For this discussion, I shall be tracing the effects of deforestation. First of all, deforestation will, as the term expresses, shall lead to less trees and therefore less CO2 depletion in the atmosphere.
This slight decrease in CO2 depletion leads to more greenhouse gases in the air, which could lead to warmer temperatures. Those warm temperatures can cause certain species on land, who are used to the temperature in the past, to start depleting in population. The ecosystems that have these organisms will have their food chains tweaked to the point of possible species extinction from extinction or scarcity of food source, which could lead to overpopulation of another species which competed against the previously alive species for other resources that are separate from the possibly extinct food source of the now dead species. This dominant species could completely destroy their ecosystem by consuming resources faster than they previously did so due to competition from the now dead species. This could lead to the destruction of the resource in that area and, eventually, the destruction if the whole ecosystem.
Another consequence of CO2 levels being risen is the increase in acidic rain. H2O(water) could interact with CO2(carbon dioxide) and create carbonic acid(acid rain). This acid rain could increase acidity in the soil in which it lands on. Some consequences for this can be seen in the link: (http://soilwater.com.au/bettersoils/module2/2_3.htm.) If the plants in the area where to die because of the acidity, there would be a smaller amount of CO2 consumers AND a decrease in the overall food supply of that ecosystem. Consequences of that are shown in the previous paragraph. Also, if that was the primary food source of the entire ecosystem, then the ecosystem would die in an even simpler way, by lack of food.
Lastly, a consequence of the root of all these problems, deforestation, is what it is going to be used for. If it is used for firewood, firewood converts O2 and some of its carbon atoms into CO2. If it is used for building, it will eventually catch molds that will decompose it into methane and other greenhouse gases. So, in deforestation, both its absence and use create CO2 and/or other greenhouse gases. This is not good, and I would like to say that I am an advocate for the reduction and/or the destruction of deforestation.