People presume all living things died in the flood. But the Bible does not say that!
Consider the following:
Before the flood came God said: "And, behold, I, even I, do bring a flood of waters upon the earth, to destroy all flesh, wherein [is] the breath of life, from under heaven; [and] every thing that [is] in the earth shall die" (Gen 6:17)
And talking about the aftermath of the flood, the Bible says:"And all flesh died that moved upon the earth, both of fowl, and of cattle, and of beast, and of every creeping thing that creepeth upon the earth, and every man: All in whose nostrils [was] the breath of life, of all that [was] in the dry [land], died. And every living substance was destroyed which was upon the face of the ground, both man, and cattle, and the creeping things, and the fowl of the heaven; and they were destroyed from the earth: and Noah only remained [alive], and they that [were] with him in the ark." (Genesis 7:21-23)
- All flesh which had the breath of life was destroyed
- It further specifies four distinct groups which perished: man, cattle, creeping things, fowl of heaven
From this we can presume:
- Many of the creatures that breathe water (in whose nostrils the breath of life is not, though they have flesh) survived the flood
- Trees which have neither "flesh" nor "nostrils" might have survived (probably should have survived)
Furthermore speaking about the trees, the Bible says:
Job 14:7 "For there is hope of a tree, if it be cut down, that it will sprout again, and that the tender branch thereof will not cease."
So it's highly likely that many trees survived the flood just like the creatures that live in the water