Distinguishing vegetation communities

Understand the difference between land cover, vegetation, ecosystems, and habitat Understand the general procedure used for mapping land cover using remote sensing Understand the importance of scale and MMU. Be able to construct a classification scheme for mapping. Understand the role of photointerpretation and interpretation keys. Understand the importance of accuracy assessment in mapping.

Vegetation The act or process of vegetating All of the plant life in a particular region (e.g., the vegetation of Wyoming) or period (e.g., Pleistocene vegetation) Ecosystem An interacting system of biotic (plants, animals, microorganisms) and abiotic factors (the environment) Land Cover All of the features occupying the land surface including vegetation, unvegetated areas, natural and human affected Habitat Habitat includes the physical requirements that a species requires to live.

Scope the project Acquire the aerial photography (or satellite data) Develop a classification scheme (mapping legend) Explore the area on the ground (if possible) Develop an interpretation key Create land cover units (make the map) Assess the accuracy of the product Refine as necessary

What is the desired mapping scale? What is the MMU? What resources are available (data, money, etc.)? How much time is available to do the project? How accessible is the map area?

The minimum mapping unit is the smallest area that will be digitized or classified on your map. Very important decision because it determines what patch sizes will be subsumed and which will be retained Will have different effects on map depending on the spatial configuration of the area (E.g., is the area composed of large homogeneous areas or is it patchy) Sometimes maps have different MMUs for some types (e.g., riparian) than others MMU is limited by resolution of the imagery

Copper Mountain, Colorado (IKONOS image) MMU determines which clearcuts get mapped

What qualities does the aerial photography need to have to accomplish the mapping task? Dates/times Spatial scale/resolution Spectral resolution (panchromatic, true color, false color IR, etc.) Geometric properties (orthorectified, vertical, oblique, etc.) Amount of overlap for stereo viewing, etc. Are suitable photos available (e.g., NAPP) Are contractors available to fly if no archive is suitable? Costs, timing, etc.

How many types do you want to map? How should you divide up the features you are interested in? What resources do you have? How will your interpretation be used? What do the funders want! Can be very controversial!

How would you classify this produce?

Must be useful Types must be detectable using the data you have Should be hierarchical Categories must be mutually exclusive Require explicit definitions of each class

I. Vegetated A. Forest 1. Evergreen a. Spruce-fir forest i. Spruce-fir with winterberry understory b. Lodgepole pine forest c. etc. 2. Deciduous B. Shrubland II. Non-Vegetated

1a. Trees (woody plants usually over 5m tall) present and forming % cover. 2a. Trees with their crowns interlocking, forming % [FOREST] a. Deciduous species contribute >75% of the total tree cover Deciduous Forest 4a. Upland a. Acer saccharum dominant in the canopy a. Forest of sheltered hillsides or pockets (coves), with moist comparatively rich soils, sometimes bouldery; Acer saccharum usually strongly dominant; herb layer may contain rare species such as Dryopteris goldiana, Panax quinquefolius, or Impatians pallida Acer saccharum-Fraxinus americana-Tilia americana Forest Alliance 6b. Forest of mid-elevation slopes and ridgelines; Acer saccharum typically co-dominant with Betula alleghaniensis and/or Fagus grandifolia Acer saccharum-Betula alleghaniensis-Tilia americana Forest Alliance 5a. Quercus rubra dominant in the canopy etc. 4b. Wetland etc. 3b. Deciduous species contribute <75% of the total tree cover etc. 2b. Trees forming open to very open strands, with crowns not usually touching etc. 1b. Trees absent, or less than 5m tall, or forming <10% cover etc.

Critical for understanding the distribution of land cover in the real world Helps you choose useful ancillary data Useful for understanding aerial photos back at the computer Nice to get out once in a while

What characteristics of this landscape might be important for making a map using aerial photography?

How would you classify this vegetation and where are the boundaries??

Interpretation keys should include the following: Explicit written description of each type in the classification Examples of each type as it appears in the aerial photography being used A list of key features of the type that can be used to distinguish it from other types Can take the form of a dichotomous key like you would use for keying out plants or animals Should be organized into an easy-to-use notebook or in some kind of digital format (e.g., hyperlinked web key)

Classification can take two basic forms: Manual photointerpretation of the imagery On hard copy using clear overlays or other tools On computer screen by digitizing with mouse Per-pixel classification of digital imagery Not used as commonly with aerial photography because the spectral resolution is not as good as in multispectral satellite imagery. Will talk about this more in the context of satellite data

Wetland community mapping – University of Wisconsin

Horticulture map at University of Wisconsin Individual shrubs delimited with carefully rectified orthophoto

Accuracy assessment is crucial for any mapping project Requires extensive field work to compare what is on the ground to what is designated on the interpreted photo Can be expensive – field work costs money Can be quantified using a suite of accuracy assessment metrics

If product accuracy is not sufficient must refine Assess the original data – are problems related to the information content of the data? Assess the interpretive process – are problems related to inconsistent or poor photointerpretation? Does the interpretive key need to be revised/amended? Assess the classification scheme – is the list of types appropriate and mappable. Would moving “up” the hierarchy be useful and if so would the map still be appropriate for users?

Habitat is usually a combination of land cover with other spatially distributed environmental drivers Climate Soils Proximity to water Availability of cover Contiguity of cover types needed for different parts of the life cycle Availability of food/prey Etc. Typically combine these as spatial layers in a GIS

GIS Habitat model schematic for Wild Boar

Land cover is the collection of features occupying the land surface Air photos are useful for mapping land cover, especially at fine scales Land cover mapping is a process with a series of important steps, each of which must be carefully executed Our ability to accurately map land cover can be limited by the quality of the photography or other data that we are interpreting Important to be realistic about what can be accomplished