Answer: left subclavian vein, right subclavian vein
Explanation: The thoracic duct carrying lymph empties into a large vein which is located at the left side of the neck. Its called the left subclavian vein. Also the right subclavian vein empties into a large vein found in the right side of the neck, itz called the right subclavian vein.
I believe they cannot start with big trees and bushes because the there is not enough nutrients in the soil, so instead pioneer species pave the way for primary succession.
