Passage Map:
P1: Introduction to the importance of forests and on line 12 talks about two specific areas we need to understand for forest policy making purposes. Lines 10-12 give some author stance like "should" and is a hint at the roadmap for the passage that we will explore the two specific areas
P2: Oxygen and Forests; author does not buy into the oxygen argument
P3: Importance of biodiversity
P4: Critics (pro environment people) have exaggerated claims and do not realize some of the benefits of the things they dislike (e.g. commercial plantation) ; random side note I underlined the part on lines 42 that stats are being exaggerated because it read like one of those inference detail questions where the answer choices would be like "some reports over state the impact of deforestation"
The author's stance is somewhat given in line 10 with "should" as it shows what the author thinks is important. Line 21 in calling the oxygen argument a "myth" is another stance. Lines 35-39 show the author likes the biodiversity argument. P4 - you just get the feeling that the author is somewhat critical about pro-environmentalists based of the evidence selected and how he/she critiques them
Scale: Not really useful in this passage because it seems to be made up of two separate scale; one scale is for the oxygen argument and the other is for biodiversity. There is probably a third scale on wether or not the stats are exaggerated (P4).