate’, which means ‘determine, fix, appreciate the value’ or ‘approximately
determine the duration, the amount, the importance of something’. The two dictionary definitions highlight its
subjective aspect and the disparity in the use of the term where the action can be assessed is accurate or
approximate. In 1986, Usher in the introduction to his book ‘Wildlife Conservation Assessment’ emphasizes that
evaluation is more intuitive than a scientific concept. Here, we note that assessing is to make a judgment on the
value or to determine the importance of something. ‘In general, assessment corresponds to a more or less
subjective scoring or rating system of the value of the objects’ (Bioret et al., 2009). The objectivity of the evaluation
is difficult to achieve, so the assessment must be rigorous, precise and critical, and the choice must be justified so
the results can be shared.
In general, for each habitat group, experts essentially agree on criteria for assessing their condition. However they
may differ on the relative importance to each selected criteria. When there are differences, they are often
associated with differences of conceptual interpretation, such as the importance to be given to the presence of
invasive species (Weisberg et al., 2008). This refers to the delicate question of what processes or interactions are
the most ‘important’ in the functioning of each ecosystem (Boitani et al., 2014). We must therefore recognize that
these choices are based on the state of the consensus (and the state of knowledge) in the scientific community at
the moment when methods are developed.
FAVOURABLE CONSERVATION STATUS
The evaluation leads to a judgment on the value assigned to an object, in this case the conservation status of a
habitat. As the object is complex, the evaluation must go through a simplification process to improve its
understanding by many actors (Le Moigne, 1999). For the sake of the evaluation, it is important to identify which
processes to consider and to define threshold or 'reference' values i.e. the values when a habitat is changing status.
These values can be ecological thresholds in the case of non-linear relationship related to pressures (Huggett,
2005). When such relationships do not exist or have not been studied, they can be simple evaluation benchmarks
(e.g. the presence of perennial halophytes indicating the terrestrialisation of lagoons).
For a habitat, the reference status can be defined from a ‘natural’ state, i.e. undisturbed by human activity, but it
can also mean the best reachable status in areas where man is considered a part of the ecosystem. The term
‘reference status’ can be misleading. For clarity in the use of the term and following Stoddard et al. (2006), the
term ‘desired optimal status’ is used in the evaluation methods proposed in France by the MNHN (Lepareur et al,
2013; Viry, 2013; Maciejewski et al, 2015, Charles et al, 2015). The desired optimal status can refer to a natural
status, a little disturbed status or the best status in balance with human practices.
This terminology acknowledges that the conservation objective is a societal choice and not a biological value
(Blandin, 2011).
There are different approaches to establish the desired optimal state and they can be combined. The main
approaches proposed (e.g. Andersen et al, 2004; Borja et al, 2012; Johnson et al, 2013) are:
i.
ii.
iii.
iv.
defined from the actual observed status, i.e; based on descriptive statistics of existing data. This approach
requires comparable data series which limits its use at the moment at a large scale and for many habitats;
to refer to a historical condition, arbitrarily chosen; e.g. the beginning of the Holocene, the midnineteenth century, or the entry into force of regulations. However, there is often little precise historical
data. Moreover, to be consistent the choice of a historical reference should be valid for all habitats
(including a reference to the areas), which is difficult to achieve. For example, for riparian habitats, the
reference could be the state before significant pollution linked to the industrial revolution. But this period
is not relevant in terms of forested areas;
to simulate a reference state via mathematical modelling based on existing data. However, there are no
sufficiently reliable habitats models available and the thresholds issue are often not addressed;
to consider collective expertise (naturalists, managers and experts) together with field indicators to reach
a consensus on one or more references.
Although the concept of reference value in the Habitat Directive refers to a conservation target, it is to be
distinguished from the idea of an operational objective, corresponding to a goal in a defined period of time.
In the assessment methods developed by the MNHN, the operational target takes the form of an adjustable
value and is called ‘selected favourable state’ (Fig. 1). It is characterized for each habitat present in France
according to current knowledge. This is the threshold beyond which the conservation status is considered
favourable (although some indicators could be unfavourable).
The desired optimal state and the selected favourable state are not absolute values but objectives based on
scientific evidence (Carnino & Touroult, 2010; Louette et al., 2015.) in a given socio-economic and cultural
context.
The methods for assessing conservation status are mostly based on the quantification of the unfavourable
status. This approach is generally well scientifically supported, including the risk of extinction for species in
the red lists or the risk of ecosystem collapse. In these cases, the favourable status is implicitly reduced as the
habitat not being in unfavourable status. A distinctive feature of our methodological framework is the choice
to quantify both favourable and unfavourable status.
HABITAT DYNAMICS AND ITS CONSEQUENCES FOR ASSESSING CONSERVATION STATUS
THE TYPE OF SUCCESSION OF THE HABITAT
It is recognized that almost all habitats in metropolitan France, including forests, have been directly or
indirectly affected by man and cannot be considered as primary. Moreover, it is very difficult to identify
natural vegetation or communities, in most ecosystems. Two major categories of habitats can be recognised
(Frontier et al., 2008) based on their devlopment:
i.
ii.
habitats that are part of a gradual succession, described in the Interpretation Manual EUR 28. They
can correspond to an entire vegetation series, or be limited to the mature stage or blocked at a
transitional stage due to soil, climatic factors or to natural disturbances (e.g. floods). They represent
the dominant expression of natural terrestrial vegetation and are called ‘natural habitats’ in the
Habitats Directive;
habitats that are part of a blocked succession, described in the EUR 28 Interpretation Manual as
theoretically transition states, but that can be maintained by human activities, for example by regular
export of biomass (mowing, grazing in agropastoral habitats). The current distribution and
composition of these habitats are inseparable from human activity in Western Europe. They are
called ‘semi-natural habitats’ in the directive (e.g. the majority of agro-pastoral habitats, some
lagoons, or some types of forest such as chestnut groves).
For natural habitats, even when they are not primary, the long-term goal (the desired optimal status) implicitly
corresponds to a high degree of naturalness, which implies that all its structural elements and processes are
natural (original and intact) (Machado, 2004). Nevertheless, the favourable status does not necessarily
correspond to the maximum degree of naturalness.
For semi-natural habitats, naturalness obviously cannot be the favourable reference status. The chosen
favourable status is a balance between natural processes and anthropogenic intervention maintaining the
habitat type within the limits of the typology. In this context, the transition stages to another habitat, whether
they are related to intensification or abandonment of management, are considered unfavourable. This
statement is an inherent consequence of using a typology. However the perspective of changing scale for
ecosystem assessment will allow to partially correct this situation.
THE SITUATION OF THE ASSESSED HABITAT WITHIN THE SUCCESSION
The dynamics of ecological succession results from factors or disturbance of variable extent and frequency
(Chapin et al., 2002). The time scales are also variable depending on the processes (Carpenter & Turner, 2001).
Thus, the existence of pioneer habitats is inseparable from frequent disturbances (cyclic successions)
exporting the material derived from primary production (Frontier et al., 2008). For example, in the habitat
type ‘3220 Alpine rivers and the herbaceous vegetation along their banks’, in the absence of floods will rapidly
change possibly to another habitat type ‘3230 Alpine rivers and their ligneous vegetation with Myricaria
germanica’ (Viry, 2013). For these very dynamic, cyclical, habitats it seems relevant to consider all successional
stages and to have indicators on the factors responsible for the dynamics, e.g. flood frequency. The desired
optimal status corresponds to the full expression of the succession, all of which must be considered at
appropriate temporal and spatial scales to integrate all processes.
The dynamics of a habitat is determined by both the nature and the intensity of disturbances and pressures,
and the habitat resilience (Frontier et al., 2008). For example agro-pastoral habitats can have an almost
immediate respond to strong pressures such as the modification of the trophic level due to fertilization.
However, the restoration of deep coral reefs (part of ‘1170 Reefs) will take hundreds or thousands of years,
assuming it is ever possible (Roberts et al., 2006). In practice, it is therefore necessary to adapt the evaluation
frequency to the nature and the dynamics of the habitat but also by the type of disruption and pressure.
SOME KEY METHODOLOGICAL CHOICES
There are different definitions and methods to highlight the habitat’s species: diagnostic species (Chytrý et al.
2002), faithful species (Bruelheide, 2000), indicator species (Dufrene & Legendre, 1997; Bensettiti (coord),
2001-2005.) or characteristic species as defined in phytosociology (Royer, 2009). All these methods highlight
species that are statistically more frequent (and/or abundant) in a community than in others, and thus help
habitat characterization and determination in the field. Applied for this purpose, these methods do not
provide precise information on the role of each species in the functioning of the habitat. The Habitats Directive
recommends using typical species for assessing the conservation status of the habitat. However, no
satisfactory definition of typical species is proposed. After several inconclusive trials to define and establish
lists of typical species (Maciejewski, 2010), we decided to focus on a list of indicative species of a specific
aspect of the ecosystem’s functions. Species functional traits are studied to establish lists of functional groups,
i.e. sets of species that have similar relationships with an ecosystem process or to environmental conditions
(Hooper et al., 2005). For example, marine benthic species (or groups) were identified based on their
sensitivity or tolerance to organic enrichment (Hily 1984). These functional groups have been widely used in
the evaluation of coastal water quality and form the basis of several indices used in the marine environment.
We do not take specific account of the species of conservation value in the assessment because (i) there is
no shared definition, and (ii) they do not provide information on the structure and functions of the habitat.
Finally, unless it was specifically justified, we also rejected species richness and associated indices (Shannon,
Simpson, etc.) as a conservation status indicator. Indeed, these measures do not take into account the identity
of the species nor their functional role. Tilman et al. (1997, 2014) show a composition effect on ecosystem
processes and also show that the loss of diversity is an important factor in changing ecosystem functioning.
However, at the scale of a Natura 2000 site, the precise relationship between species diversity and key
ecological processes is not yet established for the majority of natural ecosystems (Naeem 2002). In addition,
an oligotrophic habitat undergoing eutrophication will see its composition changed with an increase in species
richness, but its conservation status will be degraded. It was also shown that in some ecosystems the loss of
species richness could reach 75% without the variety of functional groups diminishing in the ecosystem due
to functional redundancy of species (Fonseca & Ganade 2001; Cadotte et. al., 2011). Although in specific
compartments diversity measures are also a possible approach (Helm et al., 2015).
FROM KNOWLEDGE TO ASSESSMENT AND MANAGEMENT
The use of habitat typologies in nature conservation’s programs is essential (e.g. for surveying, mapping).
After the identification, it is necessary to collect information on habitats (e.g. ecological, economic, social, or
cultural) in order to guide the actions and to achieve the objectives. This is the diagnostic step. It is possible
to distinguish whether the information concerns the past (history management, old aerial photographs, past
land use), the present (habitat conservation status, population inventory, land use) or projections about the
future (prioritization of stakes, development projects).
In the diagnosis, the conservation status should be separated from the concept of ecosystem health, which is
centred on ecosystem services (Costanza et al., 1992; Callicott et al., 1999). Indeed, ecological functions are
an ecosystem’s biological processes resulting from the interactions between its compartments, while
ecosystem services correspond to the benefits received by man in the process.
To improve the readability and feasibility of the evaluation, the proposed methods only make a statement at
the present time. A consideration of the past, such as the management history, is important but access to
information is not the same everywhere. Dutoit (1996) showed that the impact of different management
regimes cannot be generalized from one site to another. This is why we designed an assessment of the
conservation status without judging the past or predicting the future. It is then much easier to compare the
evaluations between sites and to compare experience.
The conservation status of a habitat is not only the result of management practices; this is why the evaluation
of the conservation status does not directly assess the effectiveness of management. The evaluation of
management is therefore a different and complementary exercise to conservation status assessment.
CONCLUSION
The evaluation of the conservation status of habitats is a key element of the ecological diagnosis included in
management documents. Habitats are spatial objects that integrate ecological conditions, they include many
species and highlight functional aspects of an ecosystem. Habitat survey allows managers to take into account
a wide range of environmental factors.
Conservation and management of these complex objects requires the establishment of a habitat typology.
This common language is an important step to reach a consensus among the different actors of conservation
science. But even if creating types and defining their limits provides a validation of their existence, it can also
fix our vision of a natural environment that is dynamic and constantly changing. An assessment at the scale of
the eco-complex would partly correct this ‘fixist’ vision by integrating the dynamics as an intrinsic property of
the eco-complex. The habitat assessment would be considered as one element of the diagnosis of a wider
ecosystem. The assessment of the conservation status would have a fractal nature; the process can take place
at different scales from the plot to the site and then the eco-complex. The proposed methodological approach
is common to all habitats which represents a major advantage for assessing in a global and synthetic way all
the habitats of an eco-complex at a given scale. More broadly, this common approach provides elements to
design projects and to connect monitoring and evaluation programs at a larger scale, with the aim to improve
the coherence between nature conservation policies.
Public policies were consolidated by adding habitat conservation to species protection. However, the
principles remain more or less modelled on those for the species. On-going and anticipated developments
will better integrate the dynamic and functional aspects of the ecosystems. Since 2008, a first step in this
direction was taken in the marine environment with the implementation of the Marine Strategy Framework
Directive that fully integrates the ecosystem approach with existing policies. What now seems obvious to the
marine environment, a vast environment with few natural borders and global issues, should be reflected in
policies for terrestrial environments. Without questioning the progress made in the last twenty years by the
implementation of the Habitats Directive, which has taken into account both natural habitats and the habitats
for species, it is now essential to continue research and to consider an evolution of public policies. The
challenges related to global changes and the adaptation capacity of communities should lead to an expansion
of the conservation objectives and the associated evaluative framework.
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