Wednesday, February 1, 2012

Rainforest Ecology

Today in class I outlined some of the basics of tropical rainforest ecology. What a lush ecosystem. Like all living systems, the tropical rainforest is influenced by physical and chemical conditions. One of these is the poor soil. Doesn't it seem strange that a system with as much biodiversity would grow on some of the poorest soils?

Rainforest ruins

Today I summarized some of the reasons for the nutrient-poor soil of the tropical rainforest. The over-riding issue is the steady rainfall. As we discussed last semester, water is a super efficient solvent, and whatever nutrients reach the soil of the tropical rainforest are dissolved and leached into deeper levels of the soil where plant roots can't reach them.

Another reason for the nutrient-poor soils of the tropical rainforest: Most of the plants are evergreen. Rather than returning nutrients to the soil, they hold onto their leaves, preserving the hard-to-obtain nutrients like nitrogen and phosphorus within their own plant body. Sometimes leaves will stay on a plant for years, enough time for lichen colonies like this one to establish and thrive. You can determine through a quick visual that there are several species of lichen on this leaf, another example of rainforest diversity and biological complexity.

Leaf Lichens

One of the most striking features of the rainforest floor is the fact that any organic matter that falls is quickly utilized by micro-organisms like fungi or the many insects that make use of plant material for their nutrition. Here's a picture I took in Mexico of a termite "highway." Under the protective layer termites are rushing to and from their nests with leaf material.

Termite thoroughfare

Termite highway

Perhaps most exciting of all was the chance to see the activity of leaf-cutter ants, which play a complex and vital role in the rainforest ecosystem.


50 comments:

  1. The work of the ants is really interesting. It's interesting to see them working together as a community for their own protection.

    -Pooja Sahani

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  2. Although the thought of it scares me, the termite highway is actually pretty interesting to think about!

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  3. I'm honestly still fascinated how the soil is so poor. It' s understandable because of all the rain and lack of nutrients, but somewhere so diverse such as rainforest would make you think otherwise.

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  4. It's interesting how the rainforest is another example of the Mechanistic Theory and adaptation. When I was in the Japanese Bamboo and Rainforests, I never thought about how poor the soil was for the plants, instead, I wanted to get into air conditioning as soon as possible.

    -Emily Brewster

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  5. I am still shocked that the evergreen trees have such a huge and negative impact on the soil. I'm also intrigued by the fact that the leaves on evergreens can suck up all the nutrients and even preserve nitrogen and phosphorous for years.

    -Chelsea Mencio

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  6. Before class today, I always envisioned tropical rain forests as colorful, wet and lush. I never associated it with having poor soil, it just doesn't add up appearance wise, since rain forests are so full of life and color. But after learning about it, it makes sense that the evergreen trees would impact the soil as well as the rain and lack of nutrients.

    - Lindsey Felcher

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  7. It's fascinating to me how the lichen is able to adapt to the poor nutrients in the soil by creating a home on another plant, such as that leaf. The species in the rain forest have learn how to live around the poor nutrients in the soil.

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  8. How interesting that leaves can sometimes stay on these plants for years at a time... and the photo of the lichens reminded me of how there is still so much biodiversity we are unaware of because it appears in easily missed or unexpected places.

    - Gunita Singh

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  9. I could not believe that rain forests have such bad soil. With all the different types of vegetation I did not think it would be possible. But the fact that the trees keep their leaves is pretty interesting because it gives the lichen that grows on the leaves a chance to thrive.

    Kevin Walsh

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  10. If the soils are poor, so how do plants manage to grow in such conditions? I know there is a enough rain in the area but it doesn't make sense how the plant life can manage to stay evergreen.

    Kelvin

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  11. I was very interested to hear that the rain forests have nutrient-poor soil. I suppose it makes sense because because of the excess rain, but I had never thought about that before. I also think the fire ants are very fascinating in that they can move something much bigger than they are and that they are all so organized about it.

    Brittney Decker

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  12. I am amazed with the scale of evolution that the rainforest has undergone. It is a very complex ecosystem, and over many years has adapted to the given climate and temperature. What is most interesting to me is the variety of animals and how they survive in this environment with poor soil. The Leaf- cutter ants are a great example of evolution of species in the tropical rainforest.

    Nora Donahue

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  13. I didn't realize how many different types of trees the rainforest has. It's interesting to see how some trees such as the evergreens can have a negative effect on the nutrients in the soil.
    Brittany Sebade

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  14. The termite highway is interesting because they build it to protect themselves from predators. I also like that the highway has another job, to transport food.

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  15. I found the pictures of the "termite highway" noteworthy because I have seen groups of ants together before but never such a mass amount. I find it interesting that the ants gather leaves that fall quickly because some other organism will take it if they do not. I did not realize before that this is one of the reasons why rain forests lack a great amount of top soil. Organisms take the organic matter for nutrients, rather than letting it sit on the forest floor and turn top soil.

    Amanda Durocher

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  16. Prior to class today, I was unaware of that the spots on the leaves of evergreens are lichen. I had previously that such spots indicated the aging of the leaf. It is interesting to note how much biodiversity can exist on one plant.

    -Cheryl Tang

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  17. Usually when I picture a lush rainforest I envision a thick canopy with soggy soil and a lot of rain. In these pictures though the dirt looks drier than sand. It is pretty incredible that the rainforest can support so much life with such poor soil conditions and that creatures are able to create life out of practically nothing.

    -Adrian Dresser

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  18. It is clearly very extraordinary how every single organism in this tropical rainforest plays a vital role in utilizing all their resources to preserve the natural habitat of the botanic environment. Specifically, pictures captures regarding the micro-organisms such as fungi and insects caught my attention. They represent the produce and consumer of the ecosystem. Both of them take advantage of the climate as they can also act as a catasylt protein to the environment.
    -Lena Wang

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  19. I find it interesting that every single living thing in the rainforest is so diverse, yet interacts with one another, has an effect on one another, and all depend on sunlight as a source of life and energy.

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  20. The leaf cutter ants are my favorite. It's amazing that they can carry so much when they are so small! I love the video of them carrying leaves.

    Anne Thompson

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  21. Before this class, I never would have believed someone if they told me that the rainforest's soil was poor. Fascinating. I suppose it makes sense when you explain it.

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  22. I remember walking in a rainforest in Australia many years ago and the soil was so wet that it was gross to constantly step in mush. At that time, I thought it was probably the best kind of soil to grow things, what did I know. The weather was humid and the temperature was so high that I saw many large insects roaming around the grounds. What I found interesting was a colony of big green ants moving food through a "highway" like the one above. It was the most fascinating thing to watch, until it started mistaking us as food. Naturally, that did not end very pleasantly for us.

    - Thomas Cui

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  23. Like Cara said above, I would have never assumed that a rainforest's soil was poor. Something else I also found interesting about today's lecture is that rainforests are very susceptible to human impact.

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  24. When I think of heavy rainfall, I only think that it will be good for plants and wildlife but I know now that too much can have bad effects. Also, it is amazing how organized those termites are.

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  25. I always thought that the rainforest would have the richest soil of all biomes. But after lecture and reading this it makes sense to me. It makes me curious to go to a rainforest and watch how fast organic matter gets used up. Also the ants freak me out...but it is amazing how they work!

    -Jess Musto

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  26. I've never been to a rainforest, and when I see rainforest in pictures or movies, I always though there must be a lot of nutrients in the soil to keep plants tall and green. It is quite stunning that the relationship between soil and plant is very different from most of other plants. Soil's inability to gain nutrients sounds intereting, since it is a natural result without human interferance.

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  27. When I think of a rainforest, I automatically assume that it would have rich soil. This information was very interesting to me considering it proves the exact opposite of what I thought! Also, the video on the ants is really interesting to me because I find it fascinating how efficient ants work to complete a common task. I also don't understand how such a small ant can carry a leaf that is so much bigger than itself!

    - Molly Munroe

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  28. I never thought the rainforest's soil would be so nutrient deficient, but after reading this article and lecture today, it makes a lot of sense. I find the video of the leaf ants extremely amusing because I have never seen anything like that.

    -Johnmichael Faustini

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  29. It's so hard to believe that the leaves can stay on a plant for years. It just seems natural that in due time, they fall off for new leaves to grow, but clearly not in this case. Very interesting to say the least!

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  30. It's amazing how plants fend for themselves and hold on to their leaves in order to obtain nutrients they know are hard to obtain. It seems like plants find ways to adapt to a wider range of environments than I had originally assumed. For example, the cactus that you showed us in class adapted to a tropical rainforest.

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  31. When i went zip lining in Ecuador a few years ago across a Tropical Rainforest i was unaware about all the diversity of plants beneath me. Reading your blog now is interesting because i did not know of the poor soil that the plants were growing in and everything that was happening in the ecosystem.

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  32. The photograph of the ants is very eye catching and captivating; great photo! It is spectacular that there are living organisms perpetuating natural cycles in every type of environment.

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  33. I always pictured the grounds of the rainforest to be drenched, but it is interesting to see how these plants have adapted and been able to access water so far down. Also, the way ants can communicate and work together so well is really amazing. The amount of leaves they can carry compared to their body weight is incredible!

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  34. I was also quite fascinated by the fact that the rainforest has such poor soil. I just always assumed that because it supports such a diverse and lush range of species that the soil would be fertile, but it is not.

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  35. It fascinates me the way such small ants work together to protect themselves as such a large community! I also really loved the Bittersweet Double Helix. The fact that a vine can grow upwards towards the sun with such design is beautiful to see.

    Thank you for showing us this blog!
    Cibelle Levi

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  36. I am still so surprised that the tropical rainforest has such poor soil. However, this blog and our last lecture made me understand why the soil is so poor. I think it is very interesting that any organic matter that falls to the ground is utilized so quickly! It is interesting to see something as little as ants work so quickly to make use of the plant material.

    -Nicole Marino

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  37. It is very fascinating to see the animals working together, as well as working with the vegetation in the rainforest. It is also interesting to see an environment that is so abundant with trees, plants, animals etc., while if you describe the soil conditions apart form everything else, it seems as though nothing would be able to thrive there.

    -Meredith Miller

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  38. Just as everyone mentioned, I was very surprised to learn that rainforest soil is low in nutrients. After thinking about water’s properties it does make sense. The rainforest is so diverse, yet they must adapt to similar conditions, such as low nutrients in the soil.

    -Matt Auerbach

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  39. I am also very shocked to see that the rainforest has such poor soil, yet there is still so much life in the rainforest. I also think it is so interesting how microorganisms use plants for their nutrition. Like many other people, the way that the ants help each other carry food supply and work together to protect themselves fascinates me. Thank you so much for sharing this with us!

    -Emily Shalev

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  40. I also find it fascinating that out of such poor soil there can grow such a diverse array of plants. Though in class we attributed this biodiversity to the tall growing evergreen trees which get their nutrients from photosynthesis rather than from the soil, it left me wondering how ALL the plants are able to sustain life there. Do they ALL preform photosynthesis? (In class we discussed how some species of plants grow on/through others by mutualism or parasitism. Or how plants simply grow in the canopies.) However, I have trouble understanding how this accounts for the high level of biodiversity seen in the rainforest. Have certain plants that do not grow tall enough for photosynthesis adapted so they do not need nutrients from the soil? I hope we get a chance to discuss and answer this in class!

    Thank you for sharing your travels with us. Though the termite high-way does give me the creeps, it is fascinating how even the smallest organisms can play such vital roles in the food chain/ecosystem they inhabit.

    - Alex Shadrow

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  41. Thanks Professor Hammer for this post. This is very interesting and fascinating. It's incredible how poor soil can create so much biodiversity and how so much biodiversity can survive in such conditions. The world is really a unique place!

    - Stephen Wong

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  42. This was really fascinating, because I never had thought about how harsh conditions in rain forests were. I did not think about how the constant rain was actually in a way hurting the plants, and how there is very little solar insolation.

    -Julian Tantzen

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  43. The ants really are fascinating! I also never realized how nutrient-deficient the soil in rain forests are.

    -Silvia

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  44. I would have never thought that under all of that lush vegetation was poor/ dry soil. I also was unaware that organic matter that falls onto the ground of a tropical rainforest is utilized by microorganisms that somehow make use of the materials. Just out of curiosity, do other soils like those in tropical rain forests make use of organic matter that falls to the ground? Overall, this was really interesting to learn about!

    -Mary Rassias

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  45. It is amazing to see that even when the soil is so poor organisms like the insects can adapt and work together to survive. On another note, I have a tree by my house that resembles the one in the first photo, do you think there is any way to help increase the nutrients in the soil or is it impossible?

    -Christina Fleury

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  46. While I understand why rain forests have such nutrient-poor soil, it is still hard to believe. When I think of a rainforest, I think of luscious greenery and many different animal species. I would think that the living things in the forest need plenty of nutrients to survive, but some plants, such as the evergreens, really are more self-sufficient then many people would think.

    -Ashley Waters

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  47. I find it interesting that the soil could have a chance to soak up nutrients from objects that fall to the rain forest floor. Yet, the termites and ants stop that from happening. I also really liked the video of the ants. I've always wanted to see ants close up as they are carrying something much larger than themselves.
    -Jessica Cordero-Wilson

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  48. Sorry for such a late reply. I completely forgot to write here, but this blog helped me to study for the test. I would never guess that rainforest has such a poor soil. Moreover, I always thought it has the richest soil. Good thing you taught us about it. It's interesting how anything that falls down is basically utilized immediately. It is also strange in a way that leaves can stay on trees for so long! I guess I just always have a chance to observe the changes in the season, but there are just so many places on Earth that don't have it.

    Thanks,
    Diana Freyman

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  49. Sorry for the late reply. It is hard to believe that the soil in rainforest is so nutrient poor. You would think it would be lush and full of life, but considering that the trees are evergreen and do not shed there leaves, it makes a lot of sense.

    Thanks
    Kristen Henlin

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  50. I think its so interesting how the soil in the rainforest has so much poor soil. I found it interesting how the leaves can stay on the trees for so long and the animals living there use it to there advantage like the ants and termites. I like that video of the ants moving through the rainforest I thought that was really cool how they move so fast.

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