Tree line

Columns: Location | Approx . longitude | Approx . latitude of tree line | Notes
Norway | 24°E | 70°N | The North Atlantic current makes Arctic climates in this region warmer than other coastal locations at comparable latitude . In particular the mildness of winters prevents permafrost | West Siberian Plain | 75°E | 66°N | Central Siberian Plateau | 102°E | 72°N | Extreme continental climate means the summer is warm enough to allow tree growth at higher latitudes , extending to northernmost forests of the world at 72°28 ' N at Ary-Mas ( 102° 15 ' E ) in the Novaya River valley , a tributary of the Khatanga River and the more northern Lukunsky grove at 72°31 ' N , 105° 03 ' E east from Khatanga River | Russian Far East ( Kamchatka and Chukotka ) | 160°E | 60°N | The Oyashio Current and strong winds affect summer temperatures to prevent tree growth . The Aleutian Islands are almost completely treeless | Alaska | 152°W | 68°N | Trees grow north to the south-facing slopes of the Brooks Range . The mountains block cold air coming off of the Arctic Ocean | Northwest Territories , Canada | 132°W | 69°N | Reaches north of the Arctic Circle because of the continental nature of the climate and warmer summer temperatures | Nunavut | 95°W | 61°N | Influence of the very cold Hudson Bay moves the treeline southwards | Labrador Peninsula | 72°W | 56°N | Very strong influence of the Labrador Current on summer temperatures as well as altitude effects ( much of Labrador is a plateau ) . In parts of Labrador , the treeline extends as far south as 53°N . Along the coast the northernmost trees are at 58°N in Napartok Bay | Greenland | 50°W | 64°N | Determined by experimental tree planting in the absence of native trees because of isolation from natural seed sources ; a very few trees are surviving , but growing slowly , at Søndre Strømfjord , 67°N . There is one natural forest in the Qinngua Valley

Example questions:
What is the approximate longitude of the Artic tree line whose location shares land borders with Mongolia ? | What is the approximate longitude of the Artic tree line whose location entered the Canadian Confederation on July 15 , 1870 ? | What is the approximate longitude of the Artic tree line whose location is a vast mountainous area in Siberia ? | What is the approximate longitude of the Artic tree line whose location is the largest U.S. state by area ?

Answers:
160°E | 132°W | 102°E | 152°W