Learn Arabic (Modern Standard): المحمية ليست فقط مكانا سياحيا، بل بيئة آمنة أيضا. - The sanctuary is not only a tourist place, but also a safe environment.

The phrase uses ليست فقط (is not only) followed by the first point, then بل (but/rather), the second point, and finally أيضا (also). In Arabic, أيضا typically goes at the very end of the sentence or clause, unlike in English where 'also' usually sits right next to 'but'.

Why does مكانا سياحيا end with an alif?

It is in the accusative case (mansub) because it is the predicate of ليست (is not). The verb ليس acts like كان (was), meaning it leaves its subject in the nominative case but forces its predicate into the accusative case, adding the '-an' sound and the written alif.

Since there are no short vowels written, what grammatical case does بيئة آمنة take when spoken?

It also takes the accusative case, spoken as 'bi'atan aminatan'. The word بل acts as a coordinating conjunction here. Since it links بيئة (environment) directly to مكانا (place), they must share the exact same grammatical case.

The lesson mentioned using فحسب for 'only'. Could I use it in this sentence instead of فقط?

Yes, but the word order would change. While فقط can sit comfortably before the noun, فحسب usually comes after the phrase it modifies. If you used it here, the sentence would be: المحمية ليست مكانا سياحيا فحسب، بل بيئة آمنة أيضا.