Academic literature on the topic 'Forest soils Victoria Gembrook'

An autumn fuel-reduction burn of low intensity (200-250 kW m-1) was performed in a Eucalyptus obliqua forest near Gembrook, Victoria. The aim of the study was to evaluate the effect of a single burn on floristics, biomass, N content and N2 fixation. The fire burnt 50% of the area in a mosaic pattern, significantly reducing understorey vegetation cover (by 90%) and plant density (by 70%) in burnt areas immediately after the fire. Understorey cover was restored to 40% of the original value 1 year later, but 33% of the understorey species were still absent from burnt areas. In the whole site mosaic, biomass declined by 30 t ha-1 (3 kg m-2) (10%) and N content by 100 kg ha-1 (10 g m-2) (18% excluding soil N, 2% including soil N). These losses were due to significant losses of biomass and N from the understorey only (88%, 85%), standing dead trees (57%, 62%), fallen wood (73%, 60%) and litter (69%, 70%). One year later, there was no significant increase in either biomass or N content. Burnt areas had five times the total nitrogenase activity of unburnt areas, owing to significantly greater specific nitrogenase (C2H2 reduction) activity, three times the nodule weight and 20 times the plant density of unburnt areas for the dominant legume (Pultenaea scabra). Using a calibration ratio for C2H2:N2 of 2.68 :1 derived from glasshouse growth studies, N2 fixation for P. scabra was estimated as 15 g ha-1 year-1 in burnt areas and 3 g ha-1 year-1 in unburnt areas, with a mean of 9 g ha-1 year-' for the whole site mosaic. Adding superphosphate to burnt areas increased estimated N2 fixation significantly by 14%, mainly by increasing nodulation. Losses of N due to the burn (100 kg ha-1) were considerably greater than gains from increases in N2 fixation (6 g ha-1 year-1) one year after the burn. Even allowing for N2 fixation by other, infrequent legumes and greater N2 fixation in subsequent years, these data suggest that the N lost in the burn is more likely to be replaced by inputs from soil reserves and rainwater than from N2 fixation by legumes.

A comparison was made of pH (1:5, soil: 0.01 M CaCl2) and easily extractable forms of Al [0.01 M CaCl2 (Alca); 1 M KCl (AlK); and 0.05 M CuCl2 (AlCu)] between forest and pasture soils near Bendigo, Victoria. Perennial pasture growth is required in this region to reduce groundwater recharge as part of the management of dryland salinity, but pasture growth may be inhibited by Al and Mn toxicity as a consequence of soil acidification. Both forest and pasture soils were found to be acidic (mean pH of 4.0 and 4.3 respectively) and AlCa concentrations are sufficient to anticipate toxicity to sensitive species. The forest site was cleared of timber over 50 years ago, and has since acidified by 63 kmol H+ ha-1, which is accounted for by organic anion accumulation in the forest regrowth. The forest soil has lower concentrations of AlCa, for a given pH, and more Al complexed to organic matter (Alcu-AlK), even though forest and pasture soils have equal amounts of organic carbon. The different A1 concentrations in forest and pasture soils are accounted for by a lag in A1 response to acidification, and greater complexation of Al with organic matter in the forest soil.

The Rushworth Forest is a Box and Ironbark open sclerophyll forest in central Victoria that has been subject to a long history of gold mining activity and forest utilisation. This paper documents the major periods of land use history in the Rushworth Forest and comments on the environmental changes that have occurred as a result. During the 1850s to 1890s, the Forest was subject to extensive gold mining operations, timber resource use, and other forest product utilisation, which generated major changes to the forest soils, vegetation structure and species cover. From the 1890s to 1930s, concern for diminishing forest cover across central Victoria led to the creation of timber reserves, including the Rushworth State Forest. After the formation of a government forestry department in 1919, silvicultural practices were introduced which aimed at maximising the output of tall timber production above all else. During World War II, the management of the Forest was taken over by the Australian Army as Prisoner of War camps were established to harvest timber from the Forest for firewood production. Following the War, the focus of forestry in Victoria moved away from the Box and Ironbark forests, but low value resource utilisation continued in the Rushworth Forest from the 1940s to 1990s. In 2002, about one-third of the Forest was declared a National Park and the other two-thirds continued as a State Forest. Today, the characteristics of the biophysical environment reflect the multiple layers of past land uses that have occurred in the Rushworth Forest.

Basalt-derived krasnozems are generally well-structured soils; however, there is a concern that intensive agricultural practices may result in an adverse decline in soil organic carbon, organic matter chemistry, and structural quality over time. A study was conducted on loam to silty clay loam krasnozems (Ferrosols) near Ballarat in south-western Victoria to assess changes in soil C, soil structural stability, and C chemistry, at the 0–10 cm soil depth, under 3 paired sites consisting of adjacent long-term forest (Monterey pine or eucalyptus) v. 30 year cropping [3 year pasture–2 year crops (potato and a root crop or grain)]. Soil structural stability was also characterised in the A and B horizons under long-term eucalyptus and several cropped sites. Organic C levels in the A horizons for all the soils were relatively high, ranging from 46 to 89 g/kg. A lower organic C (30%), associated mainly with loss of the sand-sized (>53 m) macro-C fraction, and a decrease in exchangeable Ca and Mg was found in the agricultural soils, compared with forest soils. Physically protected C in the <53 m fraction, as indicated by UV photo-oxidation, was similar among soils. Wet sieving indicated a decline of both C and N concentration in water-stable aggregates and the degree of macro-aggregation under agricultural soils, compared with the forest soils. However, soil structural changes under cropping were mainly related to a decline in the >5 mm sized aggregates, with no deleterious increase in the proportion of 0.10 mm aggregates. Solid state 13C NMR spectroscopy indicated a decrease in O-alkyl and alkyl C under pasture and cropping compared with forest soils, which was in agreement with the decline in the macro-C fraction. Characterisation of C chemistry following UV photo-oxidation showed that charcoal C (dominant presence of aryl C) accounted for 30% of the total soil organic C, while other functional groups (polysaccharides and alkyl C) were probably protected within micro-aggregates. Based on soil organic C and aggregate stability determinations alone, the implications for soil physical quality, soil loss, and diffuse pollution appear minimal. macroorganic carbon, soil aggregation, charcoal, photo-oxidation, potato rotation, CP/MAS 13C NMR spectroscopy.

Abstract. Well-drained, aerated soils are important sinks for atmospheric methane (CH4) via the process of CH4 oxidation by methane-oxidising bacteria (MOB). This terrestrial CH4 sink may contribute towards climate change mitigation, but the impact of changing soil moisture and temperature regimes on CH4 uptake is not well understood in all ecosystems. Soils in temperate forest ecosystems are the greatest terrestrial CH4 sink globally. Under predicted climate change scenarios, temperate eucalypt forests in south-eastern Australia are predicted to experience rapid and extreme changes in rainfall patterns, temperatures and wild fires. To investigate the influence of environmental drivers on seasonal and inter-annual variation of soil–atmosphere CH4 exchange, we measured soil–atmosphere CH4 exchange at high-temporal resolution (< 2 h) in a dry temperate eucalypt forest in Victoria (Wombat State Forest, precipitation 870 mm yr−1) and in a wet temperature eucalypt forest in Tasmania (Warra Long-Term Ecological Research site, 1700 mm yr−1). Both forest soil systems were continuous CH4 sinks of −1.79 kg CH4 ha−1 yr−1 in Victoria and −3.83 kg CH4 ha−1 yr−1 in Tasmania. Soil CH4 uptake showed substantial temporal variation and was strongly controlled by soil moisture at both forest sites. Soil CH4 uptake increased when soil moisture decreased and this relationship explained up to 90 % of the temporal variability. Furthermore, the relationship between soil moisture and soil CH4 flux was near-identical at both forest sites when soil moisture was expressed as soil air-filled porosity (AFP). Soil temperature only had a minor influence on soil CH4 uptake. Soil nitrogen concentrations were generally low and fluctuations in nitrogen availability did not influence soil CH4 uptake at either forest site. Our data suggest that soil MOB activity in the two forests was similar and that differences in soil CH4 exchange between the two forests were related to differences in soil moisture and thereby soil gas diffusivity. The differences between forest sites and the variation in soil CH4 exchange over time could be explained by soil AFP as an indicator of soil moisture status.

The Wombat Fire Effects Study was established to address a number of questions in relation to the effects of repeated low-intensity fires in mixed species eucalypt forest in the foothills of Victoria. This study has now been going for 25 years and has included the study of understorey plants, fuels, bats, terrestrial mammals, reptiles, invertebrates, fungi, birds, soils, tree growth, fire behaviour and weather. This forest system has shown a high resilience to fire that is attributed here to the patchiness and variability in the fire characteristics within a fire and the relatively small proportion of the landscape being affected. A means of comparing the level of “injury” caused by low-intensity prescribed fire with high intensity wildfire is proposed so that the debate about leverage benefits (the reduction in wildfire area compared to the area of planned burning) can be more rational. There are some significant implications for assessing the relative environmental impacts of wildfire compared with the planned burning program being implemented in Victoria since the Victorian Bushfires Royal Commission recommendations (Teague et al. 2010).

Nine phascogales (7 females, 2 males) were radio-tracked between March and July 1999 to investigate the spatial organisation of this species in spatially limited habitat near Euroa, Victoria. In this area, approximately 3.6% of the original woodland vegetation remains after 150 years of agricultural clearing. Most wooded habitat is confined to narrow linear strips along roads and streams. However, these remnants are on fertile soils and, because they have not experienced intensive harvesting, the density of large old trees is over 10 times that found in nearby State Forests and Parks. Female phascogales were monitored for 13–38 days over periods of 5–15 weeks. The size of home ranges of females was 2.3–8.0 ha, and averaged 5.0 ha. This value is one-eighth the mean home-range size previously recorded for the species in contiguous forest in Victoria. All individuals used multiple nest trees, with nests generally located in trees >80 cm diameter at breast height. Although fragmented and spatially limited, the stands of large old trees on productive soils near Euroa provide a network of well connected, high-quality habitat for phascogales. The relatively dense population of phascogales in these remnants suggests that prior to agricultural clearing and timber harvesting, phascogales may have been much more common in Victoria than at present.

Pseudomys novaehollandiae is ‘Endangered’ in Victoria, where it is presently considered to be extant at only three localities Loch Sport, Providence Ponds, and Wilsons Promontory. This study aimed to determine indicators of suitable habitat for the species that could assist in identifying potential habitat and sites for planned re-introductions as part of a recovery program. Vegetation and site data (soils, topography, rainfall, fire age-time since fire) were assessed at localities where P. novaehollandiae was recorded. The species occurred in five structural vegetation groups - open-forest, woodland, heathland, shrubland, grassland, with the most common being open-forest and woodland. Grassland and shrubland were restricted to coastal sand-dunes in south Gippsland. Understorey vegetation at most sites was dominated by sclerophyllous shrubs ranging in cover from 10 - 70%. Classification of quadrats produced eight floristic groups in which the trend was for quadrats to cluster according to geographical location. Ordination confirmed the classification pattern and vector-fitting produced significant correlations between vector points and five variables: species richness, latitude, longitude, fire age and annual rainfall. The study identified a range of vegetation communities where P. novaehollandiae occurs and provided evidence that the species is not restricted to floristically rich and diverse heathlands. The findings can be used to determine further localities with suitable habitat. However, factors other than vegetation are also likely to be important in predicting suitable habitat.

The relationship between selected chemical properties and nitrogen mineralization and nitrification was examined in soils collected from 39 sites of varying history. All sites were on podzolized sands; such soils represent more than 95% of the P. radiata growing area in south-east of South Australia/western Victoria. Given their uniformity in texture and similarity in pedogenesis, the organic matter concentrations of the sampled soils were highly variable (loss-on-ignition 0.8-10.2%). Total nitrogen was highly correlated with loss-on-ignition (r2 = 0.95, P<0.001). Nitrogen mineralization was correlated neither with total nitrogen nor loss-on-ignitition (i.e. P > 0.05), but was correlated with organic phosphorus (r2 = 0 70, P < 0.001), suggesting a major effect of phosphorus on nitrogen mineralization in these soils. On the basis of nitrate production during a 56-day aerobic incubation of disturbed soil, 18 soils were classed as strongly nitrifying (having a high potential to nitrify) and 18 as weakly nitrifying (having a low potential to nitrify). This separation reflected differences in other soil properties, with discriminant analysis giving a 91.7% correct classification into the two groups using only pH and Bray (II) extractable phosphorus for discrimination. Strongly and weakly nitrifying groups could also be discriminated on the basis of their value/chroma rating (after ignition), with a 94.4% probability of correct classification. Within each classification, nitrogen mineralization was correlated with total nitrogen (r2 =0.59 and 0.65, P< 0.001, for strongly and weakly nitrifying soils, respectively) but with a different relationship in each case. The significance of this difference in nitrogen dynamics is discussed in relation to site-specific forest management practices.

Soil samples taken in the Wombat State Forest in Victoria, at depths of 0-2, 2-5, and 5-10 cm before and after burning fuel loads of 0 (unburnt control), 15, 50, 150, and 300 t ha-1 were analysed for pH, exchangeable cations and cation exchange capacity, available and total P, organic carbon and soil moisture, over a 2-year, 2000 mm rainfall period. Short term responses (up to 6 months) occurred in levels of exchangeable NH4+, K+, and Mg2+, and long term changes (2 years or longer) over the period of the study were observed for pH, available and total P and exchangeable ca2+ at the 0-2 cm soil depth for the burnt treatments. Following burning (and 108 mm of rain), changes in soil chemical parameters were strongly correlated with fuel load and the quantity of fuel burnt. Changes through the 0-10 cm profile for the various chemical parameters are described, together with seasonal variations. For similar yellow podzolic soils, measurement of soil pH may be a useful criterion for monitoring soil chemical changes following slash and fuel reduction burning, provided that accurate estimates of fuel loads, composition and amount burnt can be established.