Seasonal Seed dispersal of Callitirs verrucosa (2011-2012)

Full description

The data set contains distance measures of primary (wind-borne) and secondary (on ground) seed dispersal during spring, summer and autumn, using empirical observations and detailed measurement of wind characteristics. Seeds were collected from populations of C. verrucosa within the reserve. was placed parallel to and 100 m from the burn edge within the burnt site.

For the empirical observation of seed dispersal we chose six release locations, three locations in each of two sites about 6 km apart that had both recently undergone a planned burn, one in spring 2009 and the other in autumn 2011. Within those two sites the three release locations were positioned 800 m apart from each other along a transect that was placed parallel to and 100 m from the burn edge within the burnt site.

To assess primary (wind-borne) seed dispersal 20 randomly chosen seeds were released from each of three different heights (1 m, 2 m and 3 m) at each of the six sites, giving a total of 360 seeds released per season. Seeds were only released within a horizontal wind speed range of 8 - 25 km/h. At lower wind speeds seeds would not take-off and at higher wind speeds seeds could not be relocated. This data set could be reused in a similar study carried out for the same species in a different location.

To understand the effect of standing vegetation on the secondary (on-ground) seed dispersal, we established groups of 10 seeds on the ground within 10 m of each of the six previous release locations. Seed were left for 4 days before relocated and distances to the starting point were measured. This was repeated during all 3 seasons. Out of the 180 seeds released,161 (89%) seeds could be relocated. This data set could be reused in a similar study carried out for the same species in a different location.

Wind measurements were taken on a sand dune crest in the site that was burned during autumn 2011 using an ultrasonic anemometer (Model WindMaster (Part 1590-PK-020), Gill Instruments Ltd, Lymington, UK). Measurements continued for two weeks in spring, summer and autumn. The anemometer measured horizontal wind speed, horizontal wind direction, and vertical wind speed every 0.1 s, producing a dynamic, three dimensional wind speed vector. Measurements were taken at 2 m height. This data set could be reused in models requiring wind data from this area during spring, summer and autumn.