Resumo

HERNANDEZ-NICOLAS, Nancy et al. Diagnosis for the ecological conservation of Jatropha spp. (Euphorbiaceae) and their habitats in the Tehuacan-Cuicatlan Reserve, Mexico. Rev. biol. trop [online]. 2015, vol.63, n.1, pp.23-33. ISSN 0034-7744.

Jatropha spp. is an important phytogenetic resource used as food, medicine, and biofuel. In this study, we verified the taxonomic identity of Jatropha species for The Biosphere Reserve Tehuacan-Cuicatlan, and the Ecological Land Units (ELU) occupied by them. We assessed the conservation status of their habitats, and the vulnerability of Jatropha spp. populations. A total of 15 sampling sites were selected in the Reserve. The taxonomic work was based on specimens, original descriptions and type material from herbaria and those available on-line. ELUs were classified using biophysical variables, and gvSIG software. Ecological attributes were determined using a quantitative analysis by the point-centered quarter method; disturbance was estimated through site indicators, and the conservation status of the Jatropha populations was assessed using the Method for Evaluation of the Risk of Extinction of Plants in Mexico (MER). Jatropha frequently dominated the physiognomy of plant communities. The current distribution of Jatropha species in the Reserve was mainly determined by elevation, temperature, and precipitation variables. The confirmed species were Jatropha ciliata Sessé ex Cerv., Jatropha neopauciflora Pax, Jatropha oaxacana J. Jiménez Ram. & R. Torres, Jatropha rufescens Brandegee, and Jatropha rzedowskii J. Jiménez Ram., which are distributed in four of the six defined ELU. J. neopauciflora and J. rzedowskii were the most widespread species; this last species concur in four, J. oaxacana in two, while J. rufescens and J. ciliata in one ELU, being the most restricted. The richness of the genera in the associated communities ranged from 16 to 42. The maximum and minimum importance Value indexes were observed in San Nicolas Tepoxtitlan for J. neopauciflora (53.75%) and J. rzedowskii (1.50%). The disturbance index varied from 0.22 to 0.82, with an average of 0.51, where the livestock variable had a high contribution. Considering the risk categories of MER, we concluded that J. oaxacana requires special protection, and J. ciliata and J. rufescens were species under extinction risk. The conservation status of the plant communities inhabited by populations of Jatropha spp. was moderate, taking into account the rate of disturbance. The main factors affecting the habitats of Jatropha were livestock and human activities; the floristic composition of the surrounding plant communities has low richness. These results support the urgent need of conservation strategies to avoid the loss of important wild growing species of Jatropha populations. Rev. Biol. Trop. 63 (1): 23-33. Epub 2015 March 01.

Palavras-chave : Jatropha species; ecological land units; Tropical Deciduous Forest; disturbance; vulnerability; Mexico.

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