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37-641: Wapadsberg Pass (English: Wagon Trail Pass) is a mountain pass situated in the Eastern Cape province of South Africa , on the regional road R61 , between Graaff-Reinet and Cradock . Wapadsberg Pass lies on the tarred regional road R61, between Nieu-Bethesda and Cradock, 17 km east of the N9 in the Eastern Cape Province of South Africa. It is named after the Wapadberg (a section of

74-425: A ridge . Since mountain ranges can present formidable barriers to travel, passes have played a key role in trade, war, and both human and animal migration throughout history. At lower elevations it may be called a hill pass . A mountain pass is typically formed between two volcanic peaks or created by erosion from water or wind. Mountain passes make use of a gap , saddle , col or notch . A topographic saddle

111-639: A carpet of Cladonia spp. lichens . The proportion of trees to lichen mat increases southwards towards the "forest line", where trees cover 50 percent or more of the landscape. A southern treeline exists in the New Zealand Subantarctic Islands and the Australian Macquarie Island , with places where mean annual temperatures above 5 °C (41 °F) support trees and woody plants, and those below 5 °C (41 °F) do not. Another treeline exists in

148-579: A few mosses, lichens, and species of grass do so. In addition, no trees survive on any of the subantarctic islands near the peninsula. Southern Rata forests exist on Enderby Island and Auckland Islands (both 50°S) and these grow up to an elevation of 370 metres (1,200 ft) in sheltered valleys. These trees seldom grow above 3 m (9.8 ft) in height and they get smaller as one gains altitude, so that by 180 m (600 ft) they are waist-high. These islands have only between 600 and 800 hours of sun annually. Campbell Island (52°S) further south

185-487: 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

222-531: A nearby mountainside, as with the Eisenhower Tunnel bypassing Loveland Pass in the Rockies, to allow faster traffic flow throughout the year. The top of a pass is frequently the only flat ground in the area, and may be a high vantage point. In some cases this makes it a preferred site for buildings. If a national border follows the ridge of a mountain range, a pass over the mountains is typically on

259-786: A style of street racing which may take place on these roads. There are thousands of named passes around the world, some of which are well-known, such as the Khyber Pass close to the present-day Afghanistan-Pakistan border on the ancient Silk Road , the Great St. Bernard Pass at 2,473 metres (8,114 ft) in the Alps , the Chang La at 5,360 metres (17,590 ft), the Khardung La at 5,359 metres (17,582 ft) in Ladakh , India and

296-545: A supply of moisture through the early part of the growing season. However, snow accumulation in sheltered gullies in the Selkirk Mountains of southeastern British Columbia causes the tree line to be 400 metres (1,300 ft) lower than on exposed intervening shoulders. In some mountainous areas, higher elevations above the condensation line, or on equator-facing and leeward slopes, can result in low rainfall and increased exposure to solar radiation. This dries out

333-492: A too-cold summer climate (tundra) that none have any indigenous tree species. The Falkland Islands (51°S) summer temperature is near the limit, but the islands are also treeless, although some planted trees exist. Antarctic Peninsula is the northernmost point in Antarctica (63°S) and has the mildest weather—it is located 1,080 kilometres (670 mi) from Cape Horn on Tierra del Fuego —yet no trees survive there; only

370-888: Is also used, particularly in Europe. In the highest mountain range in the world, the Himalayas, passes are denoted by the suffix "La" in Tibetan, Ladhakhi, and several other regional languages. Examples are the Taglang La at 5,328 m (17,480 ft) on the Leh-Manali highway , and the Sia La at 5,589 m (18,337 ft) in the Eastern Karakoram range. Scotland has the Gaelic term bealach (anglicised "balloch"), while Wales has

407-413: Is analogous to the mathematical concept of a saddle surface , with a saddle point marking the minimum high point between two valleys and the lowest point along a ridge. On a topographic map , passes can be identified by contour lines with an hourglass shape, which indicates a low spot between two higher points. In the high mountains, a difference of 2,000 meters (6,600 ft) between the summit and

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444-524: Is often much lower than in corresponding altitudes inland and in larger, more complex mountain systems, because strong winds reduce tree growth. In addition, the lack of suitable soil, such as along talus slopes or exposed rock formations, prevents trees from gaining an adequate foothold and exposes them to drought and sun. The arctic tree line is the northernmost latitude in the Northern Hemisphere where trees can grow; farther north, it

481-445: Is sometimes distinguished from a lower timberline , which is the line below which trees form a forest with a closed canopy . 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"). 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

518-537: 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: Trees exist on Tierra del Fuego (55°S) at the southern end of South America, but generally not on subantarctic islands and not in Antarctica. Therefore, there is no explicit Antarctic tree line. Kerguelen Island (49°S), South Georgia (54°S), and other subantarctic islands are all so heavily wind-exposed and with

555-556: Is taken over all days whose mean temperature is above 0.9 °C (33.6 °F). A growing season of 94 days above that temperature is required for tree growth. Because of climate change , which leads to earlier snow melt and favorable conditions for tree establishment, the tree line in North Cascades National Park has risen more than 400 feet (120 m) in 50 years. Several types of tree lines are defined in ecology and geography : An alpine tree line

592-771: Is the Brenner pass in the Alps . Some mountain passes above the tree line have problems with snow drift in the winter. This might be alleviated by building the road a few meters above the ground, which will make snow blow off the road. There are many words for pass in the English-speaking world. In the United States, pass is very common in the West , the word gap is common in the southern Appalachians , notch in parts of New England , and saddle in northern Idaho . The term col , derived from Old French,

629-433: Is the highest elevation that sustains trees; higher up it is too cold, or the snow cover lasts for too much of the year, to sustain trees. The climate above the tree line of mountains is called an alpine climate , and the habitat can be described as the alpine zone . Treelines on north-facing slopes in the northern hemisphere are lower than on south-facing slopes, because the increased shade on north-facing slopes means

666-547: Is too cold all year round to sustain trees. Extremely low temperatures, especially when prolonged, can freeze the internal sap of trees, killing them. In addition, permafrost in the soil can prevent trees from getting their roots deep enough for the necessary structural support. Unlike alpine tree lines, the northern tree line occurs at low elevations. The arctic forest–tundra transition zone in northwestern Canada varies in width, perhaps averaging 145 kilometres (90 mi) and widening markedly from west to east, in contrast with

703-594: The Palakkad Gap at 140 metres (460 ft) in Palakkad , Kerala , India . The roads at Mana Pass at 5,610 metres (18,410 ft) and Marsimik La at 5,582 metres (18,314 ft), on and near the China–India border respectively, appear to be world's two highest motorable passes. Khunjerab Pass between Pakistan and China at 4,693 metres (15,397 ft) is also a high-altitude motorable mountain pass. One of

740-460: The Sneeuberg mountain range ) which it traverses. The Xhosa name for this pass is 'eGolokoqo, an onomatopoeic rendering of the crunching of wagon wheels on the primitive tracks of the 19th century. This Eastern Cape location article is a stub . You can help Misplaced Pages by expanding it . Mountain pass Aa mountain pass is a navigable route through a mountain range or over

777-424: The snowpack takes longer to melt. This shortens the growing season for trees. In the southern hemisphere, the south-facing slopes have the shorter growing season. The alpine tree line boundary is seldom abrupt: it usually forms a transition zone between closed forest below and treeless alpine zone above. This zone of transition occurs "near the top of the tallest peaks in the northeastern United States, high up on

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814-458: The border, and there may be a border control or customs station, and possibly a military post. For instance, Argentina and Chile share the world's third-longest international border , 5,300 kilometres (3,300 mi) long, which runs north–south along the Andes mountains and includes 42 mountain passes. On a road over a pass, it is customary to have a small roadside sign giving the name of

851-456: The desiccation of foliage , especially of shoots that project above the snow cover. The actual tree line is set by the mean temperature, while the realized tree line may be affected by disturbances, such as logging . Most human activities cannot change the actual tree line, unless they affect the climate. The tree line follows the line where the seasonal mean temperature is approximately 6 °C or 43 °F. The seasonal mean temperature

888-514: The dry mountains of the western United States, to 1.4 °F (0.78 °C) per 1,000 feet (300 m) in the moister mountains of the eastern United States. Skin effects and topography can create microclimates that alter the general cooling trend. Compared with arctic tree lines, alpine tree lines may receive fewer than half of the number of degree days (above 10 °C (50 °F)) based on air temperature, but because solar radiation intensities are greater at alpine than at arctic tree lines

925-581: The famous but non-motorable mountain passes is Thorong La at 5,416 metres (17,769 ft) in Annapurna Conservation Area , Nepal. Tree line The tree line is the edge of a habitat at which trees are capable of growing and beyond which they are not. It is found at high elevations and high latitudes . Beyond the tree line, trees cannot tolerate the environmental conditions (usually low temperatures, extreme snowpack, or associated lack of available moisture). The tree line

962-440: The giant volcanoes in central Mexico, and on mountains in each of the 11 western states and throughout much of Canada and Alaska". Environmentally dwarfed shrubs ( krummholz ) commonly form the upper limit. The decrease in air temperature with increasing elevation creates the alpine climate. The rate of decrease can vary in different mountain chains, from 3.5 °F (1.9 °C) per 1,000 feet (300 m) of elevation gain in

999-434: The mountain is defined as a mountain pass. Passes are often found just above the source of a river , constituting a drainage divide . A pass may be very short, consisting of steep slopes to the top of the pass, or a valley many kilometers long, whose highest point might only be identifiable by surveying . Roads and railways have long been built through passes. Some high and rugged passes may have tunnels bored underneath

1036-437: The number of degree days calculated from leaf temperatures may be very similar. At the alpine tree line, tree growth is inhibited when excessive snow lingers and shortens the growing season to the point where new growth would not have time to harden before the onset of fall frost. Moderate snowpack, however, may promote tree growth by insulating the trees from extreme cold during the winter, curtailing water loss, and prolonging

1073-479: The pass and its elevation above mean sea level . Apart from offering relatively easy travel between valleys, passes also provide a route between two mountain tops with a minimum of descent. As a result, it is common for tracks to meet at a pass; this often makes them convenient routes even when travelling between a summit and the valley floor. Passes traditionally were places for trade routes, communications, cultural exchange, military expeditions etc. A typical example

1110-464: The predominance of conifers ): The alpine tree line at a location is dependent on local variables, such as aspect of slope, rain shadow and proximity to either geographical pole . In addition, in some tropical or island localities, the lack of biogeographical access to species that have evolved in a subalpine environment can result in lower tree lines than one might expect by climate alone. Averaging over many locations and local microclimates ,

1147-696: The similar bwlch (both being insular Celtic languages). In the Lake District of north-west England, the term hause is often used, although the term pass is also common—one distinction is that a pass can refer to a route, as well as the highest part thereof, while a hause is simply that highest part, often flattened somewhat into a high-level plateau. In Japan they are known as tōge , which means "pass" in Japanese. The word can also refer to narrow, winding roads that can be found in and around mountains and geographically similar areas, or specifically to

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1184-467: The soil, resulting in a localized arid environment unsuitable for trees. Many south-facing ridges of the mountains of the Western U.S. have a lower treeline than the northern faces because of increased sun exposure and aridity. Hawaii's treeline of about 8,000 ft (2,400 m) is also above the condensation zone and results due to a lack of moisture. On coasts and isolated mountains, the tree line

1221-459: The southwesternmost parts of the Magellanic subpolar forests ecoregion, where the forest merges into the subantarctic tundra (termed Magellanic moorland or Magellanic tundra). For example, the northern halves of Hoste and Navarino Islands have Nothofagus antarctica forests but the southern parts consist of moorlands and tundra. Some typical Arctic and alpine tree line tree species (note

1258-454: The telescoped alpine timberlines. North of the arctic tree line lies the low-growing tundra , and southwards lies the boreal forest . Two zones can be distinguished in the arctic tree line: a forest–tundra zone of scattered patches of krummholz or stunted trees, with larger trees along rivers and on sheltered sites set in a matrix of tundra; and "open boreal forest" or "lichen woodland", consisting of open groves of erect trees underlain by

1295-444: The tree line, above which they are unable to grow at all. Given a certain latitude, the tree line is approximately 300 to 1000 meters below the permanent snow line and roughly parallel to it. Due to their vertical structure, trees are more susceptible to cold than more ground-hugging forms of plants. Summer warmth generally sets the limit to which tree growth can occur: while tree line conifers are very frost-hardy during most of

1332-517: The treeline rises 75 metres (245 ft) when moving 1 degree south from 70 to 50°N, and 130 metres (430 ft) per degree from 50 to 30°N. Between 30°N and 20°S, the treeline is roughly constant, between 3,500 and 4,000 metres (11,500 and 13,100 ft). Here is a list of approximate tree lines from locations around the globe: 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

1369-469: The year, they become sensitive to just 1 or 2 degrees of frost in mid-summer. A series of warm summers in the 1940s seems to have permitted the establishment of "significant numbers" of spruce seedlings above the previous treeline in the hills near Fairbanks, Alaska . Survival depends on a sufficiency of new growth to support the tree. Wind can mechanically damage tree tissues directly , including blasting with windborne particles, and may also contribute to

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