The effect of concentrated smoke products on the restoration of highly disturbed mineral sands in southeast Victoria

Summary Recent studies have recognized the potential of broad‐scale surface application of smoke compounds for enhancing germination from the soil seed‐bank in fire‐prone vegetation communities. Results suggest that smoke technology may play, in the future, a significant role in the restoration and management of areas supporting indigenous vegetation. An important step in the development of smoke‐based restoration tools is the conduct of in situ field trials in a range of geographical locations and environmental conditions. However, most of the published work on the effectiveness of smoke products in promoting seedbank germination has been conducted at sites in southwestern Australia. The present study examines the effect of commercially available smoke‐water products on the regeneration of a highly disturbed former mine‐site at the Royal Botanic Gardens Cranbourne, in southeastern Victoria. Various combinations of concentrated smoke products and topsoil harvested from a nearby heathy woodland community were applied to exposed, uniform mineral sands to test their effect on seedling density and species richness of regrowth. The trials showed that after 12 months a number of common, herbaceous species including Austrodanthonia setacea, Opercularia varia and Platysace heterophylla were recorded in significantly higher numbers in areas treated with a commercial smoke‐water. However, there was no overall improvement in the density of seedlings or the richness of species as a result of the application of the smoke products. Similarly, total seedling density and species richness were not affected by the addition of topsoil, either alone or in combination with smoke products.     

Testate amoeba records indicate regional 20th‐century lowering of water tables in ombrotrophic peatlands in central‐northern Alberta,Canada

Testate amoebae are abundant in the surface layers of northern peatlands. Analysis of their fossilized shell (test) assemblages allows for reconstructions of local water‐table depths (WTD). We have reconstructed WTD dynamics for five peat cores from peatlands ranging in distance from the Athabasca bituminous sands (ABS) region in western Canada. Amoeba assemblages were combined with plant macrofossil records, acid‐insoluble ash (AIA) fluxes and instrumental climate data to identify drivers for environmental change. Two functional traits of testate amoebae, mixotrophy and the tendency to integrate xenogenic mineral matter in test construction, were quantified to infer possible effects of AIA flux on testate amoeba presence. Age–depth models showed the cores each covered at least the last ~315 years, with some spanning the last millennium. Testate amoeba assemblages were likely affected by permafrost development in two of the peatlands, yet the most important shift in assemblages was detected after 1960 CE. This shift represents a significant apparent lowering of water tables in four out of five cores, with a mean drop of ~15 cm. Over the last 50 years, assemblages shifted towards more xerophilous taxa, a trend which was best explained by increasing Sphagnum s. Acutifolia and, to a lesser extent, mean summer temperature. This trend was most evident in the two cores from the sites located farthest away from the ABS region. AIA flux variations did not show a clear effect on mineral‐agglutinating taxa, nor on S. s. Acutifolia presence. We therefore suggest the drying trend was forced by the establishment of S. s. Acutifolia, driven by enhanced productivity following regional warming. Such recent apparent drying of peatlands, which may only be reconstructed by appropriate indicators combined with high chronological control, may affect vulnerability to future burning and promote emissions of CO₂.     

The Siak, a tropical black water river in central Sumatra on the verge of anoxia

The Siak is a black water river in central Sumatra, Indonesia, which owes its brown color to dissolved organic matter (DOM) leached from surrounding, heavily disturbed peat soils. The dissolved organic carbon (DOC) concentrations measured during five expeditions in the Siak between 2004 and 2006 are among the highest reported world wide. The DOM decomposition appeared to be a main factor influencing the oxygen concentration in the Siak which showed values down to 12 μmol l⁻¹. Results derived from a box-diffusion model indicated that in addition to the DOC concentration and the associated DOM decomposition the water-depth also plays a crucial role in regulating the oxygen levels in the river because of its impact on the turbulence in the aquatic boundary layer and the surface/volume ratio of water in the river. Model results imply furthermore that a reduced water-depth could counteract an increased oxygen consumption caused by an enhanced DOM leaching during the transition from dry to wet periods. This buffer mechanism seems to be close to its limits as indicated by sensitivity studies which showed in line with measured data that an increase of the DOC concentrations by ~15% could already lead to anoxic conditions in the Siak. This emphasizes the sensitivity of the Siak against further peat soil degradation, which is assumed to increase DOC concentrations in the rivers.     

两种异养性鞭毛虫实验种群数量动态的比较研究

1999年4－8月从武昌东湖PFU样本中分离纯化了两种异养性鞭毛虫,对四种不同浓度Ceraphyl培养液中的种群增长进行了比较研究,结果表明这两种异养性鞭毛虫种群的数量动态显著不同,聚滴虫在四种浓度Ceraphyl培养液中均呈逻辑斯谛增长;而舞行波豆虫在四种浓度Ceraphyl培养液中的增长曲线均为抛物线。拟合组建了种群增长方程,并论证了方程可信度及其参数的生态学意义。     

Yield,Yield‐related Traits and Response of Potato Clones to Late Blight Disease,in North‐Western Highlands of Ethiopia

Late blight disease of potato caused by Phytophthora infestans poses a significant threat to potato production in Ethiopia. The development of new high yielding genotypes with adequate late blight disease resistance will provide a strong component of an integrated management strategy for farmers. The objective of this study was to determine late blight resistance and yield of potato clones under field condition in north‐western Ethiopia. Twenty‐four clones (17 from the International Potato Centre B3C2 population and seven widely grown cultivars) were evaluated at three locations. The experiment was laid in a randomized complete block design with two replications. Late blight resistance and yield‐related traits were determined. Results showed that clones differ significantly for all traits across locations. The following five clones combine high to moderate resistance to late blight with high yields: 396029.250, 395017.229, 396004.263, 396034.103 and 395077.12. These clones are useful genetic resources for resistance breeding against late blight disease and for enhanced yields.     

南方沿海地区城市水土流失类型及特征——以珠海市三灶区为例

通过野外实地考察结合遥感技术手段开展珠海市三灶区城市水土流失重点调查。三灶区水土流失类型以人为侵蚀为主 ,主要是由于开发平台建设、取土采石和修筑公路造成 ,侵蚀类型复杂多样 ,多沿交通道路两侧以及城市建成区周遍地带分布 ,侵蚀模数相差很大 ,最大侵蚀模数和最小侵蚀模数之间相差 3个数量级 ,充分反映了城市水土流失的特点。     

基于空间面板STIRPAT模型的水足迹影响因素分析——以山东省为例

随着中国水资源供需矛盾加剧,虚拟水成为地区水资源管理中不可或缺的一环,为提高地区水资源综合利用效率和探索水资源区域一体化管理提供了新思路。采用“自下而上”法核算了山东省17个城市农业、工业、生活、生态与灰水足迹,在分析2009—2018年水足迹时空分布规律基础上,综合运用探索性空间数据分析方法、面板数据STIRPAT模型和空间杜宾模型,揭示了水足迹的空间自相关特征,量化分析了人口数量、富裕程度、技术进步、城镇化和产业升级等影响因素对水足迹的本地影响效应与空间溢出效应。结果显示：(1)2009—2018年山东省水足迹总量均呈现波动上升的变化趋势;空间布局上呈现东部沿海和西部平原水足迹高,中部山地水足迹低的特点。(2)山东省水足迹具有正向的空间自相关性,相比地理位置相邻,水足迹的空间相关性受人口数量因素影响更大,表现出明显的“高高”聚集和“低低”聚集特征,但是受到经济因素的主要影响,区域间水足迹空间相关性随时间发展逐渐下降。(3)人口数量是山东省水足迹增长的重要来源,经济增长是推动各地区间水资源竞争关系的最重要因素。城镇化能够缓解本地水资源压力,技术进步和产业升级不仅能缓解本地水资源压力,...     

油蒿(Artemisia ordosica)的蒸腾作用及其群落的水分状况

 本文对比研究了处于不同生境的油蒿群落中油蒿的水分生理生态特性。结果表明：(1)半固定沙丘的油蒿比固定沙丘油蒿长势好,前者的生物量约为后者的4—5倍;(2)半固定沙丘土壤导水率是固定沙丘的10倍左右;(3)叶温与气温之差和水势能较好地反映油蒿的生长状况,而蒸腾速率与扩散阻力反映不十分敏感。     

Regulation of Intercellular Water Exchange in Various Zones of Maize Root under Stresses

Apical root meristems and segments of root elongation zone were sampled from 4- to 5-day-old Zea mays L. seedlings. The vacuolar ATPase and pyrophosphatase, the tonoplast marker enzymes, and the tonoplast -, -, and -aquaporins were visualized by means of indirect immunofluorescent microscopy with the use of the respective antibodies. Following cell plasmolysis (700 mM mannitol, 2.5 h), the vacuolar ATPase and pyrophosphatase were detected in cell wall pores where plasmodesmata remained detached from the plasmolyzed protoplasts. This finding provides further evidence for existence of the vacuolar symplast in the elongation zone of maize root, which may ensure intercellular continuity of plant tissues. The pulsed NMR method was used to study the self-diffusion of water molecules. The diffusive decay in the root elongation zone was nonexponential, and it was transformed to three exponential terms with characteristic coefficients of self-diffusion; two of these coefficients (D ₂ and D ₃) characterize the water self-diffusion in the cytoplasmic and vacuolar symplasts of root, respectively. The root apical meristem was also investigated with NMR technique by virtue of paramagnetic doping of the apoplast. This approach allowed selective studying of water diffusion within the symplast compartments. Partial dehydration with PEG-6000, 12 and 20%, for 2.5 h and chemical stressors (ABA and salicylic acid, 0.1 mM, 24 h) were applied to modify water permeability of plasmodesmata and tonoplast aquaporins. The transcellular water permeability increased in the root meristem under the action of all stress factors. In the root elongation zone exposed to partial dehydration, the water exchange in the apoplast became the dominant component. Other stress factors affected water relations in different manners. ABA elevated the water permeability of the vacuolar symplast, in contrast to salicylic acid that decreased water conductance of both the cytoplasmic and vacuolar symplasts.