Changes in floristic composition and physiognomy are decoupled along elevation gradients in central Argentina

GIORGIS. M. A.; CINGOLANI A. M.; GURVICH D. E.; PAULA A. T.; CHIAPELLA J.; CHIARINI F.; CABIDO M.

APPLIED VEGETATION SCIENCE

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2017

1402-2001

Questions: Most vegetation descriptions tacitly assume that floristic compositionand physiognomy are tightly linked. However, the two vegetation propertiesmay 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: Centralmountains of Argentina, between 500 and 1700 ma.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 randompermutations.Results: In general, floristic types were significantly and positively associatedwithmore than one physiognomic type and vice 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 gradient.The open low woodland with shrubs was the only restricted physiognomy,significantly absent fromthe upper part of the gradient.Conclusions: We highlight the importance of considering the two vegetationproperties independently when characterizing vegetation patterns in heterogeneoussystems, since they show decoupled responses to environmental gradients.We note that the assumption of a direct link between floristic compositionand physiognomy may induce bias into the understanding of vegetation patternsand processes. Hence, we encourage managers and restoration practitionersto consider the complete range of possible physiognomic types under eachfloristic type.