Question: What is the approximate longitude of the Artic tree line whose location entered the Canadian Confederation on July 15 , 1870 ?

text: Tree line
Worldwide distribution -- Arctic tree lines
Like the alpine tree lines shown above , polar tree lines are heavily influenced by local variables such as aspect of slope and degree of shelter . In addition , permafrost has a major impact on the ability of trees to place roots into the ground . When roots are too shallow , trees are susceptible to windthrow and erosion . Trees can often grow in river valleys at latitudes where they could not grow on a more exposed site . Maritime influences such as ocean currents also play a major role in determining how far from the equator trees can grow as well as the warm summers experienced in extreme continental climates . In northern inland Scandinavia there is substantial maritime influence on high parallels that keep winters relatively mild , but enough inland effect to have summers well above the threshold for the tree line . Here are some typical polar treelines :
The tree line is the edge of the habitat at which trees are capable of growing. It is found at high elevations and high latitudes. Beyond the tree line, trees cannot tolerate the environmental conditions (usually cold temperatures or associated lack of available moisture). :51 The tree line is sometimes distinguished from a lower timberline or forest line, which is the line below which trees form a forest with a closed canopy. :151:18
 At the tree line, tree growth is often sparse, stunted, and deformed by wind and cold. This is sometimes known as krummholz (German for crooked wood). :58
 The tree line often appears well-defined, but it can be a more gradual transition. Trees grow shorter and often at lower densities as they approach the tree line, above which they cease to exist. :55
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