Dear Colleagues, I wonder if some of you might be interested in
participating in this study of enemy release in Norway maple (Acer
platanoides), a troublesome introduced tree in North America. For 2 years
the Transatlantic Norway Maple Study has compared leaf damage from
populations on either side of the Atlantic. We found a significantly
higher herbivory in Europe, but still probably too small to explain this
tree's much lower average population densities in its native range. So we
are turning our attention to seed and seedling viability, in the content
of the soils around the trees.
This would make a great little study for individul researchers, or their
students. Very little work is required. All participants will be
co-authors on whatever publication results from this. See below in this
email for the protocol.
Since this is a transatlantic study, I'd be grateful if you could forward
this email to colleagues in Europe who might be interested.
Sincerely,
Jonathan Adams
Seed viability comparison protocol
This study is intended to test a prediction of the enemy release
hypothesis, that seed predation and seedling survivorship should be
greater within the introduced range of a species than in its native range.
Greater survivorship should contribute to its greater success in its
introduced range.
1) Collect seeds from stands of Norway maple with at least 10 individuals
over 2m tall in a hectare (or less). Choose trees in a woodland setting
only, not isolated trees surrounded by grass or concrete in parks. (FOR
HINTS OF DISTINGUISHING NORWAY MAPLE FROM SUGAR MAPLE PLEASE ASK ME TO
SEND YOU MY IDENTIFICATION GUIDE).
2) Collect seeds if possible when still on tree but almost ready to fall
(breaking away easily when touched). Otherwise collect newly fallen seeds
on ground.
3) Collect at least 200-250 seeds randomly from at least 3 trees.
4) Using a trowel or spade, scoop up about 1 litre of soil from the top
10cm of the soil beneath the canopy of the trees. Collect it from at least
5 points scattered through the stand, and mix it all together.
5) Put the soil in a plastic bag, mix in about 100-150 seeds evenly with
the soil. Fold over the bag, ensuring the soil is moderately moist, and
place it in a fridge at around 3 C for 120 days. Open up the bag for a
minute to let some air in every couple of weeks, then seal it back up (to
prevent drying).
6) Take the other 100 or so seeds left over. Put them in a beaker full of
water and boil them for 1 minute to sterilize them. Bring them out, let
them air dry and then we will send them to colleagues in France to x-ray
for seed predation.
7) After 120 days take the chilled seeds, spread them in trays, about 10cm
deep, covered and moist at around 22-25 C in a greenhouse. After 2 weeks
tip out the trays, sift through the soil and record how many seeds have
germinated, how many have not germinated. Send the results to Jonathan
Adams ([EMAIL PROTECTED]).
8) put the seeds back in trays in a rough grid at a density of one
germinated seed every 5cm, and let them grow at the same temperature, in
sunlight. Keep watered. Record the mortality after 1 month, 2 months, 3
months. Send the results to Jonathan Adams
([EMAIL PROTECTED]).
