According to Vedic civilization, kṣatriyas are considered to be great personalities because if anyone goes to a kṣatriya king to ask for charity, the king will never refuse. The trees are compared to those noble kṣatriyas because everyone derives all kinds of benefits from them—some people take fruit, others take flowers, others take leaves, others take twigs, and others even cut the tree, and yet the tree gives to everyone without hesitation.
Unnecessarily cutting trees without consideration is another example of human debauchery. The paper industry cuts many hundreds and thousands of trees for its mills, and with the paper so much rubbish literature is published for the whimsical satisfaction of human society. Unfortunately, although these industrialists are now happy in this life by dint of their industrial development, they do not know that they will incur the responsibility for killing these living entities who are in the form of trees.
This verse, quoted from Śrīmad-Bhāgavatam, was spoken by Lord Kṛṣṇa to His friends when He was taking rest underneath a tree after His pastime of stealing the clothes of the gopīs (vastra-haraṇa-līlā). By quoting this verse, Caitanya Mahāprabhu teaches us that we should be tolerant like trees and also beneficial like trees, which give everything to the needy persons who come underneath them. A needy person may derive many advantages from trees and also from many animals, but in modern civilization people have become so ungrateful that they exploit the trees and animals and kill them. These are some of the sinful activities of modern civilization.