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Chapter #5 (pp. 167 &emdash; 182 & pp. 210-215) |
MOUNTAINTOPS
Relicts and endemics are found on mountaintops because they are ecologic islands, isolated from each other by changes in elevation. Throughout California, the climate on mountaintops is similar and plants and animals have adapted to this. The coldest temperatures, the most intense sunlight, and the strongest winds are present on mountaintops. Soil is shallow, nutrient poor, and coarse, with an acidic pH. BIOTIC ZONATION Subalpine and alpine communities occur in the Sierra Nevada (most abundantly), Klamath Province, the Cascades, the Great Basin, the Transverse Ranges, and the Peninsular Ranges. The drought-tolerant and snow tolerant ecologic islands of the Pinyon-Juniper Woodlands are also present on mountaintops. Subalpine Forest- The subalpine zone is the upper limit for trees...the alpine zone has no trees. Precipitation in the subalpine zone usually falls in the form of snow. Trees in the upper timberline are bent and twisted by wind (krummbolz or bent wood). Three winter phenomena shape the trees: snow loading (creates snow knees), blowing ice particles, and dehydration. Tree branches that protrude above the snow level in the winter are subject to ice blast, which damages tree tissue and leads to dehydration and tissue death due to water loss. At times, wind may be so great that ice crystals, which form from fog or clouds, can be evaporated without ever becoming liquid. This causes a decline in temperature and tissue death. Trees such as the conifers have developed protection from the harsh weather of the mountaintops. Conifers withdraw water from cells in the twigs and stems so they are not damaged from ice crystals. However it may not protect enough in extreme cases. Desiccation and abrasion as well as supercooling damages new foliage and create an awkward distribution of branches and foliage. Temperature dictates the limits for tree species. This upper limit is reached where the temperature may drop to -400 F, the point at which water
Freezes instantly. Photosynthesis of plants in this area is limited. In some areas the annual rate of photosynthesis is so slow that cellular respiration uses all of the plants carbohydrates, thereby preventing new growth.
Photosynthesis can occur if snow is present and experiments have shown that water transport and photosynthesis may begin in spring as long as the ground is not frozen. However, under the best circumstances at the treeline, photosynthesis and the growth rate are slow. Most of the trees in the subalpine zone are five-needle pines that occur in single-species stands, aside from the Mountain Hemlock. It resembles a fir but has blunter needles that protrude from the circumference of the branchlets. Two relict species of juniper (of the cypress family) also occur in the subalpine zone. They are the Sierra Juniper and Pygmy Juniper. Each has small flat scales that adhere tightly to it branches. In order to germinate, their seeds must pass through the digestive tract of an animal because of the need for scarification through acid treatment. The five-needle pines are the most abundant pine of this zone. They have short needles that form in clumps of five. In the Californian subalpine region there are four species and though their ranges overlap, each species occurs in a pure stand. The four species are the Whitebark, Limber, Foxtail, and Bristlecone Pines. (pp.167-171)
Other pines that sometimes occur in the subalpine zone are Lodgepole Pines and Western White Pines, both typical components of Lodgepole-Red Fir Forest, at lower elevation. They have a "cornflake" bark, and the needles are concentrated on the tips of the stems.
Limber Pines and Whitebark Pines are nearly identical in appearance. Whitebark Pine is probably the most common subalpine pine. They grow in open woodland with very little understory. The oldest Whitebark Pine recorded in the Sierra Nevada was a full 1000 years of age. Limber Pines have only limited distribution in the Sierra Nevada. They grow mostly in small groves in dry sites in association with Lodgepole Pines. The oldest recorded Limber Pine was a 2500 year old specimen near Robinson Lake, in the Onion Valley area of the eastern Sierra Nevada, and a 2300 year old specimen has been found on Mount San Jacinto. Most specimens, however, are no older than 250 years.
Foxtail Pines differ in appearance from other trees they may grow with. Needles grow all along the branchlets and the weight of these needles may cause the branchlets to droop. In spite of their great age, Foxtail Pines never reach the size of Sierra Redwoods. However, they are quite large for subalpine species. The largest Foxtail Pine is located at about 10,000 feet on a ridge above Timber Gap, in the Sequoia National Park. The effect of the wind is that branches may all grow out of one side of the tree, a phenomenon known as flagging. Another effect of the abrasive wind is that all the bark containing the living tissues needed to nourish a few living branches remains on the leeward side of the trunk. This sometimes causes what are known as "piggyback" trunks, a phenomenon that occurs when a branch on the leeward side of the trunk begins to grow erect. (Schoenherr pp. 172 &emdash; 176)
Foxtail Pines are distributed on well drained soils. They have a well developed root system. Foxtails only occur in California. They are distributed within 300 miles, between the Klamath Province and southern Sierra Nevada. Foxtails grow best on southfacing slopes with deep soil. Seedlings require heat to germinate.
Bristlecone Pines are common in the White Mountains, the Inyo Mountains, the Lastchance Mountains, and the Panamint Mountains. They occur in Nevada, Utah, Colorado and New Mexico. Their cones bear sharp spines on the end of each scale. Bristlecones have been dated as old as 4000 years in California. The oldest Bristlecone ever dated was 4900. Bristlecones grow in harsh conditions. 12 inches of rain, snow is 99% of their precipitation, and their soil is nutrient poor in the White Mountains. When using Carbon 14 methods for dating trees after 2500 years the dating was consistently underestimated by 1000 years. By studying Bristlecone Pines we have learned how ancient civilization developed in Europe.
History of Subalpine Vegetation
Whitebark Pine is the most widely distributed. it occupies the central Sierra on glacier scoured terrain with little soil. Only four to five generations of Foxtail and Limber Pines have occurred since the end of the Pleistocene. It is possible there has been only three generations of Bristlecone Pines since the retreat of the glaciers. Foxtail and Bristlecone Pine have been experimentally hybridized. Whitebark is a northern species and Limber Pine is a Rocky MOuntain species. Fossil Foxtail and cones are found in Pleisticene deposits at Clear Lake in the Northern Coast Range. This locality is 5000 ft below and 65 miles south of the nearest presently growing population in the Klamath Mountains. There is evidence all over the Great Basin that Bristlecone Pines grew more than 2000 feet lower than they do today. (pp.178 &emdash; 182)
One of the interesting phenomena documented for mountaintops in general is that they seem to attract certain kinds of insects. Monarch Butterflies are migratory, thus they commonly occur in the high country in the course of their migration. Many other species of insects become concentrated on mountaintops, a phenomenon known as hilltopping. It seems to be related to mating behavior. Most hilltopping butterflies are males and females seem not to remain there long. Furthermore, the males on the hilltops engage in territorial patrolling behavior.
The California Tortoise-shell is an example of a butterfly that undergoes mass emigration with population outbreaks. The species is particularly renowned for its massive outbreaks on Mount Shasta, where millions may appear in favorable years.
There are three common but inconspicuous butterflies that characterize the alpine region of the Sierra Nevada. Riding’s Satyr is gray with an irregular light band across the wings and two black spots. It is mothlike appearance, relying on its coloration to conceal it when at rest. The Ivallda Arctic with its dull yellow-brown color enables it to blend with the granite rocks upon which it rests with open wings. The small Apollo or Phoebus Parnassian is a cream to snow white with black and red spots on its wings.
One of the strangest examples of an alpine animal is the Mount Lyell Salamander. It has a flathead, which is specialized for living in cracks and under rock flakes. It is a lungless salamander that can absorb oxygen through its skin. The distribution of this salamander and its relatives is an enigma. Its nearest relatives are the web-toed salamanders, most of which are restricted to limestone. Two are found in limestone caves in Western Europe and two others are found in limestone in California.
Over their entire lives they probably move no more than a few meters.
Very few animals stay in the alpine zone year-round. Of the birds that occur there on occasion, non is more truly alpine than the Gray-crowned Rosy Finch. It is the only bird known to nest about timberline. It usually makes its nest among rocks, out of the wind, but it also have been reported to nest at the top of a glacier. They eat a wide variety of seeds and insects, commonly feeding on or near the edge of snowfields. When insects such as mayflies emerge from mountain lakes, the birds feed voraciously in flocks, catching them on the water and in midair.
There are three ecological rules or principles, based on surface-volume ratio and color, that relate to temperature regulation, body form, and distribution among endothermic animals. There rules are based on minimizing head lost or gained by radiation.
Among mammals of the alpine zone there are three basic strategies
for dealing with harsh winter. Animals can migrate, they can
hibernate, or they can remain active by storing food or somehow
making use of available food.
(Schoenherr pp. 210 to 215)
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The Lilies of the Valley (pages 167-182 & pages 210-215) |
The subalpine zone is the life zone. It is the upper limit for trees, no trees here. Precipitation, falls almost entirely as snow, around 10" per year. Krummholz are found in the upper timberland and are trees that are twisted and bent by the wind. The three winter phenomena that shape trees are:
The pine family is Pinaceae. The most common pines in the sub-alpine are five &emdash;needle pines in single-species strands. The four species of subalpine pines can be divided into two groups.
Lodgepole pines occur in clumps of two.
Whitebark pine is the most common and grows in clumps at or near the
tree line, and cones are favorites of squirrels and birds.
The Foxtail pine oldest specimen dates back 3300 years and is found
on the south side of Split Mountain.
Flagging is where the branches of the trees grow out one side of the tree. Piggyback is where the branches on the leeward side of the trunk grow erect.
Bristlecone Pines cones bear sharp spines on the end of the scale and date back 4600 years, named Methuselan and is said to be the oldest living thing. Bristlecone Pines grow in the harshest climate possible, the White Mountains of the Sierra Nevada.
In the Subalpine Forest Whitebark Pine is the most common. Subalpine vegetation has not always been distributed in an island like mosaic.
During 10 to 12 million years ago the Sierras began to ride the east got drier due to the rain shadow increase and the summer precipitation decreased.
Animal life in this area includes Golden-mammals Golden squirrels,
Clark’s Nutcracker, and Gray Jay. 30 other species of birds are typical
of the subalpine zone but migrate during the winter to other places.
Animals in the Alpine zone include birds and mammals that occur in
montane communities, this zone becomes to cold for ectothermic species
and a decrease in numbers of species at higher elevations. For example
there are salamanders (Mount Lyell, monarch butterflies, California
Tortoise-shell, Riding’s Satyr, Ivallda Artic, and Small Apolla or
Phoebus Parnassian. Very few animals stay in the alpine zone
year-around. Mammals have three ways to deal with the harsh winter.
Animals can migrate, they can hibernate, or they can remain active by
storing food or somehow making use of available food.
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Danielle Gobert, Ann Mason, Eugenie Steinman & Stacy Holland Chap. 5 (pp. 167-182, 210-215) Summary |
Mountaintops are separate from one another due to low elevations and climate, leading to their characterization as ecologic islands. Relicts and endemics are found in these areas. Related species are found on adjacent mountaintops. Mountaintop climate is similar in every mountain range in California, where the coldest climates, most intense sunlight and strongest winds occur. Almost all precipitation here is through snowfall. Summer growing season is short and the soil is nutrient poor and acidic.
BIOTIC ZONATION
Subalpine Forest
The subalpine zone is the upper limit for trees. The alpine zone has no trees. Precipitation, in the form of snow, is approximately 30 inches per year.
At upper elevations, the trees are bent due to the extreme winds (this is known as krummholz). Winter conditions shape these trees, such as the snowloads. The various winter conditions can cause death in the trees as the cells become damaged (mechanical damage and vital-water hypothesis).
The upper elevations that trees may reach are directly related to temperature. The -40 degree isotherm (where pure water freezes instantly) limits northward distribution of trees in the Arctic. Photosynthesis is limited in this area due to the cold temperature. However, some plants are able to carry on photosynthesis underneath the snow.
Most trees of this zone are five-needle pines. In the northern Sierra the Mountain Hemlock is present, being the most common subalpine tree, which looks like a fur but its needles are blunter and stick out all around the branches. It grows where soil is thick and moist to support this cold-tolerant and moisture-requiring tree.
Two species of junipers (Cypress family) are found in this zone. Leaves are small and flat and tightly adhere to branches, with berrylike cones which are a good food supply for the zone's animals. The Sierra Juniper and the Pygmy Juniper (also called the Common Juniper) are found here, both of which are relicts. They both have widespread distribution to the north, and their patchy distribution in California may be due to the need for their seeds to pass through an animal's digestive tract in order to germinate.
The five-needle pines are the most characteristic pine in the subalpine zone, dominating the Subalpine Forest. These have short needles in clumps of five. There are four common species: Whitebark, Limber, Foxtail and Bristlecone Pines. Lodgepole and Western White Pines are also found. Whitebark is the most common, with its cones being a great food source for animals.
The carbon-14 method is used in determining how many years ago a plant or animal died. However, this method often underestimates the age of materials which are older than 2500 years. This way of determining age often produces ages which are 1000 years too young.
Animals of the Alpine Zone (pp. 210-215)
Most animals of the alpine zone are birds and mammals that also live in other communities. There is a decreased number of species in higher elevations due to temperature. There are some salamanders present, but there are not many reptiles in general.
Mountaintops attract certain types of insects. Monarch butterflies are present during their migrations. "Hilltopping" is the concentration of insects on mountaintops, where mating is believed to be involved. The California Tortoise-shell butterfly is known for its large outbreak on Mount Shasta. The alpine zone is also home to the Riding's Satyr, the Ivallda Arctic and the Small Apollo species of butterflies.
The salamanders present in this zone are the Mount Lyell Salamander which has led scientists to study is peculiar pattern of distribution, leading to a hypothesis associated with plate tectonics where the salamanders rode on pieces of land. Another hypothesis associated with the salamanders is that they were carried by rafting (on floating trees).
Few animals stay in the alpine zone year-round. The Gray-crowned Rosy Finch is found nesting above the timberline. In accordance with ecological rules and principles, mammals of this zone tend to have large body mass, short limbs and are light-colored. These rules are associated with the mammals' ability to tolerate climates in the alpine zone. In this zone the mammals handle the harsh winters by migrating, hibernating, or remaining active.
The California Bighorn Sheep are found in the alpine zone during
the summer months. Their numbers have declined in recent years due to
disease and hunting, as well as their inability to cross highways in
order to leave the zone for the winter.
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By: The Mama's and The Papa's Pgs. 167-182 209-216 |
Relicts and endemics can be found.
Extreme climates can be found at the very top of a mountain. Here will be the coldest climate, most intense sunlight, and
strongest winds. Nearly all of the precipitation falls as snow.
Soil is shallow, nutrient-poor and course, with an acidic pH.
Biotic Zonation
The greatest abundance of alpine and subalpine communities are found in the Sierra Nevada.
Pinyon-Juniper Woodlands are mountaintop communities that are drought tolerant and snow tolerant.
Subalpine Forest
Known as the Hudsonian life zone.
The upper limit for trees
The trees are bent and twisted by the wind. Termed: krummholz
Height is dictated by the snow depth and wind intensity.
Shape correlates to snow loading, blowing ice particles, and dehydration.
Supercooling results/ an extremely rapid rate of evaporation causes an extreme drop in temperature, which
kills the tree tissue.
Photosynthesis is limited by cold temperatures
Most trees in the subalpine zone are 5-needle pines and occur in a single-strand species.
Whitebark Pine
Limber Pine The appearance of the needles distinguish these
Foxtail Pine various species
Bristlecone Pine/Pinus longaeva
Mountain Hemlock being the most common occurring in the Sierra Nevada Pg. 170
The only way to distinguish the Limber Pines from the Whitebark Pines in the areas of overlap is through their cones.
Whitebark Pine is probably the most common subalpine pine. The cones are consumed by squirrels and birds. Pg. 172
Foxtail and Bristlecone Pines are very difficult to tell apart, but fortunately they never overlap in their locations.
Foxtail Pines are thought to be the oldest living trees in the Sierra Nevada, and do not occur outside of CA.. Their
distribution is most common on coarse well-drained soil. They have a well-developed root system, and have adapted to a cold,
desertlike environment. They are drought tolerant.
Bristlecone Pines occur in only a few localities in CA. White Mnts., Inyo Mnts., Last Chance Mnts., and the Panamint Mnts.
Juniper Species in the subalpine zone/Cypress Family and relicts
1.Sierra Juniper, Juniperus occidentalis australis
2.Pygmy Juniper, Juniperus communis
In order for the juniper to germinate, their seeds must first pass through the digestive tract of an animal. This causes a
process known as scarification or an acid treatment to occur.
pg 209-216
Animals of the Alpine Zone
Most of the conspicuous animals of the alpine zone are birds and mammals.
The alpine zone becomes too cold for ectothermic species, thus there is a decrease in the numbers of species at higher
elevations.
Mountaintops tend to attract certain kinds of insects. Some species become concentrated on mountaintops and this
phenomenon is known as hilltopping.
There are three common butterflies that characterize the alpine region of the Sierra Nevada
1.Riding’s Satyr Neominois ridingsii
2.Ivallda Arctic Oeneis ivallda
3.Small Apollo or Phoebus Parnassian Parnassius phoebus
One of the strangest examples of an alpine animal: Mount Lyell Salamander, Hydromantes platycephalus
Birds
There are three ecological rules that relate to temp. regulation, body form, and distribution among endothermic animals.
Mammals that live in the alpine zone would expect to have
Mammals of the alpine zone have three basic strategies for dealing with the harsh winter.
Sheep
Mountain or California Bighorn Ovis Canadensis californiana
Peninsular Bighorn Sheep Ovis Canadensis cremnobates
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By Konocti Krowd |
BIOTIC ZONATION
The Sierra Nevada has the greatest abundance of alpine and subalpine communities, but these communities are also found in the Klamath Province, the Cascades, the Great Basin, the Traverse Ranges, and the Peninsular Ranges. Pinyon-Juniper Woodlands also qualify as mountaintop communities based on their localized distribution and evolutionary history.
Subalpine Forest: The subalpine zone is the upper limit for trees; the alpine zone has no trees. Precipitation measures from 30-50 inches per year, falling almost entirely as snow. Trees at the top of the timberline are bent and twisted by the wind. This known as krummbolz (German for "bent wood"). Snow depth and wind intensity is responsible for the trees’ height. The trees are shaped by snow loading, blowing ice particles and dehydration. Most conifers protect themselves from cold weather by withdrawing water from cells in twigs and stems. Usually, it is ice crystals forming within plant tissues that causes damage to the plant cells. The upper elevation achievable by a tree species seems to be determined by temperature, and photosynthesis is limited by cold temperatures.
In California, most of the trees of the subalpine zone are five-needle pines that occur in single species stands. The Mountain Hemlock (a member of the pine family but with blunter needles that stick out all around) is the most common subalpine tree in the Klamath Province and the Northern Sierra Nevada as far south as Yosemite.. Two species of Junipers also occur in the subalpine zone, the Sierra Juniper and the Pygmy Juniper. Junipers belong to the cypress family (Cupressaceae), These two species are relicts. The five-needle pines have short needles, less than 3-inches in length that occur in clumps of five. There are four species in the subalpine zone &emdash; Whitebark Pine, Limber Pine, Foxtail Pine and Bristlecone Pine. Lodgepole Pines and Western White Pines sometimes occur in the subalpine zone, but they are more typical components of Lodgepole-Red Fir Forest, at lower elevation. Whitebark Pine is probably the most common subalpine pine. They frequently grow in clumps at or near the treeline, in open woodland with very little understory, and they are often krummholzed. Limber Pines are widely distributed throughout desert ranges in the Great Basin, where they may be the only tree species in the subalpine zone. In So. CA groves of them occur at patchy localities on high peaks in the Transverse and Peninsular ranges.
Foxtail and Bristlecone Pines look very much alike but their distribution never overlaps. In CA, Bristlecone Pines are common only in the White Mountains on the east side of the Owens Valley. Foxtail Pines grow in the Southern Sierra Nevada and Klamath Province. Foxtail Pines seldom become krummholzed. In spite of the harsh climate and strong wind, they usually remain erect, with a single stout trunk. The effect of the wind is that the branches may all grow out of one side of the tree, a phenomenon known as flagging. The Foxtail Pines have few enemies other than the climate, and they may be the oldest trees in the Sierra. Most of the very oldest Foxtail Pines are only partly living. Foxtails don’t grow outside of CA and their disjunct distribution is not fully understood. There are several hypothesis, but perhaps the critical factor in their distribution involves seed germination and seedling survival..
In CA, Bristlecone Pines occur in only a few locations. They are distinctive because their cones bear sharp spines on the end of each scale. Otherwise, they resemble Foxtail pines. In CA, Bristlecone Pines are noteable because of their great age. Several specimens have been dated at more than 4000 years, and the oldest, dated at 4600 years, has been named Methuselah and is thought to be the oldest living thing. Bristlecones grow so slowly that their rings must be counted with a microscope. Researchers have been able to identify an absolute sequence of tree rings dating back about 8,000 years. This has provided a means of checking the accuracy of the carbon-14 dating system, which in turn has allowed European artifacts to be dated correctly.
Animals of the Alpine Zone: Most of the conspicuous animals of the alpine zone are birds and mammals that occur in other mountain communities too. Mountaintops in general seem to attract certain kinds of insects, and their concentration is known as hilltopping. Swarms of insects have been documented many times, and one study in San Diego Co. documented 45 species of hilltopping butterflies alone. Hilltopping seems to be related to mating, and most hilltopping butterflies are males. One of the strangest examples of an alpine animal is the Mount Lyell Salamander, Hydromantes platycephalus. Its scientific name, platycephalus, means flat-head which refers to its body form, which is specialized for living in cracks and under rock flakes. Ectothermic animals are not typical of cold climates, but this salamander seems to be associated with open rock habitats that are wet from snowmelt or spray from waterfalls. In late summer, when habitats become dry, these salamanders slip into fissures and cracks where they become dormant and then hibernate when winter starts. They remain dormant, living off of stored fat until the snow melts in the spring. They live for eight or nine years. The distribution of this salamanders and its relatives is an enigma. They are all part of a strange pattern of distribution. They are sedimentary animals, moving only a few meters during their entire life. They may be relicts, but this would mean they would have had to have been distributed worldwide at one time. There are many theories as to how they became distributed the way they are, but no one is certain at this time. One hypothesis is that they became distributed by plate tectonics. This hypothesis is supported by the similar distribution of other plants and animals with poor dispersal ability.
Very few animals stay in the alpine zone year round. The Gray-crowned Rosy Finch is the only bird known to nest above timberline. As is often the case in harsh habitats, these birds can’t afford to be too picky about their diet and they eat a wide variety of seeds and insects. On the tops of popular peaks such as Mt. Whitney and Half-Dome they have become quite tame. Among animals of the alpine zone there are three basic strategies for surviving the harsh winter. They can migrate, hibernate, or remain active by storing food or somehow making use of available food.
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Marilyn Cannon. Dec.3, 2002