Biotic Implications of Forest Conversion

Sheila Vega

Northeastern State University




deforestation-causes-HI_104236.jpg
Courtesy World Wildlife Federation



Introduction

Forests cover 31% of the land on the planet (1). Forests provide oxygen for breathing, homes for people and wildlife, food, water, clothing, and medicine. They act as carbon sinks, soaking up carbon dioxide from the atmosphere that would have a negative impact on the world’s climate, and play a critical role in controlling climate change. They provide watersheds. They are home to 80% of the world’s terrestrial biodiversity (2). Tropical forests are the most biologically diverse and complex forests in the world.
Tropical forests are being destroyed and degraded at an alarming rate, which has massive implications. It impacts peoples’ livelihoods, their homes and food, clothing and medicine, and it threatens animals and plants that live in the forest, sometimes to the point of extinction.

Deforestation can be caused by fires, clear-cutting for agriculture and development, conversion to plantations, and unsustainable logging for timber (1). In the Amazon, 17% of the forest has been lost in the past 50 years, due to conversion for cattle ranching (1). In Indonesia, the Sumatran forest has declined by 85%, due to conversion to palm oil and pulp plantations (2). It is estimated that the same damage is being done in Borneo (2). Originally, it is estimated that there were 6 million square miles of rainforest in the world. Now, only 2.6 million square miles remain (3).

Flora

When a tropical forest is destroyed or converted to pasture or plantation, the effect on plant life is enormous. It is estimated that in 4-square miles of rainforest, there can be as many as 1,500 flowering plants and 750 species of trees (3). When a forest is converted to pasture for livestock or agriculture, or is logged for timber, nearly all of those species essentially disappear. If that area was the only area a particular species grew, that species will go extinct.
But why should it matter to humans? Over 2,000 species of plant in tropical forests have been identified as having anti-cancer properties, and only less than 1% of the species have been analyzed (3). This means that there are potentially thousands, if not millions, of plants we could sustainably harvest, or grow in our own country, that could save millions of human lives.

Tropical forests also are home to many of the things we take for granted at home. Bananas, nuts, coffee, spices, rubber, resins, and fibers all were originally found in tropical rainforests (4).

Tropical forest flora plays a critical role in maintaining watersheds. A watershed is an area where all the water that runs off of it will run into the same, larger body of water. When rain goes through the trees of a forest, it goes slowly through the canopy. The trees and plants filter it and absorb it, and it slowly evaporates before it gets to the floor. It goes through different processes, such as denitrification, adsorption, and plant uptake of nutrients, which diminish the nutrient concentration through the watershed. A link has been shown between the concentration of nutrients and percent forest cover. When a tropical forest is converted to a non-native crop plantation or pasture, the water doesn’t go through these processes, so the end levels of nutrients is altered, which could affect the receiving end of the watershed (5). Macroinvertebrates in the water are biological indicators of water quality. Studies have shown that the macroinvertebrate communities were negatively impacted by deforestation (6). If the water doesn’t filter through the trees, the area will flood and the soil will erode, and what goes into the watershed will be polluted (7). What this means for humans is that tropical forests are essential in maintaining the water we drink. One-fifth of the world’s fresh water comes from the Amazon Basin (3). Without that supply, the world’s already-dwindling quantity of drinking water would become critically low.

Although most species of plant would be negatively affected by deforestation, occasionally there are some that thrive. The Lower montane cloud forest (LMCF) is the home to over half of Mexico’s orchid species. However, due to deforestation and conversion to cattle pasture and agricultural fields (such as coffee), 90% of the forest has been lost. More than 90% of the coffee in Mexico is grown in the shade in a plantation. In this agroecosystem, the original forest is cut down and shade trees are planted. Nitrogen-fixing legumes make up the shade layer. Even though the canopy trees are only half the height found in LMCF, and there are far fewer species of trees (only 11% of the tree density of the LMCF), these plantations retain some of the structural features of a forest, and have great potential for conservation. Studies have shown that the orchids were as successful in the coffee plantation as they are in their natural habitat. The abundance of young orchid plants suggested that the plantation has adequate conditions for seed germination. Also noticed was that the orchids grew on a different average size of branch in the plantation than they did in their natural habitat, indicating that the plants can adjust for the more open canopy in the plantation (8).
This is the exception to the rule, however. In general, most plant species are negatively affected by forest conversion, and even more so in total destruction of the forest.

Fauna

When forests are destroyed and converted to other things, it affects the wildlife population significantly. Tropical rainforests are home to over half of the world’s population of wildlife (4). It is estimated that there are over 50 million species of invertebrates living in tropical rainforests (9). In a four-square mile area of tropical rainforest, there could be up to 125 species of mammals, 400 species of bird, 100 species of reptile, 60 species of amphibian, and 150 species of butterfly (10). Animals in a tropical forest are very important. They act as pollinators for forest plants, they aid in seed dispersal, and the entire food chain is essential in the maintenance of the forest.

Most animals are negatively impacted by deforestation or conversion of forest. Mammals seem to be less affected than most, while birds are the most affected. Total clearing of the forest for agriculture has more impact on wildlife diversity than converted plantations, both shaded and unshaded (11). Gibson et al. states, “Our results demonstrate that forest conversion and degradation consistently and greatly reduce biodiversity in tropical forest landscapes(11).”
One animal that has been greatly affected by deforestation and forest conversion is the tiger. One hundred years ago, it is estimated that there were 100,000 wild tigers in the forests of Asia. Now, there are less than 3,200. The main reasons the tigers are disappearing are because of illegal poaching, tiger habitats being destroyed, and tiger prey being hunted, causing tigers to starve (12).

But how does this affect us? Tigers are at the top of the food chain. It keeps populations of deer, pig, and other species in check. If these animals were left unchecked, they would ravage their food source – plant life. If the plant life were destroyed in the forest, insects and smaller animals wouldn’t survive. Watersheds would be impacted. Insects and small animals would move to neighboring farmland and destroy the crops. The forest will eventually fade away. If the forest dies off, global climate will be impacted (13). When the tigers’ forest is destroyed, it wanders into populated areas, with the potential to hunt and kill humans. It is a chain reaction that is hard for us to stop.

Micro-climate

Studies have described the micro-climate and implications of micro-climate alteration in a humid forest in Nigeria. Micro-climate is described as, “the physical state of the atmosphere, close to a very small area of the earth surface, often in relation to living matter and pertains to a short period of time. It is the climate near the surface of the earth where plants and animals are characterized by intensity of changes with time and elevation.” In the rainforest studied, the vegetation is dense and high, to make a nearly unbroken surface. Because the canopy is so dense, very little light or water gets to the ground, and incoming and outgoing radiation is reduced. When the forest was cleared to convert it to an oil palm plantation, the ground level got much more radiation and water. When the area is natural forest, the soil gets less rain but is always damp. Conversion to plantation makes rain readily available to the soil, which alters the soil moisture content. Instead of constant moisture, the radiation constantly makes the moisture content go up and down, changing the soil properties. These changes don’t favor the original flora, causing changes in species composition. In natural forest, most of the rain is intercepted by canopy, and what finds its way to the understory is available for evaporation, cooling it. When the forest is converted, this rainfall effectiveness is decreased. Also, the relative humidity in the forest is much higher than in the open space. The micro-climate changes so much that most native species can’t survive, and diversity is greatly reduced (14).

Conclusion

Tropical forests are a vital to the entire planet. Every plant, animal, stream, and river in them is important to the balance of nature on the entire planet. But rainforests are so far away, what can we do to help them?
  • Do your research. Do the bananas you’re buying come from a source that is sustainable? Does your coffee come from somewhere they’ve clear cut and planted coffee, or somewhere like a plantation that has tried to replicate natural forest? Even if you can’t get your products from somewhere completely sustainable, there are options that are better than others.
  • Demand less. Palm oil plantations contribute to a significant portion of the world’s deforestation. Try to stop buying products that use palm oil. By demanding less palm oil, less forest will be destructed to make plantations. Go paperless. Almost all of the bills you get or magazines you subscribe to can be seen online. Do you really need a physical copy of it? By demanding less paper, less forest will be cut down to produce it.
  • Recycle. Again, you will be demanding less. Don’t waste as much by throwing it away. Reuse it if possible. If you can’t reuse it, recycle it.
  • Boycott. Some organizations contribute to deforestation by their business practices. Some put no-deforestation policies in place. Give your business to people who are committed to saving forests.
  • Get Involved. Write to lawmakers. Dr. Seuss said in The Lorax, “I speak for the trees, for the trees have no tongues.”
  • Put your money where your mouth is. There are several organizations who do work to save the tropical rainforests and the animals in them. Consider giving them your time or money to help with their contributions.

Although tropical forests may seem like a distant thing that has no effect on our own lives, the impact is actually very real. The consequences of deforestation are tragic to the people who live near the forests and for us as well.






References

1 http://worldwildlife.org/threats/deforestation. Accessed July 20, 2013.
2 http://worldwildlife.org/habitats/forests. Accessed July 20, 2013.
3 http://www.nature.org/ourinitiatives/urgentissues/rainforests/rainforests-facts.xml. Accessed July 20, 2013.
4 http://www.rainforestconcern.org/rainforest_facts/why_are_rainforests_important/. Accessed July 20, 2013.
5 Valiela, I, et al. “Deforestation of watersheds of Panama: nutrient retention and export to streams.” Biogeochemistry [online]. March 2013. Accessed July 11, 2013. http://www.whrc.org/resources/publications/pdf/ValielaetalBiogeochem.13.pdf
6 Goddard M, Post C, English W, Pike J. Examining the impacts of changing land use on biological integrity in streams using Geographical Information Systems and statistical modeling. Aquatic Ecosystem Health & Management [serial online]. April 2008;11(2):230-242. Available from: Academic Search Premier, Ipswich, MA. Accessed July 11, 2013. http://www.tandfonline.com/doi/abs/10.1080/14634980802111557#preview
7 http://viridianwood.com/how-deforestation-affects-watersheds-10. Accessed July 14, 2013.
8 SOLIS-MONTERO, LISLIE, ALEJANDRO FLORES-PALACIOS, and ANDREA CRUZ-ANGÓN. "Shade-Coffee Plantations As Refuges For Tropical Wild Orchids In Central Veracruz, Mexico." Conservation Biology 19.3 (2005): 908-916. Academic Search Premier. Web. Accessed June 22, 2013. http://onlinelibrary.wiley.com/doi/10.1111/j.1523-1739.2005.00482.x/abstract
9 http://ran.org/fact-sheet-tropical-rainforest-animals. Accessed July 20, 2013.
10 http://library.thinkquest.org/27257/rainforest.html. Accessed July 20, 2013.
11 Navjot S. Sodhi, et al. "Primary Forests Are Irreplaceable For Sustaining Tropical Biodiversity." Nature 478.7369 (2011): 378-381. Academic Search Premier. Web. Accessed June 22, 2013. http://www.nature.com/nature/journal/v478/n7369/full/nature10425.html
12 http://www.panthera.org/programs/tiger/save-tiger-fund. Accessed July 19, 2013.
13http://wwf.panda.org/what_we_do/endangered_species/tigers/last_of_the_tigers/what_if_tigers_ did_become_extinct_/. Accessed July 20, 2013.
14 Bisong, Francis E., Pius B. Utang, and Raphael Offiong. "Micro-Climate Implications Of Forest Conversion For Floral Diversity In A Humid Forest Region Of South Eastern Nigeria." Journal Of Geography & Geology 4.1 (2012): 283-290. Academic Search Premier. Web. Accessed June 22, 2013. http://www.ccsenet.org/journal/index.php/jgg/article/view/11131/0