## 3 La Selva Biological Station, Costa Rica  
Our work involved a mix of traditional and new modalities of networked sensors. In this commentary, we report on three components of our ongoing research on the biogeochemical cycles of carbon in tropical forest ecosystems, each operating at a different spatial and temporal scale. The first component involves the use of instrumented canopy towersfor eddy flux measurements. The second describes the development of novel systems of soil sensor arrays with both environmental monitoring and automated imaging for root and mycorrhizal fungal growth. The third area of research takes a downscaled approach to quantify the role of leaf-cutter ants whose life history and behavior as ecosystem engineers influence the biogeochemical cycles in Neotropical forests. We present brief overviews of these three areas of research, the multiple challenges in the installation, operation, and maintenance of the sensors and networked sensor arrays in a wet tropical forest, and the environmental conditions of high humidity, torrential rains, ubiquitous annoying insects, venomous snakes, and dynamic forest structures with frequent tree falls. Our research efforts for the last decade have centered on tropical rainforests at the La Selva Biological Station, a 1600-hectare reserve of premontane wet forest in the Caribbean lowlands of northwestern Costa Rica. This field site is extremely wet, averaging 4244 mm of annual precipitation (1958-2004), with a mean monthly rainfall above 300 mm from May through December (Figure 1). The peaks of monthly rainfall above 400 mm typically are present in June-August and November-December, and a drier period occurs from January through April. Even in the driest period in February and March, however, precipitation averages above 190 mm each month. There is little seasonal change in the mean monthly maximum and minimum temperatures. The developed area of La Selva includes more than 20 buildings with housing and dining for groups or individuals, air-conditioned laboratories and research buildings, an ambient temperature lab, shade house growth facilities, and a well-equipped GIS lab serving the research and academic community. The GIS database contains over 1000 coverages, including aerial photographs, satellite images (LANDSAT, IKONOS, QuickBird), optical scans (multispectral and hyperspectral), and active sensor images (RADAR, LiDAR) of La Selva and its broader watershed for several time periods over the past 45 years. La Selva follows the protocols recommended by the World Meteorological Organization (WMO) for sensor handling, data collection and management, and QA/QC [10]. Figure 1: Seasonal climate means for the La Selva Biological Station: (**A**) The mean daily maximum (closed circles) and minimum (open circles) air temperatures, and (**B**) the total monthly precipitation (vertical bars) and mean daily minimum relative humidity (open triangles) for the La Selva Biological Station, Costa Rica. The values are the means \(\pm\) standard errors for each month for the data collected hourly from 1957 to 2003 for the precipitation, from 1982 to 2003 for the temperature, and from 1992 to 2003 for the relative humidity. Graph courtesy of [PERSON]. The La Selva Canopy Tower Network, constructed in 2008 with funding from the U.S. National Science Foundation, consists of a network of canopy towers in an old-growth forest (Figure 2). They are linked together by both fiber optic and wireless networks, with fiber optic and electrical connections extending for 1 km to the laboratory buildings. In their original architecture, the scaffolding towers were arranged in a triangle with heights of 34 m, 42 m, and 51 m, with the two shorter towers connected by a 25-m walkway through the canopy to provide expanded access to the interior tree crowns. The modular form of these towers allows for relative ease in reconfiguring the height (Figure 3). Figure 3: La Selva Canopy Tower Network.