Tropical rainforests are the most productive ecosystems on the planet. The photosynthetic output in a single square meter of tropical rainforest is over and beyond the production of plant sugars produced in any other ecosystem. There is more available light in areas closer to the equator, and as a rainforest, you guessed it, there is ample rain. These two abiotic factors allow plants to grow vigorously; sequestering carbon faster than any other ecosystem. Plants take gaseous carbon dioxide and fix those molecules into long chains of usable carbohydrates for energy, and long polymer chains for structural support. Lucky for us, the byproduct of this carbon fixation is oxygen. The Amazon rainforest has been dubbed the lungs of the planet since 20% of the oxygen we breath was produced there. As you may know, large swaths of this biodiverse system in Brazil are on fire, and we won’t just simply lose out on oxygen (which should already be alarming enough).
In 2014, Rebecca Mueller and her team set off to better understand the function of the Amazon rainforest in the face of human disturbance. What amplifies their study is that they utilized a deforestation chronosequence. Instead of examining just an area of disturbed rainforest and comparing that to a section of unperturbed, pristine rainforest, they examined areas with three ages of disturbance. That is essentially what a chronosequence is. By using a chronosequence, you get to see a better representation of ecological succession. You get to see in more detail, how communities of plants, fungi and animals change over time.
Their publication highlighted the important link between above-ground and below-ground biota. The composition of fungi below the soil’s surface is highly dependent on the plants that grow aboveground. Their results show that as you change plant composition, the fungal community easy shifts. As fungal communities become altered, the ecosystem functioning changes from the bottom up. Beneath the soil’s surface, different assemblages of fungi may implement their own selection pressures on the plant community above, thus reiterating the certainty of ecological change in disturbed areas.
Several scientists hypothesize that these fires will be the catalyst of a positive feedback. As these fires blaze, the carbon that has been fixed into sugars and polymers are liberated, reentering the Earth’s atmosphere in its gaseous state. CO2 is a greenhouse gas, so this influx may enhance global mean temperatures, leading to more drought, which will increase the chances of even more fires. In this modern human dominated era, positive feedback loops involved with global biogeochemistry are overwhelmingly devastating and exceedingly difficult to counterbalance.
Fires are a natural, important part of many system’s ecology, but what we are seeing today in Brazil’s Amazon would not be occurring if we weren’t here. One may argue that us humans are a part of nature, and that the Amazon will bounce back, but many scientists view these wide ranging, destructive disturbances as an absolute ecological ultimatum. The little media coverage on these Amazon fires shows the general disconnect we have to our natural world. We need to make changes fast if we want to aid and maintain the functioning of our planets most productive ecosystems. The sad truth is that much of this burned rainforest probably won’t be nurtured back into the rainforest of yesteryear. Instead, it will most likely be changed into pasture for grazing animals. A truth many see as a bite too hard to swallow, is that shifting to a plant-based diet is one of the easiest, most impactful way to combat global climate change. Pun intended.