Plant Ecology

, Volume 213, Issue 8, pp 1209-1220

First online:

Elevational patterns in the vascular flora of a highly diverse region in southern Mexico

  • Silvia H. Salas-MoralesAffiliated withSociedad para el Estudio de los Recursos Bióticos de Oaxaca, A.CDepartamento de Ecología y Recursos Naturales, Facultad de Ciencias, Universidad Nacional Autónoma de México Email author 
  • , Jorge A. MeaveAffiliated withDepartamento de Ecología y Recursos Naturales, Facultad de Ciencias, Universidad Nacional Autónoma de México

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We examined general and family-specific patterns of vascular plant richness along a large elevational gradient (0–3,670 m a.s.l.), assessed the continuity of these patterns and analysed their potential underlying causes in a high diversity region of the Sierra Madre del Sur, Oaxaca, Mexico. We used a vascular plant database constructed previously. The gradient was divided into 18 200-m elevation belts. To examine elevational patterns of richness, we used both observed and estimated (interpolated) species richness, as well as genus and family observed richness, for each belt. A generalised linear model (GLM) was used to assess the effect of altitude on area-corrected species richness (standard area = 100 km2), and a numerical classification of the elevational belts based on species richness was performed. Overall, richness at the three taxonomic levels decreased with elevation, but some individual families departed from this pattern. A sharp drop in species richness was observed at 1,800 m, and the dendrogram separated two elevational floristic groups at this elevation. The GLM revealed a significant negative effect of elevation on species richness. Despite this overall decreasing pattern for vascular plants along this extensive gradient, an examination of some family-specific patterns revealed the existence of other elevation–diversity relationships, indicating taxon-specific responses to elevation. The most noticeable discontinuity in species richness, at ca. 1,800 m, is likely related to a critical temperature isocline.


Altitudinal gradient Area effect Environmental-limitation hypothesis Habitat heterogeneity Oaxaca