December 6, 1999

Second Phase Projects in Puerto Rico


The main purpose of the November 21st, 1999 trip to Puerto Rico was to do the site survey and get the technical details needed to assemble, test, and return to install reliable wireless links between the three LTER Weather Stations in the El Yunque Rainforest, the El Verde Research Station, and the Internet.

However in each visit completing previous tasks, we need to discern the outlines of future tasks. So three projects which will probably be started in the summer or fall of 2000 were explored.

The Caribbean National Forest, has facilities (Catelina, Sabena, and Visitor Center) near the north edge of the El Yunque forest, and east of El Verde, accessible by different roads from the coastal highway Route #3.



As described in Progress Report 6, Dr. Fred Scatena, a research hydrologist for the U.S. National Forest Service, stationed in Puerto Rico, (Institute of Tropical Forestry) pursues his own parallel studies of the rainforest as a collaborative part of the Luquillo Experimental Forest LTER. One set of studies involve measuring rainforest streams, their low rates, chemistry and other characteristics. In the Bisley area, south of the Sabena Forest Service work center, and close to Weather Station #3 is one of his stream monitoring stations.

While we must delay attempting to connect up this stream station at Bisley wirelessly (it will be a real challenge being at the bottom of a ravine at the bottom of the forest vegetation), it is interesting because the sensory equipment and the data logger from Sutron Corporation, of Virginia. The Forest Service favors these sensors and dataloggers, even though they are more expensive than Campbell equipment. But since both products are in wide usage, we will have the opportunity to interface to Sutron data loggers as well as Campbell - and report broader results.

The data is collected from this sensor (Sutron 8210) set by means of a PCMIA card that is in the logger, removed, and inserted into a PCMIA card slot on a desk top computer at Sabena Work Center, where a technical assistant to Fred Scatena extracts the data. This Bisley stream site will pose the most difficult wireless challenge yet. We will have to do much experimentation with different radios, spectrum analyzer, and perhaps different approaches to reaching into the stream bed - perhaps by direct paths from the top of Pico del Este or Pico el Yunque which, if the angle of penetration of the forest is high enough - from the 1000 foot mountains to the 350 foot level - may be able to get through the vegetation without another relay.

At one time there was a satellite feed from the Bisley Stream monitoring station - and some of the ground equipment is still in place. It may be that we have to resort to use of a satellite rather than terrestrial link to the Internet, and from it, thence back to El Verde, Sabena, and the Center for Tropical Studies.



Not directly part of the NSF LTER studies, but very much part of the overall biological science studies of plant and animal life in the rainforest, there is a Tree Frog Sample Monitoring of Catelina Project by a National Forest research team headed by Pedro Rios. This is all part of the Ecosystems Management of the Caribbean National Forest. Dr. Victor Cuevas, General Biologist is involved with the specific monitoring of species of the tony frogs popularly named 'Coqui' -of genus Eleutherodactylus. There are 16 species in Puerto Rico, and two of these are found on 1000 foot El Toro Peak - Richmondi and Eneidaen.

The Coqui are best known for their characteristic, surprisingly loud (even annoying when they are in built-up areas) "Co-KEY" sounds they produce at night. Those sounds, when recorded and carefully tracked, give scientists useful information about their location, density, and over time general environmental and ecological health.

In particular there is an ongoing research project recording the night sounds of the Coqui subspecies on El Toro Peak. One species begins to sing soon after dark, the other only after midnight. In order to study these sounds, researchers equipped with sound recording systems have to depart after dark, climb for up to 4 hours up an often muddy, risky, trail to get near the top of El Toro by midnight, go into blinds, and record the sounds for hours. It is tiring, it is somewhat risky, and risks changes in the weather, and is very labor intensive.

Victor Cuevas, in my meetings with him, and his supervisor, suggested that it would be outstanding if we could install wirelessly connected (to the research center) microphones during daylight, and capture the Coqui sounds without the necessity of teams going up there in the dark.

This is only one part of the larger research reality, that monitoring forest - bird and other - sounds is a help to forest research. In fact the extremely important Puerto Rican Parrot Recovery project, which involves the Forest Service, Fish and Wildlife Service, and the Puerto Rican Department of Natural Resources, needs ways to record Parrot sounds. The Parrots have just come back from near extinction over the past decades, and intense, scientifically based, management has been the key to their survival. We MAY be able to become involved also in this project - especially since it will exercise, not just sound, but real time video monitoring, wirelessly transmitted to monitoring stations.

In our visit to Dr Cuevas at Catelina Management Center, he showed us the equipment currently being used to record the forest sounds. The Sony TCM-5000EV, shown here was modified to better record the frequencies emitted by birds. We will see if we can directly interface the microphone to a device that will send the sounds as IP packets over the wireless connections. This also will be a challenge, less because of the wireless connections - for the instruments will be on the top of El Toro Peak and will have line of sight to many locations - but because of the sound interface problems.

While those at the Catalina Forest Management Center became very interested when they realized from our explanations of what our Wireless Technologies may be able to do, and that we were funded to do experiments to prove out and model wireless solutions, they expressed interest in our becoming involved immediately in the Parrot Recovery Project. We cannot, however this first NSF Project year, do everything. It will have to be a progressive process, learning what it takes to communicate in and through the rainforest, before we can handle the more exotic things.

However, one thing is clear - when compared with the data rates that are customarily used by the commercial data loggers, and even those systems from companies like Campbell and Sutron which have been adapted to the use of licensed VHF radio channels, the data rates possible by current generations of spread spectrum no license radios - from 115kbps to 11Mbps will permit the interactive transmittal of multimedia information, and data from many sites, simultaneously.



Dr. Jill Thompson, a researcher at El Verde, has been working on the problem of measuring light which reaches the forest floor through the canopy in a 'recovering' rain forest area.This is the kind of forest that the sensors at ground level operate in.


Jess Zimmerman walking out the trail from El Verde to one of the ground level research plots in the 'recovering' (from Hurricane) rainforest.


As described by Engineer Mike Willett who interviewed Jill with me, at El Verde Research Station, the problem can be expressed thusly:

"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."


The plots which Dr Thompson now monitor, exchanging data with Dr. Ned Fetcher of the University of Scranton in Pennsylvania, are just north of the El Verde Research Station. Dr. Fetcher, in a previous visit, was extremely interested in the potential presented by our wireless solutions connected to the Internet, to be able, real time, to observe the data from the plots tended by Jill Thompson.

The sketch map below shows the range of experiments in the Research Areas close to the El Verde Field Station, including the areas in which the four plots measuring light reside. In later Progress Reports we will annotate this map more usefully - but at this time we do not know all the experiments going on, only some of which will involve our wireless project.

Sketch Map