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135 Cards in this Set
- Front
- Back
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What is forest inventory?
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-Systematic accounting of various "resources" in a forest
-Provides base information for all planning and management activites at all spatial scales. -sampling is ground based and intensive |
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What are the 8 steps to designing an inventory?
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1. compile and study all existing available information concerning forest area
2. Decide on what information inventory will provide 3. Address westions regarding time and funds available 4. Discuss design details 5. Develop detailed instructions and measurement protocols 6. Develop forms and protocols for data acquisition and storage 7. Test the system 8. Train individuals |
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What are some of the difficulties when designing an inventory?
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- defining what is forest land
- combining inventory info over time -cominbing land inventory info managed by multiple agencies -combining inventories accross spatial scales -irregular program funding -increased demand for current, detailed, and accurate information on forests and othe land that is spatially accurate |
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What are some attributes of a good inventory?
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1. Current
2. There is a process in place for re-inventory 3. updating process been explicitly addressed 4. complete 5. Capable of providing information through time 6. Information is reliable 7. Inventory is scalable 8. sufficient in addressing management issues of today 9. Easily adapted for new variables 10. Makes best us of appropriate technologies 11. Ability to provide routine reports 12. Quality assurance system in place 13. Provisions for cross linkages |
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What are some attributes of affective inventory administration?
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1. provide clear lines of responsibility
2. stable and adequate funding for implemenation and maintenance 3. Implement an effective quality assurance system 4. Produce routine reports on components 5. Support innovation for on-going research |
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What is the purpose of the canadian national forest inventory (NFI)?
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Assess and monitor the extent, state and sustainable development of canada's forests in a timely and accurate manner
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What are some attributes of the NFI?
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1. network of sampling points accross population
2. stratification of sampling points, with varying sampling intensity among strata 3. Estimiation of some attributes from remote sensing 4. Estimation of wood volume and other detailed data from a ground based su-sample 5. Estimation of changes in 3 & 4 from repeated measurements 6. Compilation of NFI attributes |
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What are the three types of edges?
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1. hard edges
2. soft edges 3. imaginary edges |
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What are hard edges?
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This type includes a forest next to a clear-cut, lake , swamp or road.
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What are soft edges?
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Include a gradual change in stand differences. These differences could be a result of soil, slope or aspect variation within a forest producing different plan communities
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What are imaginary edges?
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Include legal boundaries, zoning differences or usage differences
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What is edge effect?
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refers to trees or plant communities on an edge, growing differently than those in other loacations within a stand
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What is edge effect bias?
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The bias generated by not sampling elements of interest with a polygon with 100% selection probability
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What are the two main sources of edge effect bias?
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1. Avoidance of the edge
2. Method of sampling edge |
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Explain when avoidance of sampling the edge is acceptable
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May be acceptable if no bio differences between interior of poly and edge.
May be acceptable if edge is very small in proportion to overall area |
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Explain how method of sampling can introduce bias.
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-sampling near edge portion of plot will land outside polygon
-probability of certain tree being "in" plot are reduced and hence weighting of trees value is reduced compared to if the tree was selected with appropriate probability |
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What are the attributes of tree centred viewpoint?
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-where tree has a plot around it and trees selected if sample point lands within tree plot
-when sampling on edges, portions of these tree plots can land outside boundary -reduced selection probability for that tree and all characteristics that tree represtents |
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What are the attributes of plot centred viewpoint?
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-if plot established near edge, part of actual plot could fall outside boundary.
-meaning plot did not have equal probability of being selected because area sampled is less than 100% |
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Explain direct correcton
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It is a measure of the portion of tree that falls outside boundary
-The tree is weighted greater using proportions |
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What are some issues with direct correction?
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-Many distances of tree proportions falling outside boundary to measure
-sampler is not always certain of boundary location -curved or irregular boundaries make calculations complicated |
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When is direct correction used?
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-when time and money are not an issue
-where working outside polygon is impractical or prohibited -curved or irregular boundaries make calculations complicated |
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Explain the mirage method of unbiased edge correction.
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-Fold portion of tree that falls outside boundary back on itself
-offsets selection probability bias because total area of tree is being sampled -establish mirage sampling point outside boundary |
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What are the issue with the mirage method?
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-Boundaries not straight or well defined = folding difficulty
-sampler must move ouside polygon -non circular plots are difficult to work with |
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When is the mirage method used?
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-If no issues with working outside polygon exist
-polygon with straight boundaries and 90 degree angle corners -in these cases this method is very reliable |
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Explain the reflection method
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-Reflect boundary back onto tree that has boundary slop-over
-same as rotating boundary about tree centre 180 degrees |
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What are the issues with the reflection method?
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-bias introduced in corners and narrow portions of polygon because of rotating tree onto portions already being projected onto (or something, terrible explanation in the notes)
-assymetrical inclusion zones contribue bias -sampler may need to travel outside poly |
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When is the reflection method used?
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-useful for wiggly boundaries or holes
-another mthod needs to be used where polygon narrows and in complicated corners |
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Explain the toss back method
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-set up grid which extends past the boundaries of the polygon
-each point visited and full sweep is done -all trees in polygon are counted -trees in outside boundary are added to plot pre-designated plots as extra trees |
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What are the issues with the toss back method?
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-must sample outside polygon
-need to visit all extra grid points -method not that well known -problem when sample points are far apart |
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When is the toss back method used?
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-excellent way of eliminating edge effect bias
-for operational cruisingm, where there are dense grids -useful for polygons with complicated boundaries and holes |
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What are two biased edge correction methods?
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1. half-sweep border plot
2. edge avoidance |
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What is the definition of stocking?
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The qualitative assessment of the degree of stocking, which is a relative density.
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What is the definition of density?
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Quantitative measure of the degree of crowding
-not relative to a standard -relates to stand competition |
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What are some measures of density?
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1. Sample measure
2. Indices of density |
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What are some examples of indices of density?
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Curtis' relative density
Stand density index Crown pompetition factor |
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What are the characteristic of Curtis' relative density?
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-site and age independent
-uses BA, Ha, and quadratic mean dbh |
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What are the characteristics of Stand density index?
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-based on predetermined limiting relationship between the number of trees/unit area and average tree size
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What are the characteristics of crown competition factor CCF
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-predetermined relationship between crown width and dbh for open grown trees
-calculate the ratio of crown area as if all the trees were open grown, relative to one hectare of area, expressed as a percent |
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What are the six reasons for growth and yield measurements and estimations?
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1. Assessment of treatments
2. investment into companies 3. management eg sustained yield 4. rank sites for investment 5. simulations to answer what-if questions 6. knowledge |
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What are the five problems with growth and tield?
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1.Canonly measure past growth
2. variability of biological systems 3. long term nature of forests 4. variability of management regimes 5. climate change |
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What is yield?
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cumulative growth at a given time
-may be a lag period -can represent dbh over time, height over time, weight over time, vol/ha over time, etc. |
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What is growth?
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The change in yield
-current annual invrement -mean annual invrement -periodic annual increment |
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What are the characteristics of current annual increment?
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-first derivative of yield curve
-current year's growth |
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What are the characteristics of mean annual increment?
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-cumulative growth/number of years (age)
-average annual growth up to the current time |
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What are the characteristics of periodic annual increment?
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-growth over a period/number of years in period
-average annual growth for period of interest |
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When is mai at maximum?
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When mai=cai=pai (the biological rotation age)
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What are the units of measurements for tree and stand level?
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-tree level = mm/year, m/year, or m3/year
-stand level = m3/ha/year |
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What are the levels of growth information?
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1. tree
2. stand 3. forest 4. landscape |
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What is tree level growth affected by?
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1. species, parent (genetics)
2. site - elevation, moisture, etc. 3. tree age 4. stand conditions (density) 5. agents ouside tree 6. events - fire, drought, etc. 7. human interactions |
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What are some methods used to measure tree growth?
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1. incremental borer
2. repeated measure of same tree over time 3. detailed stem analysis |
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Explain stand growth.
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The change in stand level characteristics because of...
1. tree growth 2. mortality 3. ingrowth 4. cutting |
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What are two types of plots for measuring stand growth?
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1. temporary plots TSPs
2. Permanent sampling plots PSPs |
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What is the advantage of psps over tsps?
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Psps show "real change" as the same trees measured in different time periods
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What are the 3 types of PSPs?
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1 permanent boundaries
2 permanent boundaries plus tagged trees 3 permanent boundaries plus tagged and mapped trees |
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What are the characteristics of PSPs?
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- usually fixed area plot with buffer area
- can be square or circular - often polyareal - are regulary re-measured at same time every period - long term budget item and very expensive |
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How is the growth and yield measure at forest and landscape level?
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Measure of grwoth at stand level can be used to estimate growth at forest and/or landscape level by obtaining averages of stand measures
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Whare the 3 types of models produced?
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1. stand level
2. single tree, distance independent 3. single tree, distance independent |
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Describe stand level models.
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stand level growth estimation for a stand over a short period of time
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What are yield projection models?
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fit volume per hectare as a function of age and other variables
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What is the most common yield projection model used in BC?
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Variable density yield projection system (VDYP)
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What are the advantages of stand level models over tree-level models?
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1. simpler
2. can easily program equations into portable computers 3. need stand level infor to run model 4 use a mixture of PSPs with TSPs to build models |
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What are the disadvantages of stand level models over tree-level models?
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-difficult to represent mixed species and/ or multi aged stands
-hard to estimate the results of partial cutting -get info for stand level only- no detail on individual trees |
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What are the characteristics of tree-level models?
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-growth of individual trees over time
-competition among trees can be based on stand level density measure or on tree level density/competition measures -tree level density competitive measures can be spatial or non-spatial |
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What are the two types of tree level models?
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1. Single tree distance independent growth models
2. Single tree distance dependent models |
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Give the characteristics of single tree distance-independent models.
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-competition measures aspatial
-model easch tree -> sim to get stand volumes -can include mortality by tree -can model ingrowth -requires PSP data with tagged trees -need tree list and productivity data |
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What is an example of a single tree distance-independent model?
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Prognosis BC
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What are the advantages of tree level dist. indi. over stand level?
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-easier to model mixed species
-thinning/fertilization by tree characteristics -easier to model PC but only by tree characteristics |
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What are the disadvantages of tree level dist. ini.?
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-more equations than stand level model
-cost of information is higher-need tagged psps to build model - too much info on outputs sometimes |
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What are the characteristics of single tree distance dependent models?
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-need tagged and mapped psps data for model build
-need tree list and all spatial postions of tree -can get results for pc/thinning that is spatial explicit -competition based on distance between trees |
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What is an example of a single tree distance dependent model?
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Tree and stand simulator (TASS)
-available to us as TIPSY |
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What are the advantages of single tree distance dependent models?
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-most flexible for answering what if questions
- more reflective of real growth processes -easier to model mixed species |
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What are the disadvantages of single tree distance dependent models?
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-difficult to link to forest cover maps since detailed tree info ususally required
-input data more expensive -not all info is available |
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What is the fundamental unit of radiation?
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the photon
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what is the relationship between wavelength and frequency?
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as wavelength increases the lower the frequency and lower the energy content
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What is the range in wavelengths for the visible spectrum?
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400 to 700 nanometers
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what are the three possible outcomes of EM radiation interacting with a feature on earth?
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1. absorbed
2. reflected 3. transmitted |
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What occurs to absorbed raditation?
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raises temperature of object and is reemitted as heat
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what are spectral signatures?
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the pattern of spectral responses which can desibe in form of a graph showing percent of radiation of different wavelength reflected from an object
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what are the two types of aerial photos that can be taken and their characteristics
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1. vertical -tilt from vertical < 3 degrees
2. oblique - tilt from vertical > 3 degrees |
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what are the advantages of vertical photos?
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-approximatly uniform scale
-determination of direction same as map -easier to interpret -minimal mathematical correction -can be used as a map -steroscopic more effective than oblique |
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what are the advantages of oblique photos
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-covers much more ground area per shot
-area covered by cloud cover are easier to shoot with olbique -more natural news because we are accumstomed to view -objects that are tall may be visible -determination of elevation more accuaate -may be acquired from inexpensive cameras |
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What is the focal length?
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distance between middle of camera lens and focal plane
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What are the characteristics of focal length?
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as focal lenth increases, distortion decreases
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What are the two ways to determine scale on photos?
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-photo distance/ ground distance
- focal lenth/altitude |
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what is the usual overlap on airphoto missions?
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- 60% between successsive images
- 30% between adjeacent flight lines |
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What factors are assessed when interpreting photo features?
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shape, pattern, size, tone/colour, shadow, testure, association/site, time
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Why do you assess shape on photos?
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-form object used to identigy object
-regular uniform shape indicate human involvement |
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Why do you assess shadow on photos?
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info about ovjects height, shape and orientation
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why do you assess pattern on photos?
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spatial arrangement of objects is useful for identifying an object and its usage
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why do you assess assocation/site on phots?
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associate an object with another or to its environment helps with identification
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why do you assess tone/colour on a photo?
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colour characteristics relative to other objects are used to identify features
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why do you assess texture on a photo?
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physical characteristics of object change way they appear on a photo
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why do you assess size on a photo?
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it is a measure of an objects surface area
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Why do you assess time on a photo?
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-temporal changes useful for determining historical change in an area
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To interpret tree species on an aerial photo what five tree characteristics wust be examined?
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1. crown boundary
2. crown topography 3. crown tone/ hue 4. branching habit 5. foliage density |
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what are the 4 basic concepts of digital remote sensing?
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1. spatial reolution
2. radiometric resolution 3. temporal resolution 4. spectral resolution |
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Describe spatial resolution
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-smallest unit of distance that can be determined by a sensor measurement of the target
- aka pixel size -function of platform and sensor geometry for instant of measurement -considerations: level of detail, data quality, spatial arrangement of targets |
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What is the instantaneous field of view (IFOV)?
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-angle of smallest unit recordable by a sensor
-pixel size = sensor altitude x IFOV |
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What are some examples of low, medium, high, and very high spatial resolution, respectively?
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-modis
-landsat -quickbird -aerial photography |
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What does one consider when choosing a spatial resolution?
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-suitability to task being performed
-cost of acquiring, processing and storing image -compatability with other data sets with which the imagery may be used. - which features need to be detected in imagery |
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Describe what spectral resolution is
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number and dimension of specific wavelength intervals in the EM sprectrum to which remote sensing instrument is sensitive
IE - number of specral bands/channels -location of bands in em spectrum -bandwidth of each channel |
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What are the tree spectral resolution categories?
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1. panchomatic
2. multispectral 3. hyperspectral |
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Describe the characteristics of panchromatic sesors
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-record energy in one braod group
-typically in visible and near infared -varying spatial resolutions -generally low radiometric resolution |
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Describe the characteristics of multi spectral sensors
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-record energy in multiple broad bands
-varying spatial reolution -generally low raiometric reolution -more energy revirded, less spectral detail - eg landsat |
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Describe the characteristics of hyper-spectral sensors
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record energy in upwards of hundreds of narrow bands
-varying spatial resolutions -generally high raiometric resolution -less energy recorded more spectral detail |
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What are the three technologies inforporated into lidar?
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1.laser ranging for accurate distance measurements
2. sattelite positiong to determine geographic postion and sesor height 3. aircraft altitude measurement |
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How does lidar determine distance?
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-emits pulse of laser light and precisely measure the elapsed time for a reflection to return from ground below
-knowing speed of light and change in time, distance to target calculated |
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What does lidar stand for?
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Light detection and ranging
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what are the requirements when using lidar?
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precise gps location
-precise inertial measurement unit IMU |
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What does the accuracy of lidar measurements depend on?
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-flying height
precision of lidar instrument and processing -accuracy of sensor postion, height and altitude data -characteristics of target area |
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What are the two scales which we analyse lidar data at?
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1. tree scale
2. plot scale |
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At tree scale, what issues does lidar have with tree heights?
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-missed heights
-trees without peak (missed trees) |
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What affects the determination of tree heights?
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-sampling density
-tree dimensions -occlusion -surface reflectivity (pulse penetrates canopy without good return from peak area) |
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How does GIS represent reality?
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-with spatial positions of objects
-attributes for the objects |
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What can GIS do for us?
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-capture data
-store data -analyze data -display data -output data |
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What are some examples of GIS capturing data?
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digitizeing, scanning, field surveys, downloading existing data
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What are the two main ways of representing spatial data?
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-raster: grid over entire area
-vector: polygons, lines, points |
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What is topology?
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Spatial relationship of adjacency and connectivity among objects
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How is topolgy stored?
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-Shared geometry
-Coincidental geometry |
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What is shared geometry?
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Where coordinates of a shared line segment or vertex are stored once in the database
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What is coincidental geometry?
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where coordinates are stored for each feature; results in duplicating coordinates in the data base
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What is a relational database?
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data spread accross several tables, which are related togeth via common iddetifiers
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What is a geodatabase?
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A relational database that stores geographic data
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What are feature classes?
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collections of features that share same geometry type
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What are feature datasets?
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feature classes grouped together by a common factor.
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What do more advanced gis data analysis require to answer questions?
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-proximity (how near or distant)
-area (how large) - overlays (merge and clip info from more than one layer) - connections to existing models |
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What are the three main issues in GIS data?
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1. map projection
2. scale 3. accuracy |
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Explain the issue with map projections
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-earth is 3d, whereas maps are 2d
- must relate all data to a horizontal plane and a reference point -causes distortions |
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What are the four types of distortions for map projections?
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1. shape
2. area 3. distance 4. direction |
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What is impossible to do in practice with map proojections?
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maintain true shape and area on same map
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What is needed in order to display different sets of data and to analyze
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The same projection and datum
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What are some ways to test positional accuracy?
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-larger scaled map
-GPS -survey data -internal evidence -check for shoddy work |
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What is attribute accuracy?
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the closeness of attribute values to their true value
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What are the two tyypes of data sources?
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1. digital data - remote sensing
2. ground data - gps points |
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What is required to link data?
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1. all data must be in common spatial coordinate system
2. must know projection 3. need control points to link data to ground 4. start with basemap and then connect all data to this |
