Floristic differentiation in limestone outcrops of southern Mexico and central Brazil: a beta diversity approach (original) (raw)
2009, Http Redalyc Uaemex Mx Redalyc Src Inicio Artpdfred Jsp Icve 57712091005
A major goal in conservation biology is the protection of the largest possible number of species in areas that sometimes are relatively small. To this aim, knowing the spatial arrangement of biodiversity may be crucial (Whittak-Abstract: We studied the spatial arrangement of fl oristic diversity in two systems of limestone outcrops, located in two distant Neotropical sites: the region of Nizanda (S Mexico) and the Paranã Valley (Central Brazil). We addressed the question whether their vegetation could display a similar zonation, and we explored the relative effects of distance and an environmental gradient on α-, βand γ-diversities. The limestone outcrops at both sites are similar in size and in elevation, but strongly differ in between-outcrop distance by an order of magnitude. At each study site three individual limestone outcrops were selected; in each of them three plant communities along the edaphic gradient were distinguished (a xerophytic scrub and two tropical dry forests types, one of which had a more xeric character than the other), and sampled for structural variables and fl oristic composition in 100-m 2 plots. At both study sites, structural variables responded similarly to the edaphic gradient. Species density was larger in Nizanda for both αand γ-diversity, but the largest value of β-diversity was obtained in Paranã. The edaphic gradient produced larger mean β-diversity values than the simple distance effect, with the interaction of both factors resulting in an even larger β-diversity. Classifi cation analyses by site showed larger fl oristic similarities between the two xerophytic communities than those existing between them and the more mesic forests. The spatial arrangement of diversity showed that both αand γ-diversity were smaller for the xerophytic communities. As hypothesized, the more extreme changes in community physiognomy were associated with larger β-diversity values. Nizanda Paranã Xerophytic scrub Hechtia caudata L.B.Sm. (Bromeliaceae) Hechtia sp. (Bromeliaceae) Cnidoscolus aconitifolius (Mill.) I.M.Johnst. (Euphorbiaceae) Cnidoscolus sp. 1 (Euphorbiaceae) Bursera schlechtendalii Engl. (Burseraceae) Commiphora leptophloeos (Mart.) J.B.Guillet (Burseraceae) Cephalocereus nizandensis (Bravo et MacDoug.) Buxb. (Cactaceae) Cereus sp. 1 (Cactaceae) Pseudosmodingium multifolium Rose (Anacardiaceae)* 1 Cabralea canjerana (Vell.) Mart. (Meliaceae)* 1 Tropical dry forest on bare rock Bursera excelsa (Kunth) Engl. (Burseraceae) Commiphora leptophloeos (Mart.) J.B.Guillet (Burseraceae) Ficus pertusa L.f. (Moraceae) Ficus pertusa L.f. (Moraceae) Ficus petiolaris Kunth (Moraceae) Ficus insipida Willd. (Moraceae) Randia thurberi S.Watson (Rubiaceae) Randia armata (Sw.) DC. (Rubiaceae) Pseudobombax ellipticum (Kunth) Dugand (Bombacaceae) Pseudobombax tomentosum (Mart. et Zucc.) A.Robyns (Bombacaceae) Pilosocereus collinsii (Britton et Rose) Byles et G.D.Rowley (Cactaceae) Cereus sp. 2 (Cactaceae) Comocladia enlgeriana Loes (Anacardiaceae) Astronium fraxinifolium Schott (Anacardiaceae) Spondias purpurea L. (Anacardiaceae) Myracrodruon urundeuva Fr.All. (Anacardiaceae) Bursera simaruba (L.) Sarg. (Burseraceae) Commiphora sp.nov. (Burseraceae) Tropical dry forest on deeper and continuous soil Tabebuia impetiginosa (Mart.) Standl. (Bignoniaceae) Tabebuia impetiginosa (Mart.) Standl. (Bignoniaceae) Ceiba grandifl ora Bartlett (Bombacaceae) Chorisia pubifl ora (A.St.-Hil.) G.Dawson (Bombacaceae) Cnidoscolus megacanthus Ined. (Euphorbiaceae) Cnidoscolus sp. 2 (Euphorbiaceae) Bauhinia divaricata L. (Caesalpinaceae) Bauhinia ungulata L. (Caesalpinaceae) Cordia dentata Poir. (Boraginaceae) Cordia glabrata (Mart.) DC. (Boraginaceae) Lysiloma divaricatum (Jacq.) J.F.Macbr. (Mimosaceae) Anadenanthera peregrina (L.) Speg. (Mimosaceae) Apoplanesia paniculata C.Presl (Fabaceae) Luetzelburgia sp. (Fabaceae) Thouinia villosa DC. (Sapindaceae) Dilodendron bipinnatum Radlk. (Sapindaceae) Plumeria rubra L. (Apocynaceae) Aspidosperma subincanum Mart. (Apocynaceae) Jacaratia mexicana A.DC. (Caricaceae) * 2 Cecropia saxatilis Snethl. (Cecropiaceae) * 2 Ximenia americana L. (Olacaceae) Ximenia americana L. (Olacaceae) Other habitats Alibertia edulis (Rich.) A.Rich. ex DC. (Rubiaceae) in moist forest Alibertia edulis (Rich.) A.Rich. ex DC. (Rubiaceae) in TDFS Celtis iguanaea (Jacq.) Sarg. (Ulmaceae) in riparian forest Celtis iguanaea (Jacq.) Sarg. (Ulmaceae) in TDFS Guazuma ulmifolia Lam. (Sterculiaceae) in riparian secondary vegetation Guazuma ulmifolia Lam. (Sterculiaceae) in TDFS * Species belonging to different families but with a similar distribution and similar morphological attributes. 1 Small trees with compound leaves. 2 Tall trees with soft wood and large lobate leaves.
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