Learn Hardcore German: Nach dem Regen wirkt der Wald wieder lebendig, und der Wanderweg ist nicht mehr so nass. - After the rain the forest looks lively again, and the hiking trail is no longer so wet.

nach den Regen – den is accusative (or dative plural), not used after nach.
nach der Regen – der is nominative or feminine dative; Regen is masculine, so this doesn’t fit.

Why does the verb come after Nach dem Regen? Could I say Der Wald wirkt nach dem Regen wieder lebendig instead?

German main clauses have the finite verb in second position (the V2 rule).

In the sentence:

Nach dem Regen wirkt der Wald wieder lebendig
- First “slot”: Nach dem Regen (a time phrase)
- Second “slot”: wirkt (the verb, must be in second position)
- Then: der Wald wieder lebendig

If you start with the subject instead:

Der Wald wirkt nach dem Regen wieder lebendig
This is also fully correct. You just changed what comes first, but the verb still stays in second position.

So both are okay:

Nach dem Regen wirkt der Wald wieder lebendig.
Der Wald wirkt nach dem Regen wieder lebendig.

They mean the same; the first one emphasizes the time (“After the rain...”), the second emphasizes the forest.

Why is it wirkt der Wald and not ist der Wald? What is the difference between wirken and sein here?

Both are possible, but they don’t mean exactly the same:

ist der Wald wieder lebendig
→ “the forest is lively again”
This states it as a fact, an objective condition.
wirkt der Wald wieder lebendig
→ “the forest seems / appears / comes across as lively again”
This focuses more on how it looks/feels to an observer, the impression it gives.

So wirken in this sense is close to:

“to seem”
“to appear”
“to come across (as)”

Using wirkt adds a bit of subjectivity: to me / to the eye, the forest looks alive again.

Why is lebendig not lebendige or lebendiger in wirkt der Wald wieder lebendig?

In this sentence, lebendig is a predicative adjective used after a verb like sein (to be), werden (to become), wirken (to appear), etc.

Predicative adjectives in German:

do not take endings:
- Der Wald ist lebendig.
- Der Wald wirkt lebendig.

Adjective endings (like -e, -er, -en) are used when the adjective directly describes a noun in front of it (attributive position):

der lebendige Wald (the lively forest)
ein lebendiger Wald

So:

Der Wald wirkt lebendig. ✅ (predicative, no ending)
Der lebendige Wald wirkt schön. ✅ (attributive, with ending)

Why is it der Wald (with der) here and not den Wald or dem Wald?

Der Wald is the subject of the verb wirkt, so it is in the nominative case.

Masculine noun Wald:

Nominative singular: der Wald
Accusative singular: den Wald
Dative singular: dem Wald

In this sentence:

Wer oder was wirkt lebendig? – Der Wald.
(Who or what seems lively? – The forest.) → nominative.

So der Wald is correct.
If it were an object, you might see den Wald or dem Wald, but here it is the subject.

What exactly does wieder mean in wieder lebendig, and why is it placed before lebendig?

wieder means “again”.

Word order:

In wieder lebendig, wieder modifies the adjective lebendig (“lively again”).
Adverbs like wieder normally come before the adjective or participle they modify.

So:

Der Wald ist wieder lebendig. – The forest is lively again.
Der Wald ist lebendig wieder. ❌ sounds wrong/unnatural.

In the whole sentence:

Nach dem Regen wirkt der Wald wieder lebendig.
Focus: after the rain, the forest again appears lively (it wasn’t lively in between).

What does Wanderweg mean exactly, and how is it formed? Why is it capitalized?

Wanderweg is a compound noun:

wandern = to hike
der Weg = the path / way

So der Wanderweg = hiking trail / footpath for hikers.

In German:

Nouns are always capitalized.
Compound nouns are written as one word, with the last part determining the gender and plural.

Here:

Gender: der Wanderweg (masculine, because Weg is masculine)
Plural: die Wanderwege

It is capitalized because it is a noun.

Why is it ist nicht mehr so nass and not something like ist kein mehr so nass?

The phrase nicht mehr means “no longer / not anymore”.

nicht negates verbs, adjectives, adverbs, or whole clauses.
mehr here means “anymore / any longer”.

So:

ist nicht mehr so nass = “is no longer so wet” / “is not as wet anymore”.

kein is used to negate nouns:

Ich habe kein Wasser. – I have no water.
Das ist kein Wanderweg. – That is no hiking trail.

Here we are negating the adjective phrase so nass, not a noun, so we must use nicht mehr, not kein.

What is the difference between so nass, sehr nass, and zu nass?

All three modify how wet something is, but with different nuances:

so nass
- “so wet / that wet / this wet”
- Often used in comparisons or relative statements:
  - nicht mehr so nass – not so wet anymore / not as wet anymore
  - so nass wie gestern – as wet as yesterday
sehr nass
- “very wet”
- Simply intensifies the adjective:
  - Der Weg ist sehr nass. – The path is very wet.
zu nass
- “too wet” (excessive, more than desirable)
- Implies a problem:
  - Der Weg ist zu nass zum Wandern. – The path is too wet for hiking.

In the original sentence nicht mehr so nass = “not as wet anymore”, a relative comparison (compared to before).

Why is there a comma before und: ..., und der Wanderweg ist nicht mehr so nass.? In English we don’t always put a comma there.

In German, you generally do place a comma before und when it connects two independent main clauses (each with its own subject and finite verb).

Here:

(Nach dem Regen) wirkt der Wald wieder lebendig
– main clause with verb wirkt and subject der Wald
der Wanderweg ist nicht mehr so nass
– main clause with verb ist and subject der Wanderweg

Since both parts are full clauses, a comma is standard:

Nach dem Regen wirkt der Wald wieder lebendig, und der Wanderweg ist nicht mehr so nass.

In German, this comma is more obligatory than in English.

Can I say Nach Regen instead of Nach dem Regen? What is the difference?

Nach Regen is grammatically possible but sounds more abstract or general, and is less common in everyday speech.

Nach dem Regen
→ usually refers to a particular rain event, e.g. after the (recent) rain.
Nach Regen
→ more like “after rain (in general)”, without a specific rain shower in mind. It can sound a bit poetic or technical, depending on context.

In normal, concrete descriptions of weather you’ve just experienced, Nach dem Regen is the natural choice.

Could I also say Nachdem es geregnet hat, wirkt der Wald wieder lebendig instead of Nach dem Regen? Is there a difference?

Yes, you can say both, but they are different structures:

Nach dem Regen
- nach is a preposition
  - noun phrase in the dative.
- Nach dem Regen wirkt der Wald wieder lebendig.
Nachdem es geregnet hat
- nachdem is a subordinating conjunction that introduces a subordinate clause.
- Nachdem es geregnet hat, wirkt der Wald wieder lebendig.

Meaning:

Both mean roughly “After it has rained, the forest seems lively again.”

Nuance:

Nach dem Regen focuses on the time period after the rain.
Nachdem es geregnet hat focuses more on the event of raining itself.

Grammatically:

With nachdem, the verb in that clause goes to the end:
- Nachdem es geregnet hat, ...
With nach, you simply use a noun phrase (dem Regen) in the dative.

Both are correct and natural.