Plant Migration Research Articles

Relation between extinction and assisted colonization of plants in the arctic-alpine and boreal regions.

Assisted colonization of vascular plants is considered by many ecologists an important tool to preserve biodiversity threatened by climate change. I argue that assisted colonization may have negative consequences in arctic-alpine and boreal regions. The observed slow movement of plants toward the north has been an argument for assisted colonization. However, these range shifts may be slow because for many plants microclimatic warming (ignored by advocates of assisted colonization) has been smaller than macroclimatic warming. Arctic-alpine and boreal plants may have limited possibilities to disperse farther north or to higher elevations. I suggest that arctic-alpine species are more likely to be driven to extinction because of competitive exclusion by southern species than by increasing temperatures. If so, the future existence of arctic-alpine and boreal flora may depend on delaying or preventing the migration of plants toward the north to allow northern species to evolve to survive in a warmer climate. In the arctic-alpine region, preventing the dispersal of trees and shrubs may be the most important method to mitigate the negative effects of climate change. The purported conservation benefits of assisted colonization should not be used to promote the migration of invasive species by forestry.

Spatial summer–autumn distribution of the diamondback moth, Plutella xylostella (L.) and its parasitoids in cauliflower fields

AbstractAgricultural intensification and greater production of Brassica vegetable and oilseed crops over the past two decades have increased the pest status of the diamondback moth (DBM), Plutella xylostella L., and it is now estimated to cost the world economy US$4–5 billion annually. Our understanding of some fundamental aspects of DBM biology and ecology, particularly host plant relationships, tritrophic interactions, and migration, has improved considerably but knowledge of other aspects, e.g. their spatial distribution and relative abundance, remains surprisingly limited. In this study, the summer–autumn spatial distribution of the diamondback moth, P. xylostella, and its parasitoids, including Diadegma anurum, Cotesia plutellae and Oomyzus sokolowskii in cauliflower fields south of Tehran were assessed from late May until October 2011. Each plant was presumed as a sampling unit and sampling was carried out every two weeks. The spatial distribution pattern of all life stages of diamondback moth and i...

An Analysis on the Distribution of Maquis-Shrubland: Karabuk-Safranbolu Basin (Turkey)

Karabuk-Safranbolu basin is located in the Western Black Sea Region in the northwest of Turkey. The basin lies within 100 km from the coastline and is an important area, as it hosts Euro-Siberian and Mediterranean plants species. The focus of the study is maquis formation. Occupying a large place on the earth, Maquis communities are commonly distributed over the regions where the Mediterranean climate prevails. These regions are the Mediterranean Region, California, Chile, the Cape and Australia. Distribution of the Mediterranean plant species in the Euro-Siberian phytogeographic region, and vice versa, is related to climate changes and plant migration in the past. Karabuk-Safranbolu basin sets a model for such distribution. The study aims to determine the maquis shrubland formation within the Karabuk-Safranbolu basin and examine the vertical-lateral distribution patterns. The methodology is based on a regional approach. ArcGIS 10.3 was used for preparing cartographic materials. Within the scope of the study, certain maps of the region such as topographical, physical, slope, aspect, soil, geological, geomorphological and forest management maps were examined as the materials of the study as well as using some meteorological data. The elements of maquis shrubland in the region were detected through field surveys and their distribution patterns were addressed.

Population demographic history of a temperate shrub, Rhododendron weyrichii (Ericaceae), on continental islands of Japan and South Korea.

Continental islands provide opportunities for testing the effects of isolation and migration on genetic variation in plant populations. In characteristic of continental islands is that the geographic connections between these islands, which are currently distinguished by seaways, have experienced fluctuations caused by sea‐level changes due to climate oscillations during the Quaternary. Plant populations on the islands have migrated between these islands via the exposed seafloors or been isolated. Here, we examined the demographic history of a temperate shrub, Rhododendron weyrichii, which is distributed in the southwestern parts of the Japanese archipelago and on an island of South Korea, using statistical phylogeographic approaches based on the DNA sequences of two chloroplast and eight nuclear loci in samples analyzed from 18 populations on eight continental islands, and palaeodistribution modeling. Time estimates for four island populations indicate that the durations of vicariance history are different between these populations, and these events have continued since the last glacial or may have predated the last glacial. The constancy or expansion of population sizes on the Japanese islands, and in contrast a bottleneck in population size on the Korean island Jeju, suggests that these islands may have provided different conditions for sustaining populations. The result of palaeodistribution modeling indicates that the longitudinal range of the species as a whole has not changed greatly since the last glacial maximum. These results indicate that exposed seafloors during the glacial period formed both effective and ineffective migration corridors. These findings may shed light on the effects of seafloor exposure on the migration of plants distributed across continental islands.

Intercontinental disjunctions between eastern Asia and western North America in vascular plants highlight the biogeographic importance of the Bering land bridge from late Cretaceous to Neogene

AbstractThis review shows a close biogeographic connection between eastern Asia and western North America from the late Cretaceous to the late Neogene in major lineages of vascular plants (flowering plants, gymnosperms, ferns and lycophytes). Of the eastern Asian–North American disjuncts, conifers exhibit a high proportion of disjuncts between eastern Asia and western North America. Several lineages of ferns also show a recent disjunct pattern in the two areas. In flowering plants, the pattern is commonly shown in temperate elements between northeastern Asia and northwestern North America, as well as elements of the relict boreotropical and Neogene mesophytic and coniferous floras. The many cases of intercontinental biogeographic disjunctions between eastern Asia and western North America in plants supported by recent phylogenetic analyses highlight the importance of the Bering land bridge and/or the plant migrations across the Beringian region from the late Cretaceous to the late Neogene, especially during the Miocene. The Beringian region has permitted the filtering and migration of certain plant taxa since the Pliocene after the opening of the Bering Strait, as many conspecific taxa or closely related species occur on both sides of Beringia.

Die Neuordnung pflanzengeografischen Wissens als „Transitzone“ Wallacea. Ein amerikanisches Expansionsprojekt auf den Philippinen, 1902–1928

The Reshaping of Phytogeographical Knowledge as the "Transition zone" Wallacea: An American Expansion Project in the Philippines, 1902-1928. This paper examines the development of a concept that to this day plays an important role in biogeography: the region Wallacea. Focussing on the work of the American tropical botanist Elmer D. Merrill in the Philippines, I argue that his research on the geographical movement and settlement of Philippine plants reflects a shift in the United States' scientific and cultural understanding of the Pacific area towards a notion of "American tropics". While inventorying plants for the American administration from 1901 to 1923, the composition of Philippine flora prompted Merrill to question biogeographical regionalization in Wallace's Malay Archipelago. Not being able to situate the Philippine flora within "Asian" or "Australasian" biota, Merrill described the islands as an area of trans-regional plant migration. Together with the paleontologist Roy E. Dickerson, he later conceptualized the region Wallacea as biogeographical "transition zone" between the Philippines and Australia. In addition to the scientific conceptualization, Wallacea constitutes a space between two biogeographical subregions, whose flora was considered as being part of both, but could not be unambiguously attributed to either of these regions. In this respect, the plants resembled the inhabitants of the United States' insular overseas territories, who were legally defined neither as aliens nor as citizens. In this sense, Wallacea embodies epistemic as well as geopolitical boundaries, while its case also illustrates some of the ways in which colonial interests in the usability of plants found expression in botanical research during the early period of American overseas expansion.

Ecological constraints increase the climatic debt in forests.

Biodiversity changes are lagging behind current climate warming. The underlying determinants of this climatic debt are unknown and yet critical to understand the impacts of climate change on the present biota and improve forecasts of biodiversity changes. Here we assess determinants of climatic debt accumulated in French forest herbaceous plant communities between 1987 and 2008 (that is, a 1.05 °C mean difference between the observed and bioindicated temperatures). We show that warmer baseline conditions predispose plant communities to larger climatic debts, and that climate warming exacerbates this response. Forest plant communities, however, are absorbing part of the temperature increase mainly through the species' ability to tolerate changing climate. As climate warming is expected to accelerate during the twenty-first century, plant migration and tolerance to climatic stresses probably will be insufficient to absorb this impact posing threats to the sustainability of forest plant communities.

The 2017 IBS Alfred Russel Wallace Award

Announcements frontiers of biogeography 8.2, e31469, 2016 The 2017 Alfred Russel Wallace Award The IBS Board is pleased to announce that Mar- garet Bryan Davis will be the next to join the distinguished list of recipients of the Alfred Russel Wallace Award. The Wallace Award will be given at the upcoming IBS biennial meeting in Tucson, Arizona, USA (January 9-13, 2017), and was established by the IBS in 2004 to rec- ognize a lifetime of outstanding contributions by an eminent scholar in any subdiscipline of biogeography. Professor Emeritus Margaret Bryan Davis of the University of Minnesota has a long and distinguished career of outstanding contribu- tions to biogeography, and deserves credit for placing paleoecology squarely in the main- stream of biogeography and ecology. Her pa- pers combine magisterial reviews and thought- ful syntheses with a long series of carefully de- signed and elegant empirical studies aimed at addressing specific, focused questions. Professor Davis’ work established many of the current tenets of Quaternary biogeogra- phy: that species shift ranges in response to climate change, these changes are individualis- tic, and that as a consequence communities are transient. Other ideas, such as the role of path- ogens in forest history and the timescale of migrational lags, remain on-going topics of re- search and productive debate. Her ideas opened up new fields of fertile investigation that continue today, including postglacial pat- terns and rates of plant migration, the transi- ence of ecological communities, stand-scale forest history, the mid-Holocene hemlock de- cline in eastern North America, and how pollen data record vegetation. A mark of a truly great scientist is the ability to reconsider, and revise or even reject, strongly held views. Margaret Davis welcomed critiques, and demonstrated that conceptual breakthroughs were not always as effective as hoped. She stood her ground and asked diffi- cult questions, but when others provided com- pelling evidence, she yielded. Professor Davis was rigorous, critical, and set high standards for the field, always with a focus towards doing the best science and getting closer to the truth. She inspired countless young scientists by her professional example, as well as by the quality of her work and thinking. Professor Davis had – and continues to have – few equals in combining rigorous, ana- lytical approaches with broad, discipline- spanning syntheses. The IBS Board notes with thanks, the work of the Wallace Award Committee: Ingolf Kuhn, Mark Lomolino, Jonathan Losos, Susanne Renner, Kathy Willis, and Dov Sax (chair). International Biogeography Society Board frontiers of biogeography, ISSN 1948-6596 — © 2016 the authors; journal compilation © 2016 The International Biogeography Society

The Root-Associated Microbial Community of the World's Highest Growing Vascular Plants.

Upward migration of plants to barren subnival areas is occurring worldwide due to raising ambient temperatures and glacial recession. In summer 2012, the presence of six vascular plants, growing in a single patch, was recorded at an unprecedented elevation of 6150 m.a.s.l. close to the summit of Mount Shukule II in the Western Himalayas (Ladakh, India). Whilst showing multiple signs of stress, all plants have managed to establish stable growth and persist for several years. To learn about the role of microbes in the process of plant upward migration, we analysed the root-associated microbial community of the plants (three individuals from each) using microscopy and tagged amplicon sequencing. No mycorrhizae were found on the roots, implying they are of little importance to the establishment and early growth of the plants. However, all roots were associated with a complex bacterial community, with richness and diversity estimates similar or even higher than the surrounding bare soil. Both soil and root-associated communities were dominated by members of the orders Sphingomonadales and Sphingobacteriales, which are typical for hot desert soils, but were different from communities of temperate subnival soils and typical rhizosphere communities. Despite taxonomic similarity on the order level, the plants harboured a unique set of highly dominant operational taxonomic units which were not found in the bare soil. These bacteria have been likely transported with the dispersing seeds and became part of the root-associated community following germination. The results indicate that developing soils act not only as a source of inoculation to plant roots but also possibly as a sink for plant-associated bacteria.Electronic supplementary materialThe online version of this article (doi:10.1007/s00248-016-0779-8) contains supplementary material, which is available to authorized users.

Midwest Maize: How Corn Shaped the U.S. Heartland by Cynthia Clampitt

Midwest Maize: How Corn Shaped the U.S. Heartland, by Cynthia Clampitt. Urbana, University of Illinois Press, 2015. xxii, 288 pp. $95.00 US (cloth), $19.95 US (paper). In Midwest Maize, popular history writer Cynthia Clampitt successfully explains the history of corn in a regional context. This is no easy task. Com was and remains significant in several American regions, not just the Midwest, requiring the author to maintain focus while shifting from regional to national contexts throughout the book. The author also deserves credit for telling such a big story so succinctly. In fifteen brief chapters, Clampitt synthesizes secondary scholarship on corn farming, foodways, processing, and related topics. Readers learn about the migration of plants and people, different races and varieties of com, technological change, and dietary habits. The author relies mostly on secondary accounts, occasionally using primary sources; most significantly interviews with representatives from almost every link in the commodity chain. Midwest Maize begins long before there was a Midwest, although most of the coverage is of the nineteenth century to the present. The author traces the domestication of corn in Mexico and the subsequent spread into the mid-continent. The author pays attention to both city and country, narrating how the growth of farm country depended on the growth of urban markets, manufacturing, and developments in transportation such as canals and railroads. Historians will recognize the significant impact of William Cronon's Nature's Metropolis (New York, 1991) on the book at numerous places. Naturally, farmers figure prominently in the book. The utility and adaptability of corn as human and animal food is shown throughout. There are two chapters on living with in which farmers' voices are prominent. One of the later chapters includes historical recipes for corn dishes as well as context for their preparation and consumption. Readers will learn about sweet corn and the associated canning industry, how popcorn became a popular snack, and the leading roles that Midwesterners played in those events and processes. There are several praiseworthy aspects of the book. General readers will be rewarded with an appropriate recognition by the author of the many contributions of First Nation's people to the development of com. There is a good discussion of the role of corn in the beef industry that compares grass-fed versus grain-finished beef. The author also makes sense of com as food through a discussion of the process of nixtamalization as well as breeding and genetically modified organisms. The author reflects the contemporary scientific consensus that the process of genetic modification has produced far more benefits than problems, despite critiques that contemporary breeding practices designed to maximize quantity have resulted in a crop of diminished quality. …

Nuclear migration events throughout development.

Moving the nucleus to a specific position within the cell is an important event during many cell and developmental processes. Several different molecular mechanisms exist to position nuclei in various cell types. In this Commentary, we review the recent progress made in elucidating mechanisms of nuclear migration in a variety of important developmental models. Genetic approaches to identify mutations that disrupt nuclear migration in yeast, filamentous fungi, Caenorhabditis elegans, Drosophila melanogaster and plants led to the identification of microtubule motors, as well as Sad1p, UNC-84 (SUN) domain and Klarsicht, ANC-1, Syne homology (KASH) domain proteins (LINC complex) that function to connect nuclei to the cytoskeleton. We focus on how these proteins and various mechanisms move nuclei during vertebrate development, including processes related to wound healing of fibroblasts, fertilization, developing myotubes and the developing central nervous system. We also describe how nuclear migration is involved in cells that migrate through constricted spaces. On the basis of these findings, it is becoming increasingly clear that defects in nuclear positioning are associated with human diseases, syndromes and disorders.

Late Holocene expansion of ponderosa pine (Pinus ponderosa) in the Central Rocky Mountains, USA

AbstractAimPonderosa pine (Pinus ponderosa) experienced one of the most extensive and rapid post‐glacial plant migrations in western North America. We used plant macrofossils from woodrat (Neotoma) middens to reconstruct its spread in the Central Rocky Mountains, identify other vegetation changes coinciding with P. ponderosa expansion at the same sites, and relate P. ponderosa migrational history to both its modern phylogeography and to a parallel expansion by Utah juniper (Juniperus osteosperma).LocationCentral Rocky Mountains, Wyoming and Montana, and Black Hills, Wyoming and South Dakota, USA.MethodsPlant macrofossils were analysed in 90 middens collected at 14 widely separated sites in the northern part of the range of P. ponderosa var. scopulorum. Middens with and without P. ponderosa were 14C dated to pinpoint time of appearance at each site. Sensitivity experiments using a bioclimatic model were used to evaluate potential climatic drivers of late Holocene expansion.ResultsPinus ponderosa colonized the Black Hills region by at least 3850 yr bp (all ages given in calendar years before present). It expanded into the eastern Bighorn Mountains of northern Wyoming by 2630 yr bp, quickly spreading north in the western Bighorns from 1400 to 1000 yr bp. Concurrent with the latter expansion, P. ponderosa spread c. 350 km to the Little Belt and Big Belt Mountains in western Montana, establishing its northern limit and the modern introgression zone between var. scopulorum and var. ponderosa. Expansion in the Central Rockies of P. ponderosa involved two known haplotypes.Main conclusionsPinus ponderosa expanded its range across large parts of northern Wyoming and central Montana during the late Holocene, probably in response to both northward and westward increases in summer temperature and rainfall. The underlying climatic driver may be the same as for the contemporaneous expansion of J. osteosperma, but will remain undetermined without focused development and integration of independent palaeoclimate records in the region.

A “rediscovered” record of Ainsliaea brandisiana (Asteraceae) from Thailand and its biogeographic significance

Ainsliaea brandisiana was regarded as distributed only in southeastern Myanmar. Koyama once reported the occurrence of A. brandisiana in Thailand in 1983, whereas Tseng thought it was a new species and described it as A. spnocephala in 1988. This treatment was accepted by Freire in 2007. Thus, the record of A. brandisiana from Thailand reported by Koyama was not valid. However, during a field trip in Phu Soi Dao National Park of northeastern Thailand, we found a remarkable species of Ainsliaea growing in mountain forests at the elevation of 1600 m. After detailed and comprehensive examination, we determined that it was A. brandisiana. This “rediscovered” record of A. brandisiana suggested a close phytogeographical connection between the mountain forests flora of southeastern Myanmar and that of northeastern Thailand, although they were separated by the lowlands rain forests of Thailand peninsula. We proposed a new hypothesis that there might be a plant migration route connecting southeastern Myanmar, northeastern Thailand and the Hengduan Mountains. Here, we described and illustrated A. brandisiana and provided photographs of its live specimens in the field, its habitat, morphological details of its floret, its distribution map and a key to all the known species of Ainsliaea from Thailand.

Seeds at risk: How will a changing alpine climate affect regeneration from seeds in alpine areas?

Alpine areas are both regional water reservoirs and zones of high species endemism. Increasing temperatures and earlier snowmelt have already caused upward migration of species, changes in flowering phenology and increasing frost damage in plants. Thus, significant loss of diversity in alpine areas is imminent. Plant migration and distribution shifts occur mainly via seeds, which also provide the genetic diversity required for adaptation. The ability of plants to shift their distribution in response to climate change will depend on seed dispersal, germination and seedling success under new environmental conditions. Despite the critical importance of seeds and seedlings for species adaptation, migration and persistence, the majority of studies concerning climate change in alpine areas have mostly focused on the response of adult plants to warming. Temperature during seed development, as well as the temperature to which seeds are exposed post-dispersal, has been found to have strong effects on seed longevity, germination and seedling survival. Therefore, global change (particularly, warming) is expected to greatly impact regeneration of seeds in alpine areas. Despite evidence that climate change is advancing flowering phenology in several mountain ranges around the world, under natural and artificial warming, the cascade effects that early flowering can have on seeds and seedlings have been poorly studied. Indeed, while a literature search on Web of Science using the search terms “germination”, “alpine plants” and “climate change” revealed 50 studies, of which only 7 directly examined the effect of warming on germination and establishment of seeds of alpine plant species. Here, we discuss the findings of these studies. We identify critical questions regarding seeds and seedlings of alpine species that require urgent research and recommend experimental approaches. Answering these questions will assist in predicting the impacts of global warming and in conservation and management of plants in alpine areas.

Modelling the effect of habitat fragmentation on climate‐driven migration of European forest understorey plants

AbstractAimThe rate of climate change might exceed the migration capacity of plants, particularly where habitats became fragmented by human land use. Except for some tree species, the extent to which habitat fragmentation decreases migration rates has nevertheless been little evaluated. Here, we compare simulated migration rates of understorey herbs, which comprise the big part of temperate forest plant diversity, under varying levels of fragmentation at a continental scale.LocationEurope.MethodsWe combined simulations of demography and seed dispersal to simulate migration of 16 hypothetical forest herb species through a virtual, continuously forested landscape of 50 × 50 km and through 1179 50 × 50 km regions spanning most of the European Union's territory plus Norway and Switzerland. Each region was subdivided into a 250‐m raster of sites, which were rated as suitable to a species if covered by forest according to current land cover maps and future land cover scenarios. The 16 hypothetical species were defined by combinations of those trait values that control demographic and dispersal processes.ResultsIn continuous forests, simulated migration rates of the 16 species varied between ~95 and ~225 m/y. Current forest fragmentation was predicted to reduce migration rates to about 70% on average across the continent, but to below 25% in many parts of western and southern Europe. Under future land use, migration rates might slightly increase in economically marginal regions.Main conclusionsOur results indicate that even on a continuously forested continent most understorey herbs would be unable to track climate warming and that habitat fragmentation will reduce migration rates to values an order of magnitude lower than expected climate velocities in parts of Europe. We conclude that, instead of concentrating conservation efforts in protected areas, facilitating the movement of species through the average countryside should become a conservation priority.

Consideration of dispersal processes and northern refugia can improve our understanding of past plant migration rates in North America

AbstractAimAccording to the palynological record, rapid plant migrations following the retreat of the last glacier were common in North America and Europe. However, providing an explanation for these rapid migration rates has been challenging considering modern‐day seed dispersal distances. We used the newly developed seed dispersal functionality in a hybrid dynamic global vegetation model (DGVM) to simulate two theories that have been proposed to explain rapid plant migrations: long‐distance seed dispersal and northern refugial populations.LocationIdealized landscapes representing temperate and boreal regions of North America.MethodsVegetation migration rates for three species (Acer rubrum, Fagus grandifolia and Picea glauca) were simulated in response to climate change across a landscape. All simulations included long‐distance seed dispersal; however, we compared landscape colonization rates both with and without the presence of northern refugial populations.ResultsFor all three species, the colonization rates were faster when there was a northern refugial population. Increasing the number of locations of refugia further increased the rate of landscape colonization, and this was most effective when refugial populations were spatially separated. The perceived migration rates (i.e. the time it took to spread the furthest distance away from the southern refugium) were approximately twice as fast when a refugium was present. For example, A. rubrum had a perceived migration rate of 119 m yr−1 without refugia and a perceived migration rate of 204 m yr−1 with a northern refugium.Main conclusionsThe simulated migration rates that matched the rapid migration rates observed in the pollen record for Acer were only achieved when both long‐distance dispersal and northern refugial populations were included in the simulations. Even with refugial populations, migration rates for P. glauca and F. grandifolia were slower than historical rates. The results of this study are consistent with the hypothesis that plant migration rates calculated from the pollen record overestimate the ability of most species to track rapid climate change.

The establishment of Central American migratory corridors and the biogeographic origins of seasonally dry tropical forests in Mexico

Biogeography and community ecology can mutually illuminate the formation of a regional species pool or biome. Here, we apply phylogenetic methods to a large and diverse plant clade, Malpighiaceae, to characterize the formation of its species pool in Mexico, and its occupancy of the seasonally dry tropical forest (SDTF) biome that occurs there. We find that the ~162 species of Mexican Malpighiaceae represent ~33 dispersals from South America beginning in the Eocene and continuing until the Pliocene (~46.4–3.8 Myr). Furthermore, dispersal rates between South America and Mexico show a significant six-fold increase during the mid-Miocene (~23.9 Myr). We hypothesize that this increase marked the availability of Central America as an important corridor for Neotropical plant migration. We additionally demonstrate that this high rate of dispersal contributed substantially more to the phylogenetic diversity of Malpighiaceae in Mexico than in situ diversification. Finally, we show that most lineages arrived in Mexico pre-adapted with regard to one key SDTF trait, total annual precipitation. In contrast, these lineages adapted to a second key trait, precipitation seasonality, in situ as mountain building in the region gave rise to the abiotic parameters of extant SDTF. The timing of this in situ adaptation to seasonal precipitation suggests that SDTF likely originated its modern characteristics by the late Oligocene, but was geographically more restricted until its expansion in the mid-Miocene. These results highlight the complex interplay of dispersal, adaptation, and in situ diversification in the formation of tropical biomes. Our results additionally demonstrate that these processes are not static, and their relevance can change markedly over evolutionary time. This has important implications for understanding the origin of SDTF in Mexico, but also for understanding the temporal and spatial origin of biomes and regional species pools more broadly.

Effects of shoreline hardening on nitrogen processing in estuarine marshes of the U.S. mid-Atlantic coast

Multiple stressors affect estuarine shorelines including erosion, sea level rise and impacts from human development of adjacent lands. Increasingly common features of coastal development are vertical shoreline stabilization structures such as bulkheads. Bulkheads are designed to prevent land loss and flooding through the construction of a vertical wall anchored to the land. However, they break the connection between land and water and are barriers to upland plant migration. This disconnect can affect hydrology, alter nutrient and sediment supplies, and lead to marsh loss. We measured the effects of bulkheads on sediment nitrogen fluxes, including denitrification (DEN), at three representative estuarine shoreline types: natural marsh (no bulkhead), bulkhead without marsh, and bulkheads with marshes of varying widths. Sediment cores were taken mid-marsh or, 2 m seaward of bulkhead in sites lacking marsh in northern, central and southern coastal regions of North Carolina. Concentrations of N2 and O2 were measured using a membrane inlet mass spectrometer. In addition, sediment organic matter and inorganic nitrogen concentrations were quantified. Average DEN rate was 93.1 ± 7.0 µmol N m−2 h−1 with the highest rates in the summer and lowest rates in the winter. Sediment oxygen demand was positively correlated with DEN rate (R2 = 0.43, p < 0.01), which suggests that DEN is affected by carbon lability. DEN was not affected by bulkhead presence (R2 = 0.01, p = 0.52), but marsh presence significantly affected yearly DEN rates (R2 = 0.13, p < 0.01). These data indicate that bulkheads do not directly affect nitrogen processing, but indirectly reduce cycling rates through marsh loss.

Alien plants in Poland: research directions and putting the results into practice

Abstract The aim of this study was: (i) to complete and verify the prior review of research on alien plants conducted in Poland and the practical use of their results, and (ii) to attempt to assess the contribution of the research from the area of Poland to the research conducted on an international level. The analysis was performed based on the information gathered during a literature search which covered the last 200 years, using over 1400 publications out of the 3000 which were available in the pool. As a result, the main areas of biological sciences in the context of the research undertaken on alien plants in Poland (distribution, ecology and biology of the species), the most common thematic studies (new species, new localities, and lists of alien species), and the most often investigated species, as well as tendencies over time were indicated. Although studies on the migration and distribution of alien plants in Poland have over 100 years of tradition, and the part of the studies conducted by Polish researchers contributes to the international scale research, it is still necessary to further analyse many issues and answer numerous questions.

Temperate origin and diversification via southward colonization in Fatsia (Araliaceae), an insular endemic genus of the West Pacific Rim

Islands isolated by oceans that act as a geographical barrier for plant migration often possess high species endemism and have been deemed as a natural laboratory for studying species divergence. Fatsia Decne. & Planch. (Araliaceae), with three species, is one of the few plant genera absent in continents while exclusively spanning continental and oceanic islands. The nuclear ribosomal internal transcribed spacer (nrITS) phylogeny uncovered a pattern with reciprocal monophyly of Fatsia oligocarpella Koidz. (Bonin) and Fatsia polycarpa Hayata (Taiwan) vs. paraphyly of Fatsia japonica (Thunb.) Decne. & Planch. (Japan and Ryukyus), suggesting ancestry of the species in Japan and a likely temperate origin; whereas, lack of monophyly of all three allopatrically distributed species at chloroplast DNA (cpDNA) trnL–trnF spacer likely resulted from lineage sorting. In spite of the limited habitats for F. oligocarpella, unexpectedly high genetic variations in this species of oceanic islands were likely attributable to multiple colonizations and recurrent gene introgression. Biogeographical analyses suggested that Fatsia likely diverged via southward colonization in Bonin Islands and Taiwan during the late Pliocene to Pleistocene. Besides, Fatsia species with an allopatric distribution provide a perfect model for testing speciation modes of insular endemics. Nonzero gene flow between species was detected based on MIGRATE and STRUCTURE analyses of DNA sequences and microsatellite fingerprints, suggesting that allopatric speciation is less likely.