The basic spatial entity for the research of natural forests is always represented by a locality of natural forest (locality). It is an equivalent to a small special protected area (SSPA). In GIS, a locality is distinguished at two spatial levels.
We have been gathering (and updating) information about a locality through attributes related to the area (stand representation) for most of the natural forests.
In some localities left to spontaneous development the locality is represented by a tree (stem) and the attributes are related to a point as a representative of standing or laying tree (point/line representation). Therefore such locality can be characterized more precisely by assessing data about trees (stems) that form it.
STAND (polygon) representation of natural forestPolygon in GIS usually represents stand group. In some cases, this stand group is further divided by either boundary of the forest naturalness degree or boundary of time left to spontaneous development or by both. Data from FMP (vector forest detail) represent a basis for this type of data. In localities where data from FMP were not available we used data from OPRL (forestry contour map in digital raster format) for vectorization. Survey respondents (Evaluation of naturalness) provided us with description attributes concerning naturalness and time left to spontaneous development.
- Tree data model
- An individual (tree) is represented by one record in the database. The uniqueness of the tree is given by a unique identifier (STROM_ID). In case of more-stemmed tree the model becomes ineffective – redundancy of description attributes, coding of different stem characters etc. In the graphical form, one tree is represented by one GeoObject always visualized by one map symbol for standing stem(s) and one or more symbols for lying stem(s) of the given tree.
Tree data model - attributes
- Stem data model
- An individual (tree) is represented by one or more records (stems) in the database. One record describes one tree stem. The uniqueness of the stem is given by combination of two identifiers (STROM_ID, KMEN_ID). In the graphical form, one stem is represented by one GeoObject visualized by either one point map symbol (standing stem) or line map symbol (lying stem). Grouping GeoObjects representing more standing stems of one tree and their substitution by one map symbol is used only for the map output. The cartographic output is similar to the one from the tree data model.
Stem data model - attributes
- Standing tree
- Both data models interpret a standing stem as a point. In the tree data model, positions of all stems of the given tree are related to one (reference) position, i.e. to a point as a tree representative. In the stem data model, each stem is identified by its real position because it is located individually.
- Lying tree
- Both data models depict lying stem as a line. However, description attributes are related to a point representative of the lying stem (one database). Reference point of the lying stem is located at the base of the uprooted stem or in the centre of the stump remnant. Link between line and reference point of the line is implemented through the database, i.e. through the identifier (STROM_ID or pair STROM_ID and STEM_ID).
Description attributes differ and their completing varies with the used methodology:
whether the researched tree is a part of locality assessed by the research methodology (stem in a transect, stem outside a transect)
or by the monitoring methodology (stem in an inventory plot, stem in a core area in a transect, stem in a core area outside a transect).
