A diversity world record in a grassland at Oaxaca, Mexico

  • Carlos Martorell Departamento de Ecología y Recursos Naturales, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad de México
  • Verónica Zepeda Departamento de Ecología y Recursos Naturales, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad de México
  • Alejandra Martínez-Blancas Departamento de Ecología y Recursos Naturales, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad de México
  • Diego García-Meza Departamento de Ecología y Recursos Naturales, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad de México
  • Fernando Pedraza Departamento de Ecología y Recursos Naturales, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad de México
keywords: Chronic anthropogenic disturbance, semiarid grassland, species richness, coexistence, intermediate disturbance hypothesis

Abstract

Background: Plant richness world-records have been reported to occur either in tropical rainforests, or, at smaller spatial scales, in chronically disturbed grasslands. The tight relationship between scale and record richness suggests that there is an unyielding limit to diversity.

Hypotheses: If such limit exists, current records should hardly be beaten. Chronic disturbance in grasslands allows richness to approach the limit.

Studied species: All vascular plants at the study site.

Study site and years of study: A natural, semiarid grassland at Concepción Buenavista, Oaxaca, Mexico, in 2012 and 2014.

Methods: At 21 sites we recorded species richness in randomly sampled 0.1 × 0.1 m quadrats, and measured chronic disturbance caused by different agents. We estimated the maximum richness at each site through maximum likelihood. At one site we searched for high richness quadrats.

Results: The study site shares the current world record of plant richness at the 0.1 × 0.1 m scale with 25 species. The estimated maximum diversity at each site decreased with land degradation, but had a maximum at intermediate-high levels of livestock activity.

Conclusions: Our results support the idea of a hard limit to species richness, and thus theories of plant coexistence that envisage such limit. Our study site shares attributes with other record-holding grasslands, such as severe resource limitations and chronic disturbance by ungulates, suggesting that these conditions promote high species richness. We hope that, by reporting this diversity record, we also help to change the notion that Mexican grasslands are secondary communities having a negligible biological value.

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A diversity world record in a grassland at Oaxaca, Mexico
Published
2017-03-18
How to Cite
Martorell, C., Zepeda, V., Martínez-Blancas, A., García-Meza, D., & Pedraza, F. (2017). A diversity world record in a grassland at Oaxaca, Mexico. Botanical Sciences, 95(1), 1-7. https://doi.org/10.17129/botsci.689
Section
ECOLOGY / ECOLOGÍA