CO2 emissions from biomass combustion for bioenergy: atmospheric decay and contribution to global warming

Carbon dioxide (CO₂) emissions from biomass combustion are traditionally assumed climate neutral if the bioenergy system is carbon (C) flux neutral, i.e. the CO₂ released from biofuel combustion approximately equals the amount of CO₂ sequestered in biomass. This convention, widely adopted in life cycle assessment (LCA) studies of bioenergy systems, underestimates the climate impact of bioenergy. Besides CO₂ emissions from permanent C losses, CO₂ emissions from C flux neutral systems (that is from temporary C losses) also contribute to climate change: before being captured by biomass regrowth, CO₂ molecules spend time in the atmosphere and contribute to global warming. In this paper, a method to estimate the climate impact of CO₂ emissions from biomass combustion is proposed. Our method uses CO₂ impulse response functions (IRF) from C cycle models in the elaboration of atmospheric decay functions for biomass‐derived CO₂ emissions. Their contributions to global warming are then quantified with a unit‐based index, the GWP_bio. Since this index is expressed as a function of the rotation period of the biomass, our results can be applied to CO₂ emissions from combustion of all the different biomass species, from annual row crops to slower growing boreal forest.     

Frost tolerance in excised leaves of the common bugle (Ajuga reptans L.) correlates positively with the concentrations of raffinose family oligosaccharides (RFOs)

Mass increases in raffinose family oligosaccharides (RFOs, α 1,6-galactosyl extensions of sucrose) are well documented in the generative tissues of many plants upon cold acclimation, and they (i.e. mainly the two shortest RFO members, raffinose and stachyose) have been suggested as frost stress protectants. Our focus here was on the longer RFO members as they commonly occur in the frost-hardy evergreen labiate Ajuga reptans in its natural habitat, and accumulate to their highest concentrations in winter when the plant is faced with sub-zero temperatures. We examined the effects of RFO concentration and chain length on frost tolerance using excised leaves which accumulate long-chain RFOs under both cold and warm conditions, thereby uncoupling the acclimation temperature from RFO production. We demonstrated that frost tolerance in excised A. reptans leaves correlates positively with long-chain RFO accumulation under both acclimation temperatures. After 24 d post-excision in the warm, the leaves had increased their RFO concentrations (mainly long-chain RFOs) 22-fold to 78 mg g⁻¹ fresh weight, and decreased their EL₅₀ values (temperature at which 50% leakage occurred) from −10.5 to −24.5 °C, suggesting a protective role for these oligosaccharides in the natural frost tolerance of A. reptans .     

Observations on the control of potato cyst-nematodes, Globodera rostochiensis and G. pallida in 35 English potato soils in pots by oxamyl and resistant potatoes

The increase of 35 English field populations of potato cyst-nematodes (Globodera rostochiensis and/or G. pallida) was measured on Désirée, Maris Piper, Caxton (A25/11), Cromwell (A27/20) and clone 11233 ab 22 in pots of sandy, silty or peaty loam soil. Désirée was susceptible to all populations tested and, as in field soils, the final population (Pf) was inversely related to the initial population of potato cyst-nematode eggs (Pi) in the soil. Maris Piper and Cromwell were resistant to all G. rostochiensis populations, with one possible exception. Maris Piper was susceptible to all G. pallida populations. Caxton was susceptible to some and fairly resistant to other populations of G. rostochiensis, indicating the existence either of two biotypes within the one pathotype (Rol) as yet encountered in Britain, or the existence of an additional pathotype. Caxton and Cromwell were fairly resistant to G. pallida. Clone 11233 ab 22 was only moderately resistant to both species. Resistance to potato cyst-nematode increase varied considerably, especially in Caxton (to G. rostochiensis) and in 11233 ab 22 (to both species). Oxamyl greatly reduced the increase of G. rostochiensis populations on Désirée potatoes, with the notable exception of one population but it generally had much less effect on G. pallida populations, regardless of soil type. The difference in effect on the two species may be due to a longer period of hatching in G. pallida than in G. rostochiensis and also perhaps to a second generation in G. pallida.     

XET-related genes and growth kinematics in barley leaves

DV, displacement velocity
GA₃, gibberellic acid
REGR, relative elemental growth rate
XET, xyloglucan-endotransglycosylase

Recently Schünmann et al. (1997 ; Plant, Cell and Environment 20, 1439–1450) investigated the correlation of spatial patterns of xyloglucan-endotransglycosylase (XET) activity, XET-related mRNAs, and growth in elongating barley ( Hordeum vulgare L.) leaves. Here, methodological difficulties in the kinematic growth analysis are discussed, and it is concluded that the role that XET-related gene activity plays in the control of spatial growth patterns remains undetermined.     

Production and dormancy of wild oat (Avena fatua) seed from plants grown under soil waterstress

In 1974 wild oat plants grown from very dormant seed types fA, fB, fC originating from a single field, and in 1976 plants of type fB derived from another location were waterstressed from the time when the spikelets were just beginning to emerge until the seed was fully ripe. The seed production and dormancy of the seed were determined. Waterstress reduced the number of viable seeds per plant by 42% in 1974 and 49% in 1976. The number of viable seed produced on the tillers of the plants were reduced to a greater extent by waterstress than the number produced on their main stems. Some of the differences between the number of viable seeds produced by the three wild oat types were significant. In 1974, 78% of seed from stressed plants was dormant as compared with 90% of that from unstressed plants. Under a given soil moisture, the dormancy of the three types differed little, although seed dormancy was less in tiller seed than in main stem seed. In 1976 seed from stressed plants was 80% dormant, immediately after collection, whereas that from unstressed plants was totally dormant. Storage for 6 months at 25°C decreased these percentages to 17% and 90% and at 5°C to 72% and 98% respectively. Buried in soil immediately after collection, 66% of viable seed from stressed plants gave seedlings in the first autumn after burial as compared with 4% of seed from unstressed plants. Most of the seed from waterstressed plants gave rise to seedlings in the first autumn, and seed from non-stressed plants in the second spring. The α-amylase content was four times greater in seeds from stressed compared with non-stressed plants.     

Protocollagen proline hydroxylase in skin and muscle of some vertebrate species

Protocollagen proline hydroxylase activity was studied in skin and muscle of poikilothermic and homoiothermic animals. Lower PPH activity was found in the former than in the latter. Increased PPH activity was found in skin of young Gallus domesticus and Rattus norvegicus. In specialized skin under hormonal control, i.e. comb and wattles, increased activity in relation to sexual maturation was shown. The PPH activity in muscles of poikilotherms was lower than in those of homoiotherms. Some of the muscles had a considerable enzymatic activity. A decreasing PPH activity was noticed in birds and mammals with age. Heart muscle had more hydroxylating activity than skeletal muscle.     

Evidence of Functional Microenvironments in Lymphatic Tissue Response to Antigen

Experiments with young and aged mice support the concept that the reticular stroma of the spleen, possibly interacting with other humoral factors, is essential for the expression of immunocompetent precursors directed towards the production of 7S antibody.     

Maturing and Coordination of Web-Building Activity

Experiments are reported in which 114 Zygiella x-notata Cl.spiderlings were taken out of the cocoon before the time atwhich they normally left (2 weeks after the second molt); 67were placed on wooden frames and 47 on wire frames. Both groupsbuilt partial, irregular thread-patterns at first, and, as theygrew older, constructed more and more regular geometric orb-webs:the transition can be traced through several stages. The shapeof the web, particularly the presence of the free-sector, wasdependent on the frame; webs built in a circular wire framelacked the free-sector. It is assumed that the accomplishmentof full, regular orb webs is essentially based on the progressivehistological differentiation of the central nervous system inthe spiderlings during the developmental phase under observation;the wire frame could influence the shape of the web throughmaking construction of a retreat difficult.     

Prevalence of Aedes camptorhynchus (Thomson) (Diptera: Culicidae) and Other Mosquitoes in the Eastern Coast of Victoria

Adult mosquito populations were monitored using dry-ice baited EVS light traps at weekly intervals for four seasons (1991–95) in Avon, Bairnsdale, Rosedale and Hastings, and for three seasons (1991–94) in Tambo, in the eastern coast of Victoria. Among the 20 species of adult mosquitoes recorded, Aedes camptorhynchus (Thomson) was dominant (74–99%). Higher Ae camptorhynchus adult populations were recorded in the 1992–93 and 1993–94 seasons, than in 1991–92 and 1994–95 seasons. Rosedale shire recorded higher Ae camptorhynchus adult populations than the Avon, Bairnsdale, Hastings and Tambo shires. In all shires, two peaks of Ae camptorhynchus activity reaching high (100–1,000 adults/trap) to very high (> 1,000 adults/trap) levels were recorded, with the first peak in the middle of December (summer) and the second peak in the middle of April (autumn). the Ae camptorhynchus activity in the coastal region increased with an increase in the minimum temperature.