Persistence of alpine grass-dominated vegetation on abandoned mountain summer farms in Western Norway

Centuries of seasonal farming in the Norwegian mountains led to a decrease in forested areas, a lowering of the alpine tree- and forest lines, and an increase in grassland coverage in the subalpine zone. Since the mid-19th century seasonal farming has declined significantly. In the sub-alpine belt, this has resulted in woodland succession on former hay meadows and open grasslands and heathlands. In contrast, vegetation changes caused by seasonal farming and its decline in alpine environments may be comparatively subtle because of unsuitable conditions for tree growth. The study examines vegetation changes in a former mountain summer farming area in the alpine zone of Western Norway using data on present and previous vegetation and old photographs. On curtilages high levels of defoliation, trampling and nutrient accumulation resulted in grass- and herb-dominated vegetation that differs significantly from that of surrounding areas. This curtilage-specific vegetation is persistent and occurs even at locations that have been grazed with only low intensity for several decades. Local concentrations of nutrients are probably a key factor that maintains the grass-dominated vegetation and strongly delays or even prevents regrowth of shrub heath.     

Effects of the grazing systems on germinable soil seed bank of desert steppe

We studied a soil seed bank in the Stipa breviflora desert steppe under three grassland management systems, namely continuous grazing, rotational grazing, and no grazing, from 1999 until 2007. The germinable seed bank species in rotational, continuous and no grazing were 11, 9 and 8 species, respectively. Rotational grazing increased the number of seed bank plant species and perennial grasses. The density of germinal soil seed bank was significantly higher in the enclosed area (19,533.33 seeds/m²) than those in rotational (3,233.33 seeds/m²) and continuous grazing areas (2,553.60 seeds/m²). The vertical distribution of the soil seed bank had a similar trend: 75.06%–83.19% of the seeds are distributed in the top 0–5 cm soil layer, 14.16%–21.68% in the 5–10 cm layer, and 2.65%–4.95% in the 10–15 cm layer, which varied between the grazing treatments. Density of the soil seed bank was significantly higher in the enclosed area, and there was no significant difference between rotational and continuous grazing. The Margalef and Shannon-Wiener indices for the soil seed bank were higher for rotational grazing treatment than for continuous grazing. The Sorensen’s similarity index for the soil seed bank between the enclosed and rotational grazing areas reached 0.857.     

藏北高原高寒草地围栏禁牧和生长季降水对物种丰富度和多样性的影响(英文)

2009和2010年夏天沿藏北高原高寒草地样带调查了高寒草地生态系统(高寒草甸、高寒草原和荒漠草原)在围栏禁牧和自由放牧管理下的物种丰富度和多样性(Shannon-Wiener指数,Simpson优势度指数和Pielou均匀度指数)。研究结果显示:自2006年起藏北高原围栏禁牧在植被类型和区域尺度上没有显著改变物种丰富度和多样性。物种丰富度和多样性主要受生长季降水驱动,超过87%的变异可由生长季降水来解释。物种丰富度和多样性在自由放牧和围栏禁牧2类样地对生长季降水的响应方式一致。物种丰富度随降水呈指数型增长关系,多样性指数则呈现正线性关系。研究结果预示藏北高原地区生长季降水的变化对于物种丰富度和多样性管理至关重要,在未来高寒草地保护研究中应予以重视。     

Evaluation of the Effects of Implementing Degraded Grassland Ecosystem Restoration Technology: A Case Study on Technology for Returning Grazing Land to Grassland

Restoring degraded grassland ecosystems is of great significance for the sustainable development of grassland ecological service functions and the sustainable and healthy development of regional economies and societies. Returning grazing land to grassland technology (RGLGT) is an important strategic technology for restoring degraded grassland ecosystems and achieving the sustainable development of the society and economy of pastoral areas in China. Researching the comprehensive evaluation system of the effects of RGLGT has an important significance for evaluating and adjusting national ecological policy. Based on collecting sample surveys from 221 farmers in 16 villages of 4 towns of Yanchi County, Ningxia Hui Autonomous Region in 2017, a model for evaluating the effects of implementing RGLGT was developed. The model included the characteristics of the technology, the ecological and social benefits of the technology, and the sustainability and economic benefits of the technology, it was used to complete a comprehensive effects evaluation of implementing RGLGT in Yanchi County that was based on use of the Analytic Hierarchy Process (AHP) method. The results showed that the comprehensive effect of implementing RGLGT is good overall and had a score of 0.5946. In terms of specific effects ranked from high to low, these were the ecological and social benefits of the technology, the economic benefits, the sustainability and the characteristics themselves. The implementation of RGLGT has resulted in good ecological and social benefits and economic benefits, but sustainability and characteristics of the technology are weak.     

禁牧政策对库布齐沙漠农户土地利用行为的影响

作为草原地区涉及面最广、农牧民参与程度最高的一项生态政策,禁牧政策对农户的土地利用行为产生了重大的影响。基于参与式农户评估法及累积Logit回归模型等对禁牧政策作用下库布齐沙漠的农户土地利用行为变化进行了研究。结果表明：（1）禁牧后农户的耕地和草地利用行为发生了显著变化。耕地总面积平均增加0.83 hm²,饲草种植面积平均增加0.25 hm²,羊只数量平均减少39.44只,舍饲程度得到提高;（2）政策因子、户主特征因子、家庭特征因子、农户土地利用行为意识因子是影响农户土地利用行为转变的主要因素,各个因子对不同土地利用行为的影响程度不同;（3）季节休牧对农户耕地利用行为的影响程度较大,全年禁牧对农户草地利用行为的影响程度较大。结合研究结果对禁牧政策的改进提出了相关建议。     

Simultaneous estimates ofsynechococcus spp. Growth and grazing mortality rates in the English Channel

The marine chroococooid phycoerythrin-containingSynechococcus spp. cyanobacterium has been implicated as a substantial component of the photosynthetic picoplankton in the ocean. Although its importance as food source for heterotrophic nanoplankton is now recognized, information about the cycling ofSynechococcus biomass and its diel pattern is limited and study methodology varies among authors. The selective metabolic inhibitor method was used to simultaneously estimate growth and grazing disappearance rates ofSynechococcus in the English Channel where growth rates ranged from 0.25 to 0.72/d (mean ±SD=0.51±0.17/d) and grazing mortality rates ranged from 0.19 to 0.64/d (mean ±SD=0.48±0.17/d). Size-fractionated experiments demonstrated that up to 70% ofSynechococcus disappearance could be attributed to grazers going through a 2 μm Nuclepore filter.Synechococcus grazing mortality rates (mean=0.74 ±0.25/d) during the day were always higher than that (mean=0.2±0.20/d) during the night, while growth rates showed no clear diel pattern. A positive correlation was observed between growth rates andin situ temperature ranging from 9 to 17°C, while in contrast grazing was independent of temperature. The close similatiry between average growth and grazing rates suggests a rapid recycling ofSynechococcus biomass in English Channel coastal waters.     

2000~2010年间GPS的改进

简要介绍了GPS发展的历史和现状，GPS改进的背景，详细介绍了2000－2010年间，GPS将作的主要改进，分析了各种改进措施所带来的影响；最后对非特许有户如何面对这种改进提出了建议。     

活动态测量中滤材的选择及其应用

研究滤材对元素活动态测定结果及测定精密度的影响,综合考虑元素活动态测量结果的真实性以及土壤胶体的性质等因素,确定了2μm孔径的滤膜是用于活动态测量的较佳滤材,本研究对活动态测量方法的规范化、标准化具有重要意义。应用试验表明所选滤材适用于活动态测量。     

The piosphere revisited: plant species patterns close to waterpoints in small, fenced paddocks in chenopod shrublands of South Australia

The Waite–Nicolson rangeland management method for semi-arid chenopod shrublands predicts that smaller paddocks with medium to moderate stocking rates help to preserve the native vegetation. Vegetation cover around waterpoints in three small paddocks (<2000 ha) from Middleback Station, South Australia was studied using multivariate analysis. Data from quadrats sampled along radiating transects were tested for correlations with a number of site features and grazing history factors. Two significant associations were detected: quadrats with an abundance of Rhagodia parabolica and less palatable species such as Maireana pyramidata, and Atriplex stipitata were correlated positively with proximity to water points, paddock age and stocking rate, and negatively with paddock size. In contrast, quadrats with species such as Rhagodia ulicina and the more palatable M. sedifolia were correlated with increasing distance from the water points and paddock size, but negatively with age and stocking rates. Transect direction was not correlated with either group. Twelve of the 20 species examined, including the important forage species A. vesicaria, also were not correlated with those paddock and grazing features included here. These results suggest that the distribution of some chenopod shrub species in fenced paddocks is still possibly affected by a combination of these factors in the long term by grazing at densities of 6 ha sheep⁻¹ and that the method, although maintaining the fodder species, may not be preserving biodiversity at these grazing levels, although further study is needed.     

Similar morphological and chemical variations of Gloeocapsomorpha prisca in Ordovician sediments and cultured Botryococcus braunii as a response to changes in salinity

Most Ordovician source rocks consist of accumulation of a colonial marine microorganism, Gloeocapsomorpha prisca (G. prisca) whose nature, ecology and affinity with extant organisms have been in dispute for years. Furthermore, recent studies have shown major differences in phenol moieties between two G. prisca-rich samples. Examination of five G. prisca-rich kerogens by electron microscopy and pyrolysis studies revealed (i) the occurrence of two markedly distinct “morpho/chemical” types: a “closed/phenol-rich” type (Baltic samples) and an “open/phenol-poor” one (North American samples) and (ii) the selective preservation of the resistant micromolecular material building up the thick cell walls in the original organism. Comparison with extant Botryococcus braunii (a widespread green microalga) grown on media of increasing salinity suggests that G. prisca is likely to be a planktonic green microalga related to B. braunii, which can adapt to large salinity variations which, in turn, control its polymorphism. The large differences in colony morphology and in the content of phenol moieties observed in fossil G. prisca and the resulting occurrence of two “morpho/chemical” types, should therefore reflect depositional environments with different salinities. The presence of thick, highly aliphatic, resistant walls in G. prisca selectively preserved during fossilization, accounts for the major contribution of this organism to Ordovician organic-rich sediments and for the resulting typical signature of Ordovician oils.