What Do You See? - University Of Idaho

What do you see?Message of the Day: Depending on our managementobjectives sometimes we need to see beneath the treesFOR 274: Forest Measurements and InventoryPrincipals of Surveying Introduction Leveling Distances Terrain Description US Public Land SurveyAn Introduction to Surveying: Social and LandIn Natural Resources we surveypopulations to gain representativeinformation about somethingWe also conduct land surveys torecord the fine-scale topographicdetail of an areaWe use both kinds of surveying in Natural Resources1

What do you see?Our ability to use appropriate management responsesmay depend on aesthetic qualities of how that activityaffected the resource.Social Surveying: Where it all BeganCharles Booth:“The Life and Labor of thePeople in London”He used direct observationsof a sample of London’spopulations with repeatedstandard measurementsHis findings had direct policyimplicationsSocial Surveying: Where it all BeganThe result of Booth’s survey was a spatially explicit map ofpoverty in London in 18982

An Introduction to Surveying: What is it?Land surveying or Geomatics aims to determinethe relative position of points above, on, orbeneath the Earth’s surfaceGeodetic Surveying Very large distances Have to account for curvature of the Earth!Plane Surveying What we do in forestryAn Introduction to Surveying: Why do we Survey?Foresters as a rule do not conduct manynew surveys BUT it is very common to: Retrace old lines Locate boundaries Run cruise lines and transects Analyze post treatments impacts onstream morphology, soils, fuels, etcAn Introduction to Surveying: Types of SurveyConstruction Surveys: To collect data essentialfor planning of new projects- constructing a new forest road- putting in a culvertTypical data: grades, elevation3

An Introduction to Surveying: Types of SurveyHydrological Surveys: To collect data on streamchannel morphology or impacts of treatmentson erosion potential- Depths of water features- Mapping ShorelinesAn Introduction to Surveying: Types of SurveyTopographic Surveys: To obtain dataon natural and man-made features onthe Earth's surface to produce a 3Dtopographic mapTypical Steps include:- Establish horizontal & verticalcontrols- Locating features that may bewanted by the survey- Compute distances, angles, andelevationsAn Introduction to Surveying: Types of SurveyLand, boundary, and Cadastral (public land)Surveys: To establish property lines andproperty cornersOriginal Surveys: establish new lines and corners inunsurveyed locationsRetracement Surveys: recover previously establishedboundary linesSub-division Surveys: delineate new parcels ofownershipCondominium Surveys: provide legal record ofownership4

An Introduction to Surveying: Types of SurveyGround, Aerial, and Satellite Surveys: To collectdata over extended spatial scalesLater courses like FOR 375 andFOR 472 will cover this is detailAn Introduction to Surveying: The Main PointsForestry surveying does not needengineering precision equipment- It is rare that 1/10” accuracy isneededHowever, although less theequipment we do use is still veryaccurateAn Introduction to Surveying: The Main PointsWhen surveying:- Carefully plan the Survey- It is difficult to find forgottenequipmentA survey can be ruined by:1 missing point1 incorrectly recorded pointInclude in your plan ways todouble check your data!!!5

Leveling: DefinitionsVertical Line: A line thatfollows the direction of gravity(defined by a plumb line)Level Surface: A surface(curved on earth) where everypoint is perpendicular to theplumb lineHorizontal Surface: A planeperpendicular to the plumblineElevation: Distance along the verticalline from the vertical datum to aparticular object.Vertical Datum: A levelsurface to which elevationsare referenced. At the Datum,elevations are set to zero.Leveling: The process of measuringelevations of points (or differences inelevation)Benchmark: A permanentobject with elevation accuracymeasured.Leveling: Measuring Elevation DifferencesThe most common method to measure elevation differences isdifferential leveling.Step 1: Place the instrumentbetween A and B and make it level.Step 2: Read off the scale at A (thebacksight).The Height of the Instrument (HI) isthen:HI ZA BSStep 3: Read off the scale at B (theforesight).Foresight is often called “– sight”Backsight is often called “ sight”The Elevation at B, ZB, is then:ZB HI – FSLeveling: Measuring Elevation DifferencesAnother common method to measure elevation differences istrigonometric leveling. We use this principal a lot in forestry!Uses: Slope Correction Plot Sizes Heights6

Land Surveying Equipment: The TheodoliteA Theodolite measures bothhorizontal and vertical anglesTransits are specializedTheodolites that have atelescope that can “flip over ortransit the scope” to allow backsightingLand Surveying Equipment: Laser RangefindersLaser rangefinders use thisrelationships to calculate distance:Distance speed of light * (time/2)The time refers to time of pulse to gofrom the instrument to the tree andback againLand Surveying Equipment: Total StationsTotal Stations are essentially acombination of a Theodolite and alaser rangefinderTotal Stations are commonly usedcivil engineering projects due tothere versatility and accuracy7

Leveling: Sources of ErrorInstrumental Errors: Errors caused by limitations in the equipment Loose tripod legs, crosshair out of alignment, etc.Natural Errors: Errors caused by the environment you are working in Curvature of the Earth, Refraction of light when measuring through a scope, Metal measuring sticks can expand/contract depending on thetemperature Wind can cause instruments to wobble Rough terrain can make leveling the instrument difficultHuman Errors and Mistakes Rushing or misreading a measure Not using equipment correctly Not understanding what a measure means Recording data incorrectlyHorizontal Distance Measurements: The ChainThe chain (66 feet) is the fundamentalunit of horizontal measurement usedby forestersIt is also called the surveyor’s orGunter’s chain1 Chain 100 LinksAll distances in US Land surveys arein chains and links1 sq mile 80 x 80 chains1 acre 10 sq chainsHorizontal Distance Measurements: The ChainA Chain can be measured with:PacingThe Hip ChainSurveyor’s Chain or RopeLarge tapes8

Horizontal Distance Measurements: The ChainPacing out a chain is one of the simplest andmost useful assets for a timber cruiserExpert pacers are accurate to 1 foot in 80 onlevel terrainA pace is commonly defined as two naturalsteps – i.e. each time the same foot touchesthe groundHowever, slope and obstacles may alter thelength of your pace and this will need to beaccounted forHorizontal Distance Measurements: Sloping GroundWhen it is not practical for two people to hold a tape level onrough sloping ground of is an object is in the way, the “breakingtape” method can be used.1. A horizontal distance ismeasured out so the uphillend is on the ground (say100’).2. A chaining pin is then placedat the ground.3. A 2nd horizontal distance isthen measured and pinplaced.4. Repeat until end and add upall the measures.Horizontal Distance Measurements: Sloping GroundTo correct for slope, we use the trigonometric leveling method.9

Terrain Descriptors: Aspect, Slope, & Slope FormAspect is measured with yourcompass and is the predominantdirection of the slope from plot center.Usually thought of ecologically interms of cardinal directions butgenerally recorded as an Azimuth.Terrain Descriptors: Aspect, Slope, & Slope FormSlope is generally measured with aclinometer by averaging readings tosomething at eye level uphill and downhill.Clinometers come in 3 scales: % scale (most common) Topographic scale degreestan(α) (rise/run) % scale readingtan(35 ) (70/100) 0.70 70%Deg tan-1 (% / 100)43%: deg tan -1 (0.43) 23.27%General Site Measurements: Aspect and SlopeIf the aspect or slope gradually changes across the site:Record the averageConcave slopes: gradual increase in slopeConvex slopes: gradual decrease in slope.Each slope form can be scene as you go up hill or across hill.10

General Site Measurements: Aspect and SlopeIf the site is on a canyon bottom or narrow ridge top use theaspect of those features and the average slope of the two sidesGeneral Site Measurements: Aspect and SlopeIf the site is on a canyon bottom or narrow ridge top but is mostlyon one side of a hill use the aspect and slope of that hill-sideGeneral Site Measurements: Slope Position11

General Site Measurements: Slope PositionFOR 274: Forest Measurements and InventoryMeasures of Land Area Area Measures Reading Maps US Public Land SurveyArea Determination: A Simple Closed TransversePurpose: Locate approximateboundaries of a tract and determinethe enclosed areaMost surveys involve 3 or 4 people:- 2 people chain horizontaldistances- 1 person establishes compasslines and records values12

Area Determination: A Simple Closed TransverseStart at most reliable property corner:If you have one record each cornerwith a GPS unitArea Determination: An Example of MethodsSo how can we measure theforest cover in this image?Area Determination: Dot GridsEach block 8 acIf 40 dots per blocksquare then each dot 0.2 acresPoints:May use denser grids to increase precisionor when the region is smallShould use average of several randomorientations13

Area Determination: Line InterceptTotal Length 140 inchesAssume % of area of each landcover class (forest, clearcut, ag, etc) proportion of line intercepting thatclasse.g., 14 inches of clearcut 14/140 10% of the areaArea Determination: PlanimeterIf map scale is knownA planimeter can beused by tracing theoutline of the desiredarea and scaling itagainst a know area.Area Determination: Via a GISIf map scale and“projection” is knownUse ARC to create apolygon and basicfunctions to calculatearea of each polygon14

Map Reading: ProjectionsUniversal TransverseMercator (UTM):Known UTMPosition Grid system to find position(NATO)UTM CoordinatesNorthings(blue line)UTM CoordinatesEastings(blue line) Entire earth divided intogrid (like Lat/Long) but itsput into 60 zones This is based on a scale inmeters north and meterseast (northing and easting)Longitude &LatitudeMap Reading: ProjectionsReading The Map: 5166000 meters North 5165000 meters North 5164000 meters North One blue dash to the nextis a travel distance of 1,000meters (3,281 feet)Map Reading: UTM An ExampleUSGS Topo Quad inMaryland: UTM Zone 18:Point 001 would be read as:–18 435000 E–18 4248000 N18 435000 E means Point 001 is in Zone 18 and it is 000 meterseast of the nearest reference line (435)15

Map Reading: UTM An ExamplePoint 002 is exactly half waybetween 435 and 436 UTMreference marksPoint 002 would be read as:– 18 435500 E– 18 4248500 NHow Far Away Are The 2 points?Map Reading: UTM An ExampleA2 B2 C25002 5002 (250000 250000) 2 (500,000) 2707.1 meters, or 2,320 feetMap Reading: UTM An ExampleHow far from 001 to 003?00316

FOR 274: Forest Measurements and InventoryTopographic Maps and the U.S.Public Land Survey Using Topographic Maps The U.S. Public Land SurveyTopographic Maps: An OverviewWhat are Topographic maps: The standard maps in forestry 1:24000 scale on 7.5 Topos Great detail Topographical reliefTopographic Maps: An OverviewFollowing the Lines: Where the land slopes steeply,contours are close together, andin flat areas the contours are farapart. If 2 contours touch cliff Contours lines can never cross Where contours cross ravinesand stream valleys you see a "V"shape, with the V alwayspointing upstream.17

Topographic Maps: An Overview Map Title Adjoining USGS Map Titles Longitude & Latitude UTM Coordinates Public Land Survey System(T&R)Topographic Maps: An Overview Map Distance Scale–Absolute–Reference Contour Interval ProjectionTopographic Maps: An Overview Magnetic Declination–Check the Year! This is from the MoscowWest Quad–36 years ago declinationwas 20 –Today it is 15 Shows 3 NorthReferences– True North– Magnetic North– UTM Grid North18