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TitleSaltmarsh adjacent vegetation condition sub-index
CustodianWater and Marine Resources Division, Department of Primary Industries, Parks, Water and Environment
CreatorSteve Carter, Environmental Dynamics
DescriptionAn index which rates the condition/extent of vegetation (native riparian and rice grass) adjacent to saltmarshes.
Input data
Lineage
An expert rule system was developed to score the condition of adjacent vegetation, which incorporated the outputs from the backing vegetation expert rule system and the assessment of Spartina angelica (rice grass). The definition table is presented in below (see ‘Assigning values to ecosystem spatial units’ below). Information on expert rules systems can be found in Appendix 3 of the CFEV Project Technical Report.
The experts that helped develop the expert rule system felt that the two inputs should be equally weighted in terms of their influence on the final adjacent vegetation condition score.
The method for assigning an adjacent vegetation condition sub-index score to the saltmarsh spatial units is provided below.
Date createdJanuary 2005
Scale and coverage1:25 000; Statewide
Column headingSM_VGADJ
Type of dataContinuous but has been converted to categorical format (see Table 2).
Number of classes3
Assigning values to ecosystem spatial units
An adjacent vegetation sub-index score (0 = poor condition – 1 = good condition) was assigned to saltmarsh spatial units as SM_VGADJ using the expert rule system shown as a definition table in Table 1 (e.g. if the saltmarsh has a HIGH score for backing vegetation and a LOW score for Spartina anglica (rice grass), then assign a score of 0.4). Using fuzzy logic enables input data and output results to be continuous rather than categorical as implied here (i.e. inputs and output data can range on a continuous scale between 0 and 1, and the process of executing the expert rule system will determine its membership as being HIGH or LOW) (refer to Appendix 3 of the CFEV Project Technical Report for more information on expert rules systems).
Table 1. Expert rule system definition table for the adjacent vegetation condition sub-index for saltmarshes.
Backing vegetation (SM_BKVEG) | Spartina anglica (SM_SPADJ) | Adjacent vegetation score (SM_VGADJ) |
H | H | 1 |
L | H | 0.4 |
H | L | 0.4 |
L | L | 0 |
The saltmarsh spatial data layer has the continuous adjacent vegetation sub-index data categorised according to Table 2. The categorical data was used for reporting and mapping purposes.
Table 2. Adjacent vegetation condition sub-index categories for saltmarshes.
Category | Min to max values |
1 | 0 to <0.2 |
2 | 0.2 to <0.8 |
3 | 0.8 to 1 |
CFEV assessment framework hierarchy