## 4 Discussion  
Interior Siberia is noteworthy from the viewpoint of the conifer species that sharply changes from evergreen conifers (_Pinus sibirica, P. sylvestris, Abies sibirica, Pica obovata_) dominating west of the Yenisei River to deciduous conifers (_Larix gmelinii_ and _L.ajanderi_) east of the Yenisei (1999). _L. gmelinii_ and _L.ajanderi_ form the largest larch biome on the Earth, distributed on the continuous permafrost of Northeastern Eurasia. _Larix sibirica_ grows only on non-permafrost and may be admixed to evergreen conifers (see for details in Supplementary File S1). The larch forest that was located 4 degrees north of the pine forest, and therefore the accumulated daylight over the growing season is 200 h greater than daylight in the pine forest, which yielded about two additional weeks for photosynthesis. However, due to a 2.5 weeks shorter growing season in the north, the larch forest likely lost its only advantage to accumulate higher NEP and GPP. We compared the direct functional parameters of our two forests, the permafrost Gmelin larch forest at Tura and the non-permafrost Scots pine forest at Zotino, with findings in the same forests from recent publications. [PERSON] et al. (2017) studied energy fluxes and NEE in the Gmelin larch forest; [PERSON] et al. (2018) studied soil respiration in both Scots pine and Gmelin larch forests; and [PERSON] et al. (2019, 2020) studied transpiration and water use efficiency in Scots pine, Siberian larch and Gmelin larch in the warm subtaiga forests. We found that these ecosystem parameters during the growing season remained very similar after a decade or so: NEP = (76.5-103.6) g C m\({}^{-2}\) in 2013-2015 (2017) vs. (63-106) g (this study)  
Figure 8: Water use efficiency (GPP/E) in dry (1999 and 2005) and wet (2000 and 2008) years in the Gmelin larch forest (**left**) and Scots pine forest (**right**) during May—September (V–IX). in the permafrost larch forest; SR = 310 g C m\({}^{-2}\) in the pine forest in 1995-2010 [18] and 335 g C m\({}^{-2}\) (this study); SR = 217 g C m\({}^{-2}\) in the permafrost larch forests 1995-2010 [18] vs. 105 g C m\({}^{-2}\) (this study). Average CO\({}_{2}\) uptake in our permafrost larch forest, \(-\)(3-6 umol m\({}^{-2}\) s\({}^{-1}\)), was smaller than \(-\)(6-13 umol m\({}^{-2}\) s\({}^{-1}\)) in non-permafrost boreal sites around the world: in North America, a jack pine forest [60], a black spruce forest [61]; in Central Siberia, fr-spruce or fir-birch forests [51]; in Northern Finland, a subarctic birch forest [62]. Compared to other larch forests on continuous permafrost, the maximal mid-summer net uptake in our Gmelin larch forest was close to that of an _L. gmelinii_ forest in eastern Siberia \(-\)5 umol m\({}^{-2}\) s\({}^{-1}\)[53] and was much smaller than reported for an _L. cajanderi_ forest, \(-\)(10-18) umol m\({}^{-2}\) s\({}^{-1}\), in the \"Spasskaya Pad\" site near Yakutsk, also eastern Siberia [10]. The maximal net uptake in this forest was comparable to that of a productive non-permafrost _L. sibirica_ forest in Mongolia [63]. The daily uptake rates in our larch forest during mid-summer and, thus, the cumulative NEE during the growing season were considerably lower than in other mature boreal forests, including the same species of larch reported in the literature. This may be due to the smaller LAI (<0.6) of our Gmelin larch forest compared to other forests (e.g., 1-4 at the BOREAS study sites in Canada [60; 61], [64] and that of the Cajander larch forest near Yakutsk with an LAI of \(\sim\)2 [10]. Another crucial reason for the large differences in NEE between various boreal forests, including the Cajander larch forest near Yakutsk and our Gmelin larch near Tura, was the low active layer depth of 0.8 m and cold soils. ALD was 1.2-1.4 m [10] and reached 1.8 m [1] in Cajander larch forests on warm sandy soils in Yakuttia within the permafrost zone. The physiological activity of larch trees in the permafrost ecosystem followed the soil temperature increase in the upper soil horizon.