Howl, O cypress, for the cedar is fallen - Jerusalem or the temple having been likened to Lebanon and its cedars, the prophet carries on the image, speaking of the priests princes and people, under the title of firs, cypresses and oaks, trees inferior, but magnificent. He shows that it is imagery, by ascribing to them the feelings of people. The more glorious and stately, "the cedars," were destroyed. Woe then to the rest, "the cypress;" as our Lord says, "If they do these things in the green tree, what shall be done, in the dry?" Luke 23:31, and Peter, "If the righteous scarcely be saved, where shall the ungodly and the sinner appear?" 1-Peter 4:18.
For the defensed forest is come down - That which was closed and inaccessible to the enemy. All which was high and lifted up was brought low, "came down," even to the ground .

Howl, fir tree - This seems to point out the fall and destruction of all the mighty men.

Wail, (b) fir tree; for the cedar is fallen; because the mighty are laid waste: wail, O ye oaks of Bashan; for the forest of the (c) vintage is come down.
(b) Showing that if the strong men were destroyed, the weaker were not able to resist.
(c) Seeing that Lebanon was destroyed, which was the strongest fortress, the weaker places could not hope to hold out.

Howl, fir tree; for the cedar is fallen,.... By which are designed the princes, nobles, and magistrates of the land: so the Targum interprets them of kings and princes; see Nahum 2:3,
because all the mighty are spoiled; which is an explanation of the figurative expressions in the former clause, and in the following; and designs rich men, as the Targum paraphrases it, who at this time would be spoiled of their wealth and substance.
Howl, O ye oaks of Bashan; which the Targum interprets of governors of provinces; and men of power and authority are doubtless intended; see Isaiah 2:13,
for the forest of the vintage is come down; or rather, "the fortified forest"; meaning the city of Jerusalem, which was a fortified place, and like a forest full of trees, for number of inhabitants, but now cut down and destroyed; see Isaiah 10:16.

fir tree . . . cedar--if even the cedars (the highest in the state) are not spared, how much less the fir trees (the lowest)!
forest of . . . vintage--As the vines are stripped of their grapes in the vintage (compare Joel 3:13), so the forest of Lebanon "is come down," stripped of all its beauty. Rather, "the fortified" or "inaccessible forest" [MAURER]; that is, Jerusalem dense with houses as a thick forest is with trees, and "fortified" with a wall around. Compare Micah 3:12, where its desolate state is described as a forest.

Fir - tree - Houses and towns built with firs. The cedar - Much less shall ye escape. Ye Oaks - Used in that country for building palaces, cities, towns, and fortresses. The forest - Jerusalem, compared to a forest, in regard of the many and tall houses in it. In short, all are called to cry, for the miseries that will come upon all. Come down - Is laid desolate.