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TitleSaltmarsh condition assessment (aerial photo assessment)
CustodianWater and Marine Resources Division, Department of Primary Industries, Parks, Water and Environment
CreatorWater and Marine Resources Division, Department of Primary Industries, Parks, Water and Environment
DescriptionVarious condition data for saltmarshes collected by inspecting aerial photographs. Includes data on:
Input data
Lineage
Aerial photographs of the most recent flight runs (27/02/86 – 14/02/03) over Tasmania were assessed for evidence of impacts such as grazing, roading, drainage, within and immediately adjacent to saltmarshes (Table 1). Photographs were examined using a stereoscope to obtain a clear, magnified view of the saltmarshes and their associated impacts. Scoring systems for impacts were deliberately kept simple (+/-10%) to minimise the error in this highly subjective process. A single operator processed all of the saltmarshes to remove inter-operator error. Spatial data showing locations of native vegetation and Spartina angelica (rice grass) were also used, in conjunction with the aerial photograph assessment, to provide extra detail on those impacts.
The input variables, assessed using aerial photography, were scored between 0 (disturbed) and 1 (pristine) according to the details in Table 1.
Table 1. Summary of variables assessed using aerial photographs for the saltmarsh condition assessment. Scores indicate condition, (0 - degraded, 1 - pristine).
Variable | Assessed within or adjacent to saltmarshes? (column name) | Score | Other comments |
Drainage disturbance | Within (SM_DRWIN) and adjacent (SM_DRADJ) | 1 – absent, 0.5 – little, 0.25 – moderate, 0 – extensive | Presence/extent of drainage channels, realignment of natural drainage |
Grazing | Within (SM_GRWIN) and adjacent (SM_GRADJ) | Present (0) or absent (1) | Apparent grazing inferred from context i.e. local knowledge, evidence of horses, cattle tracks, or if adjacent to farm and no evidence of fences. |
Landfill | Within (SM_LFWIN) and adjacent (SM_LFADJ) | 1 – absent, 0.5 – little, 0.25 – moderate, 0 – extensive | Apparent landfill associated with industrial, agricultural, housing or other developments inside the saltmarshes was recorded |
Lateral extent of backing vegetation | Adjacent (SM_LEVEG) | % Native, % Exotic, % Other* (estimated to the nearest 10%) | Extent of boundary that has each certain type of vegetation class touching it. |
Natural vegetation condition | Adjacent (SM_VEGCON) | 1 – intact, 0.5 – good, 0.25 – moderate, 0 – disturbed | Inferred from adjacent vegetation/context/local knowledge. |
Roads or tracks | Within (SM_RDWIN) and adjacent (SM_RDADJ) | 1 – absent, 0.5 – little, 0.25 – moderate, 0 – extensive | |
Spartina anglica (rice grass) | Adjacent (SM_SPADJ) | Present (0) or absent (1) | Incorporated known distributions and aerial photography evidence. |
Urban development | Adjacent (SM_UDADJ) | 1 – absent, 0.5 – little, 0.25 – moderate, 0 – extensive | Housing adjacent. |
Width of backing vegetation | Adjacent (SM_WIDVEG) | % Native, % Exotic, % Other* | Within a 100 m width buffer around the saltmarsh. |
*Includes areas within the buffer that are not vegetation. Those areas that were natural (e.g. water, rocks, etc.) were included in the Native score, while those that were not (e.g. urban), were combined with the Exotic score.
Date createdJuly 2004
Scale and coverage1:25 000; Statewide
Column headingrefer to Table 1.
Type of dataCategorical
Number of classesvarious number of classes depending on the variable (see Table 1).
Assigning values to ecosystem spatial units
All of the data collected from the aerial photographs, for the different condition variables were assigned to the saltmarsh according to the details presented in Table 1.
CFEV assessment framework hierarchy