I am working on long-distance seed dispersal of grey sallow willow, focusing on seeds that are uplifted above the canopy and then may travel very long distances.
I would like to put some seed traps above the canopy level (around 6m) to measure how many seeds are uplifted. However I am not sure how to do this. I am thinking about using a funnel seed trap as outlined in Cottrell 2004 (linked), but extending the pipe to 6m and perhaps keeping it upright by tying to trees in the surrounding area, but I'm not sure this is a viable idea as I have no prior experience in seed traps at all.
Any guidance/experience in this area much appreciated!
http://www.jem-online.org/forrex/index.php/jem/article/view/283
You have to use sticky traps to collect catkins because they are wind dispersed! This type of trap is perfect for seeds that travel long distances. The higher the cards are placed, the more likely they are to collect them.
Please have a look at this useful link.
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2745.2008.01400.x/full
The above link describes seed trap use in Jacaranda copaia, which is wind dispersed. However, there is no description of the type of traps used!
Andrew :-)
Sticky traps seem like a good idea for Salix.
If you are looking at long-distance dispersal, it is likely that your capture rate will be very small, so you will need a very large surface area in total - but lots and lots of small traps for statistical purposes and to avoid the wind blowing them over!
Mike
I have tried a similar method as you describe and it worked well, but I found that I would need a very large number of traps to obtain a suitable sample.,
Thanks everyone! I'm working on making my sticky seed traps :)
Just roughly, how many does 'a large number' mean? Are we talking 10, 50, 100?
Additionally - how should seed traps be oriented? If I was trying to capture seeds from a single plant, I would put them all facing towards the plant, but what do you do in areas where there are many of the same plant and it isn't clear which seeds have come from which plant?
Traps can be placed horizontal, vertical, and 30 degree angle for capture of insects, so I presume it will be the same to catch catkins. But make sure you don't catch birds! I don't think it matters which way they face if they are between trees, but obviously they must face towards plants on the extremities of the population. Place them high. Total trapping area should be approximately 6% of the total ecosystem area I think. That's what I used in my fruit collection study. As far as which tree the seeds come from, I think you will have to sum the dispersal kernels to produce the population distribution. Otherwise, you can do genetic studies to determine maternal trees or use mark and recapture methods.
I hope this helps!
6% of even the source area may be huge! Basically, as many traps as you can get/make. As for direction, do you have anything like a prevailing wind direction?
If you can, do a trial first to work out trapping rates and differences among directions...
Mike
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