A Sensor Network for Microclimatic Soil Variables on the Alpine Tundra

Abstract:

The alpine tundra is markedly sensitive to climate change. It contains a wide range of microhabitats ranging from those imposed by position on periglacial patterned ground to those along the gradient of distance from the edge of late summer snowfields. Currently, we investigate the effects of microhabitat on the distribution of alpine plant species and their functional traits, which reflect changing alpine climates. To strengthen our knowledge of the effects of microhabitats and microclimatic variables on alpine plants, and to increase our access to sensor data, we are developing near real-time soil temperature and moisture sensors. These sensors must be unobtrusive in wilderness areas, findable, underground (and under the snow) yet suitable for year-round in-situ deployment in the harsh and at times extreme conditions of the snowy alpine tundra. They must also be able to communicate with online data servers so that data can be obtained year-round. We are testing deployments of sensor meshes that include main nodes that can record temperature and moisture data and transmit that information via the Iridium satellite network to servers on the Internet combined with leaf nodes that can collect and store the same information, but that will use LoRa short distance radio technology to send the information to the main node(s). In the currently-envisioned sensor network, the main nodes will cost more to deploy and have greater power needs, while the leaf nodes will be smaller, cheaper devices functioning as a loosely-organized mesh network. The main node will receive leaf node data and forward both its own data and that of the leaf nodes via Iridium. Current field testing of the prototypes has produced encouraging results. Data has been transmitted from leaf nodes to a main node, from a main node to Iridium satellites and from a main node to a data server on the Internet where the data could be accessed in near real-time. This architecture, built on the Arduino Open Source Hardware development technology, will enable the deployment of a reasonable number of in-situ sensors that provide near-real-time access to both soil moisture and temperature data without physical access to the alpine research sites, and can be used in other settings where remote and timely access to data is necessary.