D.B.H. or Diameter Breast Height Tree Measure

D.B.H. or Diameter Breast Height Tree Measure A trees diameter at your breast or chest height is the most common tree measurement made on a tree by tree professionals. It is also called DBH for short. The only other measurement made of a tree as important is a trees total and merchantable height. This diameter is measured over the outside bark using a diameter tape at the point foresters call breast height. Breast height is specifically defined as a point around the trunk at 4.5 feet (1.37 meters in metric using countries) above the forest floor on the uphill side of the tree. For the purposes of determining breast height, the forest floor includes the duff layer that may be present  but does not include unincorporated woody debris that may rise above the ground line. It may assume a 12-inch stump in commercial forests. DBH has traditionally been the sweet spot on a tree where measurements are taken and where a multitude of calculations are made to determine things like growth, volume, yield and forest potential. This spot at breast level is a convenient way of measuring a tree without the need to bend your waist or climb up a ladder to take the measurement. All growth, volume and yield tables are calculated to correspond with DBH. How to Measure DBH There are at least three devices you can use to measure a tree diameter. The most commonly used device is a diameter tape that reads directly into a measurement of diameter in given increments of your prefered unit of measurement (inches or millimeters). There are calipers that will hug the tree and the measurement is read using the caliper scale. There is also the Biltmore stick that is designed to use a sighting angle at a given distance from the eye and reads the left and right trunk sighting. Measuring the diameter of a normally shaped tree is straightforward. There are other situations where measuring DBH should be handled differently. Measuring a forked tree below DBH: Measure the tree diameter just below the fork swell. The measurement should be made at the normal spot if the tree forks above DBH.Measuring multiple stems from ground root sprouts: Measure each stem diameter at diameter breast height.Measuring a straight tree on a slope: Measure dbh at the upper side of the slope.Measuring a leaning tree: Measure the diameter at 4.5 feet from the base and up the lean.Measuring a Swelling Tree Base or Buttress: Measure the tree just above the swell. If the buttress stops before DBH, measure as usual.

The Geographic Adventures of Captain James Cook

The Geographic Adventures of Captain James Cook James Cook was born in 1728 in Marton, England. His father was a Scottish migrant farm worker who allowed James to apprentice on coal carrying boats at the age of eighteen. While working in the North Sea, Cook spent his free time learning math and navigation. This led to his appointment as mate. Searching for something more adventurous, in 1755 he volunteered for the British Royal Navy and took part in the Seven Years War and was an instrumental part of the surveying of the St. Lawrence River, which helped in the capture of Quebec from the French. Cook'sFirst Voyage Following the war, Cooks skill at navigation and interest in astronomy made him the perfect candidate to lead an expedition planned by the Royal Society and Royal Navy to Tahiti to observe the infrequent passage of Venus across the face of the sun. Precise measurements of this event were needed worldwide in order to determine the accurate distance between the earth and sun. Cook set sail from England in August, 1768 on the Endeavor. His first stop was Rio de Janeiro, then the Endeavor proceeded west to Tahiti where camp was established and the transit of Venus was measured. After the stop in Tahiti, Cook had orders to explore and claim possessions for Britain. He charted New Zealand and the east coast of Australia (known as New Holland at the time). From there he proceeded to the East Indies (Indonesia) and across the Indian Ocean to the Cape of Good Hope at the southern tip of Africa. It was an easy voyage between Africa and home; arriving in July, 1771. Cook's Second Voyage The Royal Navy promoted James Cook to Captain following his return and had a new mission for him, to find Terra Australis Incognita, the unknown southern land. In the 18th century, it was believed that there was much more land south of the equator than had already been discovered. Cooks first voyage did not disprove claims of a huge landmass near the South Pole between New Zealand and South America. Two ships, the Resolution and the Adventure left in July, 1772 and headed to Cape Town just in time for the southern summer. Captain James Cook proceeded south from Africa and turned around after encountering large amounts of floating pack ice (he came within 75 miles of Antarctica). He then sailed to New Zealand for the winter and in summer proceeded south again past the Antarctic Circle (66.5 ° South). By circumnavigating the southern waters around Antarctica, he indisputably determined that there was no habitable southern continent. During this voyage, he also discovered several island chains in the Pacific Ocean. After Captain Cook arrived back in Britain in July, 1775, he was elected a Fellow of the Royal Society and received their highest honor for his geographic exploration. Soon Cooks skills would again be put to use. Cook's Third Voyage The Navy wanted Cook to determine if there was a Northwest Passage, a mythical waterway which would allow sailing between Europe and Asia across the top of North America. Cook set out in July of 1776 and rounded the southern tip of Africa and headed east across the Indian Ocean. He passed between the North and South islands of New Zealand (through Cook Strait) and towards the coast of North America. He sailed along the coast of what would become Oregon, British Columbia, and Alaska and proceeded through the Bering Straight. His navigation of the Bering Sea was halted by the impassible Arctic ice. Upon yet again discovering that something did not exist, he continued his voyage. Captain James Cooks  last stop was in February, 1779 at the Sandwich Islands (Hawaii) where he was killed in a fight with islanders over the theft of a boat. Cooks explorations dramatically increased European knowledge of the world. As a ship captain and skilled cartographer, he filled in many gaps on world maps. His contributions to eighteenth century science helped propel further exploration and discovery for many generations.