Here’s a Gazprom aerial photo which illustrates this better than 1000 words. (Yamal is the location of some huge Gazprom natural gas fields.) From the colors, I presume that the picture is taken in fall as the larch have changed color. Spruce do not appear to be in evidence here – they have a more southerly treeline. The remarkable relationship between the rivers and the larch “forest” is not discussed in Briffa (2000) or Briffa et al (2008).