Tree Elders & Drought

Thanks to National Public Radio (USA): How Is A 1,600-Year-Old Tree Weathering California’s Drought? CHRISTOPHER JOYCE It’s been a brutal forest fire season in California. But there’s actually a greater threat to California’s trees — the state’s record-setting drought. The lack of water has killed at least 60 million trees in the past four years. […]

via Tree Elders & Drought

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Wildfires and burning management

Geography Directions

By Joseph J. Bailey, University of Nottingham, UK.

Wildfires often occur as part of a natural cycle and they are important for the health of many ecosystems across the world by making the soil more suitable for seeding, for example. Indeed, many species (especially plants) have specific adaptations to wildfires such as fire-activated seeds and thermal insulation, while others rely on fires clearing space for their seedlings to grow (e.g. S. giganteum). The cause of wildfires may be natural or human-mediated (more information), and burning vegetation to make space for agricultural land, and as a means of managing natural fires, is common in many parts of the world (FAO).

NASA’s Marshall Space Flight Center Archive: Fire and Smoke, Democratic Republic of the Congo (NASA, International Space Station, 05/16/02) obtained via Flickr under a CreativeCommons License (link to source).

Two key processes have the…

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Climate of North America: General Characteristics and Climate Regions

North America, the third largest continent is spread over 24,346,000 sq km. North America includes all of the mainland and related offshore islands lying North of the Isthmus of Panama which connects it with South America. It has a variety of climate, from the dry, bitter cold of the Arctic to the steamy heat of the tropics. The interior of Greenland, always at subzero temperatures is permanently covered by an icecap,. The North American tundra, the vast treeless plain of the far north, has temperature rises above freezing for only a short period each summer. In the far south there are low-lying areas which are always hot and rainy.

Most part of the rest of North America is cold in the winter and warm in the summer, with moderate precipitation. Some areas have mild winters and long, hot summers and others have harsh winters and short summers. North America extends to within 10° of latitude of both the equator and the North Pole, embraces every climatic zone, from tropical rain forest and savanna on the lowlands of Central America to areas of permanent ice cap in central Greenland. Subarctic and tundra climates prevail in N Canada and N Alaska, and desert and semiarid conditions are found in interior regions cut off by high mountains from rain-bearing westerly winds. Fortunately , a large part of the continent has temperate climates very favorable to human settlement and agriculture.


Canada’s climate varies wildly based on geography, from perma-frost in the north to four distinct seasons towards the equator. In this region the temperature can climb up to 35 degrees Celsius in the summer and descend to a chilly -25 degrees Celsius during winter.

 Canada’s climate is characterized by its diversity, as temperature and precipitation differ depending on where you are and what time of year it is. Other than the North where it’s above freezing for only a few months a year, most Canadian cities are within 300 km of the southern border, where mild springs, hot summers and pleasantly crisp autumns are common during the majority of the year.

The West Coast

British Columbia’s coast have the most temperate climate in Canada. Warm airstreams from the Pacific Ocean keep the vegetation growing. It rarely snows in the low-lying areas, and the Coastal Range and the Rocky Mountains block the Pacific air from the Prairies. The moist air leaves the coast over the mountains, so it cools and falls on the western slopes in heavy amounts of rain and snow. The valleys between the mountain ranges experience hot summers almost completely devoid of precipitation.

The Prairies

The Canadian Prairies extend east from the Rocky Mountains to the Great Lakes. Farming is out in force in these regions. Cold winters and humid, hot summers are the norm, with a tolerable amount of snow and rain. Spring showers and temperate autumn weather makes the Prairies one of the top grain-growing areas of the world.

The Great Lakes-St. Lawrence Region

Over half the population of Canada lives near the Great Lakes or along the St. Lawrence River. Winter is very snowy and wind-chilled, while summers are humid and longer than elsewhere in Canada. Rainfall is sufficient to sustain some of the best farming areas in Canada.

Atlantic Canada

This region features one of the most rugged and most variable climates anywhere in the country. In winter, temperatures can vary wildly as Arctic air is replaced by maritime air from passing storms. Snowfall is relatively heavy, and fog is often present in spring and at the onset of summer. July is the warmest month with an average temperature of 16 to 18 degrees Celcius.

The North

North of the Prairies and the populated Great Lakes-St. Lawrence Region is a vast boreal forest. This area is snow-covered most of the year, and summer lasts approximately two months. Above the tree-line lies the Arctic. Here, temperatures rise above freezing only a few weeks a year, and the ground remains permanently frozen.


The climate in USA varies across different parts of the country. Generally, the western and southern parts of US have warmer weather as compared to the eastern and northern parts. The eastern/northern parts of US experience harsh winters with heavy snowfall but the summers are pleasant. The western/southern part has extremely hot summers and comparatively tolerable winters. Find out where you are likely to stay in the US and plan accordingly.
USA can be divided into six climate regions, excluding Alaska, Hawaii and outlying territories. The climate varies considerably between different regions.

  • Northwest Pacific
  • Mid/South Pacific
  • Midwest
  • Northeast
  • Southeast
  • Southwest

Northwest Pacific:

(Includes states like Oregon and Washington to the crest of the Cascade Mountains)

This is the perhaps the wettest part of the country. There are scattered rain showers all year round. Temperatures are mild averaging around 32.2 degree C. The summer months are pleasantly warmer but never too hot. You can see fogs along the coast during the warmer weather but the fog is less dense during mid-day.

Mid/South Pacific Rockies:

(Includes states like California, Idaho, Montana, Wyoming, Colorado, Utah and Nevada)

These states have generally dry and delightful summers. California has excellent weather all the year round, with the northern part of the state somewhat cooler (quiet chilly in the winter but seldom freezing). There are very few places in California that experience snow, and the state is known for its nice weather. Mostly all the cities have tolerable winters.

The winter months in the other states like Montana, Idaho and Wyoming can be very cold, with temperatures dropping well below 0 degree F. Colorado, Utah and Nevada are known for their excellent skiing.


(Includes states like Dakotas, Kansas, Illinois, Iowa, Minnesota, Wisconsin, Michigan, and Indiana)

This region is moderately dry. Precipitation occurs mainly in late spring and early summer. Summers are pleasant but winter time can be harsh, with lots of snow and heavy chilly winds. Extremes within the Midwest can drop down to -50 degree F.


(Includes states like Ohio, Pennsylvania, Washington DC, Maryland). 

This entire area is moderately rainy. In winter, the region experiences heavy snow and freezing rain. Summers are usually pleasant, sunny and warm. The fall is especially beautiful in wooded areas.


(Includes states like portions of Arkansas and Louisiana, Kentucky, West Virginia, Virginia)

Like the Northeast, this entire area experiences moderate rains fairly evenly throughout the year. The Spring, Summer and Fall seasons are all very pleasant. Some snow and freezing rain falls in winter but for the most part, the winters are quite mild and short lived.Southern Florida, like California, usually has excellent weather all the year round.


(Includes states like Arizona, New Mexico, Texas, Oklahoma and western portions of Arkansas and Louisiana) 

This is the hottest and high rainfall region of the US. You must be prepared to face heavy rains accompanied with thunder storms, dangerous lightening and occasional tornadoes. The winters are generally short but some freezing rains do occur. The spring and fall seasons are quite long and temperatures are generally excellent. The summers are very hot with temperatures approaching and exceeding 100 degree F on many days.


 The Climate in Mexico varies according to its topography. Along the both coasts  of the country the climate is hot and humid, unbearably so in the summer. Inland communities at higher elevations such as Guadalajara (5200 ft above sea level) and in particular close-by Lake Chapala, are much dryer and more temperate. Mexico City with its much higher elevation of 2300 sq meters above sea level, can reach freezing temperatures in the winter. You’ll be surprised to find snow-capped volcanoes. San Miguel de Allende also experiences colder winters due to its close proximity to Mexico City.

About three times as large as Texas, it is shaped roughly like a wedge, widest in the north and tapering to the narrow Isthmus of Tehuantepec in the south. It is situated between 14° and 32°N, the northern half of the country lying outside the tropics.

Almost two-thirds of the country consists of plateaux and high mountains with a climate that is warm-temperate; other parts have a tropical climate with temperature reduced by altitude.

There are three important climatic influences which help to determine the character of the climate in Mexico and her different regions. The cold Californian current, which sweeps southwards on the Pacific coast, has the effect of lowering temperatures and reducing rainfall on the west coast as far south as the tip of the peninsula of Lower California.

This and the influence of the North Pacific anticyclone help to make much of northwestern Mexico desert or semi-desert; this is a continuation of the dry zone of the United States in southern California, New Mexico, and Arizona.

The warm waters of the Caribbean Sea, and the influence of the constant northeast trade winds, make the eastern coastal region a typical tropical coast with a marked single wet season in summer. The weather and climate of this region, particularly south of Tampico, have much in common with that of the Caribbean Islands.

An important influence is the presence to the north of the great continental landmass of North America. This area becomes very cold in winter – particularly when cold air sweeps down from the Canadian Arctic – and very warm in summer. The northern part of Mexico shares these extreme temperature conditions.

In winter cold waves, or ‘northers’, can bring near-freezing conditions for a few days to the east coast as far south as Tampico or Veracruz. Snow has fallen as far south as Tampico, which is within the tropics. The west coast is protected from such cold waves by the mountains and plateaux of central Mexico.

As in other mountainous South and Central American countries, the climatic zones are described on the basis of altitude, using Spanish terms: tierra caliente, the area below about 600 m; tierra templada, the land between 600 m and 1,800 m; and tierra fria, the mountains and plateaux above this level.

Only a very narrow coastal belt on the Pacific shore falls into the tierra caliente category, but there is a more extensive area on the Caribbean shore, including the whole Yucatan peninsula.

The largest part of Mexico falls into tierra templada and tierra fria. This division takes little account of rainfall and is mainly on the basis of temperature. In most of the tierra fria, frost is frequent at night in winter and snow can occur anywhere, but only lies above 3,000-3,600 m/10,000-12,000 ft.

The rainy season over the whole country is the period of high sun from May to October. The rest of the year is not completely rainless, but the amount and frequency of rain in the winter season is low.

The wettest part of the country is the lowland on the Caribbean coast; the north coast of the Yucatan peninsula is relatively much drier than the east coast or the interior. Annual rainfall here is between 1,000  and 1,500 m, but some places in northern Yucatan get less than 500 mm.

The shores of the Pacific and Gulf of California, north of the Tropic of Cancer, get less than 250 mm of rain a year, but this increases southwards to between 1,000 mm and 1,500 mm. Rainfall is heaviest where the coast is backed by high mountains.

On the plateau, where some of the winter precipitation may fall as snow, the annual rainfall is rather less than on the coast. Much of the plateau is sheltered from maritime influences by the high mountains of the eastern and western Sierra Madre so that it has a reduced rainfall. Annual amounts of 500 mm/20 in or less in the extreme north to 875 mm in the centre and south are typical of the central highland region.

Most climate in Mexico has sunny weather for a large part of the year. The cloudiest regions are the wetter parts of the east coast and the northern part of the Pacific coast, where low cloud and fog are formed over the cold ocean current. The drier regions of the interior and much of the tierra templada have high amounts of sunshine: as much as seven or eight hours a day in the drier months to five or six during the wetter season.

Both the east and west coasts of Mexico are occasionally affected by tropical storms those develop in the Caribbean or the Pacific and bring two or three days of heavy rain. These are most likely to occur in the months August to October. Very few of these reach the strength of fully developed hurricanes; if they do, the east-coast districts are more liable to severe damage.


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Physical Divisions of North America: An Overview

North America can be divided into five physical regions: the mountainous west, the Great Plains, the Canadian Shield, the varied eastern region, and the Caribbean. Mexico and Central America’s western coast are connected to the mountainous west, while its lowlands and coastal plains extend into the eastern region.

Western Region

Young mountains are found in the west. The most familiar of these mountains are the Rockies, North America’s largest chain. The Rockies stretch from the province of British Columbia, Canada, to the U.S. state of New Mexico.

The Rocky Mountains are part of a system of parallel mountain ranges known as the Cordilleras. A cordillera is a long series of mountain ranges. Although cordilleras exist all over the world, in North America, “the Cordilleras” indicate the massive mountain ranges in the western part of the continent. The Cordilleras extend from Canada all the way to the Isthmus of Panama.

The Sierra Madre mountain system is part of the Cordilleras. The Sierra  Madre stretch from the southwestern United States to Honduras. The Sierra Madre include many high volcanoes (up to 5,636 meters) that stretch across Mexico south of the cities of Guadalajara and Mexico City.

Volcanic mountain ranges in Guatemala, Honduras, Nicaragua, Costa Rica, and Panama are also considered part of the Cordilleras. Volcanic eruptions and earthquakes occur frequently in this region. It contributes to the rich, fertile soils of the region.

Some of the Earth’s youngest mountains are in the Cascade Range of the U.S. states of Washington, Oregon, and California. The mountains include temperate rain forest—a biome unique to the area. The temperate rain forest receives an incredible amount of precipitation, between 254 to 508 centimeters  annually.

The temperate rain forest supports a wide variety of life. The Sitka spruce, western red cedar, and Douglas fir are trees native to North America’s temperate rain forest. Some of these trees grow to more than 90 meters  tall and 3 meters  in diameter. Black bears, Roosevelt elk, and marmots are indigenous animal species.

The three major desert regions of North America—the Sonoran, Mojave, and Chihuahuan—are all in the American southwest and northern Mexico. These large deserts are located in the rain shadows of nearby mountains. The mountains block precipitation and accelerate the movement of hot, dry wind over these regions. The Sonoran is in the rain shadow of the Coast Ranges, the Mojave is in the shadow of the Sierra Nevada, and the Chihuahuan is in the shadow of the Sierra Madre.

Great Plains

The Great Plains lie in the middle of the continent. Deep, rich soil blankets large areas of the plains in Canada and the United States. Grain are  grown ba plenty  in this region hence it is called the “Breadbasket of North America,”. The region  feeds a large part of the world. The Great Plains are also home to rich deposits of oil and natural gas.

 The grassland or prairie regions of the Great Plains make up the largest biome in North America. Extreme weather prevents the growth of large plants but is perfectly suited to the native grasses that dominate the region.

Native grasses vary in size from 2 meters in tall grass prairies to only 20 or 25 centimeters in short grass prairies. Native animal species include bison, prairie dogs, and grasshoppers.

Canadian Shield

The Canadian Shield is a raised but relatively flatplateau. It extends over eastern, central, and northwestern Canada. The Canadian Shield is characterized by a rocky landscape pocked by an astounding number of lakes.

The Tundra, stretching along the northern borders of Alaska and Canada to the Hudson Bay area, is a biome common to the Canadian Shield. Tundra is where low temperatures and precipitation levels hinder tree growth. The tundra is characterized by permafrost—soil that is frozen for two or more years. This permafrost keeps moisture near the soil’s surface, promoting vegetation growth even in the extreme, Arctic conditions of the tundra.

During the summer, this top layer of soil thaws less than 10 centimeters (only a few inches) down, forming numerous shallow lakes, ponds, and bogs. Lichens, mosses, algae, and succulents take advantage of these shallow waters. In turn, they provide food for the caribou and musk ox that are typical of this area.

Eastern Region

This varied region includes the Appalachian Mountains and the Atlantic coastal plain.North America’s older mountain ranges, including the Appalachians, are near the east coast of the United States and Canada.
The Atlantic coastal plain extends from river, marsh, and wetland regions east of the mountains toward the sandy beaches of the Atlantic coast. Wetland areas are a biome of the eastern region and consist of areas of land whose soil is saturated with permanent or seasonal moisture. The Florida Everglades is the largest wetland system in the United States, covering more than 11,137 square kilometers) of southern Florida.

The Everglades is a biologically diverse region and contains several bordering ecosystems. Sawgrass marshes are the most iconic plant community of the Everglades and thrive on the slow-moving water of the wetlands. Alligators nest in the sawgrass, while wading birds such as egrets, herons, spoonbills, and ibises make their breeding grounds in other wetland tree species, such as cypress and mangrove.

Caribbean Region

The Caribbean Region includes more than 7,000 islands, islets, reefs, and cays. The region’s islands and smaller islets are varied in their topography; some have relatively flat and sandy terrain while others are rugged, mountainous, and volcanic.

The coral reefs and cays of the Caribbean Sea are among the most spectacular biomes in North America. A reef is a ridge of jagged rock, coral, or sand just above or below the surface of the sea. Some coral reefs surround islands, such as the Bahamas, Antigua, and Barbados. Others are found off the Florida Keys (a low bank or reef of coral, rock, or sand.

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