Puerto Rico LTER Project Report:

We left for Puerto Rico on Sunday, November 21st, 1999. We settled at a humble hotel near the foot of El Yunque. Resources we take for granted on the mainland, are sparse in PR, such as basic communications. We had no phone in our rooms, and were therefore unable to tie into the Internet for email and other access needs that seem so easy in the US mainland.

Luquillo LTER Sites

Monday, we met with Doug Schaefer, an LTER researcher at the University of Puerto Rico in San Piedras. We talked about present operations and future plans. We talked about our ideas about how wireless could best facilitate their requirements, and to determine exactly what equipment was being used. It was a very productive brain storming session. It is fairly clear now that the two LTER sites, Wisconsin and Puerto Rico, have effectively standardized on the Campbell Scientific Data Loggers. This will make the effort to provide interfaces between the wireless and the data logger equipment easier, since both sites will have the same basic data needs.

Doug Schaefer provided ideas and descriptions about some aspects their present operation. For the first phase, our primary interest will be three meteorological stations. One each of three stations are located at Bisley, Pico del Este, and at El Verde. If not already so, each station will be equipped with the Campbell Scientific Data Logger, model CR10X.

The weather station at El Verde is on the roof of the El Verde station, itself, and is not an effective tool in that spot. Shaded by the trees from sun, precipitation and wind, the station can not provide the data desired. Doug is moving the weather station to the top of the 70ft tall experimentation and observation tower located just south and up the hill from the research center.


The parameters of meteorological data acquired includes Min/Max Temperatures, Relative Humidity, Precipitation, Wind Direction and Speed.

We had a general discussion about the LAN to be installed at El Verde, the Web site administration, and talked about other parties involved with the meteorological stations and their rolls.

The National Forest Service Research Stations


One individual is Fred Scatena with the National Forest Service at Sabana. Fred works with all three sites. His primary point of interest is the experimentation tower at Bisley, where they track the normal parameters of weather, but also includes measurements of light.

The parameters of light include light arriving at the forest canopy as well as the light reflected back from the forest canopy. It also includes the measurements of the wavelengths of light most active in the roll of photosynthesis as well as other light spectrums, providing a direct correlation between forest productivity and effective hours of light the forest receives.

The Bisley location actually has three recording stations. One at the water shed, measuring stream flow, water level, and also pH, dissolved oxygen and conductivity. The second at the base of the tower at Bisley, and a third at the top of the tower at Bisley.

The water shed site was run by the National Forest Service years ago with a satellite uplink. Although the satellite uplink is no longer active, the gear remains, in this case the data logger is a Sutron 8210 unit.

This station is monitored via a physical visit to the site, and the data is downloaded to a PCMCIA memory card. The PCMCIA data is then downloaded to a PC at the research center.

Two weather monitoring sites reside up hill from the water shed location. At the end of a trail running approximately 1/4 to 1/2 mile from the forest access road, exists a tower similar to the one at the El Verde station. This tower, however, extends to a height of approximately 110 to 120 feet. At the top there is weather measurement equipment, such as at El Verde, but in addition includes light measurement equipment, such as the quantum light sensor, which measures a wide range of light spectrum, including IR, as well as the PARE light sensor, which is primarily sensitive to the light spectrum most effective in the photosynthesis process of plants.

The other weather station, near the base of the tower is used primarily for parts, but also offers a comparative measurement of the environment above the forest canopy vs the environment below the canopy.

Since hurricanes have hit the island a few times in the past several years, Fred was able to point out some distinct features that could be attributed to the effects of the storm. One is that the foliage on the forest floor is greater after the hurricanes wipe out the foliage of the forest canopy, which allows greater amounts of light to hit the forest floor. Another is the trees at the top of the ridge survive the storms better than those nestled within the confines of the valleys. He proposed that the root system was better at the ridge tops and trees, which easily loose their leaves in a strong wind could shed the wind loading that would topple a typical valley grown tree. These concepts, with the ability to monitor and test predictions in real time will greatly enhance the understanding of the major impacts on the forest, such as those great changes caused by hurricanes.

The Bisley site offers several challenges. One, the site has no power other than naturally generated, such as by solar. Two, the line of site to other locations can be considered marginal, as the site can see no location other than part of the tower sites at El Yunque. Three, the tower site is already fairly populated with sensors, and the addition of a solar panel may interfere with present light measurements. Four, since radios consume more power than the measurement instruments, the solar panel would have to be fairly large, which increases the wind loading during storms. It is clear that the radio interface challenge of the project, along with acquiring line of site to the research centers has been met with the larger challenge of powering the radios and interface equipment of the remote locations.

Pico Del Este:

Rain measurements in the continental US are typically presented in inches. The rain fall at Pico Del Este is presented in meters. Approximately 5 meters, or 16 feet of rain fall at Pico Del Este per year. A unique result of measurement here concluded more water was being produced by the mountain top rain forest than what was being measured in rainfall. This observation, which one could easily attribute to experimental flaw, is now being tested for the concept of "Cloud Drip". Not related to true rainfall, which is condensation resulting in precipitation due to changes in temperature or pressure, the idea regarding cloud drip is condensation due to physical contact between the water vapor of the cloud and a solid object. The top of the rain forest is located within the clouds much of the year. The cloud, or water vapor, comes into contact with the forest itself, such as the shrubs, leaves, tree trunks, etc. The water vapor of the cloud condenses on the solid object, resulting in a drop of water. This in turn, reaches the point in size where the drop falls to the ground and together with other such drops of water, becomes a significant portion of the water shed of the rain forest at the highest elevations.

So, simply put, the weather stations of Pico Del Este consist of several monitoring stations. It also includes a unique sensor system, which is a rain fall gauge, covered from rain, but able to trap moisture from the water vapor of the cloud. This allows it to condense on a screen (the solid object) and be measured in the same capacity as rainfall.

Providing networking to the Sabanna station will be a challenge. It sits in a very low part of the valley, surrounded by trees. We have more work to do regarding this site.


One of the more colorful projects we may undertake is the monitoring of the rare Puerto Rican Parrot. A low in the population put the bird at extremely endangered, nearly extinct. The project to rebuild the population has resulted in a buildup of the bird population to about 45 birds at present.

We met with Victor Cuevas, regarding both the monitoring of the Coqui frog as well as on the imminent parrot release. Some are going to be released fairly soon to start the natural re-population.

This is of course, a very sensitive matter, as failure could result in a large impact of the existing base of birds. Monitoring of the birds while being kept in a cage in a remote location is necessary. The birds will be put in the remote location for a time period while still in their cage. This step is used to help acclimate the birds to the surroundings. Of course this represents a risk due to natural and human predators. The need to monitor the area is normally done by a human, but this in itself could be an impact on the acclimation effort. In addition, the monitoring of the process in itself could provide insight to the modification of future releases, as well as the security efforts.

If we can remotely monitor the location wirelessly, via a real-time video camera and audio, the impact on the environment should be greatly alleviated.


The monitoring of the Coqui frog inhabiting the high areas of El Toro is also an opportunity to reduce the time required of researchers and of physically intruding upon the area to the environment. The researchers usually have a small window of time to capture the unique characteristics of the Coqui frog. This species, at the top of El Toro, sings its song "Coe---Key" usually at midnight. Other Coqui, located elsewhere on the island, usually start their song at dusk.

To record the Coqui, researchers hike four hours into the area. They set up recorders, such as the Sony TCM-5000EV, modified for a frequency response that enables the enhanced recording of birds, or in this case the Coqui.

Several variables come into play for this effort, stacking the cards toward failure of the effort. One could be the weather changes, dropping rain on the researchers, ruining the ability to record well. Another is the chance of injury to the researcher hiking in the dark for four hours each way. Yet another is the lack of energy to focus on the job after the long hike, as well as the impact of the intrusion possibly resulting in a disturbance that will keep the Coqui from singing. Yet another, the Coqui might just have decided to take the night off.

To wirelessly capture the Coqui song and other noises of the rain forest without human intervention offers a great deal of opportunity. The song could be placed on an audio server for archival and on-demand retrieval. The digitized recordings could be made available on the Internet to other researchers as well as the interested listener, from K-99. It is clear that the system could be remotely accessed without human intrusion once the microphones, encoding gear and radios were in place. The major items to overcome are again, power and line of sight.


This project covers a plot of ground to measure the ecological phenomenon in an open area. This area was at one time fairly well forested, but due to a hurricane or some other event, the area is now without a great deal of canopy. The researcher, Jill Thompson, measures the parameters of the plot with several sensors spread over a large area. This area is a grid pattern, such as an equally spaced quad of sensors located at 5,10,15,20 and 25 meters, etc., to cover the desired observation / experimentation area.

The plots are large, and require a great deal of wire to connect each sensor to the data logger. Working with the wire appears to be more cumbersome and troublesome than the cost. The physical dynamics of the area, of which there are several plots of this type, become a logistics and man power related problem.

The parameters measured are primarily light, moisture and pH. We feel there may be a very low cost solution to the problem by using very low power radios and creating a simplistic network of low cost, "smart" sensors. These sensors could possibly talk via IP to one another, however, it is likely a more simple method would be used, and IP be reserved for the central host.

Another problem faced by the researchers seem to be the cost of a quality sensor. All sensors have a limited life time, but the difference between one sensor cost and another can be as much as 600%. We will experiment in this area as well, trying to encapsulate a low cost sensor in a high quality glass tube to alleviate the effects of ultraviolet radiation clouding the sensor's epoxy coating.

This plot observation area interests us a great deal, since it is addressing the needs of radio communications in an area of very low cost, high quality data recording in a very unique manner.

Mike Willett

Technical Assistant


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