Changes in plant densities in a mesic species-rich grassland after imposing different grazing management treatments

Changes in plant density were evaluated monthly in the first three vegetation seasons after imposing different grazing management treatments on abandoned semi‐natural grassland in the Czech Republic. There was no agricultural management in the 5 years before the start of the experiment in 1998. A completely randomized block experiment was established with the following five treatments: unmanaged control, intensive continuous grazing, extensive continuous grazing and a harvest in June followed by either intensive or extensive continuous grazing for the rest of the growing season. The sward was maintained at a target height of 5 and 10 cm under the intensive and extensive grazing managements respectively. An almost immediate increase in the densities of all sward components, especially grass tillers, occurred after the introduction of grazing on the previously abandoned grassland in comparison with the unmanaged control treatment. Trifolium repens was able to colonize and increase the number of its stolon growing‐points in all managed treatments, particularly in intensively grazed patches during the second and third experimental seasons. Delay to defoliation in both treatments containing a harvest in June resulted in an increase in the number of forb plants, particularly in the number of Taraxacum spp. plants, most probably due to an enabling of its seed production. It is evident that increases in plant density as a function of intensive defoliation are not restricted to the frequently documented effect on grass tillers but also can occur in many legume and forb species in species‐rich grasslands.     

Life strategies and spatial arrangement of grasses in a Mediterranean ecosystem in Greece

The temporal and spatial distribution, and the life strategies, of fifteen grass species in a Mediterranean evergreen sclerophyllous formation at Petralona (Chalkidiki, Greece) were studied in order to identify the relationships between species, and among species and the environment, which allows for the coexistence of species. The grass species were grouped into (i) early annual species that were characterized by early germination and a relatively long growth period; they did not need excessive resources and were distributed over the entire site, (ii) late annuals that were characterized by late germination and a short growth period; they required resources within this limited period and were competitive in capturing them and so were confined to the most productive sites of the site and (iii) perennial grasses that were characterized by early germination and vegetative reproduction; they were tolerant to nutrient shortages and hence maintained their distribution on the site. The spatial arrangement of species can be considered as a response to the selective pressures of the seasonal water and resource availability in a Mediterranean environment. This environment posed temporal limitations on the activity of early annual and late annual species, which restricts them in time and space. The perennial species overcame this by being flexible in their resource capture and use, because of their ability to store nutrients.     

山西矿区农业持续发展的择抉:矿区生态重建

基于山西采煤引发的大量地表塌陷、废弃岩土压占土地、人为水土流失加剧、区域性水破坏和污染等严峻的现实，提出：借助于现代采矿业的经济实力和运用现代生态工程技术，进行矿区生态重建（ＥｃｏｌｏｇｉｃａｌＲｅｃｏｎｓｔｒｕｃｔｉｏｎ），是扭转山西长期以来“输出资源、留下污染”、“捧着金碗讨饭吃”的唯一选择。本文围绕矿区生态重建中的核心问题——土地复垦（ＬａｎｄＲｅｃｌａｍａｔｉｏｎ），分析了山西矿区生态重建的现状和问题，论述了山西矿区生态重建的迫切性、必要性和可能性，提出了进行山西矿区生态重建的战略框架     

蜜蜂幼虫、蛹的研究进展

对蜂蛹的营养成分,药理作用和功能因子等方面的基础研究进展进行了综述,并对蜂蛹在开发中存在的问题进行了探讨,对蜂蛹的开发利用前景进行了展望。     

女性花草保健功能茶的研制

以茶叶为主要原料,针对女性消费群体,选择具美容养颜、抗老青春、苗条瘦身、怡心休闲花草保健配方,探讨它们与不同茶类在外观、口感、风味上的最佳配比,并强化其保健功效,筛选并形成多系列、多种类、多花色的女性系列花草保健功能茶.     

A new chelonibiid from the Miocene of Zanzibar (Eastern Africa) sheds light on the evolution of shell architecture in turtle and whale barnacles (Cirripedia: Coronuloidea)

The fossil history of turtle and whale barnacles (Coronuloidea: Chelonibiidae, Platylepadidae, Coronulidae and †Emersoniidae) is fragmentary and has only been investigated in part. Morphological inferences and molecular phylogenetic analyses on extant specimens suggest that the roots of whale barnacles (Coronulidae) are to be found among the chelonibiid turtle barnacles, but the hard-part modifications that enabled early coronuloids to attach to the cetacean skin are still largely to be perceived. Here, we reappraise a fossil chelonibiid specimen from the Miocene of insular Tanzania that was previously referred to the living species Chelonibia caretta. This largely forgotten specimen is here described as the holotype of the new species †Chelonibia zanzibarensis. While similar to C. caretta, †C. zanzibarensis exhibits obvious external longitudinal parietal canals occurring in-between external longitudinal parietal septa that abut outwards to form T-shaped flanges, a character so far regarded as proper of the seemingly more derived Coronulidae and Platylepadidae. Along with these features, the presence of a substrate imprint on the shell exterior indicates that †C. zanzibarensis grasped its host's integument in much the same way as coronulids and platylepadids, albeit without the development of macroscopic parietal buttresses and bolsters. Thin section analyses of the inner parietal architecture of some extant and extinct coronuloids conclusively demonstrate that vestiges of comparable external parietal microstructures are present in some living members of Chelonibiidae. This observation strengthens the unity of Coronuloidea while significantly contributing to our understanding of the evolution of the coronuloid shell structure in adapting to a diverse spectrum of hosts.     

三江源地区草地植物功能性状与蒸散发关系研究

蒸散发作为调控区域水分收支的重要支出项,受植物性状的影响。本研究于2021年5月—2021年9月对三江源及其周边共5个区域(海晏(HY)、同德(TD)、玛多(MD)、曲麻莱(QML)、可可西里(KKXL))的实际蒸散发及植被数据进行收集,通过相关性分析解释植被变化过程对环境的适应策略。结果表明：三江源草地植物多以丛生或密丛生为主,其中比叶面积与株高、叶片干物质含量、生长型和种子类型间呈显著负相关(P<0.05)。生长季实际蒸散发日、月动态在5个区域均呈现单峰变化趋势,生长季累积量为HY(309.97 mm)>TD(279.58 mm)>QML(247.90 mm)>MD(239.42 mm)>KKXL(230.35 mm)。分析植物功能性状与实际蒸散发之间的相关性,表明株高、比叶面积、叶片干物质含量、生长型和种子类型均与实际蒸散发呈现一定相关性,其中生长型相关性最大(R²=0.74)。     

有限元方法在汽车碰撞事故再现中的应用展望

应用有限元方法可以充分考虑到汽车和碰撞对象的弹塑性变形，从而提高事故再现的精度。随着高性能计算机的日益发展，基于并行计算的有限元方法将在汽车碰撞事故虚拟再现分析中以较高的计算精度得到事故发生前汽车的运动速度大小和方向，从而为事故分析和鉴定提供科学的理论依据。     

The effect of plant mycotrophy and soil disturbance on soil microbial activity

In cropping systems, the choices adopted for the tillage system used and plants cultivated can strongly influence the soil microbial population and its functional profile. Arbuscular mycorrhizal fungi are an important component of soil microbiome and their mutualistic symbiosis with the majority of higher plants grant the latter a wide range of benefits. The extraradical mycelium developed by these fungi expands the volume of soil influenced and harbours a diversity of microbes establishing a distinct environment of complementary interactions. We assessed how growing plants with different levels of mycotrophy modifies the biological activity profile in the soil under Mn toxicity and whether this is modified by soil disturbance. Following mycotrophic plants, soil contained a more active microbiome than after the non-mycotrophic plants, as expressed by higher values of soil basal respiration or dehydrogenase activity. Additionally, the count of phosphorus solubilizes and activity of phosphatase were greater after mycotrophic plants. Even among mycotrophic plants, different profiles of biological activity can be distinguished after growing a legume or grass. ERM disruption by soil disturbance decreased most of the parameters studied and for phosphatase activity and P solubilizers in a more significant way. These results indicate that even under Mn toxicity, the microbiome associated with AMF symbiosis following mycotrophic plants growth presented a higher biological activity and had a differential biological response towards the stress imposed by soil disturbance, when compared with the microbiome associated with non-mycotrophic roots.