Franciscan spirituslity isn’t the easiest thing to distill down, and there are a lot of conceptions and misconceptions about what it is.
First and foremost, i’d Say it’s “incarnational”, that is, an emphasis on Christ as he was when he was alive. The focus is on God incarnated. As part of that, Franciscan spirituality often looks long and hard at the crucified Christ, as he was suffering on the cross, sacrificing himself for all humankind. As Franciscans, we share in that crucifixion and suffering, in the crosses we carry, try to do so joyfully. But also, we see the face of Christ suffering on the cross in those people who are suffering all around us. In them, is Christ incarnate, in all his suffering. That’s why Franciscans are so often involved with the homeless, poor, oppressed, and marginalized. The “crucified” become The Crucified, and to gaze upon The Crucified will change you. I don’t know if it’s truly a “low Christology” as opposed opposed to a “high Christology”, as there’s both, but it’s similar…it’s incarnational, and it’s also affective, meaning heart-based.
Christ lived simply and poorly, and so st Francis tried to emulate that, because Franciscan spirituality is in a sense about trying to be as much like the incarnate Christ as possible. So followers of Franciscan spirituality try to live simply (poverty), and see the beauty of God in those things. I think “poverty” for most non-Vowed is best played out in simplicity, and minimum necessary, such as maybe choosing to drive a Honda instead of an Aston Martin, even if you work in a job that would allow you to afford such a car. It doesn’t necessarily mean you have to live poorly, but but a high-end status symbol kind of life isn’t very Franciscan.
As for the environment, Franciscan spirituality is not all about the bird bath St Francis, but St. Francis did recognize God’s hand in everything, especially creation and nature, which to the Franciscan is beauty and wonder that only God could create. He wrote a poem about it, called “Canticle of Brother Sun” or “Canticle of the Creatures”. You can tell by the language he used, that he felt a close connection to all of God’s creation, referring to “brother sun” and “sister moon”. Because it is part of God’s Creation, it deserves our care and respect. Just as our body’s are temples, so is the Earth. Again, there’s the incarnational theme of God’s hand at work in the physical world. Nature is not god to be worshipped, but is a reflection of God and heaven in the same way a masterpiece painting is a reflection of the artist. Unfortunately, most of us fail to pause long enough and gaze at the wonder of a stone and all the colors in it to really grasp the subtle beauty there. We all get busy, forget, or perhaps didn’t realize just that a piece of granite can be every bit as beautiful as the Grand Canyon. We wouldn’t destroy a Rembrandt, so we also don’t destroy the environment. And whereas environmental quality directly affects or has the potential to affect the quality of life for virtually every human being on earth, it’s worth taking seriously.