Rainforests: Biodiversity and Threats

Rainforests are some of the most interesting landscapes on the planet. They’re our oldest living ecosystems, with some having survived in their present form for over 70 million years. Interestingly, while they only take up 6% of Earth’s landmass, rainforests are home to half of the world’s flora and fauna species.

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“A rainforest is simply an area of tall, mostly evergreen trees and a high amount of rainfall.”

These collections of ecosystems have even more interesting qualities. Rainforests help both humanity and the environment; through climate regulation, providing resources, and more.

There are two types of rainforests: temperate and tropical.

Temperate Rainforests are located in mid-latitudes and tend to have much milder temperatures than tropical ones. They’re mostly found in coastal/mountainous areas, and they’re not very biologically diverse. However, they’re extremely biologically productive due to less decomposition than tropical rainforests.

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Californian redwoods: very old and very big
  • high average temperatures: due to closeness to the equator, typical daytime temperature of 84°F, strong solar energy from direct sunlight
  • nutrient-poor soil: nutrients aren’t stored for long, plants absorb nutrients decomposed organic matter quickly
  • high levels of biodiversity: lots of species of organisms with different ecological roles, different rainforests have unique biodiversity
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Jaguars can be found in the Amazon Rainforest

Tropical rainforests are hugely biodiverse, which is crucial for the survival of their rainforests and our planet.

In case you’re unsure, biodiversity is the number and types of species within an ecological community. For example, the Amazon rainforest has 40,000 plant species, 1,300 bird species, 3,000 fish species, 427 mammal species, and 2,500,000 insect species. Several factors play into why rainforests have such high biodiversity, like high climates, massive sizes, and the canopy structures of trees.

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The plants in tropical rainforests are important for global climate and medicine.

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  • Lapacho → used to treat cancer, alleviates pain from chemotherapy, can fight infections
  • Canellila → treats ovarian cysts, believed to increase likelihood of conception
  • There could be more but we haven’t explored enough!
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Roots of a Wasai tree

Fungi species help regulate plant populations and could be the future of tackling garbage.

Fungi play key roles in tropical rainforest environments as mutualists, saprotrophs, and pathogens.

  • Saprotrophs → organisms that feed on decaying organic matter, decomposers
  • Pathogens → a microorganism that can cause disease (which is important here!)
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Mushrooms!

There are more microorganisms, but we don’t know too much about them yet.

In tropical rainforests, microbial processes occur at a tremendous scale. There’s a huge amount of decomposers on the forest floor, including bacteria, fungi, termites, who break down the nutrients in organic matter. This process is aided by the Mycorrhizae fungi, which works in mutualism with plants. they attach to plant roots and help uptake roots more efficiently. They’re mutualists because both organisms benefit: plants provide fungi with sugars and starch in return for ‘their service’. Mycorrhizae may also help plants resist disease and drought!

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Mycorrhizae
  • actinomycetes
  • mycorrhizae
  • fungi
  • protists

Mammals are also very useful for plant prosperity.

You’re probably used to bees, hummingbirds, and maybe even bats as pollinators — animals important for plant reproduction. However, in tropical rainforests, several other unique mammals are also responsible for this process. Plants attract them through a concoction of specially designed traits, like alluring scents, flashy colors, and nutritious pollen. Seed dispersion is another ecological function some rainforest mammals provide. Lemurs pollinate palm trees in Madagascar, and Borneo’s fig trees have their seeds dispersed by orangutans.

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Unfortunately, tropical rainforests are under attack.

Damming, invasive species and logging are two huge threats to tropical rainforests, specifically the Amazon. Let’s dive into these issues from an Amazonian perspective, and potential means for solutions through monitoring biodiversity!

Monitoring Biodiversity

Biodiversity is measured as an attribute of two components: richness and evenness. Richness refers to the number of species within the rainforest and their population sizes, whereas evenness means the proportions of species present in an ecosystem. The more proportionally equal species are (similar population sizes), the greater the evenness.

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High Population Size!
  • beta diversity → biodiversity differences when comparing habitats
  • gamma diversity → diversity of habitats within a unit/area

Damming

Large, well-backed hydroelectric projects in the Amazon rainforest have led to massive environmental losses. Unfortunately, these dams are often inefficient because of their basin design — meaning that these huge areas of rainforest are taken over by a system ineffective at electricity generation. Also, there are very high carbon emissions from these renewable dams, so the benefit over fossil fuels isn’t prominent.

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Hydroelectric Dam in the Amazon
  • affected terrestrial species: monkeys

Deforestation

Since 1970, over 600,000 square kilometers of the Amazon rainforest have been destroyed. Today, 40 football fields worth of the forest are cleared each minute.

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  • giant brazilian otter estimated wild population of 1000–5000
  • white bellied spider monkey population has declined by at least 50% in the last five decades.

Invasive Species

One of the biggest causes of environmental disturbances, like the decline in pasture productivity and biodiversity losses, is the presence of herbaceous weeds → an invasive species. These dangerous plants are the main invasive species present in the Amazon region and are a major threat to its vegetative biodiversity. Some examples are Vismia Guianensis, Paspalum Virgatum, Mimosa Pudica, Senna Obtusifolia, and Cyperus Rotundus.

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Cyperus Rotundus

Monitoring Species

A potential way to address these issues is by measuring biodiversity.

  • quadrats: sampling population sizes in a small area of a habitat to estimate local distribution of that species
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Quadrats
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16 year old interested in anything impact-driven, data or tech. joshuaopayne.com

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