This sidra which provides us with guidance on how to behave in going forth to battle, on relations with comrades in-arms, the enemy and prisoner, includes too a passage concerning our relations with the plant world.

When thou shalt besiege a city a long time, in making war against it to take it, thou shalt not destroy the trees thereof by wielding an axe against them; for thou mayest eat of them, but thou shalt not cut them down; for is the tree of the field man, that it should be besieged of thee? Only the trees of which thou knowest that they are not trees for food, them thou mayest destroy and cut down, that thou mayest build bulwarks against the city that maketh war with thee, until it fall. (20, 19-20)
The last clause of verse 19 is difficult to understand. We shall first cite Rashi who regards it as a rhetorical question motivating the prohibition:

Ki has here an interrogative meaning: "Really?" Is the tree of the field a man who is besieged by you, to suffer famine and thirst just like the inhabitants of the city? Why then should you cut it down?
The Jewish Publication Society version of the Bible reproduced above follows, like that of Buber--Rosenzweig, Rashi's explanation. Ibn Ezra however differs and refuses to see here an interrogatory statement. He disposes of the suggestions that the word "not" or the interrogative Hebrew prefix (ha) is to be understood in order to make it read, as Rashi wished: "Is the man a tree of the field to be besieged of thee?" Ibn Ezra asks: "What point is there in saying:'Don't cut down a fruit tree because it is not like man who can flee from you'.” He continues:

In my opinion, we have no need of all this. But this is the meaning: "for thou mayest eat them and thou shalt not cut it down for the tree is man's life."' for he taketh a mans life to pledge" i.e. he taketh in pledge something on which man depends for his livelihood.

Hirsch followed Ibn Ezra, basing himself on the rabbinic dictum in the Sifrei which reads:

The life of man is only from the tree.
These two explanations reflect not only divergent grammatical approaches to the text. Some regard it as a utilitarian precept designed to protect man from the willful destruction of things from which he derives benefit. The author of Sefer Ha-hinukh who always tried to detect an educational motive behind every mitzvah commented as follows:

This precept is designed to inculcate love of the good and beneficial. This will lead to the avoidance of destructiveness and the promotion of our well being This is the way of the pious and the worthy who love peace and rejoice in the well being of all men. bringing them near to the Law. They do not suffer the loss of even a grain of mustard, being distressed at the sight of. any loss or destruction. If they can help. they prevent any destruction with all the means at their disposal. But it is otherwise with the wicked. the embodiments of destructive spirits who revel in the corruption of the world. Corrupting themselves. Man is measured by his own yardstick. In other words. he is always affected by his own attitude, and he who desires good and rejoices in it, will always be granted to enjoy it.
The above explanation fits in with the idea that the tree in the text is merely an example, a prototype. Our Sages understood the prohibition to destroy fruit trees as implying that it was forbidden willfully to destroy anything of benefit to mankind. Here is Maimonides' formulation of the law:

One may not cut down fruit-bearing trees outside the (besieged) city (for purposes of war) nor divert from them the water conduit, so as to make them wither as it is stated: "thou shalt not destroy the trees thereof'. Whoever cuts them down is liable for the penalty of lashes. But this does not apply merely to the case of a siege, but in all cases. Whoever cuts down a fruit bearing tree, in a destructive manner, is liable to lashes. But it may be cut down. if it damages other trees or causes harm to neighbouring fields or because it fetches a high price. The Torah only forbad willful destruction. This is the case not only with trees. But whoever breaks utensils, tears garments, demolishes a building, stops up a well and willfully destroys food violates the prohibition of "thou shalt not destroy..." (Mishneh Torah, Melakhim 6, 8, 10)
We are not precluded from making use of God's creations. Indeed we are bidden "subdue it", exploit to the full the natural resources He has placed at our disposal. conquering the desert and uprooting vegetation where it causes damage. But it is willful destruction of the gifts of nature that have been bestowed on us that we are warned against.

It does not matter whether the object of our destructive efforts belongs to us. No man has an exclusive right to even his own property. The earth is the Lord's and the fullness thereof. the Psalmist states. Everything is granted to us in trust. Besides. man must be protected against self-destruction. Once man is allowed to rule himself and his property without let or hindrance, there is no knowing where it will lead him. The Talmud formulates this danger as follows:

He who in anger tears garments. breaks his utensils. squanders his money! shall be accounted by you as if he worshipped idols. For such are the workings of the evil inclination. Today he says to you: Do this and tomorrow, Do the other, till the point is reached when he says to you, Serve idols, and he will go and do so. (Shabbat 105b)