Browsing by Author "OTAIZA, RD"

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    SHRUB CLUMPS OF THE CHILEAN MATORRAL VEGETATION - STRUCTURE AND POSSIBLE MAINTENANCE MECHANISMS
    (1984) FUENTES, ER; OTAIZA, RD; ALLIENDE, MC; HOFFMANN, A; POIANI, A
    Previous studies have claimed that the Chilean matorral is more open than the California [USA] chaparral and have attributed this dissimilarity largely to the role of man in Chile. The Chilean matorral has a structure better described as shrub clumps that merge to form a continuous vegetation matrix only in very mesic habitats, where it is comparable to the California chaparral. Evidence is presented that these clumps have been present for at least the last 26 yr and that even without human disturbance they are likely to maintain themselves. Evidence for the latter pertains to seed dispersal, seed germination and establishment, seedling survival and the diameter size structure of shrub clumps. Differences between the California chaparral and Chilean matorral may be more profound than previously thought and are due not only to different degrees of human disturbance, but also to the presence of periodical natural fires in California and not in Chile and to different shrub recruitment patterns and mammalian herbivore activity in the 2 areas.
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    VERTICAL-DISTRIBUTION OF CHITONS (MOLLUSCA, POLYPLACOPHORA) IN THE ROCKY INTERTIDAL ZONE OF CENTRAL CHILE
    (1985) OTAIZA, RD; SANTELICES, B
    The patterns of vertical distribution of chitons in various exposed rocky shore habitats of central Chile are described. The density and size of the individuals were determined at different levels on intertidal rock walls, in pools and on boulders. A group of 4 spp. [Chiton barnesi, C. granosus, Callistochiton viviparus and Acanthopleura echinata] was found on rock walls while another group of 4 spp. [Ischnochiton pusio, Tonicia elegans f. lineata, Chilton cumingsi and C. latus] was found in tidal pools and on boulders. The species showed vertical separation on rock walls and segregation according to a range of increasing frequency of water movement in pools and on boulders. Only the 2 spp. with largest adult individuals (A. echinata (Barnes) and C. latus Sowerby) showed vertical segregation in size. Small-sized species and small individuals of large-sized species were found higher on rock walls or in zones where water movement is less; large chitons occur in zones of greatest water impact. This suggests that water movement may be a significant factor in setting the lower limits of distribution of these herbivores. Some of the species examined were extremely abundant (600 .cntdot. m-2) with densities of 1-2 orders of magnitude greater than for other chiton species elsewhere.