Canadian Journal of Botany - Revue Canadienne de Botanique (1997) 75, 939-945

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J. Pino, F.X. Sans and R.M. Masalles (1997)
Effects of intrinsic and environmental factors on seedling survival of Rumex obtusifolius in Mediterranean alfalfa crops
Canadian Journal of Botany - Revue Canadienne de Botanique 75 (6), 939-945
Abstract: This paper focusses on the survivorship pattern of seedlings of Rumex obtusifolius L. in the irrigated alfalfa crops (Medicago sativa L.) in central Catalonia (NE Spain). The relationship between this pattern and seasonal environmental change was evaluated by monitoring seedling cohorts that had germinated at different times of the year for 31 months. Paired comparisons of cohort survivorship curves were performed over their life-spans and for their coexistence period, using Peto and Peto's log rank test. The significance of intrinsic variables such as age and size in determining seedling survival was tested using hierarchical log-linear analysis applied on a three-way contingency table and by means of Goodman and Kruskal's association coefficients. Results showed that seedling cohorts emerging at different times in the year exhibited a similar Deevey type III survivorship pattern. Therefore, survivorship was scarcely affected by seasonal environmental variation. However, since age had little effect on seedling survival compared with size, this age-specific survivorship pattern was, in fact, a consequence of both size-dependent mortality and changes in size distribution with age. In the first weeks of life, cohort size distribution was greatly skewed to the smallest classes, with the highest mortality rates, and therefore the risk of death in the cohort was high. Afterwards, the frequency of the largest size classes increased with age, thus reducing the risk of death of the cohort.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website


Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation
population dynamics/ epidemiology

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.


Rumex obtusifolius (weed) Alfalfa/lucerne (Medicago sativa) Spain (continental)
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