As humans continue to urbanize, we further the negative consequences we are causing on our environment. As humans burn for agriculture and for other purposes, as well as deforestation, we are increasing the concentration of carbon dioxide, methane, and industrial chemicals in the atmosphere. As a result, we allow the Earth to retain more heat. In turn, we contributed to global warming, or the elevation of earth’s temperature. As a result of the elevation in temperature, some species cannot survive or successfully reproduce, and they would eventually extinct. As a result, species often migrate north or up in elevation. However, species that have less mobility might move too slow to outrun the climate change. Some might be too slow compared to their supplement species, species that they need help from in order to survive (like pollinators to many plants), and would therefore die before being able to migrate to an ideal location. Some might depend on species that are moving too slow, and they as a result die off before they could outrun the climate change. For example, butterflies can fly away faster than a lot of plants. However, they only like to lay their eggs on specific species of plants and would have to wait for those species of plants to migrate first (75). Some might even encounter migration barriers. It can be as simple as a crossing a road that makes it difficult for species to migrate. As a result, species on average move 3.8 miles toward the pole every decade, according to Camille Parmesan. She called it “poleward movement”. Therefore, assisted migration becomes a concept that emerged to move species to places where they can have a better future in response to climate changes and the difficulties they have when migrating on their own. Choosing the destination of migration cannot be a place where species will currently adapt to best at the moment or a place where they will adapt best when they harvest. It has to be in the middle of the two suggestions so that plants won’t just grow in the beginning and then die off, or not being able to make it to the harvest time initially.
The pros of assisted migration would be to save endangered species and other species of commercial importance by migrating them to an ideal location to sustain their population. The arguments for cons of assisted migration exist as well. First of all, it is almost impossible to accurately predict what kind of effects assisted migration can do to species. We don’t know what species need to have in order to survive, especially in terms of soil microbes or microclimatic condition (77). They might not be able to survive in the new location just because the temperature is more desired to them. They might also become invasive species in their new location, causing destructive problems to the ecosystem. They would also threaten baselines set up by conservation efforts in their new ecosystem because they do not exist in that ecosystem prior to the baseline. I think another possible problem of assisted migration is the need of constant management. As species are assisted to move north, climate would eventually catch up and species would have to move again. It is a constant process within decades, making such project unrealistic in the long term. As a result, assisted migration remains a heated debate for ecologists and environmentalists.
Assisted migration into urban forests is helpful for the urban areas, but might not be feasible. According to Puth in the article on species richness in New York metropolitan region, species richness is generally decreasing in the city. Migrating species into the urban forests can increase species richness. However, it is not feasible because there is not much space for species to migrate into with the concentration of human population and species in the urban ecosystem. It might cause problems of unfriendly competition for survival needs. The high price of real estate in urban areas might also increase the cost for assisted migration. Also, the migrated species might become invasive and hurt the urban ecosystem. Lastly, urban ecosystems should be warmer than other ecosystems surrounding it. As a result, it doesn’t make much sense to migrate animals into urban forests from ecosystems within the range of 200 kilometers.
Assisted migration from urban forests, is more feasible and is great for endangered species and species with commercial needs. They might be able to survive better in the new location and therefore sustain their population in the future. It would also be feasible because outside urban forests, there is more space and are cooler. However, the possibility of becoming invasive species and the possibility of not being able to adapt to the new environment has to be taken into consideration.
