Final answer:
Cutting down trees leads to higher CO₂ levels because trees that absorb atmospheric CO₂ are removed, diminishing carbon sequestration and releasing stored carbon when they are burned or decay. Invasive species often thrive under elevated CO₂, altering community composition and potentially escalating CO₂ levels. Added CO₂ intensifies climate change, impacting global biodiversity.
Step-by-step explanation:
Cutting down trees, a process known as deforestation, contributes to higher CO₂ levels because trees play a crucial role in the carbon cycle. Trees absorb CO₂ from the atmosphere and use it during photosynthesis to create food for themselves and release oxygen as a byproduct. When trees are cut down, not only is this carbon-absorbing function lost, but the carbon stored in the wood is released back into the atmosphere if the wood is burned or decays, thereby contributing to elevated CO₂ concentrations. Furthermore, deforestation can lead to a reduction in native plant species and an increase in invasive species, which may not be as effective in capturing CO₂. This shift in plant communities can exacerbate the increase in CO₂ because invasive species are often less efficient at sequestering carbon than native species.
Experiments have shown that under elevated CO₂ conditions, some invasive plant species become more competitive, potentially leading to changes in community composition. For instance, invasive C4 grasses exhibit a stronger response to higher CO₂ levels compared to native species, which might alter fire frequencies and intensity due to a positive feedback loop. Additionally, plants have demonstrated varied responses to elevated CO₂ when combined with other climate factors, such as extreme drought, fire, and interactions with biocontrol agents, which are all critical components of ecosystem dynamics and biodiversity.
Moreover, a significant rise in atmospheric CO₂ has been documented over the past centuries, predominantly due to the burning of fossil fuels and the loss of forests' capacity to absorb CO₂. The increasing levels of this greenhouse gas contribute to climate change, which is expected to have profound effects on biodiversity in the future.