questions: asking about air-layer/grafting in litchi. 
 answers: types of layering:
there are two main types of layering:
1. ground/simple layering: this is a type of layering whereby the original plants are set in the ground with the stem nearly horizontal, which forces side buds to grow upward. at the end of the growing season, the side branches will have rooted and can be separated while the plant is dormant.
2. air-layering: air layering is done by peeling the bark from the middle of a branch and covering this exposed wood with moss and plastic wrap. roots will form inside the moss and you can cut the rooted tip from the plant. it is useful for plants that are hard to propagate by cuttings or if you want your new plant to have a larger size than could be accomplished by taking cuttings.