It kinda depends on where you live really... Tirol, Upper Austria and a few others are really good. I find that, where the higher density of native Austrians is, it is cleaner. That may sound a little racist, but it is just my opinion. I only ever see Austrians at the recycling depots, sorting through their trash and waste, and every now and then I see a Norwegian too
The environment here is very much something that they take seriously in the countryside areas. I go hiking almost every day and have seen plenty of people, myself included, cleaning up after tourists and have also seen initiatives where they go out and find people who are littering on hiking trails and in the town centers and give them a 'slice of local opinion'.
The recycling systems are good-great in most areas, but it becomes difficult for the people handling the process to do the recycling correctly as most people just throw whatever they want wherever they want instead of correctly separating the waste.
In the cities it is certainly a lot harder to enforce rules and regulations about the recycling system, but In the area that I currently live I have received a fine twice now for disposing of my waste incorrectly at the depot, and once leaving a battery in my mixed waste trash.
As for green etc. Austria is investing tons of money at the moment to create eco buildings (Buildings that give more power back to the grid than they take), you can see a perfect example of one or two near the Nachsmarkt in Vienna.
There are still a few kinks in terms of how every person here needs a car, but it is improving, and the country has already taken massive steps towards putting the infrastructure down that is required to make a 'green' land, moving forward I think we will see some great things. There are some stats for last years green power initiatives on the government site worth looking at, it you are researching. They reflect some incredible advances, nearly 70 something% of the country already has the capability to run with green energy sources alone.
In terms of simple mentality, I would say the Austrians are well ahead of many countries. They care for their environment greatly, you can see this in most areas of Austria, cities of Vienna and Salzburg excluded.
A great example: My wife, a friend and I managed to retrieve 2 trash bags full of waste whilst hiking after a tour group of Americans came through early that morning and had littered tissues, cans of energy drinks and food wrappings etc. along their way. We went to the recycling depot, and the man there asked us from where this all came, so we told him the whole story and about 10 minutes later the police had gone to the gasthof in town where they were staying and had straightened them out, and given the tour leader a hefty fine.
Future sustainability of the forests is also not bad, I have seen plenty of places where they are cultivating new forest, and even met a ranger once who complained that people keep walking off of the paths and stepping on the sprucelings (I think that is what he called the young trees that were beginning to grow). They are smart enough to only allow hunters to certain privileges with their licenses, and even that is very limited compared to other countries.
Oddly enough, most of the local initiatives are just locals that see each other on the trail, or around town and then at a pub, strike up a conversation and suddenly there is a small trash militia that goes out every Saturday to pick up all the crap left behind by tourists and young oblivious teenagers
The churches used to be rather heavily involved, from what I have read and heard from friends and family here, but lately (The last 15 years) they have taken massive steps back because their resources are dwindling and they need to focus on maintaining what they have. (I find this hard to believe, as even now, my wife has to give money monthly to the church, and nothing has changed anywhere in the last 5 years ) But hey, that's the kindling for a religious debate best kept off the forums
I hope this helped you, and have an awesome day ahead!