Biofuels and other approaches for decreasing fossil fuel emissions from agriculture

Biofuels offer one method for decreasing emissions of carbon dioxide (CO2) from fossil fuels, thus helping to meet UK and EU targets for mitigating climate change. They also provide a rational option for land use within the EU that could be economically viable, provided that an appropriate financial and policy environment is developed. If 80% of current set‐aside land in the UK were used for production of biomass crops for electricity generation, about 3% of current UK electricity demand could be met from this source. Considering possibilities for increasing yields and land area devoted to such crops over the coming decades, this could possibly rise to 12%. These estimates exclude consideration of developments in electricity generation which should increase the efficiency of conversion. Also, the use of combined heat and power units at local level (e.g. on farms or in rural communities) gives additional energy saving. Dedicated biomass crops such as willow, poplar, miscanthus, switchgrass or reed canary grass are perennials: in comparison with annual arable crops they would be expected to deliver additional environmental benefits. The elimination of annual cultivation should give a more stable environment, beneficial for farmland biodiversity. Some increase in soil organic matter content is likely, leading to some sequestration of carbon in soil and long‐term improvements in soil quality. The impact on water quality may be positive as nitrate losses are small and a similar trend is expected for phosphate and pesticides. However, these crops may well use more water than arable crops so their impact on water resources could be negative – an issue for further research. Agricultural land can also be used to produce liquid fuels for use in transport. At present biodiesel can be produced from oilseed rape and ethanol from either sucrose in sugar beet or cellulose from virtually any plant material. In the short‐term, liquid biofuels are an easy option as they require little change to either agriculture or transport infrastructure. However, their benefits for CO2 emissions are much less than for biomass used for generating electricity. It is therefore necessary to debate the priorities for land use in this context.     

Disturbance, Herbivory, and Propagule Dispersal Control Dominance of an Invasive Grass

Despite the dramatic changes invasive plants cause to ecosystems and communities, factors that control dominance of invasive species after establishment in a community are poorly understood. Most active management relies on catastrophic disturbances of invasive-dominated communities to increase richness and diversity of plant communities. This study examines the importance of propagule dispersal and deer herbivory on continued dominance of Phalaris arundinacea after a non-catastrophic, short-term disturbance to monotypic stands of this invasive grass. The disturbance caused no change in P. arundinacea cover among treatments during any year of the study and, thus, simulates disturbance intensity more likely to be encountered in unmanaged settings. Despite the small disturbance, the combinations of disturbance + seeding and disturbance + seeding + deer exclusion caused greater species richness than controls even three years after disturbance. Increased invasion of P. arundinacea stands caused few effects on the dominant, as P. arundinacea biomass was unaffected after the first year. Selective herbivory by deer of species other than P. arundinacea increased the effects of disturbance and seeding, and aided in continued dominance of the grass. The tolerance of P. arundinacea for direct anthropogenic effects, including poor water quality and hydroperiod fluctuations, and indirect effects, such as increased herbivory by historically high deer populations, indicates the complexity of determining persistence of invasive species.     

不同生境两种生态型芦苇叶片质膜H~ -ATPase的比较(英文)

利用两相法纯化质膜微囊,研究了分布于西北沙漠地区的两种生态型芦苇(Phragmites communis Trin.)(水生芦苇和重度盐化草甸芦苇,分别简称为水芦和盐芦)叶片质膜H -ATPase的部分性质。结果显示,与水芦相比,盐芦质膜H -ATPase的ATP水解活性升高,Km值由1.27 mmol/L降至0.30 mmol/L,但Vmax没有显著差异。并且该酶活性对温度的敏感性和pH谱型也发生了变化。以对硝基苯磷酸盐为底物,低浓度时盐芦的质膜H -ATPase水解活性高于水芦,高浓度时则没有差异。Km在水芦和盐芦中分别为3.61 mmol/L和1.92 mmol/L,但Vmax在两种生态型中没有差异。钒酸盐抑制实验表明,两种生态型的质膜H -ATPase磷酸-酶区的催化性质不同。胰酶对质膜H -ATPase活性的活化谱型也存在差异,说明该酶C末端的结构或性质发生了变化。此外,与水芦相比,盐芦质膜H -ATPase的质子泵活性及与水解活性的耦联程度也升高了。以上结果说明,当芦苇从水生环境向盐渍环境过渡时,质膜H -ATPase的催化性质发生了变化,这些变化可能是由酶结构的修饰和不同的同工酶谱引起的。H -ATPase催化性质的变化可能是对盐渍生境的适应性反应。     

Robustness of linkage maps in natural populations: a simulation study

In a number of long-term individual-based studies of vertebrate populations, the genealogical relationships between individuals have been established with molecular markers. As a result, it is possible to construct genetic linkage maps of these study populations by examining the co-segregation of markers through the pedigree. There are now four free-living vertebrate study populations for whom linkage maps have been built. In this study, simulation was used to investigate whether these linkage maps are likely to be accurate. In all four populations, the probability of assigning markers to the correct chromosome is high and framework maps are generally inferred correctly. However, genotyping error can result in incorrect maps being built with very strong statistical support over the correct order. Future applications of linkage maps of natural populations are discussed.     

Metal storage in reeds from an acid mine drainage contaminated field

Phragmites australis has been used to treat acid mine drainage (AMD)-contaminated soil. However, the mechanism about metal translocation in reeds was not widely reported. This study investigated metal (Fe, Al, and Mn) storage location in reeds grown in five different sampling sites of an AMD field. As expected, the more metals in soil, the more metals entered the belowground organs of plants. Reeds grown in soils with the highest levels of metals accumulated 0.16 ± 0.04 mg/g Mn, 16.29 ± 4.15 mg/g Fe, and 1.31 ± 0.22 mg/g Al in roots. Most of the iron was sequestered in the roots, while Al was transferred to the shoots. Histological staining found that most of the iron was sequestered in the exodermis, while Al extended the endodermis of roots. Al even entered the stele of roots grown in soil with higher Al levels. The epidermis, cortex, and central cylinder of rhizomes were the main tissues for Fe and Al storage. The more metals in rhizomes, the stronger intensity of the staining was observed around the vascular systems of rhizomes. No structural difference was observed among reeds collected from different sites. Further studies may be needed to enhance the transfer of metals in reeds and increase the phytoremediation efficiency.     

An in-situ mobile interstitial water and sediment sampler (MISS)

An inexpensive, easily constructed sampler for collecting interstitial water and sediment, seperately or combined is presented. The instrument has been developed for use in wetlands and shallow water as a tool for taxonomical and ecological investigations. Different to other samplers, our sampling depth is down to more than one meter at defined depths. Sampling showed highly reproducable sampling results for both, hydrophysical-chemical and biological analysis, which will be shown in the article.     

Up-regulation of glutathione metabolism and changes in redox status involved in adaptation of reed (Phragmites communis) ecotypes to drought-prone and saline habitats

The glutathione (GSH) metabolic characteristics and redox balance in three ecotypes of reed (Phragmites communis), swamp reed (SR), dune reed (DR), and heavy salt meadow reed (HSMR), from different habitats in desert regions of northwest China were investigated. The DR possessed the highest rate of GSH biosynthesis and metabolism with the lowest levels of total and reduced GSH and its biosynthetic precursors, gamma-glutamylcysteine (gamma-EC) and cysteine (Cys), of the three reed ecotypes. This suggests that a higher rate of GSH biosynthesis and metabolism, but not GSH accumulation, might be involved in the adaptation of this terrestrial reed ecotype to its dry habitat. The HSMR shared this profile although it exhibited the highest reduced thiol levels of the three ecotypes. Two key enzymes in the Calvin-cycle possessing exposed sulfhydryl groups, NADP(+)-dependent glyceraldehydes-3-phosphate dehydrogenase (G3PD) and fructose-1,6-bisphosphatase (FBPase), and other two key enzymes in the pentose-phosphate pathway (PPP), glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6-PGD), had very similar activities in the three reed ecotypes. Compared to the SR, the DR and HSMR had higher ratios of NADPH/NADP+ and NADH/NAD+, indicating that a more reduced redox status in the plant cells might be involved in the survival and adaptation of the two terrestrial reed ecotypes to long-term drought and salinity, respectively. These results suggest that changes of GSH metabolism and redox balance were important components of the adaptation of reed, a hydrophilic plant, to more extreme dune and saline habitats. The coordinated up-regulations of the rate of GSH biosynthesis and metabolism and reduction state of redox status of plant cells, conferred on the plant high resistance or tolerance to long-term drought and salinity.     

Aluminium and phosphate uptake by Phragmites australis: the role of Fe,Mn and Al root plaques

Aluminium, a potentially phytotoxic metal, is an important constituent of many mine water discharges but has largely been neglected in the literature. The behaviour of this element in the rhizosphere of the wetland plant Phragmites australis was investigated in the laboratory in the presence and absence of Mn and Fe root plaques. Electron microscopy and chemical extraction techniques were utilized to determine the physico-chemical properties of the plaques and any association of Al. Both Mn and Fe plaques occurred as amorphous coatings on root surfaces with uneven distributions. Al was not adsorbed onto the surface of either plaque type but formed a separate phosphate deposit closely resembling the Fe and Mn plaques. Phosphorus was also found to be adsorbed to the surface of the Fe plaques (but not the Mn plaques). Both mechanisms were found to immobilize P at the root surface but this did not significantly reduce the concentration of P in aerial plant tissues that was sufficient to ensure adequate growth.     

隐秘螳臂相手蟹攀爬芦苇行为的昼夜变化

蟹类是潮滩沼泽(本文简称潮沼)湿地生态系统底栖动物重要组成之一。蟹类对潮沼植物活体的牧食以及对潮沼植物上筑巢繁殖鸟类的巢捕食表明,潮沼蟹类会攀爬上潮沼植物。然而对于潮沼中蟹类攀爬植物的行为了解甚少。隐秘螳臂相手蟹(Chiromantes neglectum)是长江口及邻近潮沼生态系统中的优势底栖动物之一。本研究在长江口芦苇(Phragmites australis)潮沼中通过野外直接观测计数估计潮沼地表、潮沼植物(芦苇)上隐秘螳臂相手蟹密度的昼夜变化,来分析其攀爬芦苇行为的时间变化规律。攀爬芦苇隐秘螳臂相手蟹密度和地表隐秘螳臂相手蟹密度均具有显著的昼夜差异(所有P0.05),根据隐秘螳臂相手蟹攀爬密度、地表密度的昼夜变化结合野外行为观测发现,隐秘螳臂相手蟹一般在日落前后(17:00~19:00时)开始攀爬芦苇,在日出后(7:00时以后)大部分隐秘螳臂相手蟹都已经从芦苇上撤离回到潮沼表面。隐秘螳臂相手蟹攀爬比例也具有显著的昼夜变化(P0.05),在夜间时段(19:00~5:00时)攀爬比例高于白天时段(5:00~19:00时)(P0.05),夜间时段攀爬比例在0.16~0.34之间,白天时段攀爬比例在0.02~0.15之间。隐秘螳臂相手蟹相手蟹的总密度在各观测时间段间差异显著(P0.05),夜间时段总密度要高于白天时段(P0.05),表明隐秘螳臂相手蟹在白天时段会较多利用潮沼表面的洞穴,从而呈现出从潮沼植被、潮沼地表到潮沼表面洞穴间的昼夜移动。此外,不同观测日期之间隐秘螳臂相手蟹攀爬密度、地表密度、总密度和攀爬比例均存在显著差异(所有P0.05),但是规律性不明显。隐秘螳臂相手蟹的植物攀爬行为似乎与取食芦苇叶片有关系,同时又受到光照强度昼夜变化的影响,具体影响隐秘螳臂相手蟹攀爬芦苇行为的因素以及隐秘螳臂相手蟹攀爬芦苇行为对潮沼湿地生态过程的影响有待进一步研究。