BentTree,This may be too late, considering it's been a few days since you thanked everyone. Take all of this as the opinion of a close reader and editor. Please don't take it as condescending criticism. I mean well, even though it's abundant and direct.
The two italic formatted sentences suggest that Leeta is thinking, interior discourse. Yet she's recalling direct discourse, dialogue. As potent as the words are, the formatting context required too much effort for me to figure out and stopped my forward movement in the story. Consider dialogue quotes instead.
Separating the causation of Otek's two phrases by their effect on Leeta disrupts the barely begun train of causation. Cause sentence, effect sentence, return to original cause sentence; new paragraph, new cause not immediately related to the original cause. Causation is disjointed. The connection between hoisting and tree climbing isn't made until the end of the second paragraph, causing another disruption in causation. I had to start over and found myself jumping around trying to figure out what Leeta is doing, what her predicament is, what her purpose is, and what besides sexual discrimination opposes her purpose.
[Throbbing] suggests anticipation, some sexual context too. Consider parallels or contrasts with burning muscles: cramped, charlie horsed, aching?
[her rigging] 'the rigging' gets away from unnecessarily possessive context and authorial direction of the action. It's obvious the rigging and harness are hers.
[snapped] made me think Leeta twanged a shock cord or the carabiner broke; 'clipped'?
There's a lot of movement and context in the 1st sentence of the second paragraph, but little causation or opposition, therefore little emotive appeal. Although it shows movement, it's not dramatic (causal) action. However, the context of the sentence provides character and setting description, milieu introduction, genre mode introduction, and the magnitude of the place and situation's scale. All to the good in my opinion.
I don't think [massive] and [towering] are coordinate adjectives. Actually, towering is a gerund adverb posing as an adjective while massive is plainly a descriptive adjective.
[Then] is a superfluous term in most cases, consider recasting the sentence. 'Swivelling upside down, she set her climbing spikes with a firm kick of each heel.'
[swivelling] has a connotation of horizontal rotation, consider 'flipping,' 'spinning,' or some such term which connotates rotation through the vertical axis.
[each heel] consider recasting to simplify, 'both heels.'
[Having achieved solid leverage] is a sharp rise in the language tenor compared to the rest of the excerpt, an awkward construct, and follows a sentence with similar syntax; gerund modifier clause, main clause, conjunction clause. Consider recasting and running into the previous sentence of which it is rightly an appositive clause. 'kick of each heel, planting a firm foothold and gaining solid leverage.'
That last sentence of the second paragraph is a train wreck run-on sentence. First she reflects on her achieving her desired position, next she prepares by tightening the rope, then she focuses on the meaning of the task. Consider recasting into smaller bits.
[prepared to hoist] infinitive verb construct and nearly a tautology of [pulled the rope tight].
[growing platform full of newly germinated seedlings] consider simplifying 'germination platform of seedlings'
[three hundred meters, from the middle level to high] another redundancy, an absolute measurement followed by a relative one of the same distance. Consider some such simplification as 'seedlings from the middle level three hundred meters to the high'
[light giving canopy] illogical, a forest or tree canopy blocks light.
[Then] again, at the beginning of the third paragraph, a superfluous term.
[Then came the shrill rhythmic warning call] Consider recasting the sentence with more robust verbs and simpler modifiers, like; 'A rhythmic warning shrilled'
[quickly pried] does she pry her heels out with a lever? consider simplifying and the preciseness of verb, 'ripped'
I'm confused about Leeta's orientation to the tree. I've got her upside down, but I'm uncertain whether she's facing the trunk or facing away. If she's got her heels dug in, I'm seeing her as facing away.
That last incomplete paragraph begins the inciting moment of the plot movement. Wonderful, having the inciting moment in the first thirteen lines is ideal. Danger is directly implied. I'm hooked and would read on, even though I would expect causation, tension, and opposition, the three corners of plot, to be less than ideally realized.