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This article highlights results obtained during a systematic study of the bryophyte species Pleurochaete squarrosa in the Allondon valley. This xerophytic and terricolous moss is frequent and abundant in dry grasslands. It has been defined as an indicator species of dry areas, more precisely of the plant association Teucrio - Xerobrometum erecti. This discovery made it possible to situate Pleurochaete squarrosa in the evolution of the dynamics of plant associations, from dry glades to hemlines. Sensitive to its immediate environment, its presence can allow the implementation of measures favorable to its preservation, as well as to the dry environments, threatened by the undergrowth and the loss of the alluvial dynamics of the Allondon. [ABSTRACT FROM AUTHOR]

Seven land pieces, described by botanist and field biologists, Jacques Bordon and Denis Jordan, as particularly rich in species were under study during the summer of 2015 on the Vuache mountain mass. Phytosociological survey as well as Landolt ecological factors permitted the identification of fourteen vegetal associations, described and chart-made. These unveiled a vast diversity of environments, from fen to semi-dry lawn sometimes prevailing in mosaic form on a restricted surface. The richness of the land is jeopardized by the invasion and colonization of bushes and small scrubs, the development of neophytes, the predominance of a competitive species or, even more, an overly abundance of soil litter, as a result of lack of adequate care. The elaboration of this study has warranted the establishment of an initial detailed status of these sites, as a result of which a ground-work of adequate management measures pertinent to each land piece were spelled out. These measures could serve as a basis for the development of a future management plan of the Vuache mountain mass environment [ABSTRACT FROM AUTHOR]

The concepts of diagnostic species and fidelity have been used frequently in European phytosociology but rarely in North American vegetation classification. We developed a classification of the vegetation of a mountainous area of northern Utah and compared the diagnostic species approach with the indicator-species approach of habitat type classification sensu Daubenmire prevailing in the U.S. Interior West. A total of 157 forest and nonforested plots were described by vascular plants and basic environmental factors. Clustering with RandomForest classification and ordination reduced the original number of plots to 26 meaningful vegetation units. Of these 26 units, 22 were strong, having four or more faithful species. Four units were weak, having less than three faithful species. We identified species diagnostic of particular vegetation units that are potentially useful for recognition of these units in the field. We proposed vegetation types at the level of vegetation alliances and associations, and correlated them with environmental factors. We found our vegetation units to be more strongly associated with the underlying environment than major habitat types sensu Daubenmire. Our approach to classification has the potential to directly link vegetation with the physical environment and could be the basis for a substantial improvement of vegetation classification in the central Rocky Mountains. [ABSTRACT FROM AUTHOR]