This answer, admittedly, benefits from the discussion here, but I propose it because 1) the technical forestry term, if it's right, would tend not to be recognized in a literary text, and 2) in English "crooked" trees or wood are very often said to be "gnarled." Depending on what you do with перелески, which likely should not be "grove" in the case of these kinds of trees, then you could have:

thickets of gnarled trees
growths of gnarled trees
patches of scrub growth
patches of gnarled scrub growth (though scrub is already, characteristically, low-growing and tending to be gnarled)

"Scrub growth" gives an image of a lower height - more like shrubs or bushes. But if you do more research on what grows on such slopes in Kazakstan, perhaps you could find out which suits better. But none of these suggestions are super-specific to one latitude belt or type of terrain.

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Note added at 1 day11 hrs (2010-06-05 12:38:02 GMT)
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CORRECTION: gnarled, not grarled!!