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Annual losses of weed seeds due to predation in organic cereal fields
Autor: Westerman, P.R.; Wes,J.S. Kropff; M.J., Werf; W. van der
In:
Journal of Applied Ecology
Bandangabe: 40
Seite: 824 - 836
Jahr: 2003
Einordung:
Institut: Professur Phytomedizin
Abstract:
1. Post-dispersal seed losses in annual arable weed species are little understood or quantified, but may be of significance for natural population control, especially if they might be manipulated. We hypothesised that weed seed predation on the soil surface was significant and measured rates in the field to estimate annual seed losses due to predation.
2. Temporal patterns of weed seed losses due to predation (‘demand’) as well as weed seed production (‘supply’) were measured from May-June until harvest in August during 2-week exposure periods in four organic cereal fields in The Netherlands. The proportion of weed seeds lost to predators Mi (seeds consumed • seeds exposed-1 • 14 d-1) was measured in 1999 and 2000, using cards containing seeds of Stellaria media, Chenopodium album, or Avena fatua. Seed production, Yi (seeds • m-2 • 14 d-1), was measured in 2000, using seed traps.
3. Annual seed loss due to predation, (seeds consumed • seeds produced-1 • y-1), was calculated based on Mi and the exposure period of seeds to predators, starting with seed shed and ending with seed burial. The importance of the length of the exposure period on total seed loss was explored using a model.
4. The temporal trend in Mi was consistent among farms and years: high in June and early July, lower in the second half of July, and negligible in August and after harvest. Total seed production varied considerably among fields, i.e. 800 - 16 000 seeds • m-2 • y-1. The timing of peak seed production also varied substantially.
5. Calculated ranged from 32 to 70%, when assuming continuous exposure of seeds to predators from seed shed till crop harvest. When exposure was limited to 2 or 4 weeks after seed shed, decreased to 18-57% or 28-67%, respectively. Differences between fields and weed species were mainly due to differences in the timing of seed shed.
6. Synthesis and application. Our results suggest that seed predation in organic cereal fields is an important factor shaping the population dynamics of arable weeds. Agricultural practices and environmental conditions that advance weed phenology, such as an early crop sowing, and postpone seed burial following hot and dry weather, will result in higher proportions of weed seed loss in cereals.
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Letzte Änderung des Eintrages:
02.02.2010
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