Torah as the tree of life for all creation

ובמד' עץ חיים היא למחזיקים כו'.

And in the Midrash: "It is a tree of life to those who hold fast to it…"

The Sefas Emes opens with the verse describing the Torah as a "tree of life" for those who grasp it firmly.

כי התורה נותנת חיים לכל הנבראים ומזוני דכולא בה עכ"ז תלוי בכח ההחזקה שמחזיקין בנ"י בתורה ויודעים זאת.

For the Torah gives life to all the creatures, and the sustenance of everything is in it; nevertheless, this depends on the power of the "holding" — that Bnei Yisrael hold fast to the Torah and know this.

Although the Torah is the source of life and sustenance for all of creation, that flow is activated specifically through Bnei Yisrael's firm attachment to the Torah and their conscious recognition of this truth.

כמו כן נתברר שהוא עץ החיים לכל חי.

In the same measure it becomes clarified that it is the tree of life for every living thing.

To the degree that Bnei Yisrael hold fast and recognize the Torah's role, it becomes evident to all that the Torah is truly the life-source of every creature.

וכן במשנה גדולה תורה שנותנת חיים לעושי' בעוה"ז ובעוה"ב שהעושה ומקיים התורה זוכה שגם חיי עוה"ז יהי' רק ע"י התורה.

So too in the Mishnah: "Great is Torah, for it gives life to those who do it, in this world and in the World to Come" — for one who performs and fulfills the Torah merits that even his life in this world will be solely through the Torah.

The Mishnah's praise that Torah gives life "in this world and the next" means that one who lives by the Torah draws even his worldly vitality directly from it, not from any other source.

ובכלל בנ"י תלוין כל הנבראים כנ"ל.

And included within Bnei Yisrael, all the creatures are dependent, as above.

Since Bnei Yisrael are the conduit of the Torah's life-force, all of creation is, in effect, sustained through them.

ז"ש וכי תבאו כו' ונטעתם כו'.

This is the meaning of "And when you come [into the land]… and you shall plant…"

The Sefas Emes now applies this to the verse about entering Eretz Yisrael and planting fruit trees.

פי' שבנ"י יטעו ויקשרו כל אילני מאכל הכל בא"י שהיא מלכותו ית' והבן:

That is, that Bnei Yisrael should plant and bind all the fruit-bearing trees — everything — into Eretz Yisrael, which is His kingship, blessed be He — and understand this.

"Planting" hints that the task of Bnei Yisrael is to root and connect all the world's nourishment and produce to Eretz Yisrael, which represents Hashem's sovereignty, thereby linking all sustenance back to its holy Source.

Summary: The Torah is the tree of life and the source of sustenance for all creation, but this flow is activated through Bnei Yisrael holding fast to it and recognizing it; one who lives by the Torah draws even his worldly life from it. Thus all creatures depend on Bnei Yisrael, whose task — hinted in "you shall plant" — is to bind all of the world's nourishment to Eretz Yisrael, the seat of Hashem's kingship.