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Bromeliads and Biodiversity
ABSTRACT
The mango is a non-native species to Costa Rica. One can expect that this newer species would have less diversity of other organisms within its branches. When the biodiversity of tank bromeliads is compared on mango trees vs. the native inga tree there is a surprising result. The raw data shows that there tends to be even more organisms on mango bromeliads than inga bromeliads.
INTRODUCTION
Non-native species can take a beating. Many people argue that they are invasive, bring pests and crowd out native plants (Garden). The mango, a species from south East Asia, is commonly found in Costa Rica but only in places people are. One would find it nearly impossible to find a mango deep in the rainforest. People either willingly plant them around their property or leave the seeds after enjoying the fruit. Mangos are so integrated in Costa Rica that many visitors do not realize that this plant is not native.
This experiment was to see if the mango tree had a negative effect on the biodiversity within the tank bromeliads that frequently grow on them and other trees that grow in the tropics. Tank bromeliads, a kind of epiphyte that holds water between its leaves, grow on many of the trees, both native and non-native in the rainforests of Costa Rica. Within these relatively small plants there is a plethora of life (Wilhelm Foissner, et al). They contain everything from huge fuzzy spiders that one would see in a pet store to mosquito larvae.
The only way to completely observe all the organisms within a bromeliad is to dissect it. The results of the dissections did not align with the original hypothesis. One would think that because the mango is not native there would be less biodiversity found within the bromeliads attached to them. Data indicated the opposite.
MATERIALS AND METHOD
In order to determine if the biodiversity within tank bromeliads on non-native species is different than that of those bromeliads attached to a native species, the large epiphytes were collected into a five gallon bucket and dissected. Great pains were taken to avoid loosing water during collection and escaping creatures during dissection. The native species used was the inga tree. The non-native tree was the mango. There was one bromeliad taken from each; a mango in the forest, one near a building, an inga in the forest and one near a building. Once the specimen was in a large washtub, ready for dissection, all escaping or flying organisms were caught with tweezers and placed in plastic resalable cups. After shaking the bromeliad upside down and counting everything attempting escape, dissection started. First the root area was analyzed and taken apart. Leaves were peeled away individually, much in the way one would take apart an artichoke. This method appears to be tried and true when it comes to bromeliad studies; Peter Armbruster et al, used the same method for their bromeliad studies. Each leaf was examined for small worms, insects or larvae that may hide in the curl of the leaf. Once all plant material was examined the water and organic material from the bromeliad that had collected on the bottom of the washtub was examined and sifted through. After all visible specimens were collected from the tub analysis began.
All captured creatures were recorded and analyzed. Then most of them were released.
RESULTS
After all the data was recorded it was found that the mango bromeliads from both locations contained more organisms than either of the ingas. The bromeliad from the mango near buildings contained nineteen creatures. The bromeliad taken from the inga near the buildings had fifteen organisms. The forest bromeliads both had more organisms within them than those found near buildings. For the bromeliad taken from the mango within the forest there were thirty-five organisms and some amphibian eggs. Fortunately, near Rancho Mastatal there was an old homestead site that was taken over by the rainforest, which is where the forest mango specimen was collected. The inga contained twenty-three organisms. All together the mango samples contained sixteen more organisms than the inga samples.
DISCUSSION
The results show that the mango does not have a negative effect on the biodiversity within the tank bromeliads that grow on them. Also it may show that the mango is not, a threat to the availability of food or shelter for the native animals of Costa Rica. Mark Sagoff author of 'Do Non-Native Species Threaten the Natural Environment?' may argue that the productivity of the mango tree makes it such a beneficial addition to Costa Rica that it could not be classified along with harmful invasive species.
Unlike the non-native English Ivy and Scotch Broom of Washington state, the mango appears to have a positive impact in Costa Rica. Costa Rica depends partially on agriculture as a means of fueling the economy. The growing popularity of the mango to Europeans and Americans has caused the export of mangos to rise 40% in the year 2004 according to InsideCostaRica.com. Export rates of mangos are expected to continue to rise. Economically, this non-native species makes sense.
How do mango trees affect the local flora and fauna? There seems to be little problem with mangos running rampant in the rainforest, crushing out other plants. As Tom McDonald said, "You can hike for hours in undisturbed forest and never find a mango tree." According to Jack Ewing, author of 'Monkeys are Made of Chocolate', tapirs, agouti and paca all have been reported feasting on mangos.
There still may be several problems that came with the introduction of mangos to Costa Rica. There could be diseases that they spread to other plants in addition to problems that we have yet to foresee. As Martin Jenkins said “This does not mean, of course, that we can continue to manipulate or abuse the biosphere indefinitely. At some point, some threshold may be crossed, with unforeseeable but probably catastrophic consequences for humans.” There is very little we know about how our actions today will affect us in the far future.
ACKNOWLEDGMENTS
Thank you to Junior for running around with me in the rainforest looking for an Inga, Amber for taking the pictures I needed for my web page, Buckito and Tom for the guidance and the huge fuzzy spider for putting things in perspective for me.
CITED LITERATURE
Anonymous. 2003. Garden flower evolves into weed. Science Washington. 301:458-459.
Armbruster, P., Hutchinson, R. A., Cotgreave, P. 2002. Oikos. 96:225-226.
Ewing, J. 2003. Monkeys are Made of Chocolate. Costa Rica. Impresos Elimar S.A.
Foissner, W., Struder-Kypke, M., Van der Staay, G. W. M., Van der Staay, S. Y. M., Hackstein, J. H. P. 2003. European Journal of Protistology Stuttgart. 39: 365-372.
Inside Costa Rica, News. InsideCostaRica.com. Last accessed 10 August 2005.
Jenkins, M. 2003. Prospects for biodiversity. Science Washington. 302:1175-1177.
Lecture. T. McDonald, Rancho Mastatal, 11 July 2005.
Sagoff, M. 2005. Do Non-Native Species Threaten the Natural Environment?. Journal of Agricultural and Environmental Ethics Guelph 18:215-236.