Carbon management of commercial rangelands in Australia: Major pools and fluxes

Land-use emissions accompanying biomass loss, change in soil organic carbon (Delta SOC) and decomposing wood-products, were comparable with fossil fuel emissions in the late 20th century. We examine the rates, magnitudes and uncertainties for major carbon (C) fluxes for rangelands due to commercial grazing and climate change in Australia. Total net C emission from biomass over 369 Mha of rangeland to-date was 0.73 (+/- 0.40) Pg, with 83% of that from the potentially forested 53% of the rangelands. A higher emission estimate is likely from a higher resolution analysis. The total Delta SOC to-date was -0.16 (+/- 0.05) Pg. Carbon emissions from all rangeland pools considered are currently 32 (+/- 10) Tg yr(-1) -equivalent to 21 (+/- 6)% of Australia's Kyoto-Protocol annual greenhouse gas emissions. The Delta SOC from erosion and deforestation was -4.0 (+/- 1.6) Tg yr(-1) -less than annual emissions from livestock methane, or biomass attrition, however it will continue for several centuries. Apart from deforestation a foci of land degradation was riparian zones. Cessation of deforestation and onset of rehabilitation of degraded rangeland would allow SOC recovery. If extensive rehabilitation started in 2011 and erosion ceased in 2050 then a Delta SOC of -1.2 (+/- 0.5) Pg would be avoided. The fastest sequestration option was maturation of regrowth forest in Queensland with a C flux of 0.36 (+/- 0.18) Mg ha(-1) yr(-1) in biomass across 22.7 Mha for the next 50 yr; equivalent to similar to 50% of national inventory agriculture emissions (as of mid 2011): and long-term sequestration would be 0.79 (+/- 0.40) Pg. Due to change in water balance, temperature and accompanying fire and drought regimes from climate change, the forecast Delta SOC from the forested rangelands to 0.3 m depth was -1.8 (0.6) Pg (i.e. 38 (12)% of extant SOC stock) resulting from a change in biomass from 2000 to 2100. For improved management of rangeland carbon fluxes: (a) more information is needed on the location of land degradation, and the dynamics and spatial variation of the major carbon pools and fluxes; and (b) freer data transfer is needed between government departments, and to the scientific community

Accounting for space and time in soil carbon dynamics in timbered rangelands

Employing rangelands for climate change mitigation is hindered by conflicting reports on the direction and magnitude of change in soil organic carbon (ΔSOC) following changes in woody cover. Publications on woody thickening and deforestation, which had led to uncertainty in ΔSOC, were re-evaluated, and the dimensional-dependence of their data was determined. To model the fundamentals of SOC flux, linked SOC pools were simulated with first-order kinetics. Influences from forest development timelines and location of mature trees, with a potential for deep-set roots, were considered. We show that controversy or uncertainty has arisen when ΔSOC data were not measured along sufficient lengths of the three Cartesian axes and the time axis, i.e. in 4D. Thickening and deforestation experiments have particularly neglected factors affecting the time and depth axes, and sometimes neglected all four axes. Measurements of thickening must use time-spans beyond the calculable breakeven date - when thickening just recovers the SOC lost through land degradation: then all ecosystems are likely to incur net sequestration. The similarity between half-life of carbon pools, and the half-time required for sequestration, mandates that millennial time-spans must be considered in design of SOC experiments. Spatial and temporal averaging of ΔSOC data that accounted for environmentally dependent decomposition rates, revealed that deforestation to pasture incurred a higher and longer-term net emission than earlier reported. Published reports on thickening or deforestation appear no longer contradictory when one considers that they only presented views from lengths of the 4D axes that were too limited. Adoption of this understanding into carbon accounting will allow more precise estimates of carbon fluxes for emission trading schemes and national reports

Testing the discrimination and detection limits of WorldView-2 imagery on a challenging invasive plant target

Invasive plants pose significant threats to biodiversity and ecosystem function globally, leading to costly monitoring and management effort. While remote sensing promises cost-effective, robust and repeatable monitoring tools to support intervention, it has been largely restricted to airborne platforms that have higher spatial and spectral resolutions, but which lack the coverage and versatility of satellite-based platforms. This study tests the ability of the WorldView-2 (WV2) eight-band satellite sensor for detecting the invasive shrub mesquite (Prosopis spp.) in the north-west Pilbara region of Australia. Detectability was challenged by the target taxa being largely defoliated by a leaf-tying biological control agent (Gelechiidae: Evippe sp. #1) and the presence of other shrubs and trees. Variable importance in the projection (VIP) scores identified bands offering greatest capacity for discrimination were those covering the near-infrared, red, and red-edge wavelengths. Wavelengths between 400 nm and 630 nm (coastal blue, blue, green, yellow) were not useful for species level discrimination in this case. Classification accuracy was tested on three band sets (simulated standard multispectral, all bands, and bands with VIP scores ≥1).Overall accuracies were comparable amongst all band-sets (Kappa = 0.71–0.77). However, mesquite omission rates were unacceptably high (21.3%) when using all eight bands relative to the simulated standard multispectral band-set (9.5%) and the band-set informed by VIP scores (11.9%). An incremental cover evaluation on the latter identified most omissions to be for objects 16 m2 allows application for mapping mesquite shrubs and coalesced stands, the former not previously possible, even with 3 m resolution hyperspectral imagery. WV2 imagery offers excellent portability potential for detecting other species where spectral/spatial resolution or coverage has been an impediment. New generation satellite sensors are removing barriers previously preventing widespread adoption of remote sensing technologies in natural resource management

Characterization of the Conformational Alterations, Reduced Anticoagulant Activity, and Enhanced Antiangiogenic Activity of Prelatent Antithrombin*

A conformationally altered prelatent form of antithrombin that possesses both anticoagulant and antiangiogenic activities is produced during the conversion of native to latent antithrombin (Larsson, H., Akerud, P., Nordling, K., Raub-Segall, E., Claesson-Welsh, L., and Björk, I. (2001) J. Biol. Chem. 276, 11996–12002). Here, we show that the previously characterized prelatent antithrombin is a mixture of native antithrombin and a modified, true prelatent antithrombin that are resolvable by heparin-agarose chromatography. Kinetic analyses revealed that prelatent antithrombin is an intermediate in the conversion of native to latent antithrombin whose formation is favored by stabilizing anions of the Hofmeister series. Purified prelatent antithrombin had reduced anticoagulant function compared with native antithrombin, due to a reduced heparin affinity and consequent impaired ability of heparin to either bridge prelatent antithrombin and coagulation proteases in a ternary complex or to induce full conformational activation of the serpin. Significantly, prelatent antithrombin possessed an antiangiogenic activity more potent than that of latent antithrombin, based on the relative abilities of the two forms to inhibit endothelial cell growth. The prelatent form was conformationally altered from native antithrombin as judged from an attenuation of tryptophan fluorescence changes following heparin activation and a reduced thermal stability. The alterations are consistent with the limited structural changes involving strand 1C observed in a prelatent form of plasminogen activator inhibitor-1 (Dupont, D. M., Blouse, G. E., Hansen, M., Mathiasen, L., Kjelgaard, S., Jensen, J. K., Christensen, A., Gils, A., Declerck, P. J., Andreasen, P. A., and Wind, T. (2006) J. Biol. Chem. 281, 36071–36081), since the 1H NMR spectrum, electrophoretic mobility, and proteolytic susceptibility of prelatent antithrombin most resemble those of native rather than those of latent antithrombin. Together, these results demonstrate that limited conformational alterations of antithrombin that modestly reduce anticoagulant activity are sufficient to generate antiangiogenic activity