Representative Conservation Value

Find further information on the Conservation of Freshwater Ecosystem Values (CFEV) Program and its data at www.dpipwe.tas.gov.au/cfev.

Attribute data

TitleRepresentative Conservation Value (RCV)

CustodianWater and Marine Resources Division, Department of Primary Industries, Parks, Water and Environment

CreatorGIS Unit, Information and Land Services Division, Department of Primary Industries and Water

DescriptionRanking of relative conservation value for Tasmania’s freshwater-dependent ecosystems

Input data

Output from the CFEV Project’s spatial selection algorithm

Lineage

RCV is a ranking or relative conservation expressed as the relative importance of a representative biophysical class, with a priority on spatial units of high naturalness. The rules (outlined below) for assigning the ecosystem spatial units with an RCV rating were developed by the CFEV Technical Management Group using the raw ranking data output from the spatial selection algorithm (Appendix 5 of the CFEV Project Technical Report). This output is included in the CFEV database for each ecosystem theme as ES_SORTIT, KT_SORTIT, etc.).

Date createdMarch 2005

Scale and coverage1:25 000; Statewide

References

Brown, M.J., Kirkpatrick, J.B. and Moscal, A. (1983). An Atlas of Tasmania's Endemic Flora. Tasmanian Conservation Trust, Hobart.

Commonwealth of Australia. (1997). Nationally Agreed Criteria for the Establishment of a Comprehensive, Adequate and Representative Reserve System for Forests in Australia. A report by the Joint ANZECC/MCFFA National Forest Policy Statement Implementation Sub-committee, Canberra. 24 pp.

Column headingES_RCV, KT_RCV, SM_RCV, RS_RCV, WB_RCV, WL_RCV

Type of dataCategorical

Number of classesES_RCV = 3, KT_RCV = 3, SM_RCV = 3, RS_RCV = 3, WB_RCV =3, WL_RCV = 3

Assigning values to ecosystem spatial units

An RCV ranking (A, B or C) was assigned to estuary, karst, saltmarsh, river, waterbody and wetland spatial units based on the Project’s conservation objectives. The conservation objectives include conserving at least two examples of every ecosystem biophysical class (e.g. Brown et al. (1983)), conserving a minimum of approximately 15% of total extent of each ecosystem theme, (e.g. JANIS biodiversity criteria, sensu (Commonwealth of Australia 1997)) and giving priority to spatial units in better condition. These conservation principles are translated to banding rules in the following sections for each ecosystem theme.

Estuaries (ES_RCV)

The banding of RCV for estuaries was based on the number, not area, of estuaries, as estuary values were dependent on the entire estuary as a unit, and not consistently on estuary size. Two examples of most biophysical classes were selected in the first 30% of estuaries selected by the spatial selection algorithm, including the best example of each biophysical class. At this point, all biophysical classes which occur in only one estuary were also selected within band A. There were no estuaries selected within the C band due to the low number of estuaries assessed. There were also a relatively low number of total biophysical classes, several of which occurred in only one or two estuaries.

The RCV banding rules for estuaries were as follows:

Assign at least the first two estuaries selected by the spatial selection algorithm for each biophysical class as A.

Note: Some biophysical classes may occur in a single estuary, in which case assign as A.

Assign estuaries selected by the spatial selection algorithm within the first 30% of total estuary number as A.
Assign all remaining estuaries as B.
No C band was assigned to this ecosystem theme.

Karst (KT_RCV)

The banding of RCV for karst was based on the number of karst systems, not area, due to the integrated nature of individual karst systems. By the time 30% of the total number of karst units had been selected by the spatial selection algorithm, an example of every class had been included in band A. At this point, 36 of the rarest karst classes had 100% of the karst systems in which they occurred selected within band A. The inclusion of at least two examples for each karst class in band A would require capturing a large proportion of the total number of karst systems. However, inclusion of the first rule (below) ensures that two examples of every class were selected within band A. C band was not populated for karst systems, due to the low number of mapped karst units and the unique biological diversity and high levels of local endemism thought to be present within individual karst systems. While a karst biological classification was not undertaken as part of the CFEV Project, the banding rules (absence of band C) recognise the biological significance of karst systems.

The RCV banding rules for karst units were as follows:

Assign at least the first two karst selected by the spatial selection algorithm for each biophysical class as A.

Assign karst selected by the spatial selection algorithm within the first 30% of total karst number as A.
Assign all remaining karst as B.
No C band was assigned to this ecosystem theme.

Rivers (RS_RCV)

The banding of RCV for rivers was based on river section length. Upon selection of 15% of the total river section length by the spatial selection algorithm (in band A), all of the biophysical classes were selected within at least two river clusters, except for one biophysical class which was totally selected within one river cluster. At this point, five of the rarest biophysical classes had 100% of the river sections in which they occurred selected, and another two biophysical classes had greater than 80% selected in band A. A large proportion of the common biophysical classes were also selected within the 15% threshold, hence some rules were set to reduce the amount of those selected within band A. An expert panel determined the rules which resulted in appropriate proportions of river sections being allocated within each RCV band.

The RCV banding rules for rivers were as follows:

Assign at least the first two river clusters selected by the spatial selection algorithm for each biophysical class as A.
Assign river sections selected by the spatial selection algorithm within the first 15% of total river section length as A, with the following exceptions:
If the biophysical classes driving the selection of the river section has a total extent >50 000 km, only assign those river sections that are selected by the spatial selection algorithm within the first 5% of total river section length as A, otherwise assign as B.
If the biophysical class driving the selection of the river section has a total extent of 10 000-50 000 km, only assign those that are selected by the spatial selection algorithm within the first 10% of total river section length as A, otherwise assign as B.
If the biophysical class driving the selection of the river section has a total extent <10 000 km, only assign those that are selected by the spatial selection algorithm within 15-50% of total river section length as B.
If the biophysical class driving the selection of the river section has a total extent of 10 000-50 000 km, only assign those that are selected by the spatial selection algorithm within 10-40% of total river section length as B.
If the biophysical class driving the selection of the river section has a total extent of >50 000 km, only assign those that are selected by the spatial selection algorithm within 5-30% of total river section length as B.
If the biophysical class driving the selection of the river section has a total extent <10 000 km, assign those that are selected by the spatial selection algorithm within 50-100% of total river section length as C.
If the biophysical class driving the selection of the river section has a total extent of 10 000-50 000 km, assign those that are selected by the spatial selection algorithm within 40-100% of total river section length as C.
If the biophysical class driving the selection of the river section has a total extent of >50 000 km, assign those that are selected by the spatial selection algorithm within 30-100% of total river section length as C.

Saltmarshes (SM_RCV)

The banding of RCV for saltmarshes was based on saltmarsh area, since saltmarshes with larger area are seen as having greater bioconservation significance (e.g. diversity and area of meso-habitats, etc.) than smaller ones. By the time of 50% of the total number of saltmarshes had been selected by the spatial selection algorithm, two examples of the majority of biophysical classes were selected within band A and these include the best examples. To ensure that an adequate proportion of the rare biophysical classes were included in band A, it was then decided that any biophysical class with an extent <100 ha should have the saltmarshes in which it occurs grouped within band A. C band was not populated as it was believed that current saltmarshes were mere fragments of their former extent, hence conservation of these remaining saltmarsh ecosystems was considered highly important.

The RCV banding rules for saltmarshes were as follows:

Assign at least the first two saltmarshes selected by the spatial selection algorithm for each biophysical class as A.

Assign saltmarshes containing any biophysical class with a total extent <100 ha as A.
Assign saltmarshes selected by the spatial selection algorithm within the first 50% of total saltmarsh area as A.
Assign all remaining saltmarshes as B.
No ‘C’ band was assigned to this ecosystem theme.

Waterbodies (WB_RCV)

The banding of RCV for waterbodies was based on the number of spatial units rather than area, as waterbody values were dependent on the entire waterbody as a unit, and not consistently on waterbody size. In most cases, two examples of every biophysical class were selected within band A upon selection of 30% of the total number of waterbodies. Where only one example was selected within the first 30%, it was usually because this biophysical class only occurred in one waterbody. At this point, approximately 40% of all waterbody biophysical classes were totally selected. Some of the more common biophysical classes have a high proportion of their occurrences selected in the first 30% of the spatial selection algorithm iterations . It was decided that a maximum threshold of 50 waterbodies would apply to the representation of each biophysical class in band A, with the remaining waterbodies selected in the top 30% assigned to band B.

The RCV banding rules for waterbodies were as follows:

Assign at least the first two waterbodies selected by the spatial selection algorithm for each biophysical class as A.

Assign the first 30% of all waterbodies selected by the spatial selection algorithm as A, with the following exception:

If the biophysical class driving the selection of the waterbody has a total number >50 of occurrences within the first 30% of waterbodies, only assign the first 50 waterbodies selected by the spatial selection algorithm with that biophysical class as A, otherwise assign as B.

Group remaining waterbodies by biophysical classes (i.e. waterbody will occur in more than one group).

Sort by Naturalness score and then selection order (i.e. conservation value ranking, the order of output from the spatial selection algorithm).

Select the top half of waterbodies within each group and assign as B; assign the bottom half within each group as C.
If a waterbody is in the top half of at least one biophysical class group (i.e. any of its biophysical classes has been assigned as ‘B’ at least once), that waterbody is assigned as B; otherwise assign as C.

Wetlands (WL_RCV)

The banding of RCV for wetlands was based on wetland area, since wetlands with larger area are seen as having more bioconservation significance (e.g. diversity and area of meso-habitats, etc.) than smaller ones. Upon selection of 20% of the total area of wetlands by the spatial selection algorithm, all of the best examples for each biophysical class were selected within band A, however, not always two examples. Upon selection of 30% of the total area of wetlands, all but one biophysical class either had two examples selected or 100% of the wetlands in which they occurred were selected in band A. Approximately four of the rarer biophysical classes had 100% of the wetlands in which they occurred selected in band A. To ensure an adequate selection of the rare biophysical classes within band A, it was decided to include 100% of wetland spatial units containing biophysical classes (i.e. the class driving the selection of the wetland polygon) with a total extent <500 ha.

When 30% of the total area of wetlands had been selected, some of the extensive classes were selected within a high proportion of the selected wetlands. The TMG decided it was not appropriate to select all of these extensive classes within band A. Hence for any biophysical class that had a total extent >5000 ha, only those selected after 12.5% of the total wetland area were allocated to band A.

The RCV banding rules for wetlands were as follows:

Assign at least the first two wetlands selected by the spatial selection algorithm for each biophysical class as A.

Assign wetlands containing any biophysical class with a total extent <500 ha as A.

Assign wetlands selected by the spatial selection algorithm within the first 30% of total wetland area as A, with the following exceptions:

If the biophysical class driving the selection of the waterbody was a total extent >5000 ha, only assign those wetlands that were selected by the spatial selection algorithm within the first 12.5% of total wetland area as A; the remaining wetlands with biophysical classes >5000 ha (selected by the spatial selection algorithm within 17.5 – 30% of total wetland area) should be assigned as B.

Group remaining wetlands by biophysical classes (i.e. wetland will occur in more than one group).

Sort by Naturalness score and then selection order (i.e. conservation value ranking, the order of output from the spatial selection algorithm).
Select the top half of wetlands within each group and assign as B; assign the bottom half within each group as C.
If a wetland was in the top half of at least one biophysical class group (i.e. was assigned as ‘B’ at least once), that wetland was assigned as B; otherwise assign as C.

CFEV assessment framework hierarchy

Estuaries>Conservation evaluation
Karst>Conservation evaluation
Rivers>Conservation evaluation
Saltmarshes>Conservation evaluation
Waterbodies>Conservation evaluation
Wetlands>Conservation evaluation