New Zealand Journal of Botany abstracts
Survival of Ulex europaeus seeds in the soil at three sites in New
Zealand
R. L. HILL*
A. H. GOURLAY
R. J. BARKER+
Landcare Research
P.O. Box 69
Lincoln, New Zealand
*Present address: Richard Hill & Associates,
P.O. Box 4704,
Christchurch, New Zealand.
Email: Hillr@crop.cri.nz
+Present address: Department of Mathematics
and
Statistics, University of Otago, P.O. Box 56, Dunedin, New Zealand.
Abstract Seed banks are a major factor in the persistence of
perennial, woody, leguminous weed species. The longevity of seeds of Ulex
europaeus, (gorse) in the soil at three sites was determined, and the
implications of these results for the selection of biological control agents
for the weed are discussed. Locally collected seeds were buried in bags at
depths ranging from 2.5 cm to 15 cm at three climatically distinct
sites. Seeds were recovered and germinated over a 10-year period to estimate
the dormancy characteristics and viability of U. europaeus seed banks at
the three sites. The decline in the seed bank conformed to a linear model using
an exponential transformation. Seeds survived longer when buried deeper, but
this influence was weak. The main determinant of seed survival was the time
elapsed since burial. Results indicate that the dynamics of the seed bank vary
from site to site. Thus, the view that U. europaeus seeds last almost
indefinitely in the seed bank may be exaggerated, at least in some sites. At
two sites, the number of viable seeds buried at a depth of 5 cm declined
to 10% of the original number within 10 years of burial and to 1% within 20
years. By contrast, data from the third site suggested that in some places seed
could survive many decades in the seed bank. Almost all seeds recovered from
the soil were viable, and losses from the seed bank were probably due to
germination. Local climatic conditions or local genotype may explain the
variation in seed longevity between sites, although this study could not
examine the relative importance of these factors. Seed-feeding biological
control agents reduce U. europaeus seed rain, and these may influence
the population dynamics of the weed within several decades in areas where the
rate of seed decline in the soil is rapid.
Keywords Ulex europaeus; seed; seed bank; gorse;
climate
New Zealand Journal of Botany, 2001, Vol. 39: 235-244
0028-825X/01/3902-0244 $7.00 (c) The Royal Society of New Zealand
2001
B00003
Received 31 January 2000; accepted 10 January 2001
PDF file of entire paper: medium quality (822K); (scanned from paper original: notes about this process)
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