what happens to the souls of dead flowers?
yes they go to heaven

what happens to the souls of dead trees who havent made a single fruit or flower yet?
they go to heaven and bare fruit there,get comforted by God,as God will punish who murdered him/her

what happens to the ones who murdered a creation of God and a part of mother nature?
Well some who murdered a human being would get punished by going to hell unless he really does his best in being forgiven,the ones who kill plants get other chances

why do we/they need to hurt mother nature?
when will they learn to love her?
how?when?

please do the best you can,we cant do these stuff forever,we dont have forever