Sandy Dunes Research Articles

科尔沁沙地恢复演替进程中群落物种多样性与地上生物量的关系

PDF HTML阅读 XML下载 导出引用 引用提醒 科尔沁沙地恢复演替进程中群落物种多样性与地上生物量的关系 DOI: 10.5846/stxb201606161165 作者: 作者单位: 湖北大学资源环境学院 湖北 武汉 430062,湖北大学,湖北大学,湖北大学,湖北大学,中科院寒旱所 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（31070370）；湖北省教育厅重点项目（D2015003）；湖北省科技厅软科学专项（2013BDF034）；生物资源绿色转化湖北省协同创新中心 Relationship between the aboveground biomass and species diversity of sandy communities during the process of restoring succession in the Horqin Sandy Land,China Author: Affiliation: School of Resources and Environmental Science; Hubei University; wuhan 430062,,,,, 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:生物多样性与生产力的关系是当前生态学中研究的重点之一，以科尔沁沙地为研究对象，研究了沙地植被恢复演替进程中物种多样性与地上生物量的关系。结果表明：（1）科尔沁沙地植被恢复演替过程中，物种数量逐渐增加，从流动沙丘的6种到固定沙丘的30种，增加了4倍。一年生草本植物在各群落中占绝对优势，但随着演替的进行，生活型呈现多样化，多年生植物种类明显增加。藜科植物在流动沙丘阶段优势度明显，之后逐渐下降；禾本科植物的种数和优势度逐渐增加，在群落中的地位逐渐增强。多重比较表明，群落的地上生物量存在显著差异（F=18.926，n=360，P < 0.001），从流动沙丘到固定沙丘（3个恢复阶段的均值计算）地上生物量增加了580%。（2）随着演替的进行，群落Simpson指数、Shannon-winner指数和均匀度指数均呈现增加的趋势。（3）回归分析显示，群落物种多样性和生物量之间存在显著的负二次函数关系即单峰型函数关系，表明中等生产力水平物种多样性较高。 Abstract:The relationship between species diversity and aboveground biomass may be affected by environmental conditions and anthropogenic activities and is one of the central topics in ecological research. However, little is known about the relationship between the biodiversity and biomass of sandy plants during community succession in semi-arid deserts. In the Horqin Sandy Land of Inner Mongolia in China, vegetation restoration occurs under proper management regimes in fragile environmental conditions, e.g., enclosing and non-grazing. During the process of restoring succession, shifting, semi-shifting or semi-fixed, and fixed sandy dunes correspond to early, middle, and late succession phases. Therefore, a field experiment was performed to examine the aboveground biomass and species diversity of sandy communities during the process of restoring succession. In early April 2014, six communities that corresponded to succession times of 1, 3, 5, 12, 15, and 20 years were selected as experimental sites. At each site, three parallel 200m line transects (20 m apart) were established along a sandy dune (across the windward slope, dune crest, and leeward slope). For each transect, 20 sampling points of 1m×1m were established at 10m intervals. At each of the 360 sampling points, species composition, coverage, height, and density were surveyed; whereas aboveground biomass was measured using a level cutting method, and the dry weight of the biomass was measured after drying in an oven at 85℃ for 24 h. The frequency of each species was calculated at each of the six sites, based on the frequency of occurrence among the 60 sampling points. (1) The number of plant species increased by 400% from the shifting sandy dune to the fixed dune, and annual herbaceous plants were dominant in each community, although perennial species increased with succession. In the shifting sandy dune community, the dominance of the Chenopodiaceae was the most exaggerated, and this level of dominance gradually decreased in the semi-fixed and fixed sandy dunes. Meanwhile, the richness and dominance of grass species gradually increased during the process of restoring succession. There was a significant difference among the aboveground biomass of six communities (F=18.926, n=360, P < 0.001), and the aboveground biomass increased by 580% from the shifting sandy dune to fixed sandy dune. (2) The Simpson, Shannon-Wiener, and evenness indices gradually increased along the restoring succession gradients. (3) Regression analysis indicated a marked relationship between aboveground biomass and species diversity. The fitting curve was a negative quadratic or a single peak function. The results of the present study support the single-peak model of the relationship between biodiversity and productivity of plant communities, with maximum biodiversity occurring at an intermediate level of plant productivity. 参考文献 相似文献 引证文献

Physicochemical Indices of Ground Water and Their Geoponic Management, in Coastal Odisha, India

&lt;p&gt;Agriculture can not exist without water. At present the old practice of arbitrary use of water in irrigation sector has become unethical. Odisha is an agrarian state in east coast of India. For better yield of crops, quality of water is intricately related to the aquifer geometry, ground water flow regime and its quality. Coastal Odisha is having an area of 14700 sqkm and demography of 1.26 million. The land has mostly water logged alluvial crop land, deciduous forests or sandy dunes with an astomosed channels of hexa-deltaic rivers. The edaphic factors demand improvement of quality of ground water which is brackish. The physicochemical properties like pH value, electrical conductivity, inorganic constituents (Na&lt;sup&gt;+&lt;/sup&gt;, Mg&lt;sup&gt;++&lt;/sup&gt;, Ca&lt;sup&gt;++&lt;/sup&gt;, K&lt;sup&gt;+&lt;/sup&gt;) of ground water used for lift irrigation have been studied. Data from thousand number of wells from the study area are covered in various seasons during the years 2009-2014 along with the yield of the major crop, i.e., paddy. The indices and parameters like EC, SAR, KI, ESP, SSP, MAR, PI and alkalinity of the ground water are determined to show its fitness for irrigation in the area. The different water management policies and present activities are discussed so that the ground water can be used efficiently for irrigation in coastal Odisha.&lt;/p&gt;

AUTOMATIC EXTRACTION OF DUNES FROM GOOGLE EARTH IMAGES NEW APPROACH TO STUDY THE DUNES MIGRATION IN THE LAÂYOUNE CITY OF MOROCCO

Abstract. In desert environments, the sandy dune movements are considered as the main threat to the livelihoods and productivity of people living in Laâyoune city, South of Morocco. Studying dunes at a large scale requires intensive fieldwork and a huge dataset. But this task is not always easy because of the high cost and the limited availability of data. In this paper we present a new approach to study and evaluate the dune dynamic using Google earth archive image acquired from 2005, 2011, 2012, and 2013. To achieve this goal, an area with 3577 meter square including 40 barchan dunes, were selected, and the barchan dunes were automatically extracted from these images using Geographic Information System (GIS) and spatial analysis techniques provided by image processing software. The result shows not only the dune shape but also direction of dunes movements, and distance separating dunes. The obtained direction is ranging from North east to South west. The average rate of movement of the extracted dunes between 2005 and 2013 was calculated and is estimated at 32m per year. Validation of these dunes movement of the Laâyoune city was confirmed by the field data and previous studies.

The Effect of Assistive Anchor-Like Grousers on Wheeled Rover Performance over Unconsolidated Sandy Dune Inclines.

Typical rovers with wheels equipped with conventional grousers are prone to getting stuck in unconsolidated sandy dune inclines as the wheels tend to sink into the sand. This phenomenon is caused by the motion of the grouser through the sand during the latter half of the rotation, in which the grouser pushes the sand from underneath the wheel upwards and towards the backside of the wheel. This creates a space that the wheel can sink into. To minimize sand movement and subsequent sinkage, we propose the concept of using an “assistive grouser”, which is attached to the side of a conventional rover wheel. The assistive grouser is designed to be able to autonomously maintain a uniform angle relative to the rover body independent of the rotation of the wheels. Rotating the wheel causes the assistive grousers to automatically penetrate into the sand slope surface at a constant angle of attack, thereby acting as an anchor and providing traction for the wheel. Maintaining a uniform grouser angle as opposed to a rotating motion also assists in extracting the grouser out of the sand without moving the sand towards the back of the wheel. Moreover, the angle of the assistive grousers is held constantly by a single dedicated motor, meaning that the angle of the assistive grousers can be optimized to provide the least amount of sinkage for each slope angle. The experimental results showed that for slope angles of 0–30 degrees, the rover equipped with the proposed assistive grousers experienced significantly less sinkage and consumed less current compared to the rover equipped with conventional grousers.

Impact of Fencing and Irrigation on Species Composition and Diversity of Desert Plant Communities in the United Arab Emirates

AbstractGrazing and water are among the most important factors influencing community structure and productivity in natural rangelands. Little is known about the independent effects of grazing and water and their interaction on plant community structure and productivity in rangelands of the arid Arab Gulf deserts. Paired sampling plots were used to compare plant species composition, diversity and plant abundances and sizes inside and outside 14‐month irrigated and 30‐month non‐irrigated exclosures constructed during dry years on sandy dunes of the arid Dubai Desert Conservation Reserve. The results showed that the negative impacts of high grazing pressures on plant productivity (plant sizes and abundances) and diversity were stronger in the non‐irrigated sites. Both irrigation (IR) and protection (PR) enhanced plant diversity and productivity of the overgrazed degraded Dubai Desert Conservation Reserve. The combined effects of PR and IR resulted in the occurrence of a total of 22 species inside the irrigated exclosures; however, none of them appeared in the irrigated grazed sites. Eighteen palatable species occurred inside, but not outside, the irrigated exclosures. Chamaephytes, which are more sensitive to human and animal disturbances, recovered more than other life forms under PR and IR. Dipterygium glaucum showed a great potential to be used for restoration projects under water IR in the Arab Gulf deserts. It is concluded that grazing and water independently affected plant diversity and productivity, but the relative role of grazing is more important than that of water in conserving desert plants, especially the palatable ones. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Comparative anatomy and chemical analysis of the vegetative organs of three species of Stigmaphyllon (Malpighiaceae)

The Brazilian Atlantic coast ‘restingas’ consist of enclaves of vegetation from northeast to southeast Brazil. This ecosystem on the eastern coast of Brazil is characterized by sandy dunes with shrubs and low forests further inland. Malpighiaceae is one of the most distinct families in such environments, with several species with economic and pharmacological importance. Despite this potential use, most studies focus on Byrsonima and Banisteriopsis. Stigmaphyllon comprises 90 species widely distributed in the Neotropical region. Nevertheless, studies with these species are scarce and focus on reproductive biology, floral morphology or taxonomical and phylogenetical approach. Thus, this paper presents novel insights regarding the anatomy, morphology and chemical composition of vegetative organs, especially the underground system, of Stigmaphyllon auriculatum, Stigmaphyllon ciliatum, and Stigmaphyllon paralias. For anatomical studies, we used botanical material fixed in a solution of paraformaldehyde and glutaraldehyde. Transverse sections of the vegetative organs were obtained from standardized samples of 3 individuals of each species. Extractions were performed separately on each species for detection of the main types of chemical compounds. We observed meaningful characters among the species, including the habit, leaf shape, the diffuse underground system, T-shaped trichomes, the shape and arrangement of the vascular tissues, among others. The chemical analysis revealed flavonoid, quinones, resins, quaternary alkaloids, free sterols and triterpenes, and condensate tannins in all species. Saponin were found only in S. ciliatum and S. paralias.

Wave–dune interaction and beach resilience in large-scale physical model tests

Large-scale laboratory experiments focusing on the main physical processes driving dune erosion have been performed in a wave flume with a sandy dune exposed to a combination of water levels and wave conditions (Tomasicchio et al., 2011b) providing observations of different interaction regimes: collapsing, overwash and breaching (Sallenger et al., 2003).The large set of data has been considered to obtain measurements of beach–dune cross-shore profile evolution, hydrodynamic properties and suspended sediment concentration.Results show that erosion develops faster during the first hundred waves, there is a clear influence of wave period (van Gent et al., 2008) and water depth on the resilience of the beach–dune system, and that sediment concentration at a given transect depends on the bar position.Furthermore, the observed data have been adopted to verify the predictive accuracy of two open source process-based profile numerical models.

Affection of aridity to anatomical structure of leave of Ulmus pumila L. var. sabulosa

In order to discuss the drought resistant mechanism of Ulmus pumila L. var. sabulosa in anatomy, the comparative observation and analysis of anatomical structure of leaves of Ulmus pumila L. var. sabulosa from the top of drifting sandy dune and inter dunes grassland in Otindag Sandy Land, Ulmus pumila from Huhhot were demonstrated by using the method of slices of paraffin wax in this paper. The results showed that the anatomical structure of the leave showed notable differences owing to different environmental condition in spite of belonging to the same species. The drought resistance of Ulmus pumila L. var. sabulosa from the top of drifting sandy dune whose habitat was the poorest was the strongest. Its leave was thick, and its epidermis cell was big. Its epidermis cell wall and cuticle were thick. Its palisade tissue was developed, and the cell of palisade tissue became smaller and densely arranged.

Composition and Architecture of Braided and Sheetflood-Dominated Ephemeral Fluvial Strata In the Cambrian–Ordovician Potsdam Group: A Case Example of the Morphodynamics of Early Phanerozoic Fluvial Systems and Climate Change

Abstract: Two fluvial facies associations, braided and ephemeral fluvial, are recognized in strata of the Cambrian–Ordovician Potsdam Group in the Ottawa Embayment and Quebec Basin in northeastern North America. Braided fluvial sedimentation was dominated by the migration of coarse-grained sandy dunes and rare unit bars and local gravels that built up low-relief 0.4–5-m-thick downstream-accreting compound bars in very wide and shallow braided channels. Rare meter-scale confluence scours, incision, and filling of decimeter-thick bypass channels, and thin (≤ 7 cm) overbank deposition also occurred. Ephemeral fluvial sedimentation was dominated by the progradation of lobate terminal splays, most of which were deflated and/or reworked into thin (10–95 cm) sheets by eolian processes during the long recurrence intervals between floods. These strata were locally incised by rare, 0.3–1.9-m-thick scour-filling high-energy supercritical bedform strata and decimeter-thick bypass channels. Both braided and ephemeral fluvial deposits consist of meter-scale stacked, high-order stratal units separated by horizontal, laterally extensive surfaces recording the recurring buildup, avulsion, and finally abandonment of channel belts. In braided fluvial strata of the Potsdam the dominance of thin (≤ 2 m) elongated compound bars with low-relief (≤ 5°) bar margins and internal accretion surfaces (≤ 15°) suggest that braided channels and in-channel compound bars expanded laterally with negligible increase in flow depth during periods of increased discharge in the absence of bank-stabilizing vegetation, similar to other examples of the pre-vegetated “sheet-braided” style. However, in areas where bedrock topography inhibited the lateral expansion of channels, thicker compound braid bars (1.2–3.5 m) with higher-relief accretion surfaces (up to 35°), like those observed in post-Silurian and modern systems, preferentially formed in relatively deep channels. Ephemeral fluvial deposits here are similar to ephemeral examples throughout geologic history in that they mostly comprise poorly confined sheet-like terminal splays that accumulated in topographic lows. However, compared to several post-Silurian examples, strata in the Potsdam exhibit considerably more eolian reworking of splays and preservation of supercritical-bedform strata, a manifestation of greater rates of surface-water infiltration due to a lack of sheltering by rooted plants and propensity for unconfined flooding. Finally, in the upper part of the Potsdam two regional ephemeral fluvial units are interstratified with two braided fluvial units, providing evidence for shifts in regional climate. The sharp, areally extensive surfaces that separate these fluvial systems are interpreted to approximate time lines, and therein provide a means for relative and absolute chronostratigraphic correlation. These changes are correlated with documented Late Cambrian to Earliest Ordovician global climate fluctuations, with semiarid conditions and related ephemeral fluvial systems corresponding to global cooling events at ca. 491 and 487 Ma.

Effects of organic amendments on sand dune fixation

Poor physical and chemical properties of sand dune soil are the main constrains in afforestation of sand dune in desertified area. The aim of this study is to improve the physical and chemical properties of dune soil in Elrawakeeb Dry Land Station using organic wastes as a fertilizer source and amendments, for sustainable sand dune stabilization program. Salvadora persica L. seedlings were transplanted in a 2 m × 2 m plots and treated with: sawdust (SW), chicken manure (CH), chicken manure with sawdust (CH + SW), sawdust with inorganic fertilizer (SW + IF), sewage sludge (SS), sewage sludge with sawdust (SS + SW), and control (C). The treatments were arranged in a randomized complete block design with four replicates. The soil chemical properties were determined from soil samples collected from the fixed sand dune (0–20 cm depth) in the second year after application. Application of organic amendments significantly (P = 0.001) increased soil organic carbon by 224 %, available P by 139.9 %, total nitrogen by 142.9 %, and mineral nitrogen by 83.5 % and decreased soil pH by 5.6 %. Incorporation of organic waste in desertified sandy dune soils increased its nutrient content and hence sustained biological fixation of sand dunes.

First record of Modicogryllus frontalis (Orthoptera: Gryllidae) from the Baltic coast

A nymph of cricket Modicogryllus frontalis was found near Czołpino (northern Poland) on sandy dunes close to the Baltic coast. It is the northernmost locality of the species in Poland and in Europe and the first record from the Baltic Coast. The distribution of the species in Central Europe is summarized and presented on the map.

Assessing Storm Impact on a French Coastal Dune System Using Morphodynamic Modeling

Muller, H.; van Rooijen, A.; Idier, D.; Pedreros, R., and Rohmer, J., 2017. Assessing storm impact on a French coastal dune system using morphodynamic modeling.Natural coastal dune systems provide protection against flooding from the ocean for many coastal communities around the world. An in-depth knowledge of their erosion mechanisms under oceanic stress can help to identify potential weak spots along the coastline and eventually prevent damage to the hinterland. The objective of this study was to assess the effects of hydro-morphodynamic phenomena on the coastal dune morphology during storm events and to evaluate their level of protection. This paper focuses on the physical processes that cause erosion and breaching of sandy dune systems, which are typically a function of the coastal morphology in combination with the hydraulic loading. An XBeach model was set up for the coast of Les Boucholeurs (France), which suffered from severe erosion, dune breaching (at six locations), and inundation of the hinterland during storm Xynthia in February 2010. The model was run for the full storm period, and it accurately reproduced the reported dune breach locations and dimensions with limited calibration. The model results were further utilized to study the temporal and spatial breaching dynamics and to understand the effect of the prestorm morphology on dune breach development. The results show that the dune behavior during the storm was strongly related to the submersion height of the dune crest and anticorrelated with its prestorm geometry (i.e. dune height and width). The governing parameters for the poststorm dune state are, in terms of alongshore-averaged erosion and in order of relative contribution: Submersion height over the dune crest, prestorm dune width, and prestorm dune crest height. Finally, additional simulations showed the limited effects of infragravity waves and the initial bathymetry used in the simulations.

Threshold temperatures for seed germination in nine species ofVerbascum(Scrophulariaceae)

AbstractLight and fluctuating temperatures are two important factors triggering seed germination. The aim of this work was to: (1) elucidate the effect of temperature, light regime and storage time on seed germination in nine taxa ofVerbascumspp., collected from different habitats in the Mediterranean area; and (2) estimate threshold temperatures for seed germination. For all taxa, germination assays were performed at constant and fluctuating temperatures, both in continuous darkness (D) and in alternating light/dark (L/D; 12 h photoperiod). Final germinated proportions (FGPs), base (Tb), optimal (To) and cut-off (Tc) temperatures were derived. At constant temperatures, seed germination was strongly suppressed under the D regime. In L/D, the effect of storage time was very small and the highest FGPs were observed from 15 to 30°C (40–100%), depending on the species.Tbranged from below 7 to above 10°C and it appeared to be constant within each seed lot.ToandTcshowed some within-lot variability and were higher for fast-germinating seeds in each lot. Considering fluctuating temperatures, germination appeared to be quicker and more complete than at constant temperatures. The germination ofVerbascumspp. is favoured in L/D and fluctuating temperatures, which explains their pioneer character when positioned near the soil surface and under a low vegetation canopy.V. arcturusandV. pinnatifidumwere shown to be less favoured by L and fluctuating temperatures, which might explain their ability to germinate in rocky areas or sandy dunes, even when they are not directly exposed to the light.

Termites Are Resistant to the Effects of Fire at Multiple Spatial Scales.

Termites play an important ecological role in many ecosystems, particularly in nutrient-poor arid and semi-arid environments. We examined the distribution and occurrence of termites in the fire-prone, semi-arid mallee region of south-eastern Australia. In addition to periodic large wildfires, land managers use fire as a tool to achieve both asset protection and ecological outcomes in this region. Twelve taxa of termites were detected by using systematic searches and grids of cellulose baits at 560 sites, clustered in 28 landscapes selected to represent different fire mosaic patterns. There was no evidence of a significant relationship between the occurrence of termite species and time-since-fire at the site scale. Rather, the occurrence of species was related to habitat features such as the density of mallee trees and large logs (>10 cm diameter). Species richness was greater in chenopod mallee vegetation on heavier soils in swales, rather than Triodia mallee vegetation of the sandy dune slopes. At the landscape scale, there was little evidence that the frequency of occurrence of termite species was related to fire, and no evidence that habitat heterogeneity generated by fire influenced termite species richness. The most influential factor at the landscape scale was the environmental gradient represented by average annual rainfall. Although termites may be associated with flammable habitat components (e.g. dead wood), they appear to be buffered from the effects of fire by behavioural traits, including nesting underground, and the continued availability of dead wood after fire. There is no evidence to support the hypothesis that a fine-scale, diverse mosaic of post-fire age-classes will enhance the diversity of termites. Rather, termites appear to be resistant to the effects of fire at multiple spatial scales.

Spatio-Temporal Patterns of Water Table and Vegetation Status of a Deserted Area

Understanding groundwater-vegetation interactions is crucial for sustaining fragile environments of desert areas such as the Horqin Sandy Land (HSL) in northern China. This study examined spatio-temporal variations in the water table and the associated vegetation status of a 9.71 km2 area that contains meadowland, sandy dunes, and intermediate transitional zones. The depth of the water table and hydrometeorologic parameters were monitored and Landsat Thematic Mapper (TM) and Moderate Resolution Imaging Spectroradiometer (MODIS) data were utilized to assess the vegetation cover. Spatio-temporal variations over the six-year study period were examined and descriptive groundwater–vegetation associations developed by overlaying a water table depth map onto a vegetation index map derived from MODIS. The results indicate that the water table depends on the local topography, localized geological settings, and human activities such as reclamation, with fluctuations occurring at annual and monthly scales as a function of precipitation and potential evapotranspiration. Locations where the water table is closer to the surface tend to have more dense and productive vegetation. The water table depth is more closely associated with vegetative density in meadowlands than in transitional zones, and only poorly associated with vegetation in sandy dunes.

The effect of pesticides on the composition of aquatic macrofauna communities in field ditches

Ditches surrounding agricultural fields in the Netherlands are predominantly used for flood control, and they accommodate aquatic plant and animal species. Studies addressing the effects of pesticides in combination with abiotic and biotic factors on aquatic biota in ditches are scarce. The current study aimed to investigate the effects of pesticides along with environmental factors, presence of other biota and time on the community composition of aquatic macrofauna in ditches next to flower bulb fields and pastures. Macrofauna samples and environmental data were collected during two consecutive years. Ponds in a sandy dune area of a nature reserve next to the polders were sampled as control sites. Data was analyzed with the variance partitioning procedure based on the redundancy analysis (RDA). The total variance in macrofauna community composition was divided into the variance explained by pesticides, environmental factors (water chemistry parameters and macrophyte coverage), time (study year and the number of the month), shared variance, and unexplained variance. The total explained variance in macrofauna community reached 22.6%. The largest proportion of explained variance was attributed to environmental factors (10.1%) followed by pesticides (5.4%) and time (4.8%). When each macrofauna group was analyzed separately, presence of other biota and environmental factors explained the largest proportion of variance in most of the macrofauna groups. Results of the study indicate that environmental factors, biotic interactions and temporal variation influence freshwater macrofauna considerably along with pesticides. We suggest that environmental managers should consider the multiple stressor contexts of aquatic ecosystems.

Dinosaur ichnofauna of the Upper Jurassic/Lower Cretaceous of the Paraná Basin (Brazil and Uruguay)

Upper Jurassic and Lower Cretaceous sedimentary layers are represented in the Brazilian Paraná Basin by the fluvio–aeolian Guará Formation and the Botucatu Formation palaeoerg, respectively, overlapped by the volcanic Serra Geral Formation. In Uruguay, the corresponding sedimentary units are named Batoví and Rivera Members (both from the Tacuarembó Formation), and the lava flows constitute the Arapey Formation (also in Paraná Basin). Despite the lack of body fossils in the mentioned Brazilian formations, Guará/Batoví dinosaur fauna is composed of theropod, ornithopod and wide–gauge sauropod tracks and isolated footprints, as well as theropod teeth. In turn, the Botucatu/Rivera dinosaur fauna is represented by theropod and ornithopod ichnofossils smaller than those from the underlying units. The analysis of these dinosaur ichnological records and comparisons with other global Mesozoic ichnofauna indicates that there is a size reduction in dinosaur fauna in the more arid Botucatu/Rivera environment, which is dominated by aeolian dunes. The absence of sauropod trackways in the Botucatu Sandstone fits with the increasingly arid conditions because it is difficult for heavy animals to walk on sandy dunes, as well as to obtain the required amount of food resources. This comparison between the Upper Jurassic and Lower Cretaceous dinosaur fauna in south Brazil and Uruguay demonstrates the influence of aridization on the size of animals occupying each habitat.

Non-mycorrhizal endophytic fungi from orchids.

Orchidaceae is one of the largest flowering plant families of the plant kingdom. The habitats of orchids are highly diverse, ranging from tree bark and damp forest floors to rock crevices, sandy dunes and semi-arid deserts. The diversity of endophytes (internal symbiotic fungi) associated with orchids is enormous. Most studies of endophytic fungi from orchids in the past have focused on mycorrhizal endophytes (internal symbiotic fungi associated with plant roots). There has, however, been an increasing trend to study nonmycorrhizal endophytes from orchids because of their physiological roles and their potential as sources of novel bioactive compounds. This review discusses the methods used in the isolation and identification of endophytic fungi from orchids, their diversity and host-specificity, their significance in orchid conservation and cultivation, and their potential application in the discovery of bioactive compounds.

Effects of elevated root zone CO2 on xerophytic shrubs in re-vegetated sandy dunes at smaller spatial and temporal scales.

The below-ground CO2 concentration in some crusted soils or flooded fields is usually ten or hundred times larger than the normal levels. Recently, a large number of studies have focused on elevated CO2 in the atmosphere; however, only few have examined the influence of elevated root zone CO2 on plant growth and vegetation succession. In the present study, a closed-air CO2 enrichment (CACE) system was designed to simulate elevated CO2 concentrations in the root zones. The physio-ecological characteristics of two typical xerophytic shrubs C. korshinskii and A. ordosica in re-vegetated desert areas were investigated at different soil CO2 concentrations from March 2011 to October 2013. Results showed that plant growth, phenophase, photosynthetic rate, stomatal conductance, transpiration rate, and water use efficiency for the two xerophytic shrubs were all increased at first and then decreased with increasing soil CO2 concentrations, and the optimal soil CO2 concentration thresholds for C. korshinskii and A. ordosica were 0.554 and 0.317%, respectively. And A. ordosica was more tolerate to root zone CO2 variation when compared with C. korshinskii, possible reasons and vegetation succession were also discussed.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-015-1091-7) contains supplementary material, which is available to authorized users.

Characterization and Provenance of Building Materials from the Roman Pier at San Cataldo (Lecce, Southern Apulia, Italy): a Lithostratigraphical and Micropaleonthological Approach

This study deals with the characterization of building materials used in a monumental pier of Roman age, located at San Cataldo, the main coastal harbour of the Roman town of Lupiae, modern Lecce (Southern Italy). In the manufacture of the outer curtains three different lithologies have been recognized, all comprised in Pietra Leccese Formation, which crops out in a broad geographical area of Salento Peninsula. Microfossils recovered from limestone blocks are used to suggest a provenance for the source-rock. Microfossils include planktonic foraminifera characteristic of the upper Miocene (Tortonian-Messinian) foraminiferal MMi11 (Neogloboquadrina acostaensis Biozone) and MMi13 (Globorotalia miotumida Biozone) biozones. The analysed lithic materials show biostratigraphical characteristics very similar to some samples from Acaya-Struda zone (some 10 km South-West from the ancient harbour): comparative analysis has been performed, supporting a clear identification of the geological origin of limestone blocks. In hydraulic concrete different lithic materials have been used and mixed with a strong mortar. Macroscopic field observation clearly define that limestone clasts, variable in size, derive from the Pliocene Uggiano la Chiesa Formation, that widely crops out locally at San Cataldo; granular fractions of mortar probably derive from beaches and/or sandy dunes, available in the surrounding area, as well.