I did not elaborate on my direction with some of the more unusual sensors. Here are a few quick thoughts:

• The various photodetectors will be used to measure the illumination with a rough spectral breakout. In other words IR, R, G, B, and UV.
• Additionally a more traditional illumination measurement will be done that can correlate to the output of a fixed, tilted solar panel. In this regard I am thinking about using an IR thermopile to measure solar irradiance (W/m²)
• The Watermark sensors will be placed at a depth of about 1m (3ft) and 20cm (8 inches) to give a relative measurement of soil moisture in the tree root zone and grass root zone, respectively. The waterproof temperature sensors will be buried along with them for soil temperature measurements.
• Separate to this project I will follow with an evaporation pan system to allow estimations of leaf water loss. The current project should have an interface to allow other sensors like the evaporation system to "just plug in".
• The GPS module would be used to provide very accurate real times for data timestamping. It could also monitor any location deviations for inexpensive precision differential GPS. This would be a big help for things like bee hive siting, tree planting, fences, etc.
• Relative humidity and dewpoint are notoriously difficult to measure accurately. The reason for having two high accuracy temperature sensors is to allow the construction of a dry bulb-wet bulb arrangement. This will allow traditional methods to be used as well as the digital humidity sensors. I am curious to see what the comparative levels of accuracy are.
• The microphone output will be monitored for large peaks (like thunder) which could enhance the data from the lightning detector. It will also be used for very long term (hourly?) averaging to create a baseline background noise measurement. Subjectively I have noticed a large increase in noise as the city of Houston grows nearer us.
• I am still researching to determine if there is a very low cost leaf wetness sensor that can be incorporated into this system. Usual sensors are simple resistive or capacitive probes (printed circuit boards), but it seems to me that they would need continuous maintenance to remove dirt and dust.