Spring Ephemeral Research Articles

模拟降雨变化对古尔班通古特沙漠土壤养分及酶活性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 模拟降雨变化对古尔班通古特沙漠土壤养分及酶活性的影响 DOI: 10.5846/stxb202102170450 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 自治区创新环境（人才、基地）建设专项（2018Q009）；国家自然科学基金（41977099，U2003214）；中国科学院青年促进会（Y201976） Effects of simulated rainfall on soil nutrient contents and enzyme activities in the Gurbantunggut Desert, China Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:土壤酶参与土壤系统的养分循环过程，是联系植物和土壤养分的关键纽带。土壤酶活性对降水格局变化响应敏感，这种响应对于缺水且养分贫瘠的荒漠生态系统显得尤为重要。然而，早春积雪完全融化后首次降雨时间及降雨量如何影响土壤养分及土壤酶活性还鲜见相关报道。以新疆古尔班通古特沙漠为研究区，在早春积雪完全融化后，设置3个首次降雨时间（积雪完全融化后第10天、20天和30天）和3个降雨梯度（5 mm、10 mm和15 mm），于植物生长旺季采集土壤样品，研究土壤养分含量和土壤酶活性的响应特征。结果表明：积雪完全融化后不同首次降雨时间下5mm降雨处理以及积雪完全融化后第30天下各降雨量处理对土壤养分和酶活性影响不显著。积雪完全融化后第10天，随降雨量增加，土壤全碳呈显著先下降后增加趋势，全钾呈显著增加趋势，而土壤微生物量碳呈显著降低趋势；积雪完全融化后第20天，随降雨量增加，速效氮、土壤蔗糖酶活性、土壤微生物量碳氮呈先下降后增加趋势，土壤全碳和多酚氧化酶活性显著下降，土壤全钾和碱性磷酸酶活性显著增加。模拟10 mm降雨，随首次降雨时间推迟，土壤全氮、速效氮、速效磷、土壤蔗糖酶活性和土壤微生物量碳呈增加趋势；模拟15 mm降雨，随首次降雨时间推迟，土壤全磷、土壤蔗糖酶、碱性磷酸酶活性和土壤微生物量碳氮呈先增加后下降趋势，而土壤多酚氧化酶和过氧化物酶活性显著增加。积雪完全融化后第10天和20天后，15 mm降雨处理下对土壤大部分指标促进效应最大。研究表明，早春积雪完全融化后，推迟首次降雨时间，添加大降雨量（15 mm）显著提高土壤微生物活性及不同养分之间的转化，能够补偿一段时间的干旱对养分转化的抑制效应，从而提高早春短命植物生长期土壤养分供给能力。 Abstract:Soil enzymes actively participate in the nutrient transformation of soil system and are the key link between plants and soil nutrients. Soil enzyme activity is sensitive to the changes in rainfall patterns, particularly in deserts where rainfall is generally low and highly spatially and temporally variable. Little is known about how the timing and amount of rainfall affect soil nutrient contents and soil enzyme activity in areas where soil moisture is driven by snowmelt, particularly in early spring following complete snowmelt. We examined soil nutrient contents and enzyme activity at three times (Days 10, 20 and 30) and three rainfall amounts (5 mm, 10 mm, 15 mm) after complete snow melt, the period of maximum plant growth in the Gurbantunggut Desert in western China. We found no response under the lowest rainfall treatment (5 mm) at any times. The addition of 10 mm of rainfall stimulated a positive response in soil nutrients (e.g., nitrogen, phosphorus) but the 15 mm addition of rainfall had the greatest promotion effect on most soil indices such oxidase, phosphatase, and peroxidase activity, particularly 10 and 20 days after complete snow melt. Our results show that delaying of first rainfall time and addition of 15 mm rainfall after snowmelt can significantly increase soil microbial activity and nutrient transformation. These treatments can compensate for the inhibition effect of drought on nutrient transformation for a certain time period and enhance soil nutrients supply capacity in the growth period of desert ephemeral plants in early spring. 参考文献 相似文献 引证文献

新疆三种独尾草的适宜分布及其对未来气候变化的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 新疆三种独尾草的适宜分布及其对未来气候变化的响应 DOI: 10.5846/stxb202110152910 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41561007，41261011）；新疆维吾尔自治区草原总站草原生态修复治理补助项目（XJCYZZ202007） Suitable distributions of three species of Eremurus in Xinjiang and their responses to future climatic changes Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:研究国内仅分布于新疆的3种短命植物阿尔泰独尾草（Eremurus altaicus）、粗柄独尾草（Eremurus inderiensis）和异翅独尾草（Eremurus anisopterus）的适宜分布及其对未来气候的可能响应，对新疆短命植物资源的分布、利用与科学保护具有重要意义。共收集了64个自然分布点，筛选了6个气候因子和2个地形因子数据，利用MaxEnt模型和地理信息系统ArcGIS软件模拟了当前气候情景下3种独尾草的生态适宜性，探讨影响3种植物分布的主导因子及其数值范围，预测3种独尾草的适宜分布对未来气候变化（2001-2040年、2041-2080年，基于温室气体中等排放情景：SSP2-4.5共享社会经济路径）的可能响应。结果表明：（1）基准气候下，3种独尾草在新疆的适宜分布存在较大差异：阿尔泰独尾草主要分布于伊犁河谷、天山北麓、阿尔泰山中段和准噶尔西部山地；两种沙生独尾草均分布于天山中段的绿洲-荒漠区过渡带，古尔班通古特沙漠西南部沙地；（2）最干月降水量（1-25mm）主要限制了阿尔泰独尾草的适宜分布；温度季节性变动指数（1150-1672）主要限制了两种沙生独尾草的适宜分布；（3）2001-2040年和2041-2080年，3种独尾草的适宜分布整体均呈缩减趋势：阿尔泰独尾草向天山北麓和准噶尔西部山地略微缩减；粗柄独尾草和异翅独尾草向古尔班通古特沙漠南缘略微缩减。 Abstract:In China,Eremurus altaicus,Eremurus inderiensis and Eremurus anisopterus are only distributed in Xinjiang.It is of great significance to the distribution, utilization and scientific protection of ephemeral plant resources in Xinjiang to study the suitable distributions of Eremurus altaicus, Eremurus inderiensis and Eremurus anisopterus and their possible responses to future climatic changes. A total of 64 natural distribution sites, 6 climate factors and 2 topographic factors were collected in this study. MaxEnt model and ArcGIS software were used to simulate the ecological suitability of the three species of Eremurus under current climate scenario. To investigate the dominant factors influencing the distribution of the three species and their numerical ranges, and to predict the possible responses of the suitable distribution of the three species to future climatic changes (2001-2040、2041-2080,the society is a medium greenhouse gas emission scenario:based on SSP2-4.5 shard socio-economic path).The research results show that:(1) Under the basic climate, there is great differences in the suitable distribution of the three species in Xinjiang:Eremurus altaicus is mainly distributed in Ili River Valley, northern foot of the Tianshan Mountain, middle of the Altai Mountain and the Western Junggar Mountains. Both of psammophytes are distributed in the oasis-desert transition zone in the central Tianshan Mountains and the sandy land in the southwest of Gurbantunggut Desert; (2) The maximum monthly precipitation (1-25mm) mainly limited the suitable distribution of Eremurus altaicus, the temperature seasonal variation index (1150-1672) mainly limited the suitable distribution of Eremurus inderiensis and Eremurus anisopterus; (3) During 2001-2040 and 2041-2080, the suitable distribution of the three species of Eremurus show a decreasing trend as a whole:the Eremurus altaicus is reduced slightly towards the northern foot of the Tianshan Mountain and the Western Junggar Mountains; Eremurus inderiensis and Eremurus anisopterus shrink slightly towards the southern edge of the Gurbantunggut Desert. 参考文献 相似文献 引证文献

Leaf-root-soil N:P stoichiometry of ephemeral plants in a temperate desert in Central Asia.

Ephemeral plants are a crucial vegetation component in temperate deserts of Central Asia, and play an important role in biogeochemical cycle and biodiversity maintenance in desert ecosystems. However, the nitrogen (N) and phosphorus (P) status and interrelations of leaf-root-soil of ephemeral plants remain unclear. A total of 194 leaf-root-soil samples of eight ephemeral species at 37 sites in the Gurbantunggut Desert, China were collected, and then the corresponding N and P concentrations, and the N:P ratio were measured. Results showed that soil parameters presented no significant difference among the eight species. The total soil N:P was only 0.116 (geomean), indicating limited soil N, while the available soil N:P (4.896, geomean) was significantly larger than the total N:P. The leaf N (averagely 30.995mg g-1) and P (averagely 1.523mg g-1) concentrations were 2.64-8.46 and 0.93-3.99 times higher than the root N (averagely 8.014mg g-1) and P (averagely 0.802mg g-1) concentrations, respectively. Thus, leaf N:P (averagely 21.499) was 1.410-2.957 times higher than root N:P (averagely 11.803). Meanwhile, significant interspecific differences existed in plant stoichiometric traits. At the across-species level, N content scaled as the 3/4-power of P content in both leaves and roots. Leaf and root N:P ratios were mainly influenced by P; however, the leaf-to-root N or P ratio was dominated by roots. Leaf and root N, P contents and N:P were generally unrelated to soil nutrients, and the former presented lower variation than the latter, indicating a strong stoichiometric homeostasis for ephemerals. These results demonstrate that regardless of soil nutrient supply capacity in this region, the fast-growing ephemeral plants have formed a specific leaf-root-soil stoichiometric relation and nutrient use strategy adapting to the extreme desert environment.

Life-history strategy and extinction risk in the warm desert perennial spring ephemeral Astragalus holmgreniorum (Fabaceae).

This study of Astragalus holmgreniorum examines its adaptations to the warm desert environment and whether these adaptations will enable it to persist. Its spring ephemeral hemicryptophyte life‐history strategy is unusual in warm deserts. We used data from a 22‐year demographic study supplemented with reproductive output, seed bank, and germinant survival studies to examine the population dynamics of this species using discrete‐time stochastic matrix modeling. The model showed that A. holmgreniorum is likely to persist in the warm desert in spite of high dormant‐season mortality. It relies on a stochastically varying environment with high inter‐annual variation in precipitation for persistence, but without a long‐lived seed bank, environmental stochasticity confers no advantage. Episodic high reproductive output and frequent seedling recruitment along with a persistent seed bank are adaptations that facilitate its survival. These adaptations place its life‐history strategy further along the spectrum from “slower” to “faster” relative to other perennial spring ephemerals. The extinction risk for small populations is relatively high even though mean λ s > 1 because of the high variance in year quality. This risk is also strongly dependent on seed bank starting values, creating a moving window of extinction risk that varies with population size through time. Astragalus holmgreniorum life‐history strategy combines the perennial spring ephemeral life form with features more characteristic of desert annuals. These adaptations permit persistence in the warm desert environment. A promising conclusion is that new populations of this endangered species can likely be established through direct seeding.

Pioneer annual vegetation of gravel-bed rivers: first insights on environmental drivers from three Apennine streams

A huge knowledge gap exists on riverine pioneer herbaceous vegetation. Despite its relevance in regulating the C metabolism at the catchment scale, and the triggering role in shrubs and trees establishment along riverbanks, little data is available on its environmental determinants. Indeed, most existing knowledge in this field refers to woody species or aquatic macrophytes neglecting the ecosystem relevance of ephemeral herbaceous vegetation. Focusing on three gravel bed rivers located in northern Italy (Baganza, Nure and Parma streams), the present study is aimed to evaluate the riverine ephemeral plant richness, considering both native and alien taxa, and the role of hydrogeomorphological disturbance and sediment quality in the observed richness patterns. At higher disturbance rates (e.g., larger river sizes), our data indicates a progressive decrease in overall plant richness, but also an increase in the coverage-abundance rates mainly due to alien species. This evidence confirms that variations in hydrology imply changes in pioneer plant species richness at in-stream periodically exposed sediments. More attention must be given to the vulnerability of pioneer vegetation to climate change and direct human impacts to fully understand the functioning of lotic ecosystems, especially the non-perennial ones.

Vezdaea aestivalis . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Vezdaea aestivalis , a lichen-forming fungus typical of ephemeral habitats, overgrowing mosses or plant remains over calcareous rocks, often on lead or zinc mine sites. Some information on its associated organisms and substrata, dispersal and transmission, habitats and conservation status is given, along with details of its geographical distribution (Asia (Georgia), Australasia (Australia (Victoria)), Europe (Austria, Belarus, Belgium, Czech Republic, former Czechoslovakia, Channel Islands, Denmark, Estonia, Finland, France, Germany, Ireland, Isle of Man, Lithuania, Luxembourg, Netherlands, Norway, Poland, Romania, Russia (Leningrad Oblast, Republic of Adygea), Slovakia, Slovenia, Spain, Sweden, Switzerland, Ukraine, UK), North America (Canada (Northwest Territories))).

The complete chloroplast genome of the ephemeral plant Isatis minima (brassicaceae) of northwest China

The complete chloroplast genome of Isatis minima, a typical ephemeral plant of Brassicaceae in the Central Asia desert, was sequenced and characterized in this study. The genome 153,642 bp in size, contains a typical quadripartite genome organization including LSC and SSC regions of 83,423 bp and 17,709 bp, and two copies of the IR regions of 26,255 bp. It has 113 unique genes, including 79 protein-coding, 30 tRNA, and four rRNA genes. Phylogenetic analysis fully resolved I. minima in a monophyletic clade with I. tinctoria. This bioinformatic data contributes to the phylogenetics systematics and evolutionary history of Brassicaceae.

Extreme precipitation increases the productivity of a desert ephemeral plant community in Central Asia, but there is no slope position effect

AbstractQuestionsAnthropogenic climate change has become a critical environmental problem and is profoundly affecting various ecosystems, especially desert ecosystems. However, very few studies have explored the effects of extreme precipitation on the community structure and ecosystem functions in drylands. Moreover, whether local microtopography will interact with extreme precipitation on plant growth by changing water retention and other processes is still unclear.LocationThe Gurbantunggut Desert in Central Asia.MethodsWe conducted a two‐year field experiment to assess the effect of extreme precipitation (+65% of ambient growing‐season precipitation amounts) on the composition and productivity of a desert ephemeral plant community growing in sand dunes of the Gurbantunggut Desert in Central Asia. We further determined how much slope position modulates this response.ResultsWe found that the cover, density, height, species richness, and biomass of ephemeral plants increased with an increase in precipitation, and the strongest direct effect of biomass was a positive effect on density of ephemeral plants. Additionally, no significant differences in the sensitivity of biomass to the increased precipitation were found between slope positions.ConclusionsThe results indicate that extreme precipitation primarily increased the above‐ground net primary production by increasing the density, rather than the height and species richness, of the ephemeral community; no interactive effects were observed between sand dune slope positions and the sensitivity of biomass to the extreme precipitation treatment.

Growing food with less water: Chilean research team finds solutions in extreme environments

Droughts pose a growing risk to food security. Glasshouse experiments show that tomatoes inoculated with rhizobacteria from ephemeral flowering desert plants exhibit greater rates of survival and growth when subjected to periods of water stress.

Multiple reproductive strategies of a spring ephemeral plant, Fritillaria maximowiczii, enable its adaptation to harsh environments

AbstractSpring ephemeral plants that experience harsh environments have developed specific reproductive characteristics. These characteristics are of great importance to the survival and reproduction of these species, particularly for rare and endangered plants. Fritillaria is a genus consisting of spring ephemeral plants with significant medicinal and ornamental value whose wild resources are highly threatened and whose reproductive characteristics and adaptative evolutionary mechanisms are still not well understood. Fritillaria maximowiczii is positioned at the most basal clade on the Fritillaria phylogenetic tree, whose reproductive characteristics remain obscure. In this study, we report the flowering dynamics, pollination biology and breeding system of F. maximowiczii. The flowering process of F. maximowiczii can be divided into seven stages. Based on the pollen/ovule ratio, the outcrossing index and a field pollination experiment on a natural population, F. maximowiczii showed high levels of outcrossing and self‐compatibility. Three types of pollinators were observed: two kinds of bumblebees, and spiders. Diverse herkogamy and dichogamy may have considerably improved its reproductive success rate. Furthermore, a special reproductive mode not previously reported in wild populations of Fritillaria, apomixis, was strongly suspected based on a high fruit setting rate (36.84%). Our study suggests F. maximowiczii has developed multiple reproductive strategies to adapt to harsh environments and ensure population reproduction, and the diverse reproductive mechanisms may be related to its primitive phylogenetic position in the genus. This study not only broadens our understanding of mechanisms of ecological adaptation in spring ephemeral plants but also provides key data for the conservation of Fritillaria.

Эколого-геоботаническое состояние растительного покрова Апшерона

The article deals with the research and processing of herbarium materials. From the research results it follows that the total number of species of the vegetation cover of Apsheron is about 36 kinds. Most types of vegetation are annual and ephemeral plants. The shrubs, semi shrubs, dwarf shrubs and semi-dwarf-shrubs are in lees numbers, but they play a great role in the formation of plant communities. Among the leading species includes mesophytes, ephemerals and ephemeroids in the herbage. An important role is also played by edificators, which are formed from subshrubs, semi-shrub types (fragrant wormwood, karagan, mountain hodgepodge, petrosimonia, salsify).

Is Plant Life-History of Biseasonal Germination Consistent in Response to Extreme Precipitation?

Future climate is projected to increase in the intensity and frequency of extreme precipitation events, and the resulting ecological consequences are often more serious than those of normal precipitation events. In particular, in desert ecosystems, due to the low frequency and strong fluctuation of extreme precipitation, the destructive consequences for desert plants caused by extreme precipitation have not received enough attention for some time. Based on statistics of extreme precipitation events (1965–2018) in the Gurbantunggut Desert, we investigated the effects of extreme precipitation (+0%, CK; +50%, W1; +100%, W2; +200%, W3; maintenance of field capacity, W4) on the plant life-history of the spring-germinated (SG) and autumn-germinated (AG) ephemeral plant Erodium oxyrhynchum by monitoring seedling emergence, survival, phenology, organ size, biomass accumulation, and allocation. The results showed that extreme precipitation caused about 2.5% seedling emergence of E. oxyrhynchum in autumn 2018 and 3.0% seedling emergence in early spring 2019, which means that most seeds may be stored in the soil or have died. Meanwhile, extreme precipitation significantly improved the survival, organ size, and biomass accumulation of SG and AG plants, and W3 was close to the precipitation threshold of SG (326.70 mm) and AG (560.10 mm) plants corresponding to the maximum individual biomass; thus, AG plants with a longer life cycle need more water for growth. Conversely, W4 caused AG plants to enter the leaf stage in advance and led to death in winter, which indicates that extreme precipitation may not be good for AG plants. Root and reproduction biomass allocation of SG and AG plants showed a significantly opposite trend under extreme precipitation treatments, which might be related to their different life-history strategies. Therefore, when only taking into account the changing trend of extreme precipitation from the Coupled Model Intercomparison Project 6 (CMIP6) climate projections data, we speculate that extreme precipitation may promote the growth of SG and AG plants from the beginning to the middle of this century, but extreme precipitation in autumn exceeding a certain threshold may adversely affect the survival of AG plants at the end of the century.

Characteristics of turbulence over the semi‐fixed desert area north of Xinjiang, China

AbstractAs the largest fixed and semi‐fixed desert in China, the Gurbantünggüt Desert undergoes a long period of snow cover in the winter and the rapid growth of ephemeral plants in the spring, presenting obvious seasonal changes in the underlying desert surface type, which can lead to variation in the turbulence of the near‐surface boundary layer turbulence over the desert. In this study, gradient tower data and eddy covariance data from 2017 were analysed to investigate the turbulence characteristics of the different surface boundary layers in the hinterland of the Gurbantünggüt Desert. The results indicate that stable atmospheric conditions in the desert occur exclusively during the early morning and at night in the desert, and the onset and duration of this stable state varies seasonally. Two regimes of intermittent turbulence occur during the night, a weak turbulent regime that occurs when the wind speed is less than the threshold and a strong turbulent regime when the wind speed exceeds the threshold, and different wind speed thresholds were observed at each level. These parameters follow a seasonal pattern of summer (July) > spring (April) > autumn (October) > winter (January) in terms of magnitude. The mean turbulence intensities of the along‐wind, cross‐wind and vertical wind are 0.5, 0.47 and 0.14, respectively, with Iu > Iv > Iw. The normalized standard deviation of the wind velocity components (σu, σv and σw) generally satisfies a 1/3 power‐law relation. Our results show that the night‐time turbulence regime classification for the Gurbantünggüt Desert strongly depends on meteorological and orographic features, and the intermittent turbulent events have the non‐stationarity of the flow in common. The results can contribute to the study of land surface processes, climate change and desertification in inland arid desert areas.

Soil microbes and seed mucilage promote growth of the desert ephemeral plant Nepeta micrantha under different water conditions

Ephemeral plants, which can complete their life cycle in two to three months, play an important role in stabilizing sand dune surfaces from wind erosion in spring in the Gurbantunggut Desert, northwestern China. Soil microbes and seed mucilage could promote seedling growth of desert species via independent effects and / or interactions. However, it is uncertain whether both factors affect growth of adult ephemeral plants when exposed to different water regimes. Intact or demucilaged seeds of Nepeta micrantha were sown in sterile and non-sterile soil and exposed to three water regimes. The results indicated that plants under middle water treatment had higher dry mass accumulation as compared to that under low and high water treatments. Soil microbes and seed mucilage could significantly increase plant growth in all three water regimes. Their interactions showed positive effect on growth only under low water treatment. Nepeta micrantha plants had the highest biomass in the treatment of intact seeds in non-sterile soil and exposed to middle water regimes. Our study provides a better understanding of the growth regulation mechanism by which water, soil microbes and seed mucilage interactively promote growth of ephemeral plants in arid desert.

Ecology and Genetics of Cyperus fuscus in Central Europe—A Model for Ephemeral Wetland Plant Research and Conservation

The ecology and species diversity of ephemeral wetland vegetation have been fairly well studied, but the biology of its characteristic species has rarely been investigated holistically. Here we combine previous results on the genetic diversity of a suitable model species (the diploid Cyperus fuscus) with new data on its historical and recent occurrence, its ecological and climatic niche, and the associated vegetation. Analysis of phytosociological relevés from Central Europe revealed a broad ecological niche of C. fuscus with an optimum in the Isoëto-Nanojuncetea class, extending to several other vegetation types. Overall species composition in the relevés highlight C. fuscus as a potential indicator of habitat conditions suitable for a range of other threatened taxa. Analysis of historical records of C. fuscus from the Czech Republic showed an increasing trend in the number of localities since the 1990s. It seems that recent climate warming allows the thermophilous C. fuscus to expand its range into colder regions. Isoëto-Nanojuncetea and Bidentetea species are well represented in the soil seed bank in both riverine and anthropogenic habitats of C. fuscus. Vegetation diversity has a weak negative effect and anthropogenic (compared to riverine) habitats have a strong negative effect on genetic diversity in this species.

Vegetation Cover and Tumuli’s Shape as Affecting Factors of Microclimate and Biodeterioration Risk for the Conservation of Etruscan Tombs (Tarquinia, Italy)

The conservation of underground tombs is affected by several physical-chemical and biological factors, which could be reduced by insulating systems able to maintain the microclimatic stability also decreasing the biodeterioration risk. In Mediterranean areas, wild ephemeral plants, which reduce their cover during the hot season, seem unsuitable for reducing summer overheating. In this study, we wish to assess the influence of vegetation cover and of overlaying soil, after the establishment of an evergreen turf of a cultivar of Cynodon dactylon, on two tombs in the Etruscan Necropolis of Monterozzi, covered by linear-shaped tumuli. Therefore, we evaluated for 10 months the thermo-hygrometric values of these tombs, together with two tombs as controls. We also evaluated the different tumuli’s morphologies and the related received solar radiation. Results confirmed that late summer and early autumn as critical microclimatic periods for the risk factors of hypogeal paintings when peaks of superficial temperature occur. A positive influence of vegetation cover on maintaining constant humidity and internal temperatures was detected, but the mounds orientation, as well as soil depth, seems to have a relevant role. Considering the naturalistic features of the area and the related cultural ecosystem services, a careful selection of wild plants is suggested.

The ecological roles of seed mucilage on germination of Lepidium perfoliatum, a desert herb with typical myxospermy in Xinjiang

Myxospermy is considered as an adaptation to unideal habitats, which is characterized as a gelatinous layer of mucilage around the seed upon contact with water. Studies on the ecological roles of seed mucilage should provide valuable information on seed germination strategy. In the present study, the germination properties of Lepidium perfoliatum L., an early spring ephemeral plant with typical myxospermy in desert of northwestern China, were investigated with the intact seeds and demucilaged seeds under different conditions. Results revealed that, firstly, the seed mucilage was essential for intact seeds to germinate quickly and efficiently under abundant or excess water condition, while had no effect on relief of seed germination at low water potential or other stressful conditions; secondly, the presence of mucilage layer stimulated intact seed germination under relatively higher temperature, appropriate light, permeable soil matrix, which helps seed germinate efficiently under favorable conditions; thirdly, the existence of mucilage may limit air diffusion into seed and subsequently reduce germination, which might be a strategy to ensure a proportion of seeds staying in soil seed bank to wait for next favourable conditions. Our results suggest that the seed mucilage of L. perfoliatum applies multiple ecological roles in protection of seed germination to avoid unfavourable conditions, which should be an adaptation strategy for population survival and succession in a harsh desert environment.

Population Genomics and Conservation of Erigenia bulbosa (Apiaceae), an Edge-of-Range Species in Pennsylvania

Premise of research. Erigenia bulbosa, or the harbinger of spring, is one of the earliest-blooming wildflowers in eastern North America. As a spring ephemeral of forests and woodlands, it is a common species throughout the Midwest. In Pennsylvania, E. bulbosa exhibits an east-west disjunct distribution, where widespread western populations are contiguous with the midwestern range and a handful of smaller populations in the eastern part of the state are restricted to the lower Susquehanna River Valley. The relative isolation of the eastern populations suggests a possible conservation concern; the smaller, less connected populations may be threatened by fluctuations in size and the potential for low genetic diversity. As a consequence, establishing regulatory measures in Pennsylvania has been problematic because of disagreement regarding how to treat E. bulbosa during the Pennsylvania Department of Conservation and Natural Resources (PA DCNR) environmental review process. Currently, populations in the east are subject to regulation, while populations in the west are not.Methodology. To better understand the population genetics of the species, we coupled field assessments of E. bulbosa with a population genomics approach. We sampled multiple individuals from eight populations and generated a genotyping-by-sequencing data set of single-nucleotide polymorphisms (SNPs) that we used to calculate population statistics (genetic variation [FST], inbreeding coefficient [FIS], and heterozygosity), estimate population structure (sparse nonnegative matrix factorization), identify clusters of genetically related individuals (discriminant analysis of principal components), estimate a NeighborNet, look at signatures of isolation by distance (IBD), and detect population differentiation (analysis of molecular variance) using the filtered SNP data set.Pivotal results. Our data reveal structure in all populations and suggest genetic isolation between the groups of populations in the eastern and western portions of the state. Genetic groups identified using multivariate methods correspond to populations. Within populations, we estimate low levels of heterozygosity, a significant signature of IBD, and that most of the genetic variation we find is due to differences between populations.Conclusions. Our results indicate that any conservation measures undertaken by the PA DCNR should be applied evenly throughout Pennsylvania. We expect that most populations will continue to be threatened by land use and other development activities. This work illustrates the strength of academic and nonacademic partnerships in fostering outcomes that inform conservation activities for local species of concern.

Effects of freezing and thawing cycle on seed germination of desert ephemeral plants.

Effects of freezing and thawing cycle on seed germination of desert ephemeral plants.

Population Dynamics and Life History Response to Precipitation Changes for a Desert Ephemeral Plant With Biseasonal Germination.

The changing availability of water resources and frequent extreme drought events in the context of global change will have a profound impact on desert vegetation, especially on herbaceous populations such as ephemerals. Erodium oxyrrhynchum is the dominant species in the Gurbantunggut Desert. It can germinate both in spring and autumn, which is important for herbaceous layer coverage and productivity. Therefore, we tracked and recorded the survival and reproduction of the E. oxyrrhynchum population under different precipitation treatments and established a population matrix model, monitored the allometry and leaf traits of the plants, and compared the performance of spring-germinating and autumn-germinating plants. Our results showed that: (1) The population dynamics were significantly affected by precipitation changes; (2) drought reduced the survival rate of the plants and accelerated the completion of their life history; (3) precipitation had a significant effect on seed production and growth rate, but not on plant height and allometry; (4) biomass, leaf area, specific leaf area, and 100-grain weight of E. oxyrrhynchum also responded to changes in precipitation; and (5) autumn-germinated plants had higher productivity, whereas spring-germinated plants exhibited higher reproductive efficiency, indicating that they had difference life history strategies. In conclusion, our results suggested that, although frequent or prolonged drought can significantly inhibit population growth, species with biseasonal germination are likely to be less affected.