The multifarms have an orchard setting. I haven't used them myself but from what I have seen you wait for the trees to mature and then the multifarm harvests them and they go straight into the multifarms inventory. If you have already messed around with multifarms you will know that you just need to put the right electron tube into the intricate circuit board. There is a good list of what the electron tubes do on the forestry wiki.
Alternatively, you can put a wooden golem beneath the tree and he will pick up all the nuts when they drop. The cheapest but clunkiest solution would be to have an array of either vanilla hoppers, obsidian pipes or transposers underneath the tree but I wouldn't recommend that if you have the resources or the research for the other two.