Competitive neighborhoods and the use of interference indices to assist in the restoration of Amsinckia Grandiflora

Conference · Wed Nov 01 04:00:00 EST 1995

OSTI ID:282965

Beesley, P

As part of the on-going efforts to reintroduce the large-flowered fiddleneck (Amsinckia grandiflora) into California native perennial bunch grass communities, we developed indices of competitive interference to predict the fecundity of individuals in populations of this rare annual forb. These indices, developed from aspects of the spatial distribution of neighboring competitors, are used as independent variables in linear regressions to predict plant fecundity of A. grandiflora individuals within a Poa secunda bunch grass population. This was accomplished by examining the distance to each competitor along with the number, basal area, and angular dispersion of competitors within a fixed radius about A. grandiflora individuals. The data was taken from individuals planted within naturally occurring bunch grass populations and within transplanted bunch grass plots controlled for density and distribution. Density, spatial pattern, and basal area all had significant effects upon A. grandiflora individuals within controlled plots. As number of competitors increases within the competitive neighborhood of A. grandiflora individuals, seed (nutlet) output declines. A similar relationship holds true for increasing competitor basal areas. Distance to competitors also influences nutlet output with fecundity falling as more competitors become closer to focal individuals. Complex interactions of the above factors were also significant with the overall trend being reduced nutlet output with increasing dispersion of competitors. Although the above regressions are highly significant (p < 0.01), the variation each describes is low. Density and an indice of distance to competitors were the only significant predictors (p < 0.05) of plant fecundity for A. grandiflora individuals found in naturally occurring Poa secunda populations. These relationships show similar trends as those found for controlled plots.

• Research Organization: Lawrence Livermore National Lab., CA (United States)
• OSTI ID: 282965
• Report Number(s): UCRL-ID--114972-4; CONF-9505323--; ON: DE96006013
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
55 BIOLOGY AND MEDICINE
BASIC STUDIES
BASELINE ECOLOGY
ECOLOGICAL SUCCESSION
ENDANGERED SPECIES
FLOWERS