A State-Based Programming Model for Wireless Sensor Networks

2.1. WSN Applications 9
WSNs are also used in precision agriculture to monitor the environmental factors
that influence plant growth, such as temperature, humidity light, and soil
moisture. A WSN has been deployed in a vineyard [15] to allow precise irrigation,
fertilization, and pest control of individual plants. Other examples for environmental
observations are the detection and tracking of wildfires, oil spills,
and pollutants in the ground, in water, and in the air.
2.1.2 Wildlife and Farm-Animal Monitoring
Monitoring the behavior and health of animals is another application domain of
WSNs. Some wild animals are easily disturbed by human observers, such as the
Leach’s Storm Petrel. To unobtrusively monitor the breeding behavior of these
birds in their natural habitat, a WSN has been deployed on Great Duck Island,
Maine, USA [85, 112]. Before the start of the breeding season, sensor nodes
are placed in the birds’ nesting burrows and on the ground. They monitor the
burrows’ micro climate and occupancy state. About one hundred nodes have
been deployed. They are expected to last for an entire breeding period (about
seven months), after which they can be recollected. Another WSN described in
[117, 118] aims to recognize a specific type of animal based on its call and then
to locate the calling animal in real-time. The heterogeneous, two-tired sensor
network is composed of so-called micro nodes and macro nodes. The smaller,
less expensive, but also less capable micro nodes are deployed in great numbers
to exploit spatial diversity. The fewer but more powerful macro nodes combine
and process the micro node sensing data. The target recognition and location
task is divided into two steps. All nodes first independently determine whether
their acoustic signals are of the specified type of animal. Then, macro nodes
fuse all individual decisions into a more reliable system-level decision using
distributed detection algorithms. In a similar approach, [64, 105] investigates
monitoring of amphibian populations in the monsoonal woodlands of northern
Australia.
WSNs have also been used or are planned to be used to monitor and track
wild species and farm animals, such as cows, deer, zebras, fishes, sharks, or
whales. In these scenarios, sensor nodes are attached to individual animals in
order to determine their health, location, and interaction patterns. In these applications,
WSNs are superior to human observers because often humans cannot
easily follow the targeted animals and because human observation is too cost intensive.
The ZebraNet [67, 81] WSN is used to observe wild zebras in a spacious
habitat at the Mpala Research Center in Kenya. A main research goal is to understand
the impact of human development on the species. The WSN monitors
the behavior of individual animals (e.g., their activity and movement patterns)
and interactions within a species. The nodes, which are worn as a collar, log
the sensory data and exchange them with other nodes, as soon as they get into
communication range. The data is then retrieved by researchers who regularly
pass through the observation area with a mobile base stations mounted on a car
or plane.
A restoration project after an oil spill in the Gulf of Alaska identified critical
habitats of the Pacific halibut by determining its life-history patterns [102]. The
knowledge of the fishes’ critical habitat aids fisheries managers in making de-