Resumo

HUGHES, Frederic Mendes; DE LA CRUZ ROT, Marcelino; ROMAO, Roberto Lisboa  e  CASTRO, Marina Siqueira de. Spatio-temporal dynamics of Melocactus ernestii subsp. ernestii (Cactaceae) in northwestern Brazil. Rev. bras. Bot. [online]. 2011, vol.34, n.3, pp. 389-402. ISSN 0100-8404.  http://dx.doi.org/10.1590/S0100-84042011000300012.

Melocactus ernestii Vaupel ssp. ernestii occurs in discontinuous outcrops in eastern Brazil. We investigated the spatio-temporal pattern of mortality events and survival of seedlings of M. ernestii relationship with plants and perennials, from the use of plots, assigned with the aid of measuring tapes, which were taken the Cartesian coordinates of the centroid of the stages of development, with subsequent analysis of point patterns based on Ripley's K function. Were mapped in plots 686 individuals of M. ernestii. The spatial pattern varied depending on the scale of the development stage and degree of weathering of the outcrops. The recruitment events and mortality were spatially structured and influenced by seasonal pulses of rainfall. Seedlings emerged ca. 50 cm from the centroid of adults. From the 136 seedlings monitored for 18 months, 84% died. The results showed that microsites initially effective in the maintenance of seed germination may not be effective in the establishment of seedlings. The magnitude of biotic interactions in stressful environments is species-specific and indicates that a positive association between adult plants and seedling survival is not consistent over time. This type of modeling population allows a better understanding of the role of positive and negative interactions as forces community structure, and may help to understand the complexity of biotic interactions in severe environmental gradients.

Palavras-chave : independent labeling model; recruitment; Ripley's K function; spatial structure.