Changes in floristic composition and physiognomy aredecoupled along elevation gradients in centralArgentina

CHIARINI, F.; GURVICH, D.E.; CABIDO, M.; TECCO, P.A.; GIORGIS, M.A.; CHIAPPELLA, J.; CINGOLANI A.M.

APPLIED VEGETATION SCIENCE

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2017 vol. 20 p. 558 - 571

1402-2001

Questions:Most vegetation descriptions tacitly assume that floristic composi-tion and physiognomy are tightly linked. However, the two vegetation proper-ties may not respond in a similar way to environmental and disturbancegradients, leading to uninformed management planning and difficulties whenattempting to restore degraded ecosystems. In this context, we addressed twomain questions: (1) how close are relations between floristic and physiognomictypes as defined by numerical vegetation classification in mountain ecosystems;and (2) how are floristic and physiognomic types distributed along the elevationgradient?Location:Central mountains of Argentina, between 500 and 1700 m a.s.l.Methods:We selected 437 sites where we performed complete floristic andphysiognomic releves. We classified eight physiognomic and eight floristic types.We tested the relationship between the two classifications through a chi squareanalysis. We tested the association between elevation and each physiognomicand floristic type with random permutations.Results:In general, floristic types were significantly and positively associatedwith more than one physiognomic type andvice versa. Physiognomic and floristictypes responded differently to the elevation gradient. Floristic types wererestricted to different sections of the gradient, although having large overlapamong them. In contrast, seven out of the eight physiognomic types did notshow elevation restriction, being distributed along the complete elevation gradi-ent. The open low woodland with shrubs was the only restricted physiognomy,significantly absent from the upper part of the gradient.Conclusions:We highlight the importance of considering the two vegetationproperties independently when characterizing vegetation patterns in heteroge-neous systems, since they show decoupled responses to environmental gradi-ents. We note that the assumption of a direct link between floristic compositionand physiognomy may induce bias into the understanding of vegetation pat-terns and processes. Hence, we encourage managers and restoration practition-ers to consider the complete range of possible physiognomic types under each floristic type