Why is the Spanish subjunctive used in this sentence?

Question

Why is the Spanish subjunctive used in this sentence?

The lines in question are from one of my favorite poems, "Mi Ultimo Adios" or "My Final Farewell" by Jose Rizal. They say he wrote it the night before he was executed by the Spanish.

http://en.wikipedia.org/wiki/Mi_%C3%BAltimo_adi%C3%B3s

The line in question is near the end:

Y cuando ya mi tumba de todos olvidada
No tenga cruz ni piedra que marquen su lugar, <<<<<
Deja que la are el hombre, la esparza con la azada,
Y mis cenizas, antes que vuelvan a la nada,
El polvo de tu alfombra que vayan a formar.

Entonces nada importa me pongas en olvido. <<<<<
Tu atmósfera, tu espacio, tus valles cruzaré.
Vibrante y limpia nota seré para tu oído,
Aroma, luz, colores, rumor, canto, gemido,
Constante repitiendo la esencia de mi fe.

Why is the subjunctive used here?

Thanks!

...I sort of changed my question halfway through, I'm talking about *both* sentences followed by the <<<<, not just one. Thanks!

Answer 1

The first one (tenga) is subjunctive because it is subordinated by "cuando" ... the lack of a marker for the tomb is a future, unrealised event. The main verb of the sentence is the imperative "Deja", which appears in line 3.

The second one is more obvious ... nada me importa (que) ... requires the following verb in the subjunctive because it expresses a subjective attitude.

Answer 2

It must be that it's future in sense.

First one - like the more colloquial "cuando ya no estés presente" - when you are no longer around. So, "cuando ya ...no tenga cruz..."

Second one - you'd probably be happy with "No importa que me pongas en..." (future sense - uncertain) I think it's the same idea, but not 100% sure on this one.