Early Stages Of Establishment Research Articles

WHAT DRIVES INTERNATIONAL ENTREPRENEURIAL FIRMS TO EXPAND OVERSEAS: A CASE STUDY APPROACH

Despite the lack of resources, entrepreneurial firms are able to expand internationally from an early stage of establishment. This study aims to explore and identify the drives of expansion for international entrepreneurial firms. This study employed a multi-case analysis approach through in-depth interviews to identify the drivers of international expansion of such firms. Based on our findings we propose a model to enrich the current understanding on the factors that drive young entrepreneurial firms’ expansion to international markets.
 
 JEL: L10; L20; M16; F22
 
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Environmental DNA revealed the fish community of Hokkaido Island, Japan, after invasion by rainbow trout.

In freshwater ecosystems, invasive salmonid fishes can have a significant impact on native fish species. Detecting the invasion and its negative effects is critical for the conservation of native fish communities. We examined the species composition and seasonal changes in the freshwater fish community, including salmonids, on the Kamikawa Plain, Hokkaido Island, Japan, using environmental DNA (eDNA) metabarcoding. We detected 23 fish species in 176 samples collected from 16 sites over 12 months (October 2018 – August 2019). Between 11 and 20 species were detected at each site, including five native salmonids (Oncorhynchus masou, Oncorhynchus keta, Parahucho perryi, Salvelinus leucomaenis leucomaenis and Salvelinus malma krascheninnikova). The invasive alien rainbow trout Oncorhynchus mykiss was detected at all 16 sites and it was the most commonly detected salmonid. Although we found no obvious competitive exclusion of native salmonids by rainbow trout in the study area, the invasive species occurred more often and at more sites than any of the natives. We also determined the occurrence and seasonal changes in the fish community, classified as native salmonids, invasive rainbow trout, Cypriniformes and other benthic fishes. There were fewer species overall in winter, but the sites with higher species richness in winter were on the lower reaches of the river. In addition, we detected domestic invaders, such as the topmouth gudgeon, Pseudorasbora parva, although they were less prevalent than rainbow trout. These results show the effectiveness of eDNA metabarcoding, which can be used for surveying species richness at an ecosystem scale. In particular, the detection of the early stages of establishment and spread of invasive species can be achieved by eDNA monitoring.

Priority effects: How the order of arrival of an invasive grass, Bromus tectorum, alters productivity and plant community structure when grown with native grass species.

Theories and models attempt to explain how and why particular plant species grow together at particular sites or why invasive exotic species dominate plant communities. As local climates change and human‐use degrades and disturbs ecosystems, a better understanding of how plant communities assemble is pertinent, particularly when restoring grassland ecosystems that are frequently disturbed. One such community assembly theory is priority effects, which suggests that arrival order of species into a community alters plant–plant interactions and community assembly. Theoretically, priority effects can have lasting effects on ecosystems and will likely be altered as the risk of invasion by exotic species increases. It is difficult to predict how and when priority effects occur, as experimental reconstruction of arrival order is often difficult in adequate detail. As a result, limited experimental studies have explored priority effects on plant community assembly and plant invasions. To determine if and how priority effects affect the success of invasive species, we conducted a greenhouse study exploring how the arrival order of an invasive grass, Bromus tectorum, affects productivity and community composition when grown with native grasses. We found evidence for priority effects, as productivity was positively related to dominance of B. tectorum and was greater the earlier B. tectorum arrived. This suggests that priority effects could be important for plant communities as the early arrival of an invasive species drastically impacted the productivity and biodiversity of our system at the early establishment stages of plant community development.

Direct and indirect effects of native plants and herbivores on biotic resistance to alien aquatic plant invasions

Abstract Biotic resistance to alien plant invasions is mainly determined by ecological interactions in two layers of the food web: competition with native plant species and herbivory by native herbivores. While the direct effect of native plants on alien plant performance via competition has been well documented across ecosystems, less is known about the direct and indirect effects of herbivores in providing biotic resistance. Our main aims were to determine whether temperate native aquatic plants and herbivores can provide biotic resistance to plant invasions, understand the underlying mechanisms and search for potential interactive effects of competition and herbivory on invader performance (i.e. growth). We mimicked natural temperate mesotrophic and eutrophic freshwater lakes in mesoscosms, by growing three native submerged plant species in monocultures (Ceratophyllum demersum, Myriophyllum spicatum and Potamogeton perfoliatus) at three competition levels (no, low and high) without and with the native aquatic generalist snail Lymnaea stagnalis. We subsequently simulated an early stage of establishment of the South American highly invasive alien plant species Egeria densa. We found that competition by native plant biomass significantly reduced invader performance but depended on native species identity. Herbivory had no direct negative effect on invader performance as the snails fed mainly on the available filamentous algae, which are commonly found in meso‐ and eutrophic systems, instead of on the plants. However, the consumption of filamentous algae by herbivores indirectly had positive effects on the invader total biomass, thus facilitating the invasion by E. densa. Nonetheless, these indirect effects worked through different pathways depending on the native plant identity. Synthesis. We found evidence for biotic resistance through competition by native plant species. However, we show that herbivores can indirectly facilitate South American plant E. densa invasion promoting its growth through selective feeding on filamentous algae, but this effect depends on the native plant species involved. Our experiment illustrates the important role of indirect interactions to understand the potential of biotic resistance in natural ecosystems.

Current Status of Magnolia vovidesii (Magnoliaceae, Magnoniales): New Data on Population Trends, Spatial Structure, and Disturbance Threats

Magnolia vovidesii has been found in a few small patches in central Veracruz, Mexico. Previous ecological studies have suggested high reproductive potential and stable population growth; however, in the last 20 years, there have been severe anthropogenic environmental impacts on the species. The main objectives of this study were (a) to document the current trend of the population, (b) to determine its spatial structure, and (c) to identify the main threats to the species in order to propose conservation and management strategies. Our results show a population in decline, caused by high mortality during early establishment stages (seeds and seedlings) and the removal of young sick trees during the reproductive stage. We found a strong spatial dependence between seedlings and reproductive individuals (young and old adults) and a weak spatial association between reproductive stages, suggesting a nursing effect, inbreeding, and pollen dependence. The main threats to the population are frequent plant removal, trails used by people, land-use change, and parasitism. These data show the urgent need to carry out prompt conservation action for the species, with special emphasis on ex situ propagation. The results of this study suggest that M. vovidesii should be transferred to the International Union for Conservation of Nature Red List category for critically endangered species.

Features of establishment of early lactation in women who gave birth after in vitro fertilization

Abstract Background Breastfeeding gives babies the best possible start in life and breastmilk works like a baby’s first vaccine. Pregnancy resulting from IVF is often associated with placental insufficiency in which the hormone-producing function of placenta can be compromised that may result in reduced lactogenesis. The aim was to study the emergence of early lactation after IVF in women with a history of infertility. Methods The study involved 34 women after IVF with a singleton full-term pregnancy with a history of tubal-peritoneal infertility. Control group comprised of 47 women with naturally occurred pregnancy. Delivery occurred naturally. All women were assessed for hormonal function of placenta for a period of 16-18, 28-32, and 37-38 weeks of pregnancy. The average daily amount of milk on a 5th day after delivery was measured. Results In the IVF group vs. control group there was a decrease in the production of hormones by the placenta (progesterone, estriol, placental lactogen) preparing the mammary glands for lactation (p < 0.05). At gestational age of 16-18 weeks progesterone level in IVF group was 172.2±10.72 nmol/l; 28-32: 274.2±8.45 nmol/l; 37-38 weeks: 343.2±9,1 nmol/l. The level of estriol at 16-18 weeks was 2.87±1.42 ng/ml; 28-32: 10.94±0.6 ng/ml; 37-38 weeks: 25.21±0.22 ng/ml. Placental lactogen at16-18 weeks: 1.15±0.2 nmol/l; 28-32: 6.39±0.69 nmol/l; 37-38 weeks: 7.23±0.59 nmol/l. On day 5 normal lactation was observed in 21(62%) and 43(91.5%) women in IVF and control group, respectively (p < 0.05). Conclusions Increased number of cases of hypolactation was observed in women after IVF, which was associated with decrease in the hormonal function of placenta. Women who have given birth to children after IVF require special attention from the side of medical personnel and from loved ones in the early stages of establishment of breastfeeding. Key messages IVF is a risk factor for hypolactation, which is associated with placental hormone-producing insufficiency. Women who have given birth after IVF require support aimed at promotion of early lactation and breastfeeding.

A competition experiment of an invasive alien grass and two native species: are functionally similar species better competitors?

Invasive plant species often outcompete natives when colonizing new areas, but the mechanisms behind their success are unclear. The limiting similarity hypothesis predicts that functionally similar species are more prone to compete than dissimilar ones. This ecological assumption can assist in the selection of a seed mixture for ecological restoration of disturbed sites, to control opportunistic exotic plants at early stages of establishment. We performed a greenhouse experiment to evaluate the competition effects of Stipa gigantea Link (Poaceae), a functionally similar species, and Lupinus luteus L. (Fabaceae), a dissimilar one, over the invasive Cortaderia selloana (Schultes & Schultes fil.) Asch. & Graebn (Poaceae). Our design included monospecific and mixed pots at three densities (one, two or four plants per pot) and different densities of the invader (0, 25, 50, 75 and 100%). We compared above-ground dry biomass, an indicator of resource limitation in growth, Specific Leaf Area (SLA), and several indexes obtained from the leaf reflectance spectrum, indicators of physiological stress. Cortaderia showed strong intraspecific competition, with lower plant biomass at higher densities. When grown in competition, Cortaderia was outcompeted by Stipa, which performed better than in unmixed pots, but was not affected by Lupinus. Slight variations in SLA and photosynthetic performance were observed in Cortaderia, demonstrating a higher plasticity than the native species, which did not show any response. Based on our results, we suggest that Cortaderia is a weak competitor compared to a similar native species, and its advantage must lie in other traits such as its facility to generate large amounts of propagules and its efficiency in early stages of seedling growth. Functionally similar species may be an adequate choice for restoration in order to outcompete invasive plants.

What are cost changes for produce implementing traceability systems in China? Evidence from enterprise A

ABSTRACTBased on the survey data and information, this paper conducts analysis on the extra cost of traceability systems for agro-product enterprises in China. Calculation on concrete pricing of traceable products is conducted with Enterprise A as an example by using break-even pricing. The price that consumers are willing to pay for 10 traceable products in Enterprise A was measured by collecting 576 valid questionnaires in three cities in China. The benefit–cost ratio, contribution margin ration and profit growth rate are figured before and after implementing the traceability system to illustrate if Enterprise A is profitable after implementing the traceability system. The results show that extra cost incurred by the traceability system of Enterprise A is not high in China; it is not the main reason for the high price of traceable products. Enterprise A increases its operating efficiency and profit growth rate after implementing the traceability system. The pricing of traceable product should consider target consumers’ willingness to pay rather than setting prices blindingly. Government support and education to consumers are important to promote the construction of traceability system at the early stage of establishment of traceability system in China.

Acorn size and tolerance to seed predators: the multiple roles of acorns as food for seed predators, fruit for dispersal and fuel for growth.

Fitness of parents and offspring is affected by offspring size. In oaks (Quercus spp.), acorns vary considerably in size across, and within, species. Seed size influences dispersal and establishment of oaks, but it is not known whether size imparts tolerance to seed predators. Here, we examine the relative extent to which cotyledon size serves as both a means for sustaining partial consumption and energy reserves for developing seedlings during early stages of establishment. Acorns of 6 oak species were damaged to simulate acorn predation by vertebrate and invertebrate seed predators. Seedling germination/emergence and growth rates were used to assess seedling performance. We predicted that if cotyledons are important for dispersal, acorns should show tolerance to partial seed consumption. Alternatively, if the cotyledon functions primarily as an energy reserve, damage should significantly influence seedling performance. Acorns of each species germinated and produced seedlings even after removing >50% of the cotyledon. Seed mass explained only some of the variation in performance. Within species, larger acorns performed better than smaller acorns when damaged. Undamaged acorns performed as well or better than damaged acorns. There was no pattern among individual species with increasing amounts of damage. In some species, simulated invertebrate damage resulted in the poorest performance, suggesting alternative strategies of oaks to sustain damage. Large cotyledons in acorns may be important for attracting seed dispersers and sustaining partial damage, while also providing energy to young seedlings. Success of oak establishment may follow from the resilience of acorns to sustain damage at an early stage.

The interplay of methane and ammonia as key oxygen consuming constituents in early stage development of Base Mine Lake, the first demonstration oil sands pit lake

The efficacy of oil sands water capped tailings technology is currently being assessed in the first pilot pit lake in the Athabasca Oil Sands region (AOSR). Base Mine Lake (BML, Syncrude Canada Mildred Lake mine, Fort McMurray AB Canada) was commissioned in December of 2012 and consists of circa 40 m depth of fluid fine tailings (FFT) overlain by circa 10 m of a freshwater cap. As this is the first oil sands pit lake, it is unknown to what extent known oxygen consuming constituents (OCC) such as methane, hydrogen sulfide and ammonia will mobilize from the underlying FFT layer in BML and impact oxygen concentrations within the water cap. Thus, the field objectives here were to characterize the physico-chemistry and geochemistry of the BML water cap from the FFT water interface (FWI) to the surface over two summers (2015 and 2016). Results identify that the ∼10 m water cap thermally stratifies and that oxygen persists, albeit at low levels (i.e. <5% saturation) to the FWI during the summer season for both years. Consistent with the FFT acting as an OCC source, aqueous CH4, ∑H2S and NH4+ concentrations were highest closer to the FWI, decreasing upwards into the water cap. As O2 persists to the FWI, ∑H2S was rapidly removed within this region, with little mobilized to the overlying water as evidenced by nondetectable ∑H2S within 1 m of the FWI. In contrast, CH4 and NH4+ concentrations were detectable higher up into the water cap, indicating incomplete oxidation at the FWI most likely due to oxygen limitation. In 2015, CH4 was the only identified variable significantly negatively related to BML water cap oxygen concentrations. However in 2016, NH4+ emerged as an important OCC negatively related to water cap oxygen concentrations in addition to CH4. Mass balance of nitrogen redox species throughout the water column are consistent with active nitrification occurring in 2016; which was not evident in 2015 results. Thus, within 4 years of commissioning, nitrification has become an active and important process affecting water column oxygen concentrations within this pit lake. This is in contrast to an absence of detectable microbial nitrification in active oil sands tailing ponds, despite high levels of ammonia. While the absence of nitrification occurring in oil sands tailings ponds has previously been suggested to reflect naphthenic acids toxicity, results here identify that some lower limit of oxygen may also be required for this metabolism to flourish and that at very low oxygen levels (i.e. <5% saturation), nitrifying microbes appear to be outcompeted by methanotrophs, at least during early establishment stages within a pit lake.

Weed Management in Common Cottonwood (Populus deltoides) Nursery Plantation

AbstractCommon cottonwood-based agroforestry system is widely adopted in Indian Indo-Gangetic plains. The stem cuttings of common cottonwood are raised in a nursery 10 to 12 months in rows spaced 0.5 mx0.5 m, before re-planting in the field. The longer duration of 10 to 12 months and wider spacing of stem cuttings in the nursery makes the entire transplants highly vulnerable to weed competition, especially during early establishment stages. The efficacy of preemergence herbicides and plastic and straw mulches for weed management in common cottonwood nursery was investigated at two sites in years 2014 and 2015. The major weed flora in the experimental field consisted of three grass weeds (crowfootgrass, feather lovegrass, and southern crabgrass), and four broadleaf weeds (scarlet pimpernel, garden spurge, niruri, and lesser swinecress). The integrated use of pendimethalin or alachlor applied PRE with paddy straw mulch significantly reduced density and biomass of both grass and broadleaf weeds compared to herbicide or straw mulch used alone, and provided similar level of weed control to hand weeding at both locations. Spreading of plastic mulch in the whole field after punching holes for common cottonwood stem cuttings, or in row spaces recorded similar weed control to hand-weeding. The integrated use of herbicides with straw mulch, and or plastic mulch alone significantly improved plant height, stem diameter, below- and above-ground biomass of common cottonwood plants compared to unweeded check. The study concluded that integrated use of herbicides plus paddy straw mulch or plastic mulch alone could be adopted for weed management in common cottonwood nursery plantations.

Gymnocoronis spilanthoides

Gymnocoronis spilanthoides

Invasive brown marmorated stink bug Halyomorpha halys (Stål) (Heteroptera: Pentatomidae) in Russia, Abkhazia, and Serbia: history of invasion, range expansion, early stages of establishment, and first records of damage to local crops

Halyomorpha halys is native to Asia, but was recently accidentally introduced to North America and Europe. This species was recorded for the first time in Russia in 2013 (2014) and in both Serbia and Abkhazia in 2015. In 2015–2017, we conducted surveys in Russia, Serbia, and Abkhazia and found that H. halys had not only successfully survived its first winters in new regions, but also started to establish locally, spread, increase populations, and damage local crops. In Sochi (Russia) and Abkhazia, H. halys was recorded to feed on 32 species and cultivars from 16 plants families. In Serbia, it has so far been observed on only four species from four plant families. H. halys is already widely spread in Abkhazia and causes serious damage to many crops: in 2016, the yield of peach, mandarin orange, persimmon and other crops fell down by 13.2–87.4% if compared to the long-term means of yield. The losses are likely to be mostly caused by feeding of H. halys. We conclude that H. halys was accidentally introduced to Russia in 2012–2013 most likely with woody plants imported to Sochi from Italy or Greece for urban landscaping before the 2014 Winter Olympics. The species established in Sochi and quickly moved to Krasnodar (Russia), Abkhazia, and beyond—to Georgia. Populations in Serbia most likely arrived in 2015 traveling on railway cars or in commodities on the Bucharest–Belgrade railway line. We discuss phenology and prospects of further expansion of H. halys in Europe.

Species wood density and the location of planted seedlings drive early‐stage seedling survival during tropical forest restoration

Abstract The success of restoration projects is known to vary widely, with outcomes relating to numerous biotic and abiotic factors. Though many studies have examined the factors associated with long‐term restoration success, few have examined which factors impact the establishment of restoration plantings. In Australia's Wet Tropics, we used a large replicated restoration experiment to assess seedling survival for 24 native rainforest species commonly used in local restoration efforts. The experiment allowed for a rigorous assessment of the effects of species functional traits, planting conditions, and landscape‐ and local‐scale biotic and abiotic factors on seedling survival. This study reports on seedling survival between three different time periods of 0–4, 4–9 and 9–31 months post planting. The probability of seedling survival was influenced by multiple factors, varying in importance over time. Across the whole study period, seedlings with high wood density and which were planted closer to intact forest consistently displayed the highest probabilities of survival. Transient factors affecting seedling survival across the three time periods included plot aspect (0–4 months only), the identity of the planter and slope (4–9 and 9–31 months). Overall, species survival did not differ between the low (6 species) and high (24 species) diversity treatments, but was significantly lower in monocultures of Flindersia brayleyana by the end of the study. We demonstrate that early‐stage seedling survival depends on species wood density and planting location. Our results support the use of species with more conservative growth strategies when limited funds are available for follow‐up plantings. High wood density species had significantly higher survival than lower wood density, early successional species typically used in rainforest restoration plantings. Synthesis and applications. Our study highlights the importance of wood density and landscape structure to the initial survival of rainforest plantings. Factors influencing seedling survival shifted over time but, most importantly, our results highlight that, when planting into abandoned pastures, it may be preferable to select species with higher wood densities to maximize survival during the crucial early stages of establishment and growth.

Sedum groundcover variably enhances performance and phenolic concentrations of perennial culinary herbs in an urban edible green roof

ABSTRACTUrban agriculture on green roofs has tremendous potential to enhance food security, economic opportunities, and community building in cities yet faces unique ecological challenges including limited soil moisture content for crops. We compared the effects of two green roof soil moisture management practices, sedum (Sedum album) groundcover versus watering, on performance and quality of three perennial culinary herbs: thyme, mint, and oregano. Individually and interactively, sedum groundcover and watering significantly impacted parameters of performance (biomass, vitality, and module coverage) and quality (total phenolic concentrations) of the three culinary herbs during early stages of establishment while having variable impacts during later developmental stages. Our results suggest that sedum groundcover can serve as a substitute for watering of hardy culinary herbs on green roofs on the basis of plant performance and quality. Findings can be applied to inform agroecological water management of herbs and other hardy specialty crops on green roofs toward enhancing their drought tolerance and advancing sustainable urban agriculture.

Limiting similarity and Darwin's naturalization hypothesis: understanding the drivers of biotic resistance against invasive plant species.

Several hypotheses have been proposed to explain biotic resistance of a recipient plant community based on reduced niche opportunities for invasive alien plant species. The limiting similarity hypothesis predicts that invasive species are less likely to establish in communities of species holding similar functional traits. Likewise, Darwin's naturalization hypothesis states that invasive species closely related to the native community would be less successful. We tested both using the invasive alien Ambrosia artemisiifolia L. and Solidago gigantea Aiton, and grassland species used for ecological restoration in central Europe. We classified all plant species into groups based on functional traits obtained from trait databases and calculated the phylogenetic distance among them. In a greenhouse experiment, we submitted the two invasive species at two propagule pressures to competition with communities of ten native species from the same functional group. In another experiment, they were submitted to pairwise competition with native species selected from each functional group. At the community level, highest suppression for both invasive species was observed at low propagule pressure and not explained by similarity in functional traits. Moreover, suppression decreased asymptotically with increasing phylogenetic distance to species of the native community. When submitted to pairwise competition, suppression for both invasive species was also better explained by phylogenetic distance. Overall, our results support Darwin's naturalization hypothesis but not the limiting similarity hypothesis based on the selected traits. Biotic resistance of native communities against invasive species at an early stage of establishment is enhanced by competitive traits and phylogenetic relatedness.

FORMATION OF THE SOCIAL CAPITAL AND ITS FACTORS FROM THE VIEWPOINT OF THE OPENING PROCESS OF PRIVATE LIBRARY

This study, targeting private library, has made clear the role of the social capital which help establish the activities of the private library. Private library aims to increase the communication and gradually contributes to regional vitalization by turning vacant stores and space into libraries. Spreads of the activity is seen originally from the city of Funabashi, based on the support of the local residents and volunteers. This study focuses on the current conditions of the private library and the details of motivations since its early establishment stage, followed by the examinations of possible social capital that leads to the expansion of the private library. This research covers the outlines of 29 private libraries, including the year in which the library was opened, the function and the address. It also looks into the motivation and the process of how the private library was opened as well as the media who have had acknowledge of private library. The research is then followed by an analysis on the characteristics of each library and the relationship between each other chronologically. As a result, (1)private library has expanded gradually with the support of those who have sympathy to the activity. (2)Moreover, in terms of the motivations, some private library is opened because of the physical circumstances such as increasing demands for a place to stalk endless books as well as for the solutions to hazards coming along with the vacant stores. While in other private library such as some complex that accommodates both library and store inside, the motivation is seen to have responded to the community revitalization, the latency time for little kids while their parents are having a long conversation and the increasing number of the visiting guests. It can thus be assumed that those motivations are closely related to the function of the annex facilities. (3)On the other hand, in terms of the media which have acknowledge of the private libraries, the contents of it has been shifted from newspapers and lectures to introductions and hearsays via neighboring acquaintance and other real time experience. Thus Through the expansion of the sympathy and the spontaneous involvement, private library has become a center that forms the social capital as well as that contributes to the community revitalization

Survival and recovery of Eucalyptus globulus seedlings from severe defoliation

Catastrophic damage that occurs at the early establishment stage of eucalypts, such as decapitation by browsing mammals, may have deleterious effects on survival, growth and tree shape. Such damage may result in a significant loss of productivity from planted forests, as well as represent a major selective force shaping patterns of adaptation in natural forests. An important recovery strategy of many eucalypts is to re-sprout from basal lignotubers, which contain a proliferation of dormant buds as well as stored carbohydrates. We investigated the genetic variation in seedling recovery following decapitation of two Eucalyptus globulus populations that differ in the extent to which they appear to allocate resources to foliar defence as opposed to recovery traits.The two contrasting populations studied were from the continuous eastern distribution of E. globulus on the island of Tasmania. One population, from the wet southern forests, has relatively small lignotubers but high foliar defences; whereas the other from the dry northern forests, has relatively large lignotubers but low foliar defences. Seedlings of 10 families from each population were subjected to artificial decapitation treatments in the nursery at 6months old, planted in a replicated field design and assessed up to 32months after treatment.The two populations differed significantly in their initial response to decapitation, with seedlings from the population with the larger lignotubers and stem base having greater survival and more shoots. Decapitation above the cotyledonary node had a more deleterious effect on survival than decapitation above the first seedling node. The surviving plants exhibited genetic stability not only in constitutive differences, but in the way they changed in response to decapitation. After 20months of growth in the field, there were no lasting treatment effects on important growth traits, with genetic-based population differences overriding the initial treatment effects. These results are consistent with differential resource allocation being part of the adaptive response of E. globulus, and show that early-age decapitation has little long-term impact on the expression of inherent population differences in growth strategies and foliar chemistry.

Alien and native plant establishment in grassland communities is more strongly affected by disturbance than above‐ and below‐ground enemies

Summary Understanding the factors that drive commonness and rarity of plant species and whether these factors differ for alien and native species are key questions in ecology. If a species is to become common in a community, incoming propagules must first be able to establish. The latter could be determined by competition with resident plants, the impacts of herbivores and soil biota, or a combination of these factors. We aimed to tease apart the roles that these factors play in determining establishment success in grassland communities of 10 alien and 10 native plant species that are either common or rare in Germany, and from four families. In a two‐year multisite field experiment, we assessed the establishment success of seeds and seedlings separately, under all factorial combinations of low vs. high disturbance (mowing vs mowing and tilling of the upper soil layer), suppression or not of pathogens (biocide application) and, for seedlings only, reduction or not of herbivores (net‐cages). Native species showed greater establishment success than alien species across all treatments, regardless of their commonness. Moreover, establishment success of all species was positively affected by disturbance. Aliens showed lower establishment success in undisturbed sites with biocide application. Release of the undisturbed resident community from pathogens by biocide application might explain this lower establishment success of aliens. These findings were consistent for establishment from either seeds or seedlings, although less significantly so for seedlings, suggesting a more important role of pathogens in very early stages of establishment after germination. Herbivore exclusion did play a limited role in seedling establishment success. Synthesis: In conclusion, we found that less disturbed grassland communities exhibited strong biotic resistance to establishment success of species, whether alien or native. However, we also found evidence that alien species may benefit weakly from soilborne enemy release, but that this advantage over native species is lost when the latter are also released by biocide application. Thus, disturbance was the major driver for plant species establishment success and effects of pathogens on alien plant establishment may only play a minor role.

Monitoring and reconstructing past biogeomorphic succession within fluvial corridors using stereophotogrammetry

AbstractPast fluvial biogeomorphic succession dynamics, i.e. reciprocal interactions and adjustments between vegetation growth and fluvial landform construction, were monitored and reconstructed using stereophotogrammetry. The four‐dimensional spatio‐temporal stereophotogrammetric analyses were based on the use of archival analogue and digital aerial photographs. First, we tested the relevance of the technique to produce floodplain digital terrain models (DTMs) and cover height models (CHMs) of the dynamic River Allier, France, and compared the models derived from photogrammetric procedures to field measurements for CHMs and to LiDAR data for DTMs. Automatic photogrammetric procedures tended to create inaccurate digital models with production of outliers, incomplete sectors and areas of confusion especially for analogue stereo‐pairs. Expert correction using stereoscopic viewing improved the vertical accuracy of the digital models, but the vegetation height tended to be underestimated: approximately 0.50 m for vegetation heights less than 10 m, up to 1.50 m for tree heights higher than 25 m. Second, we applied this method to a wooded point bar located on the channelized River Garonne, France. At the scale of the point bar, accurate biogeomorphic maps that show terrain and vegetation height changes in all three spatial dimensions were produced and accurate vegetation growth curves from the early stages of establishment until maturity were extracted. Assuming that a set of conditions is satisfied (e.g. spatial scale of investigation, quality of the photographs), our results show that the photogrammetric method applied in this research can be used operationally to detect and quantify present fluvial biogeomorphic dynamics (i.e. changes of topography and vegetation canopy height) within fluvial corridors of temperate rivers with satisfactory accuracy. Copyright © 2016 John Wiley &amp; Sons, Ltd.