Seasonal Seed Dispersal of Callitris verrucosa 

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 Callitris verrucosa within the reserve and 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 the 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.
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. The data can be used for studies dealing with wind movements in mallee during Spring, Summer and Autumn as well as comparative seed dispersal studies using the same or other wind dispersed plant species. 

We at TERN acknowledge the Traditional Owners and Custodians throughout Australia, New Zealand and all nations. We honour their profound connections to land, water, biodiversity and culture and pay our respects to their Elders past, present and emerging. The Australian Research Council (ARC), SA Native Vegetation Council, Department of Environment, Water and Natural Resources (DEWNR) (check what they call themselves these days), NSW Office of Environment and Heritage and the Nature Foundation of SA provided financial support. 

Fire management in the form of prescribed burning often causes a shift in fire season from hot and dry summer conditions to cooler, moister conditions in spring or autumn. The effects of this change on plant species which rely on efficient seed dispersal by wind after fire are unknown. Variations in wind conditions during the different seasons and changes in the amount of standing vegetation after the burn, resulting from variation in fire intensity in different seasons, may alter dispersal conditions following fire. We studied seed dispersal in different seasons for a serotinous obligate-seeder, Callitris verrucosa, growing in a semi-arid environment in South Australia. We measured primary (wind-borne) and secondary (on ground) seed dispersal during spring, summer and autumn, using empirical observations and modelling to investigate the effect of season on the dispersal distance of seeds.
Fire is and has been a common occurrence in many vegetation types across the world, impacting on the structure and function of those fire-prone ecosystems. Human influence and a changing climate are causing changes in fire regimes, particularly intervals between fires and the seasonal timing of fires. The frequencies of fires are increasing and fire seasons are tending to shift from hot and dry seasons (natural fires) to cooler and wetter seasons (prescribed burns). Clearing for farmland or urban settlements, in which fire-prone vegetation occurs demands new knowledge to understand the interactions between fire regimes and biodiversity. The study examined the effects of fire on two plant species, Triodia irritans, and Callitris verrucosa. Both species are important features of mallee vegetation and have primarily wind mediated seed dispersal but show different life history traits. The study was carried- out at Hincks Wilderness Protection Area on the Eyre Peninsula, South Australia, aiming to assess seed dispersal and population genetic variation under different fire regimes, with a view to making inferences about their resilience to changing fire regimes. 

Data not provided.