Here is a nice simple study that we did in the lab this last Fall: http://onlinelibrary.wiley.com/doi/10.1111/aec.12144/abstract
If anyone is interested in doing the experiment again for their shrub-understorey system, please feel free to contact us. The protocol is well explained in the paper, but we are happy to provide additional details. Furthermore, we do have 6 nice chambers that we can program to emulate contrasting conditions. If you do not have access to a set of chambers, we would love to collaborate and run a set of them for you this Fall, 2014. If you do have chambers, let’s all get together and run a globally replicated version of this experiment for lot’s of different species from different deserts.
1. Collect seeds from 5 different species of plants that are found both under shrubs in arid systems and in the open nearby. A total of 2000 seeds per species is recommended as a minimum.
2. Pop out hobo loggers (we used pro v2s) or comparable microenvironmental loggers and record at least a seasons worth of conditions under your shrub species and nearby in the open (non-canopied sites where your target species also occur).
3. Record plant densities at the end of that season.
4. Petri dish trials in chambers (reciprocal design) and Tz tests on seeds etc as described in the paper.
Simplified data can be found on figshare here: http://bit.ly/seedbiol