1) based on “grove” and “nature” i would assume a variety animal calls
2) “sad thoughts” seem to refer to the “what man has made of man” as it seems the poet is upset that the link of nature and soul is mended in some way. this could be reference towards deforestation or other acts we have caused to destroy nature
Oceans produce approximately 80 percent of the oxygen our planet needs to support animal life. Pollution that reaches the ocean through dumping, oil leaks, runoff, and other processes interferes with that oxygen production and poses a real threat to the oxygen content in our atmosphere. If the oxygen content decreases, it is likely that carbon dioxide will increase. This could have dramatic consequences for life as we know it.<span> </span>