Caring for our Country
Developing an integrated approach to catchment management is the only way to address the major threats to koalas, namely forest decline and habitat loss associated with reducing soil fertility, logging and broad acre burning, all of which result in significant, but unaccounted green house gas emissions.
The Federal government have announced a 'Caring for our Country' scheme and the national priorities relevant to the Five Forests catchments are reducing soil acidification, increasing soil carbon sequestration, improving the management and extent of endangered forest ecosystems and improving the lot for iconic endemic species.
Referred to in the Garnaut final draft report (pgs: 82, 354 & 404 {Table 6.1}) is the Australian 'slow pyrolysis' technology (www.bestenergies.com) that, in addition to reducing emissions from deliberate burning, as well as generating carbon negative electricity and providing the opportunity to create employment, produces a valuable soil conditioner called 'biochar' that greatly improves soil water holding capacity, Cation Exchange Capacity, soil pH, structure and fertility.
Research undertaken by BEST Energies and the NSW Department of Primary Industries, with a 300kg per hour prototype, has established that between 30 and 70% of the dry weight of the biomass is retained in the biochar. Further research is required to establish the suitability and dry weight of biochar produced from biomass sourced from the local area. These sources include biomass from Bega Valley Shire Council's waste and recycling centres, biomass removed to reduce fire hazard or for development, silvicultural thinnings from forested areas and biomass grown on agricultural land.
As illustrated in the map below and although the extent and species distribution in extant forest requires validation, the majority of the Endangered Ecological Community "Bega Dry Grass Forest" in the Middle and Wapengo catchments has been cleared for agriculture. The dominant tree species in this EEC was 'Forest Red Gum' (E.tereticornis) a primary koala feed species that, due to reduced soil fertility now regenerates poorly, grows very slowly, is generally subject to extreme dieback and where ever they grow, cannot support koalas.
The Middle lake catchment is dominated by the tansferral soil landscapes 'Tanja' on Ordovician metasediment parent materials and a smaller area of the 'Goalen Head' soil landscape, on Lower Devonian gabbro and monzonite parent materials, in the northwest corner. Both of these soil landscapes are adjacent to the erosional Murrah soil landscape where the last few koalas exist. All of the aforementioned soil landscapes have layers that are 'Strongly to Very Strongly' acid, reducing their suitability as a growth medium (Soil landscapes of the Bega- Goalen Point, 1:100 000 Sheet, M.J. Tulau, 1997)
Proven methods are required to improve soil fertility, in particular 'keyline' ploughing to address compaction and aerate soils, assist in distributing soil moisture toward ridges and maximise biological activity (www.yeomansplow.com.au/redbook). The Yeomans Plow Company (Pty Ltd) also produce a 'shank pot seeder' that when attached to the plough, is designed to drop seed or fertiliser into the sub-surface furrow.
A minimum of two passes with the plough are proposed, twelve months apart. The first to a maximum of 150mm (6 inches) depositing seed to produce biomass and the second to a greater depth, with an adapted 'shank pot seeder' or trailing air seeder, to trial injecting biochar into the channel and or spreading the material on the surface. Various species could be used to produce biomass in the first pass, including industrial hemp, when grown under the guidelines developed by the NSW Department of Primary Industries. Areas to be planted with trees require the addition of biochar, especially the proposed the 'treelines' and buffer areas along streams on the map (above). The width of streamside buffers reverses the current approach by having either a greater buffer width on first order streams (50 metres) or completely revegetating these sub-catchments, while a smaller (25 metre) buffer is proposed for second or greater order streams.
Increasing soil fertility and an associated changes to soil pH is likely reduce the suitability of the soil for the growth of unpalatable and toxic weeds, particularly Fireweed (Senecio madagascariensis) that is widespread on agricultural land and increasingly observed in forested areas.
Increasing soil fertility may also increase rabbit numbers, although soils associated with Ordovician metasediments generally contain a high proportion of stone, greatly decreasing the potential for rabbits to dig burrows. As areas planted with trees will require stock to be fenced out, fencing out rabbits could also be required. This is particularly the case for areas adjacent to first order streams on the Goalen Head soil landscape.
Womurrah: Community Forest Research Facility
In 1999 the Commonwealth and State Governments provided funding through the Natural Heritage Trust (Telstra selloff) to the Murrah/Bunga Koala Recovery Project that proposed initiating a Koala recovery project across tenures. There were two stages to the project, in the first year the major focus was to establish the potential for growing primary Koala feed trees.
Primary Koala feed trees, Forest Red Gum (foreground), planted in deep alluvial soil as part of the Koala Recovery and Riparian Restoration project.
The second year of the project was directed at setting up a feral predator exclosure consisting of public and private land, around a forested sub-catchment of about 180 hectares, in the lower Murrah River catchment. Unfortunately the NSW Forestry Commission who originally supported the proposal, changed their mind and have attempted to thwart the project ever since.
Despite this set back, the proponents have decided to continue the project on the basis that the decision whether to continue does not and should not belong to a rogue enterprise like the NSW Forestry Commission and the National Parks service.
The exclosure fence for Womurrah is just over 6.5 kilometres long and stands 2 metres tall. Steel strainers carry 8 strands of high tensile plain wire supporting wire netting that extends out for about 30cm at the top. At the edge of this extension is a single electric wire that acts as a final deterrent to any fox or cat to make it that far.
The aim is to complete the exclosure and workings bees are planned to undertake the work required. As well as completing the fence (mostly clipping on netting) flora and fauna surveys are also being undertaken. When complete and feral free, locally and regionally extinct species will be re-introduced to establish protected breeding colonies. Once established and effective feral control measures are implemented elsewhere, some of these animals will be released and monitored in unprotected areas.