Re-establishment rate of reindeer lichen species following conventional disc trenching and HuMinMix soil preparation in Pinus-lichen clear-cut stands: a survey study in northern Sweden

Abstract

The re-establishment rates of reindeer lichen following conventional soil preparation by disc trenching and gentle soil preparation using HuMinMix apparatus were calculated from data acquired in surveys of 17 Pinus–lichen clear-cut stands in northern Sweden conducted 1–15 years after the treatments. The maximum lichen cover and biomass recorded in areas scarified by disc trenching were 29% and 24% of the lichen cover and biomass measured in adjacent intact lichen mats in the surveyed stands after 15 years. By contrast, 9 years after scarification, the corresponding percentages measured in areas disturbed by the HuMinMix treatment were 91% and 100%, respectively. According to calculated linear regressions, the reindeer lichen cover could be completely re-established just one decade after HuMinMix treatment. Ground lichen diversity in the scarified areas was also inventoried. The significant increase in lichen diversity for HuMinMix, especially of early-successional species, could explain the more rapid re-establishment of late-successional lichens (e.g. Cladonia stellaris spp.), compared with disc trenching. Thus, the study demonstrates that both the degree of initial disturbance and the re-establishment rate of reindeer lichen must be considered when estimating the effects of scarification on lichen loss for reindeer grazing over time.     

A biodiversity monitoring framework for practical conservation of grasslands and shrublands

Comprehensive and standardized biodiversity monitoring schemes are needed to build scientifically sound decision-making tools for biodiversity conservation. Based on a thorough review of published literature, we propose a novel biodiversity monitoring framework to unify conservation theory and practice. The framework is built on the inter-connection among different types of indicators, and on the systematic articulation of their relationships into seven indicator approaches. Semi-natural grasslands and shrublands in Europe, which still lack a common biodiversity monitoring scheme, are used as a model for the framework. Different biotic indicators have been widely used to estimate the state of biodiversity, but we integrate these with biodiversity drivers, i.e. factors driving changes in biodiversity, to track biodiversity response to environmental changes. Precise information on biodiversity drivers (e.g. past and present management or disturbance regimes, environmental conditions, landscape patterns) has an effective indicator value, but this is often not taken into account in monitoring schemes. Our framework can be used to detect gaps in available data, translate indicator systems into practical conservation, identify combined sets of indicators to monitor biodiversity in target habitats, and recognize most suitable surrogates when information for some indicators is missing. We also take into account the effect of regional species pools in order to consider large-scale historical and biogeographical processes. We propose general guidelines to create validate and launch biodiversity monitoring frameworks for target habitats in the light of current examples of biodiversity conservation schemes (e.g. Natura 2000 in Europe).     

人工草地放牧系统优化模式研究 Ⅰ 人工草地的最大持续产量模型和最优控制方法及应用

文章以云贵高原的人工草地为研究对象，分析了草地资源分布的时空特征及增长动态，运用生物控制论方法组建了牧草资源种群保护性利用的最大持续产量模型，并以试验为例，确定了具体的保护指标与放牧管理措施，研究了单播人工草地的最优控制模型与放牧对策，进行了相应的定量分析。     

Nitrate leaching from reseeded pasture

Abstract. Nitrate leaching and soil mineral N status under grassland were measured on three contrasting soils, spanning winters 1995/96, 1996/97 and 1997/98, in Western England. The soils investigated were a freely draining silty clay loam (Rosemaund), a well drained loam (IGER 1) and a poorly drained clay loam (IGER 2). The effects of reseeding (ploughing and resowing grass) at IGER 1 and IGER 2 in autumn 1995 or 1996 were compared with undisturbed pasture. Reseeding at Rosemaund, in autumns 1995 or 1996, or spring 1996 was compared with undisturbed pasture of 3 sward ages (2, 5, >50 years).
Nitrate-N leaching losses during the winter immediately following autumn reseeding ranged between 60 and 350 kg N ha^–1 in 1995/96, depending on soil type, sward management history and rainfall. Losses were much less in the following winter when treatments were repeated (10–107 kg N ha^–1).
Reseeding in spring had little effect on soil mineral N content or leaching losses in the following autumn, compared with undisturbed pasture. Similarly, leaching losses from autumn reseeds in the second winter after cultivation were the same as undisturbed pasture (1-19 kg N ha^–1). The effect of ploughing grassland for reseeding was relatively short-term, in contrast to the effect of repeated annual cultivation associated with arable rotations.     

盐碱地与耐盐碱牧草

阐述了盐碱地形成过程、分布规律和改良方法,以及不同种牧草的耐盐性,提出了提高盐碱地牧草栽培成功率的方法。     

Ghrelin在驯鹿组织器官中的表达

为检测生长素(Ghrelin)在驯鹿体内可能表达的器官,采用反转录-聚合酶链式反应(RT-PCR)和实时荧光定量PCR(real-time PCR)技术,检测驯鹿的下丘脑、垂体、舌、食管、瘤胃、网胃、瓣胃、皱胃、十二指肠、空肠、回肠、结肠、心、肺、肝、脾、肾、膀胱、输尿管、睾丸、附睾、输精管、淋巴结、甲状腺、胰、肾上腺、胸腺、精囊腺和骨骼肌中Ghrelin的表达情况。Ghrelin在上述器官中均有表达,且在皱胃内的表达量明显高于其他器官(P0.05),其次是胰、十二指肠、睾丸和食管,与下丘脑、垂体和舌等其余器官内的表达量相比差异也显著(P0.05),这些器官内的表达量相对较少。     

Changes in species composition of abandoned sown swards after imposing seasonal cutting treatments

Abstract Seasonal cutting treatments were imposed on abandoned perennial ryegrass/white clover swards at three sites in the UK to determine the impact on species diversity and the contribution of different species to biomass. Before the cutting experiment, the abandoned swards had received no fertilizer applications and had been neither grazed nor cut for 3 years. The original sown species, Lolium perenne and Trifolium repens, had virtually disappeared during this period. Self‐sown grasses, including Agrostis capillaris, Dactylis glomerata, Festuca rubra, Holcus mollis, Poa pratensis and P. trivialis, had become dominant at two sites. Ranunculus repens was the dominant species at the third site, and self‐sown grasses, such as Holcus lanatus and P. trivialis, and Juncus and Carex species were also present. The standing herbage in 2·5 m × 2·5 m subplots was cut to 2·5 cm above ground level and removed annually in either June or October for 7 years at two sites and 6 years at the third site. Total biomass removed was generally < 4 t dry matter (DM) ha^?1, and both total and live biomass decreased over time in the June cutting treatment at two sites. There were large changes in species composition after initiating the two cutting treatments. The numbers of grass and dicot species increased, although many new species had a low frequency of occurrence. The contribution of species to biomass changed over time, with species showing a vegetative regenerative strategy decreasing over time at one site. At this site, annual cutting in June was slightly more effective than cutting in October in reducing the dominance of R. repens; cutting in early October effectively reduced Juncus spp. At two sites, there was a decrease in the contribution of the species group showing seasonal regeneration by seed, and differences between cutting dates for two species within this group at one site. L. perenne and T. repens remained at much lower levels than in adjacent unfertilized, grazed swards. Reseeding may be necessary to create species assemblages for ecological and agricultural objectives.     

The implications of controlling grazed sward height for the operation and productivity of upland sheep systems in the UK: 6. The effect of reducing stocking rate and application of fertilizer nitrogen in Wales

Abstract The implications for the agricultural productivity of the UK upland sheep systems of reducing nitrogen fertilizer application and lowering stocking rates on perennial ryegrass/white clover swards were studied over 4 years at a site in Wales. The system involved grazing ewes and lambs from birth to weaning on swards maintained at a constant height with surplus herbage made into silage, thereafter ewes and weaned lambs grazed on separate areas until the onset of winter with adjustments to the size of the areas grazed and utilizing surplus pasture areas for silage. Four stocking rates [SR 18, 15, 12 and 9 ewes ha^?1 on the total area (grazed and ensiled)] and two levels of annual nitrogen fertilizer application (N 200 and 50 kg ha^?1) were studied in five treatments (N200/SR18, N200/SR15, N50/SR15, N50/SR12 and N50/SR9). Average white clover content was negatively correlated with the level of annual nitrogen fertilizer application. White clover content of the swards was maintained over the duration of the experiment with an increasing proportion of clover in the swards receiving 50 kg N ha^?1. Control of sward height and the contribution from white clover resulted in similar levels of lamb liveweight gain from birth to weaning in all treatments but fewer lambs reached the slaughter live weight by September at the higher stocking rates and with the lower level of fertilizer application. Three of the five treatments provided adequate winter fodder as silage (N200/SR15, N50/SR12 and N50/SR9). Because of the failure to make adequate winter fodder and the failure of white clover to fully compensate for reduction in nitrogen fertilizer application, it is concluded that nitrogen fertilizer can only be reduced on upland sheep pastures if accompanied by reduced stocking rates.     

Differences in choice of diet between sheep breeds grazing mountain pastures in Norway

In the present study, the foraging behaviour of ewes from three common Norwegian sheep breeds; the long-tailed Dala sheep, and the two short-tailed breeds Spæl sheep and Norwegian Fur sheep was studied. Based on difference in body size and digestive anatomy, we expected the lighter short-tailed ewes to browse more on woody plants than the Dala ewes. The experiments were conducted during two consecutive summers within the flocks’ usual grazing areas, and we sampled the proportion of grazing time that ewes spent feeding on woody plant species. We tested the hypothesis by applying generalized linear mixed models to the feeding behaviour data. As predicted, the short-tailed ewes spent substantially more of their grazing time browsing on trees, bushes and heather compared to the Dala ewes. We discuss the results in the context of maintaining the, now threatened, pastoral landscapes of mountainous regions of Norway; short-tailed breeds should be more effective than the Dala breed in reducing tree and bush encroachment, but more detailed studies are needed to quantify the breed differences in this respect.     

驯鹿足底非规则特征形貌数学模型构建及验证

为攻克常规防滑轮胎在冰面上通过性低的难题,以驯鹿足为仿生原型,对驯鹿足底特征形貌进行分析。该文通过逆向工程技术,将驯鹿足单个足底划分为内、外侧边缘曲线、脊线凹槽面和足跟凸冠面4个典型部位。运用1st Op软件和MATLAB软件对特征部位拟合并构建数学模型,利用X射线能谱仪对驯鹿足底特征部位进行元素分析。内、外侧边缘曲线方程的决定系数R~2分别为0.994、0.992;脊线凹槽面和足跟凸冠面曲面方程的R~2分别为0.96、0.98。通过模型验证发现,模型拟合值与实际值的相对误差均值在5%以下,实现了驯鹿足底特征形貌从生物模型到数学模型的转化。能谱分析结果表明驯鹿足底除含有大量的碳、氧及氮元素外,硫、硅、铁、铝、钙5种元素含量较高,并且不同部位的元素存在差别。该研究可为工程仿生技术应用于冰路面行驶车辆胎面设计提供新的研究方向和参考依据。