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Full-Text Articles in Life Sciences

Pollen Dispersal In Low-Density Populations Of Three Neotropical Tree Species, Jason D. Nason, E. A. Stacy, J. L. Hamrick, S. P. Hubbell, R. B. Foster, R. Condit Aug 1996

Pollen Dispersal In Low-Density Populations Of Three Neotropical Tree Species, Jason D. Nason, E. A. Stacy, J. L. Hamrick, S. P. Hubbell, R. B. Foster, R. Condit

Jason D Nason

Studies of mating patterns of tropical trees, typically involving common species, have revealed that most species are outcrossed and that, in some cases, a significant reaction of outcross pollen moves long distances. We evaluated mating systems and effective pollen dispersal for three hermaphroditic insect-pollinated Neotropical tree species, Calophyllum longifolium, Spondias mombin and Turpinia occidentalis, all of which occurred at low adult densities at the study site. Mating patterns were estimated for each maternal tree within 84-ha populations of C. Longifoliuman d S. mombin in 1992 and 1993 and within a 50-ha population of T. occidentalis in 1993. Each population was …


Bird Aversive Properties Of Methyl Anthranilate, Yucca, Xanthoxylum, And Their Mixtures, Larry Clark, Bruce Bryant, Igor Mezine Jan 1996

Bird Aversive Properties Of Methyl Anthranilate, Yucca, Xanthoxylum, And Their Mixtures, Larry Clark, Bruce Bryant, Igor Mezine

Larry Clark

We tested the bird aversive properties of methyl anthranilate, yucca extracts, and Xanthoxylum spp. extracts in one- and two-bottle drinking assays that used European starlings (Sturnus vulgaris). In one- and two-bottle tests, methyl anthranilate proved to be the more potent stimulus in producing an avoidance response. Starlings avoided consuming Xanthoxylum and yucca only in the two-bottle tests. Previous studies showed that yucca was a good adjuvant in stabilizing lipophilic compounds in water. Starlings did not avoid binary mixtures of methyl anthranilate and yucca differently from what would be expected if they were only responding to the solution's methyl anthranilate content. …


Grazing Repellency Of Methyl Anthranilate To Snow Geese Is Enhanced By A Visual Cue, J. Russell Mason, Larry Clark Jan 1996

Grazing Repellency Of Methyl Anthranilate To Snow Geese Is Enhanced By A Visual Cue, J. Russell Mason, Larry Clark

Larry Clark

Methyl anthranilate (Rejex-It AG-36) is formulated as a commercial goose repellent. Frequent reapplications of this product are often necessary, and the cost/application is high ($300.00/ha). The present experiment tested the possibility that the repellency of methyl anthranilate might be enhanced by the addition of visual cues. Twelve 0.4 ha plots were assigned randomly to three treatment groups. Plots in the first group (n = 4) were sprayed with 10% Vapor Guard (an agrochemical adhesive). Plots in the second group (n = 4) were treated with a mixture of methyl anthranilate (3.4 kg/ha) and Vapor Guard. Plots in the third group …


Avoidance Of Cabbage Fields By Snow Geese, J. Russell Mason, Larry Clark Jan 1996

Avoidance Of Cabbage Fields By Snow Geese, J. Russell Mason, Larry Clark

Larry Clark

now Goose activity levels were significantly less in cabbage fields than in control fields. Although the data do not unambiguously address the issue of sulfur repellency, we believe that the activity difference is consistent with avoidance of the former and not preference for the latter. Sulfurous volatiles were readily apparent to us during our visits to cabbage fields throughout the study period. Similar odors were not detected in control fields. If sulfurous volatiles were important, then avoidance could reflect some characteristic of the cover crop (e.g., unpalatability acquired through the absorption and translocation of degra­ dation products) or it could …


Non-Mycorrhizal Uptake Of Amino Acids By Roots Of The Alpine Sedge Kobresia Myosuroides: Implications For The Alpine Nitrogen Cycle, Ted K. Raab, David A. Lipson, Russ K. Monson Jan 1996

Non-Mycorrhizal Uptake Of Amino Acids By Roots Of The Alpine Sedge Kobresia Myosuroides: Implications For The Alpine Nitrogen Cycle, Ted K. Raab, David A. Lipson, Russ K. Monson

Ted K. Raab

Non-mycorrhizal plants of the alpine sedge, Kobresia myosuroides , take up the amino acid glycine from nutrient solutions at greater rates than NO3- or NH4+. The amino acids glutamate and proline were also taken up at high rates. Total plant biomass was twice as high after 4 months of growth on glycine, compared to NH4NO3, with significant increases in both root and leaf biomass. By taking advantage of differences in the d13C signature of air in the growth chamber and the glycine used for growth, a two-member mixing model was used to estimate that a significant amount of the glycine …