Diversity Patterns and Typology of Cynosurus cristatus Grasslands (Cynosurion cristati Tüxen 1947) in the Iberian Peninsula

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Questions What is the community diversity of tall, humid herb grasslands in Western Mediterranean Europe? What are the diagnostic species of the Molinio‐Holoschoenion alliance? What underlying ecological patterns influence their diversity? Location Western Mediterranean Europe (France, Portugal and Spain). Methods We compiled a vegetation plot database of Molinio‐Holoschoenion plant communities. The initial data set of 1056 plots was filtered according to physiognomic and floristic criteria, and geographically stratified. We used hierarchical agglomerative classification and semi‐supervised classification techniques based on the k‐means algorithm as a combination of methods to define vegetation types. A DCA analysis was performed to assess the main ecological drivers of diversity in the Molinio‐Holoschoenion community. Results Seventeen vegetation types were defined, which can be classified in the following major vegetation groups: (1) tall humid grasslands on base‐poor and sandy soils; (2) Scirpoides holoschoenus grasslands on base‐rich soils; and (3) eastern Iberian and southwestern French Schoenus nigricans and/or Molinia caerulea grasslands. The water‐logging gradient was recognized as a major underlying pattern influencing the diversity and distribution of Molinio‐Holoschoenion, and at a second level, the soil factor. Conclusions We suggest a revision of the concept of the Molinio‐Holoschoenion alliance to be considered for the interpretation of habitat type 6420 of the European Habitats Directive, which should include Mediterranean wet dune slacks and tall, humid inland grasslands. This vegetation type is largely distributed on the eastern Iberian Peninsula, where base‐rich soils are predominant and Scirpoides holoschoenus grasslands comprise the main floristic composition of the alliance.

Section: Discussionsupporting

confidence: 69%

Diversity and classification of tall humid herb grasslands (Molinio‐Holoschoenion) in Western Mediterranean Europe

García‐Madrid

Rodríguez-Rojo

Cantó

et al. 2016

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“…; Blasi et al. ; Rodríguez‐Rojo & Fernández‐González ). Even alliances cannot always be clearly identified due to the occurrence of transitional grasslands between hay meadows and pastures produced by changes in management.…”

Section: Introductionmentioning

confidence: 99%

“…Their biogeographic optimum extends across the temperate Eurosiberian region (Rodwell et al. ), while favourable conditions in the Mediterranean region are restricted to valley bottoms and foothills in mountain areas with fine‐textured soils and sufficient moisture (Rodríguez‐Rojo & Sánchez‐Mata ; Rodríguez‐Rojo & Fernández‐González ).…”

Section: Introductionmentioning

confidence: 99%

“…This can be done by using formal definitions to select appropriate relevés from a large phytosociological database to represent unequivocally defined vegetation units. Here we apply these methods to a large data set of Arrhenatheretalia grasslands from the Iberian Peninsula, part of which was recently analysed using unsupervised classification methods (Rodríguez‐Rojo & Fernández‐González ). This last revision focused on Cynosurion mesic pastures and recognized eight associations on the Iberian Peninsula.…”

Section: Introductionmentioning

confidence: 99%

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Vegetation diversity of mesic grasslands (Arrhenatheretalia) in the Iberian Peninsula

Rodríguez‐Rojo

Fernández‐González

Tichý

et al. 2014

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Questions What is the diversity and main vegetation types in mesic grasslands on the Iberian Peninsula? What are the main diagnostic species of each type? What are the main environmental gradients that drive patterns of species composition? To what extent does biogeography influence community diversity? Location Iberian Peninsula (Portugal and Spain, including the French Pyrenees). Methods Formal definitions based on the Cocktail method were used to establish a typology of mesic grasslands of the Arrhenatheretalia order. This method was applied to a stratified data set of 3485 relevés, also including other types of perennial grassland. Semi‐supervised classification based on the K‐means algorithm was used to assign almost 757 relevés into the vegetation types defined by Cocktail and to identify new ones. The types were compared by means of detrended correspondence analysis (DCA) using climate data, altitude and Ellenberg indicator values as explanatory variables. Results Fourteen ecologically well‐defined associations were distinguished in the Arrhenatheretalia order: five in the Arrhenatherion alliance, two in Triseto‐Polygonion and seven in Cynosurion. Soil reaction, summer aridity and altitude were identified as the most important determinants of species composition. These lithological and bioclimatic gradients are related to the biogeographic diversity of the study area, which is the main driver of community diversity in Arrhenatheretalia grasslands; it is more important than the management practices expressed in the concept of alliances. The classification and ordination analyses also showed a clear differentiation in community diversity according to biogeographic sectors (eastern Cantabrian‐Atlantic, Galician‐Portuguese, Carpetan‐Leonese, Pyrenean, Orocantabrian/western Pyrenean and Oroiberian/Catalan‐Valencian). In addition, moisture and nutrient content were more important than altitude in differentiating Arrhenatherion and Triseto‐Polygonion communities in the Pyrenees. Conclusions We suggest a simplification of the traditional classification of the Iberian Arrhenatheretalia grasslands. For this revised classification, we propose an electronic expert system with consistent rules for assigning vegetation observations to the associations defined, and a list of the diagnostic species of each vegetation type. These results can be applied to identify and monitor the hay meadows included in Annex I of the European Habitats Directive, taking into account the biogeographic context of the indicator species.

“…The concept of the Cynosurion alliance in the European vegetation classifications is controversial since intensive permanent pastures have been incorporated into this alliance together with extensive permanent pastures (large areas of pastures under an extensive grazing system) and hay meadows under a mixed management regime (Rodwell ; Rodríguez‐Rojo & Fernández‐González ). There are some differences among authors concerning the syntaxonomical position of these vegetation types, especially with respect to the interpretation of the alliance Arrhenatherion as hay meadows and Cynosurion as pastures (e.g.…”

Section: Introductionmentioning

confidence: 99%

Diversity of lowland hay meadows and pastures in Western and Central Europe

Rodríguez-Rojo

Jíménez-Alfaro

Jandt

et al. 2017

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Questions Which are the main vegetation types of lowland hay meadows and pastures in Western and Central Europe? What are the main environmental gradients that drive patterns of species composition? Is it possible to classify these grasslands to phytosociological alliances that reflect management practices? Location Western and Central Europe (excluding the Alps and Carpathians). Methods A database of 21 400 vegetation plots of mesic grasslands across Western and Central Europe was compiled. After geographically stratified resampling, semi‐supervised classification based on the K‐means algorithm was applied to assign a subset of plots into 32 a priori association‐level vegetation types and to search for new types within the subset of non‐assigned plots. The vegetation plots assigned into the final vegetation types were submitted to another K‐means classification to show the grouping into higher‐level vegetation types. Results A total of 36 associations were distinguished in the resampled subset of 8277 vegetation plots and were grouped into four large groups: (1) eutrophic and intensively managed hay meadows and permanent pastures; (2) nutrient‐rich grasslands developed from recently abandoned fields or managed under irregular practices of mowing and manuring; (3) non‐eutrophic lowland and submontane hay meadows; (4) extensively managed pastures and Atlantic grazed hay meadows. A PCoA of the associations of these four groups showed that extensively managed pastures were floristically more similar to non‐eutrophic hay meadows than to permanent intensively managed pastures, which was more obvious in the Atlantic region than in Central Europe. Species composition of the lowland hay meadows was clearly differentiated according to biogeographic sectors. Other floristic differences were related to climate, altitude, soil base status and topography. Conclusions This analysis challenges the traditional concept of mesic grassland alliances separating hay meadows from pastures. New classification should be based mainly on the differences in management intensity rather than in management practice. Consequently, nutrient‐poor extensive pastures, which currently are not considered in the European Habitats Directive, should receive the same conservation attention as low‐intensive hay meadows, because both types of vegetation can be equally species‐rich and do not differ substantially in floristic composition from each other.