This song can be sung to celebrate the environment or for Earth Week, and if you add the second verse, it also works for Christmas time.
A song to the oak, the brave old oak,
Who hath ruled in the greenwood long;
Here ’s health and renown to his broad green crown,
And his fifty arms so strong.
There ’s fear in his frown when the sun goes down,
And the fire in the west fades out;
And he showeth his might on a wild midnight,
When the storm through his branches shout.
Then here’s to the oak, the brave old oak,
Who stands in his pride alone;
And still flourish he, a hale green tree,
When a hundred years are gone!
He saw the rare times when the Christmas chimes
Were a merry sound to hear,
When the squire’s wide hall and the cottage small
Were filled with good English cheer.
Now gold hath the sway we all obey,
And a ruthless king is he;
But he never shall send our ancient friend
To be tossed on the stormy sea.
Below: Song pdf with chords, my adaption and midi