wood suitable for arrows
Just found a place in UK that sell different species dowels these are Ash, Yellow pine, Poplar/Tulipwood, Oak, Maple, Cherry. Sapele and iroko are also available but being non European will leave alone. Which would be best.
Depending for what kind of a use the arrow would be utilized. Heavier arrows are for hunting for good penetration, ash, douglas fir, perhaps even pine. Durable arrows are good for practicing, like ash or douglas fir, because arrows might broke easily, especially when used heavier bows. Lighter arrows can be utilized for target shooting as well, especially if the ranges are not known, distances, sitka spruce would be my choice, you could use cedar as well. Grains should run evenly and straight along the shaft, there should be a correct spine for the arrow, but for a thumb release it would not matter, the spine, as long as the arrows are of same weight. It is a science of its own.