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  • 1
    Electronic Resource
    Electronic Resource
    Boston, MA, USA : Blackwell Science, Inc.
    Restoration ecology 10 (2002), S. 0 
    ISSN: 1526-100X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Local populations of plants are likely to be better adapted to a site than populations from elsewhere. Thus, local seeds should yield higher survival in restoration attempts than commercial seed stocks. We compared seedling survival from locally and commercially obtained seeds of seven species, Pseudoroegneria spicata (bluebunch wheatgrass), Elymus elymoides (squirreltail), Pascopyrum smithii (western wheatgrass), Stipa hymenoides (Indian ricegrass), Stipa comata (needle-and-thread), Chrysothamnus nauseosus (rubber rabbitbrush) and Ephedra nevadensis (Mormon tea) over three years on two sites in Utah (Dugway and Tintic) that were dominated by the introduced annual Bromus tectorum (cheatgrass). At the Dugway site we included burned and unburned seedbed treatments. For all species at Dugway, seedling survival to the first summer was higher on burned plots where B. tectorum densities were greatly reduced. First-year seedling survival was 20–30% for most species on the Dugway burned plots and at Tintic. At the drier Dugway site, only S. hymenoides and Ephedra had substantial third-year survival. Elymus and Pascopyrum survived to the third year only at the moister Tintic site. Survival to the third year was less than 3% for all species except S. comata (6% survival), and densities were low (0.2–1.0 plants/m2). However, third-year plants were well established and the grasses flowered. Pseudoroegneria and Ephedra at Dugway (on burned plots) and S. comata and Elymus at Tintic had higher first-year survival or higher survival based on survival curves from local than from commercial seeds. However, final survival was never significantly higher, although such a trend was suggested. Seed dormancy traits could also provide advantages to local populations, and we observed differences in dormancy between local and commercial S. comata and S. hymenoides seeds that may be an example.
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  • 2
    ISSN: 1442-1984
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract In this study, we explore the reproductive biology of Cercocarpus ledifolius (Rosaceae), a species showing extremely limited recruitment throughout its range in the Intermountain West, USA. We examined (1) self-compatibility, (2)the potential for wind pollination, (3) pollen limitation of seed production, and (4)loss of developing seeds. Through hand-pollination experiments, we determined that C. ledifolius flowers are highly self-compatible. Abundant seeds were produced from flowers pollinated with pollen from the same plant, and the level of seed production did not differ from control outcrossed treatments. Furthermore, we measured substantial airborne pollen loads within C. ledifolius stands, indicating transport of pollen via wind and a strong potential for wind pollination, despite apparent adaptations for insect pollination. Pollen did not limit seed production; branches on which all flowers were handpollinated with outcrossed pollen did not have greater seed production than control branches open only to natural pollination. Lastly, virtually all initiated seeds developed to maturity, indicating low seed abortion rates and minimal loss to pre-dispersal seed predators. Natural levels of fruit production were at or greater than mean fruit production for woody perennials. In summary, we found no evidence that the quantity of pollen, the source of pollen (self vs. outcrossed), or developing seed loss is seriously limiting recruitment of this species.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 76 (1988), S. 525-530 
    ISSN: 1432-1939
    Keywords: Faramea occidentalis ; Satiation ; Seed predation ; Treefall gaps ; Tropical forests
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Using the subcanopy tree Faramea occidentalis in Panama, I studied post-dispersal seed survival as a function of five characteristics describing seed locations. By simultaneously considering distance from a conspecific adult, size of the nearest conspecific adult, leaf litter quantity, proximity to logs or tree trunks, and whether or not the seed was in a gap, I was able to analyze the influences of individual factors, as well as the interactions among factors. Seed survival was significantly less in treefall gaps than in the forest understory. Seed survival was also influenced by the size of the nearest adult but in a complex interaction with distance to an adult. For seeds beneath adults, survival decreased with increasing tree size, while for seeds away from adults, survival was independent of the size of the nearest conspecific adult. Distance did not directly affect seed survival, nor did the quantity of leaf litter or the proximity to a tree trunk or a log. In a separate analysis, the relationship between distance and seed survival was consistent over four years, suggesting that single cohort studies may provide accurate insights into the consequences of dispersal. In contrast, the spatial locations of surviving seeds were not consistent over the four-year period. Transects with high survival one year did not tend to have high survival in other years, and the locations of surviving seeds in any particular year could not be predicted from the knowledge of where seeds survived in other years. While survival is patchy within a year, the locations of patches shift from year to year.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 116 (1998), S. 191-201 
    ISSN: 1432-1939
    Keywords: Key words Ants ; Patch dynamics ; Disturbance ; Treefall gaps ; Neotropics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Natural formation of treefall gaps plays an integral role in the ecological and evolutionary dynamics of many tropical forests, affecting the spatiotemporal distribution of plants and the animals that interact with them. This study examines the impact of treefall gaps on the spatial and temporal patchiness of ant assemblages in a moist lowland forest in Panama. Using pitfall traps and honey baits, we compared ant assemblages in five 1 to 2-year-old treefall gaps (ca 100 m2) and five adjacent plots (ca 100 m2) in undisturbed forest understory at three different times of year (late wet season, late dry season, and early wet season). We found little evidence that ant assemblages respond dramatically to the formation of treefall gaps and the differences in habitat qualities they produce. Ant abundance, species richness, species composition, and rates of resource discovery did not differ between gaps and forest understory. However, we did find significant differences in numerical abundance related to forest stratum (ground vs vegetation) and resource type in pitfall traps (oil-cockroach vs honey), and significant differences in ant species richness and rates of resource discovery across seasons. While habitat effects by themselves were never statistically significant, habitat and seasonal differences in species richness interacted significantly to produce complex, season-dependent differences among gap and forest habitats. These results suggest that the formation of natural treefall gaps has less of an effect on Neotropical ant assemblages compared to other groups of organisms (e.g., plants, birds) or other causes of patchiness (e.g., ant mosaics, moisture availability, army ant predation). The results of our study also have important implications for the underlying causes of habitat differences in the distribution of ant-defended plants.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 70 (1986), S. 379-385 
    ISSN: 1432-1939
    Keywords: Ant/plant interaction ; Herbivory ; Growth ; Cecropia ; Azteca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In this 15 month investigation I experimentally demonstrated that sapling Cecropia aff. obtusifolia in lowland western Ecuador grow more vigorously when occupied by the ant Azteca constructor than when the ants have been removed. Thus the interaction is directly beneficial to Cecropia juveniles. The difference in growth is associated with differences in herbivory and vine cover. Removal of ants significantly increases nocturnal Coleoptera herbivory on unoccupied plants. In contrast to the influence on beetle numbers, Azteca are ineffective against Homoptera and cecidomyiid gall flies. Although ant-occupied saplings had less chewing herbivore damage throughout the study, the ants were more effective protectors in the dry season than in the rainy season, when herbivore pressure increased. In addition to reducing herbivory, Azteca efficiently remove vines from occupied saplings.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Evolutionary ecology 12 (1998), S. 823-827 
    ISSN: 1573-8477
    Keywords: empty seeds ; Juniperus ; Parus ; seed predation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Utah juniper (Juniperus osteosperma) is one of many plant species that produce large numbers of fruits containing parthenocarpic or otherwise empty or inviable seeds. We tested the hypothesis that production of empty fruits in this species results in reduced levels of predation on fertile seeds. In a population in west-central Utah, we estimated the proportion of fruits with filled seeds in trees suffering high levels of fruit destruction by the seed-eating bird Parus inornatus and in neighbouring trees similar in crown and fruit-crop size but suffering negligible predation. We found that the heavily attacked trees had higher proportions of filled seeds. Thus, juniper may benefit from producing fruits that contain no offspring. This is the first study to demonstrate that empty seeds may reduce predation by vertebrate seed eaters and the first to demonstrate discrimination based on seed filling at the level of whole plants.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Plant ecology 107-108 (1993), S. 15-29 
    ISSN: 1573-5052
    Keywords: Consequences of seed dispersal ; Plant fitness ; Seed dispersal effectiveness ; Seed dispersal quality ; Seed dispersal quantity ; Seed disperser
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Disperser effectiveness is the contribution a disperser makes to the future reproduction of a plant. Although it is a key notion in studies of seed dispersal by animals, we know little about what determines the effectiveness of a disperser. The role of the present paper is to review the available information and construct a hierarchical framework for viewing the components of disperser effectiveness. Effectiveness has both quantitative and qualitative components. The quantity of seed dispersal depends on (A) the number of visits made to the plant by a disperser and (B) the number of seeds dispersed per visit. The quality of seed dispersal depends on (A) the quality of treatment given a seed in the mouth and in the gut and (B) the quality of seed deposition as determined by the probability that a deposited seed will survive and become an adult. In this paper I review the ways disperser behavior, morphology and physiology can influence these major components of disperser effectiveness, and when data permit present preliminary analyses of relationships among components.
    Type of Medium: Electronic Resource
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  • 8
  • 9
    Publication Date: 2014-02-25
    Print ISSN: 1385-0237
    Electronic ISSN: 1573-5052
    Topics: Biology
    Published by Springer
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  • 10
    Publication Date: 2010-10-02
    Print ISSN: 1385-0237
    Electronic ISSN: 1573-5052
    Topics: Biology
    Published by Springer
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