Phytobase: a tool for the integrated synusial approach of vegetation classification at regional to national scale

International audiencePhytobase is a relational database management system devoted to the management of vegetation survey data, following the concepts of the integrated synusial phytosociology. This 4D application has been developed from the 1990s and applied to various ecosystems (wood-pastures, forests, floodplains, wetlands and grasslands) in various regions, mostly in Switzerland and in France.Integrated synusial phytosociology considers that vegetation is organized in nested hierarchical levels, each of them being potentially described in a typological and classification system. The first, finest, level is the synusia, a concrete plant community composed of plant species co-occurring in a local similar environment, with comparable size and habitat use. Phytobase distinguishes three categories of synusiae, i.e. tree, shrub, herb and moss synusiae, classified into elementary syntaxa. They are eventually integrated into phytocoenoses, the second level of vegetation description, based on a list of synusial syntaxa co-occurring in a given phytocoenosis, such as a forest stand with its different layers, sylvogenetic phases and dependent (e.g. epiphytic) communities. Phytocoenoses are classified into elementary coenotaxa according to their synusial composition. Higher organization levels (tesela/sigmataxa and catena/geosigmataxa) are included in Phytobase as well, but only used so far for floodplain vegetation.The classification of synusiae is based on Julve’s ‘baseveg’ system. An automatic diagnostic of plot records is implemented in Phytobase, including classification in Julve’s system, assignment to an elementary syntaxon, ecological indicator values (Landolt, Ellenberg, Julve), life forms, Grime’s CSR strategies, functional traits, taxonomic diversity indices, pastoral value, etc.Each elementary syntaxon or coenotaxon is described by the centroid of all plot records that were assigned to it, and Phytobase includes various diagnostics for species (or elementary syntaxon) fidelity (IndVal, Phi, etc.), compositional homogeneity and ecology.Phytobase is freely available from the Tela-botanica website (http://www.tela-botanica.org/page:liste_projets?id_projet=18&act=documents&id_repertoire=16428), including a sample of relevés. It is used by more than two hundred registered users in Europe. The current version 8.3 has a user interface in French language but an English version is planned to allow a broader diffusion to the international community of vegetation scientists

Guide d'utilisation de Phytobase 8, base de données phytosociologiques

Documentation technique de Phytobase 8

Succession secondaire et perte de diversité végétale après réduction du broutage dans un pâturage boisé des Alpes centrales suisses

Freléchoux F., Meisser M. and Gillet F. 2007. Secondary succession and loss in plant diversity following a grazing decrease in a wooded pasture of the central Swiss Alps. Bot. Helv. 117: 37 - 56. Reduced cattle grazing pressure in the Alps has caused the reforestation of many subalpine pastures during the last decades. To understand the dynamics of natural reforestation and to evaluate how this change affects plant species diversity, we described the vegetation of a wooded pasture in the central Swiss Alps (Sembrancher, Valais) using the integrated synusial method. Based on stratified vegetation relevés in 27 plots,we defined 11 community types at the synusial level (two tree-layer, five shrub-layer, and four herb-layer synusiae), and four community types at the phytocoenosis level (pasture, tall forbs and scrub, wooded pasture and forest). The spatial distribution of these four phytocoenoses suggests that they represent successional stages after abandonment, and that the pathway of vegetation succession depends on the aspect. We suppose that on northern oriented, cool and shady locations, abandoned pastures first develop towards tall-forb meadows and scrub with Alnus viridis, and then to a preforested stage with Picea abies and Larix decidua. In contrast, on western oriented, warm and sunny location, Larix decidua (mainly) and Picea abies directly colonize the abandoned pastures, but further succession finally leads to the same pre-forested stage as on northern slopes. Plant species richness was highest in open areas and decreased by 25% as tree cover increased from 6% to 65%. According to our successional model, plant species diversity is lost more rapidly on northern slopes (with species-poor green alder scrub) than on western slopes (with species-rich young larch forests), suggesting that northern slopes most urgently need an appropriate grazing managemen

Dynamics of bog-pine-dominated mires in the Jura Mountains, Switzerland: A tentative scheme based on synusial phytosociology

A description of the bog-pine (Pinus uncinata var.rotundata) dominated vegetation of uncut oligotrophic mires affected by drainage is given. Surveys were carried out at 17 sites along the Jura Mountains (Switzerland and France) in 1993, 1994, and 1995. Raised bogs of the Jura are generally of small size, and most vegetation changes in them have occurred as a result of the indirect impact of peat cutting. This activity led to the peat drying out and to colonization by trees, in particular by bog-pines. Integrated synusial phytosociology was used to describe the vegetation where bog-pine, spruce, and birch occur. Two spatio-temporal levels of organization were considered: the synusia and the phytocoenosis. At the phytocoenosis level, four vegetation types representing bog-pine stands of uncut and deep oligotrophic peats are described with their constitutive synusial composition. They represent: (1) phytocoenoses developing in the open, wet central parts of the bogs, where trees are scattered and of small size, (2) phytocoenoses with layered tree stands of medium size and with a higher density, and (3) phytocoenoses with tall trees, developing generally near the edge of the bogs or close to peat cuttings. A generalized qualitative dynamic model of the vegetation in relation to the development of bog-pine trees was developed. It shows the spatial and temporal organization of the constituent synusiae, as well as other underlying hypothetical functional relations. The different bog-pine-dominated vegetation types described in this study appear to have coexisted since the origin of the Jura bogs as a result of local polyclimaxes induced by differential waterlogged situations. They probably all belong to the same (primary) successional series, but have been affected by both autogenic and allogenic processes. During the development of the bogs the balance between the different communities changed. In particular, the vegetation types with dense and tall pine trees have undergone a drastic expansion since the Jura bogs were first affected by drainag

Plant communities, synusiae and the arithmetic of a sustainable classification

We propose an equation to evaluate the efficiency of a classification as a function of the effort required and the population size of data collectors. The formula postulates a “classification efficiency coefficient”, which relates not only to the complexity of the object to be classified, but also to the data availability and representativeness. When applied to the classification of phytocoenoses, the equation suggests that a classification system based on vascular plants offers the best compromise between sampling effort, resolution power and data availability. We discuss the possibility of basing a vegetation classification on plot records for all macroscopic photoautotrophic organisms co-occurring in the vertical projection of a given ground area, as recently suggested by some authors. We argue that the inclusion of cryptogams in the description of phytocoenoses dominated by vascular plants should rely on a synusial approach, conceived as complementary to the traditional Braun-Blanquet approach

Long-term dynamics of aboveground fungal communities in a subalpine Norway spruce forest under elevated nitrogen input

As anthropogenic N deposition has been suspected to be the main reason for the decline of macromycetous sporocarp production in forest ecosystems, various N-fertilization experiments were started in the mid 1990s. The dynamics of ectomycorrhizal (root-inhabiting) and terricolous saprobic (litter-inhabiting) fungal communities were studied by exhaustive sporocarp inventories in a substitution Norway spruce (Picea abies) forest in two 256-m2 plots sampled for periods of 1 week at 1-m2 resolution between 1994 and 2007. N was added to the soil twice per year in one plot from the fourth year onwards. The effects of N input and time on aboveground fungal communities were assessed using redundancy analysis, principal response curves and non-parametric multivariate ANOVA. Results of this long-term experiment revealed that both ectomycorrhizal and saprobic fungal communities responded to an increase in soil N input. The ectomycorrhizal community reacted by a fast decrease in sporocarp production and in species richness, whereas the saprobic community was less affected. The response was highly species specific, especially for the saprobic community. The difference in species composition between control and fertilized plots was significant after 1year of N addition for ectomycorrhizal fungi and only after 3years for saprobic fungi. An aging effect affected sporocarp production in the whole area. For both communities, this unidirectional drift in species composition was as important as the treatment effect. This result highlights the importance of considering the respective role of treatment and year effects in long-term field experiments on fungal communitie

Modelling vegetation dynamics in heterogeneous pasture-woodland landscapes

Recent knowledge about tree regeneration, shifting mosaic in the herb layer or complex interactions between cattle activities, vegetation and landscape structure has allowed the development of a novel, spatially explicit, mosaic compartment model of the dynamics of silvopastoral ecosystems (WOODPAM). This deterministic model considers three hierarchical levels: the focal level is the phytocoenosis, represented by a cell or a patch in the landscape with a variable local stock density; herb and shrub communities as well as size-structured tree populations are the components of each patch at the lower level, spatially implicit; patches are aggregated in a pastoral management unit building the higher level, with an externally controlled global stock density