On the relationship between plant species diversity and genetic diversity of Plantago lanceolata (Plantaginaceae) within and between grassland communities

Aims and Methods The relationship between genetic diversity and species diversity and the underlying mechanisms are of both fundamental and applied interest. We used amplified fragment length polymorphism (AFLP) and vegetation records to investigate the association between genetic diversity of Plantago lanceolata and plant species diversity using 15 grassland communities in central Germany. We used correlation and partial correlation analyses to examine whether relationships between genetic and species diversity were direct or mediated by environmental differences between habitats.Important findings Both within- and between-population genetic diversity of P. lanceolata were significantly positively correlated with plant species diversity within and between sites. Simple and partial correlations revealed that the positive correlations indirectly resulted from the effects of abiotic habitat characteristics on plant species diversity and, via abundance, on genetic diversity of P. lanceolata. Thus, they did not reflect a direct causal relationship between plant species diversity and genetic diversity of P. lanceolata, as would have been expected based on the hypothesis of a positive relationship between plant species diversity and niche diversity.     

DNA from soil mirrors plant taxonomic and growth form diversity

Ecosystems across the globe are threatened by climate change and human activities. New rapid survey approaches for monitoring biodiversity would greatly advance assessment and understanding of these threats. Taking advantage of next-generation DNA sequencing, we tested an approach we call metabarcoding: high-throughput and simultaneous taxa identification based on a very short (usually <100 base pairs) but informative DNA fragment. Short DNA fragments allow the use of degraded DNA from environmental samples. All analyses included amplification using plant-specific versatile primers, sequencing and estimation of taxonomic diversity. We tested in three steps whether degraded DNA from dead material in soil has the potential of efficiently assessing biodiversity in different biomes. First, soil DNA from eight boreal plant communities located in two different vegetation types (meadow and heath) was amplified. Plant diversity detected from boreal soil was highly consistent with plant taxonomic and growth form diversity estimated from conventional above-ground surveys. Second, we assessed DNA persistence using samples from formerly cultivated soils in temperate environments. We found that the number of crop DNA sequences retrieved strongly varied with years since last cultivation, and crop sequences were absent from nearby, uncultivated plots. Third, we assessed the universal applicability of DNA metabarcoding using soil samples from tropical environments: a large proportion of species and families from the study site were efficiently recovered. The results open unprecedented opportunities for large-scale DNA-based biodiversity studies across a range of taxonomic groups using standardized metabarcoding approaches.     

Light and nitrogen competition limit Lolium perenne in experimental grasslands of increasing plant diversity

Positive species richness effects on aboveground community productivity in experimental grasslands have been reported to correlate with variable responses of individual species. So far, it is largely unknown whether more complete use of resources at the community level correlates with resource limitation of particular species and may explain their decreasing performance with increasing plant diversity. Using the subordinate grass species Lolium perenne L. as a model, we monitored populations in 82 experimental grasslands of different plant diversity (Jena Experiment) from year 2 to 6 after establishment, and measured ecophysiological leaf traits related to light and nutrient acquisition and use. Population and plant individual sizes of L. perenne decreased with increasing species richness. A decrease in transmitted light with increasing species richness and legume proportion correlated with increasing specific leaf area (SLA). Despite this morphological adaptation to lower light availability, decreasing foliar δ(13) C signatures with increasing species richness and low variation in leaf gas exchange and chlorophyll concentrations suggested a low capacity of L. perenne for adjustment to canopy shade. Leaf nitrogen concentrations and foliar δ(15) N signatures indicated a better N supply in communities with legumes and a shift in the uptake of different N forms with increasing species richness. Leaf blade nitrate and carbohydrate concentrations as indicators of plants nutritional status supported that light limitation with increasing species richness and legume proportions, combined with a N limitation in communities with increasing proportions of non-legumes, correlated with the decreasing performance of L. perenne in communities of increasing plant diversity.     

Trait means,trait plasticity and trait differences to other species jointly explain species performances in grasslands of varying diversity

Functional traits may help to explain the great variety of species performances in plant communities, but it is not clear whether the magnitude of trait values of a focal species or trait differences to co‐occurring species are key for trait‐based predictions. In addition, trait expression within species is often plastic, but this variation has been widely neglected in trait‐based analyses. We studied functional traits and plant biomass of 59 species in 66 experimental grassland mixtures of varying species richness (Jena Experiment). We related mean species performances (species biomass and relative yield RY) and their plasticities along the diversity gradient to trait‐based pedictors involving mean species traits (T_mean), trait plasticities along the diversity gradient (T_slope), extents of trait variation across communities (T_CV; coefficient of variation) and hierarchical differences (T_diff) and trait distances (absolute values of trait differences T_dist) between focal and co‐occurring species. T_mean (30–55%) and T_diff (30–33%) explained most variation in mean species performances and their plasticities, but T_slope (20–25%) was also important in explaining mean species performances. The mean species traits and the trait differences between focal species and neighbors with the greatest explanatory power were related to plant size and stature (shoot length, mass:height ratios) and leaf photosynthetic capacity (specific leaf area, stable carbon isotopes and leaf nitrogen concentration). The contribution of trait plasticities in explaining species performances varied in direction (positive or negative) and involved traits related to photosynthetic capacity, nitrogen acquisition (nitrogen concentrations and stable isotopes) as well as structural stability (shoot carbon concentrations). Our results suggest that incorporating plasticity in trait expression as well as trait differences to co‐occurring species is critical for extending trait‐based analyses to understand the assembly of plant communities and the contribution of individual species in structuring plant communities.     

Ecosystem services provided by semi-natural and intensified grasslands: Synergies,trade-offs and linkages to plant traits and functional richness

Question

Semi-natural grasslands (SNG) are important for maintaining biodiversity and ecological processes in farmland. Current pasture-based livestock production mainly occurs on intensified grasslands (IG) that have been agronomically improved. Although it is documented that SNG and IG differ in terms of plant diversity, their ability to provide ecosystem services (ES) in farmland is less explored. Here, we review the role of SNG and IG in delivering ES, illustrate their trade-offs and synergies, and examine how ES can be assessed by using plant traits and functional richness.

Results

We found that SNG generate a wider range of ES than IG. Trade-offs exist between ES that appear more pronounced in IG between high biomass production and other ES. SNG are good in providing habitat for biodiversity, supporting pollination and cultural services. SNG also have a significantly wider range of plant functional traits and a higher functional richness, suggesting that the potential to supply ES in SNG is partly driven by higher number of species and their functional diversity.

Conclusion

Clearer trade-offs were found in IG compared with SNG, supported both by the literature and the functional richness. This suggests that functional knowledge could be a good complement to understand the mechanisms behind ES generation and could help with tailoring grassland management to sustain biodiversity, ecological functions and ES. Although both IG and SNG are likely needed for the long-term sustainability of food production, both could aim for a more balanced generation of ES, increasing biodiversity and functional redundancy at the landscape scale.     

The role of area enclosures and fallow age in the restoration of plant diversity in northern Ethiopia

This study investigated the roles played by area enclosures and fallow age in the restoration of plant species richness and soil seed bank species richness in degraded mountain rangelands in northern Ethiopia. Management types (enclosures versus grazed) influenced woody and herbaceous species richness, while fallow age showed no effect on the woody species. Management, age and the doubling of fallow age influenced the herbaceous species richness and species diversity. Management showed no effect on soil seed bank species richness. Fallow age and the doubling of fallow time also showed no influence on the soil seed bank of grass species, but they were influential on the forbs species soil seed bank. The trends for restoration of plant species richness and diversity and grass seed bank in response to fallow age were positive‐linear, but they declined when the fallow ages were doubled. The exception was the forbs seed bank showed linear trends when age of restoration was doubled. The data suggest that the restoration of degraded rangelands in the high mountain zones of northern Ethiopia was still in the weedy succession stages. Long‐term monitoring will be required to gain an informed understanding of the roles played by area enclosures and fallow age in the restoration of plant biodiversity.     

Influence of plant developmental stage on microbial community structure and activity in the rhizosphere of three field crops

Seasonal shifts in rhizosphere microbial populations were investigated to follow the influence of plant developmental stage. A field study of indigenous microbial rhizosphere communities was undertaken on pea (Pisum satvium var. quincy), wheat (Triticum aestivum var. pena wawa) and sugar beet (Beta vulgaris var. amythyst). Rhizosphere community diversity and substrate utilization patterns were followed throughout a growing season, by culturing, rRNA gene density gradient gel electrophoresis and BIOLOG. Culturable bacterial and fungal rhizosphere community densities were stable in pea and wheat rhizospheres, with dynamic shifts observed in the sugar beet rhizosphere. Successional shifts in bacterial and fungal diversity as plants mature demonstrated that different plants select and define their own functional rhizosphere communities. Assessment of metabolic activity and resource utilization by bacterial community-level physiological profiling demonstrated greater similarities between different plant species rhizosphere communities at the same than at different developmental stages. Marked temporal shifts in diversity and relative activity were observed in rhizosphere bacterial communities with developmental stage for all plant species studied. Shifts in the diversity of fungal and bacterial communities were more pronounced in maturing pea and sugar beet plants. This detailed study demonstrates that plant species select for specialized microbial communities that change in response to plant growth and plant inputs.     

Effect of irradiance and plant age on the dimensions of the growing shoot of poplar

Populus euramericana (Dode) Guinier cv. Robusta plants were cultivated at irradiances of 7.5, 15 and 30 W m⁻² (32.5, 65 and 130 μmol m² s⁻¹), 400–700 nm at 22°C and a relative humidity between 40 and 60% on a gravel culture subirrigated with Hoagland's nutrient solution. The basal diameter of the growing shoot, a measure of the number of apical cells participating in growth, increased proportionally to irradiance and was correlated with mature leaf length. The development of the length of the growing shoot (L_gs) depended also on the nutritional status of the (young) shoot. L_gs was strongly correlated with the rate of height growth.     

Relation between relative growth rate, endogenous gibberellins, and the response to applied gibberellic acid for Plantago major

Relationships between relative growth rate (RGR), endogenous gibberellin (GA) concentration and the response to application of gibberellic acid (GA₃) were studied for two inbred lines of Plantago major L., which differed in RGR. A4, the fast-growing inbred line, had a higher free GA concentration than the slow-growing W9, as analyzed by enzyme immunoassay. GA₃ application increased total plant weight and RGR₃ particularly for the slow-growing line. Chlorophyll a content and photosynthetic activity per unit leaf area were decreased, while transpiration rate was unaffected by GA₃ application. The increase in RGR by GA₃ application was associated with an increased leaf weight ratio; specific leaf area and percentage of dry matter in the leaves were only temporarily affected. Root respiration rate per unit dry weight was unaffected.
The correlation between low RGR, low GA concentration and high responsiveness to applied GA₃ supports the contention that gibberellins are involved in the regulation of RGR. However, the transient influence of GA₃ application on some growth components suggests the involvement of other regulatory factors in addition to GA.     

Resistance of soil biota and plant growth to disturbance increases with plant diversity

Plant diversity is critical to the functioning of ecosystems, potentially mediated in part by interactions with soil biota. Here, we characterised multiple groups of soil biota across a plant diversity gradient in a long‐term experiment. We then subjected soil samples taken along this gradient to drought, freezing and a mechanical disturbance to test how plant diversity affects the responses of soil biota and growth of a focal plant to these disturbances. High plant diversity resulted in soils that were dominated by fungi and associated soil biota, including increased arbuscular mycorrhizal fungi and reduced plant‐feeding nematodes. Disturbance effects on the soil biota were reduced when plant diversity was high, resulting in higher growth of the focal plant in all but the frozen soils. These results highlight the importance of plant diversity for soil communities and their resistance to disturbance, with potential feedback effects on plant productivity.     

The biomarkers of fetal growth in intrauterine growth retardation and large for gestational age cases: from adipocytokines to a metabolomic all-in-one tool

Adipose tissue is no longer considered as inert; the literature describes the role it plays in the production of many substances, such as adiponectin, visfatin, ghrelin, S100B, apelin, TNF, IL-6 and leptin. These molecules have specific roles in humans and their potential as biomarkers useful for identifying alterations related to intrauterine growth retardation and large for gestational age neonates is emerging. Infants born in such conditions have undergone metabolic changes, such as fetal hypo- or hyperinsulinemia, which may lead to development of dysmetabolic syndrome and other chronic diseases in adulthood. In this review, these biomarkers are analyzed specifically and it is discussed how metabolomics may be an advantageous tool for detection, discrimination and prediction of metabolic alterations and diseases. Thus, a holistic approach, such as metabolomics, could help the prevention and early diagnosis of metabolic syndrome.     

长江中下游湿地大型水鸟种群动态和幼鸟比例研究

迁徙水鸟保护对生物多样性保护具有重要意义。开展水鸟种群数量和幼鸟比例监测,对科学评估其种群变化趋势、制定长期保护策略具有重要价值。长江中下游湿地是东亚-澳大利西亚迁徙路线上重要的水鸟越冬区之一。本研究采用野外同步调查等方法对该区域87个湿地的亟需保护和具有代表性的10种大型越冬水鸟,其中雁形目6种,分别是鸿雁Anser cygnoides、豆雁A.fabalis、灰雁A.grus、白额雁A.albifrons、小白额雁A.erythropus和小天鹅Cygnus columbianus;鹤形目4种,分别是白鹤Leucogeranus leucogeranus、白枕鹤Antigone vipio、灰鹤Grus grus和白头鹤G.monacha,进行了长期监测(2003—2019年冬季),并结合相关文献,评估其种群变化趋势、幼鸟比例和死亡率。研究结果如下：(1)2005—2019年3种水鸟(豆雁、灰雁和灰鹤)的种群数量呈上升趋势,7种水鸟(鸿雁、白额雁、小白额雁、小天鹅、白鹤、白枕鹤和白头鹤)种群数量呈下降趋势;(2)种群趋势下降组(N=7)和上升组(N=3)的幼鸟比例均值在2016—2...     

Intensified grazing affects endemic plant and gastropod diversity in alpine grasslands of the Southern Carpathian mountains (Romania)

Alpine grasslands in the Southern Carpathian Mts, Romania, harbour an extraordinarily high diversity of plants and invertebrates, including Carpathic endemics. In the past decades, intensive sheep grazing has caused a dramatic decrease in biodiversity and even led to eroded soils at many places in the Carpathians. Because of limited food resources, sheep are increasingly forced to graze on steep slopes, which were formerly not grazed by livestock and are considered as local biodiversity hotspots. We examined species richness, abundance and number of endemic vascular plants and terrestrial gastropods on steep slopes that were either grazed by sheep or ungrazed by livestock in two areas of the Southern Carpathians. On calcareous soils in the Bucegi Mts, a total of 177 vascular plant and 19 gastropod species were recorded. Twelve plant species (6.8%) and three gastropod species (15.8%) were endemic to the Carpathians. Grazed sites had lower plant and gastropod species richness than ungrazed sites. Furthermore, grazed sites harboured fewer gastropod species endemic to the Carpathians than ungrazed sites. On acid soils in the Fagaras Mts, a total of 96 vascular plant and nine gastropod species were found. In this mountain area, however, grazed and ungrazed sites did not differ in species richness, abundance and number of endemic plant and gastropod species. Our findings confirm the high biodiversity of grasslands on steep slopes in the Southern Carpathian Mts and caution against increasing grazing pressure in these refuges for relic plants and gastropods as well as for other invertebrates.     

川西北高寒草地3种主要植物的生长及物质分配对温度升高的响应

在野外自然条件下采用开顶式生长室模拟增温的方法, 研究了增温对川西北高寒草地3种主要植物(单子叶草本植物垂穗披碱草(Elymus nutans)和双子叶草本植物尼泊尔酸模(Rumex acetosa)和鹅绒委陵菜(Potentilla anserina))的生长及物质分配的影响。研究结果表明, 增温对3种植物的生长产生了显著影响, 垂穗披碱草和尼泊尔酸模的比叶面积和生物量积累在增温后显著增加, 而鹅绒委陵菜在增温后显著减少。在各组分中, 增温处理使尼泊尔酸模的叶生物量显著增加, 根生物量却显著下降, 而鹅绒委陵菜叶和茎的生物量在增温后显著减少, 根生物量却显著增加。增温对尼泊尔酸模各组分的养分含量产生了显著影响, 其中, 根部碳含量在增温后显著增加, 而氮含量在增温后显著减少。增温对尼泊尔酸模和鹅绒委陵菜的生物量在各组分中的分配产生了显著影响, 增温显著增加了尼泊尔酸模的叶重比(LMR)、根重比(RMR)和地下生物量/地上生物量(R/S), 而茎重比(SMR)在增温后却显著降低; 增温显著增加了鹅绒委陵菜的RMR和R/S, 而SMR和LMR在增温后却显著降低。增温对尼泊尔酸模和鹅绒委陵菜各组分中的碳、氮分配产生了显著影响, 增温显著增加了碳、氮在尼泊尔酸模叶片的分配比例, 并且使尼泊尔酸模根部的碳分配比例也显著增加, 而茎部的碳、氮分配比例却显著减少; 增温显著减少了碳在鹅绒委陵菜叶片的分配比例, 而根部的碳、氮分配比例却显著增加。