According to the answers of this question, "ta-form + 上で" means that the second action is performed based on the result of the first action.
If the writer had used てから, it would have meant : doing the 紹介 and then the 呼びかけ (without telling anything about the relation between them except that 紹介 is made before the 呼びかけ)
But the author uses 紹介した上で, so it means(according to the stack exchange post I linked before) that the result of 紹介する is used to do the second action (呼びかける)
I don't understand what is the "result" of 紹介 and how this result is used in the 呼びかける.
According to me, the result of a presentation is the reaction of the public, so 呼びかける should be made according to the reaction of the public but it sounds odd because since the 呼びかけ tries to raise the awareness and convince the public,it would mean that the reaction of the public was negative.
I don't think it's the correct interpretation so my very question is:
"ta-form + 上で" means that the second action is performed based on the result of the first action. In the context of this article, what is the "result" of 紹介 and how is this result used in the 呼びかける ?