Population dynamics in mature stands of Hieracium pilosella in New Zealand

The dynamics of a mature population of Hieracium pilosella under four different treatments (+/- irrigation, +/- fertiliser, +/- defoliation, and +/- fungicide & insecticide, in a full factorial design) were compared in the Mackenzie Basin, New Zealand. H. pilosella had been growing at the site f...

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Bibliographic Details
Published in:Plant ecology 2003-01, Vol.166 (2), p.263-273
Main Authors: Lamoureaux, S.L, Kelly, D, Barlow, N.D
Format: Article
Language:English
Subjects:
Animal populations
Animal reproduction
Applied ecology
Defoliation
Environmental degradation
environmental factors
Fertilizers
Fungicides
grazing
Hieracium pilosella
Inflorescences
Insecticides
Irrigation
mature plants
Mortality
nutrient availability
pesticides
plant density
Plant ecology
plant reproduction
Plants
Population decline
Population density
Population dynamics
seedling growth
Seedlings
soil water retention
stand characteristics
Stolons
vegetation cover
weeds
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Summary:The dynamics of a mature population of Hieracium pilosella under four different treatments (+/- irrigation, +/- fertiliser, +/- defoliation, and +/- fungicide & insecticide, in a full factorial design) were compared in the Mackenzie Basin, New Zealand. H. pilosella had been growing at the site for at least 30 years. Recorded variables included rosette density, inflorescence and stolon production, recruitment and mortality, and plant cover. The population appears to be regulated through density-dependent mortality interacting with density-independent reproduction. In the treated plots, irrigation and fertiliser had the greatest effects, increasing both the proportion of established rosettes producing stolons and stolon length. Irrigation also increased the likelihood of a daughter rosette becoming reproductive and decreased inflorescence abortion. Fertiliser increased the probability of an established rosette reproducing and the number of daughter rosettes produced. In unmanipulated plots H. pilosella appeared to be at or near an equilibrium density of ca. 3200 rosettes m(-2), but over longer time scales the low reproductive rates shown in this study may presage slow population decline due to plant-induced environmental degradation.
ISSN:1385-0237
1573-5052
DOI:10.1023/A:1023208218186