Across the northern hemisphere, the abnormally hot dry summer has resulted in bumper yields of many tree seeds. It also resulted in lots of forest fires. You can help. Gather acorns, chestnuts, horse chestnuts, & other big, easy-to-recognise tree seeds, and scatter them on wasteland, scrub, patches of thorn bushes, brownfield sites and so on.
As forest fires grow in number, isolated trees and small groups are more likely to survive.