Climatic dependency of soil organic carbon isotopic composition along the S–N Transect from 34°N to 52°N in central-east Asia

We explored the relationships between surface-soil (1–20 cm) organic carbon isotopic signatures and associated climatic factors in central-east Asia in an attempt to develop transfer functions that can be used to retrieve the paleoclimatic information stored in the thick eolian–paleosol sequences within the area. Our analysis shows that the negative correlation between the surface-soil organic δ¹³C values and the mean annual precipitation is robust (R² = 0.453; n = 196; p < 0.05) and the negative correlation with the growing-season (April–September) precipitation is more significant (R² = 0.4966; n = 196; p < 0.05). Our study further shows that the positive correlation between the surface-soil organic δ¹³C values and mean growing-season aridity is most significant (R² = 0.5805; n = 196; p < 0.05). We have smoothed both the organic δ¹³C values and the mean growing-season aridity values using a 3-point moving-window average-filter method in an attempt to remove some of random errors and found that the positive correlation between the two is further increased (R² =  0.7784; n =  192; p < 0.05). These robust linear relationships demonstrate their value in reconstructing paleoclimate changes in the study area. The documented climatic dependency of the surface-soil carbon isotopic composition in the study area might have resulted both from the humidity-related isotopic enrichment processes of the dominant C₃ plants (stomatal conductance and photosynthetic discrimination) and from the aridity-related abundance of C₄ plants (mainly Chenopodiaceae species) along the S–N bioclimatic gradient.     

Vertical distribution of bacterial and archaeal communities along discrete layers of a deep-sea cold sediment sample at the East Pacific Rise (∼13°N)

The community structure and vertical distribution of prokaryotes in a deep-sea (ca. 3,191 m) cold sediment sample (ca. 43 cm long) collected at the East Pacific Rise (EPR) approximately 13 degrees N were studied with 16SrDNA-based molecular analyses. Total community DNA was extracted from each of four discrete layers EPRDS-1, -2, -3 and -4 (from top to bottom) and 16S rDNA were amplified by PCR. Cluster analysis of DGGE profiles revealed that the bacterial communities shifted sharply between EPRDS-1 and EPRDS-2 in similarity coefficient at merely 49%. Twenty-three sequences retrieved from DGGE bands fell into 11 groups based on BLAST and bootstrap analysis. The dominant groups in the bacterial communities were Chloroflexi, Gamma proteobacteria, Actinobacterium and unidentified bacteria, with their corresponding percentages varying along discrete layers. Pairwise Fst (F-statistics) values between the archaeal clone libraries indicated that the archaeal communities changed distinctly between EPRDS-2 and EPRDS-3. Sequences from the archaeal libraries were divided to eight groups. Crenarchaea Marine Group I (MGI) was prevalent in EPRDS-1 at 83%, while Uncultured Crenarchaea group II B (UCII B) abounded in EPRDS-4 at 61%. Our results revealed that the vertically stratified distribution of prokaryotic communities might be in response to the geochemical settings and suggested that the sampling area was influenced by hydrothermalism. The copresence of members related to hydrothermalism and cold deep-sea environments in the microbial community indicated that the area might be a transitional region from hydrothermal vents to cold deep-sea sediments.     

Dinoflagellate cyst distribution in surface sediments along the south-western Mexican coast (14.76° N to 24.75°N)

In this study, we explore the relationship between the modern assemblages of organic-walled dinoflagellate cysts and sea-surface conditions (temperature, salinity, primary productivity) and water depth and distance to the coast. Statistical treatments were performed on 95 surface sediment samples from sites located along the south-western Mexican coast (14.76° N to 24.75°N). Redundancy analysis (RDA) illustrates that the principal parameters correlated with the regional cyst distribution are the distance to the coast and the productivity in the upper water column, which is closely related to upwelling intensity. Empirical observations coupled with RDA provide insight into the spatial coverage of some cyst taxa produced by dinoflagellate species potentially responsible for harmful algal blooms along the coast. They also allow the recognition of four zones of assemblages, which are linked to the upwelling intensity and the productivity and characterize La Paz Bay, the south-western Mexican margin (from 15.95° N to 23.11° N), the northern part of the Gulf of Tehuantepec and the southern part of the Gulf of Tehuantepec.     

Qualitative variation in roadside weed vegetation along an urban–rural road gradient

Information on mechanisms of differentiation or homogenization of urban floras is deficient, despite their importance for urban nature conservation and urban land management. Roads, as a major human promoter of urbanization, can be an initial habitat for plants dispersed by transportations. We assumed that variation in weed vegetation along urban–rural roadside gradients is small, particularly in curbside cracks. We classified vegetation occurring in curbside cracks along the National Route 3 in southern Japan and compared the characteristics of the vegetation types recognized. Species in curbside cracks were recorded on 40 plots. Three vegetation types were classified, in part related to surrounding land-use types. Although the Shannon–Wiener diversity index and the number of native species clearly differed among the vegetation types in the curbside cracks, no significant differences between the three floristic vegetation types were found in the number of non-natives and invasive alien species. This may result from the small specificity and complexity of landscape structures, due to the continuity and connectivity of paved-road networks. Of the 122 species, 44 were non-natives or invasive alien species. The vegetation types generally involved the same plant families, with large numbers of species from the Asteraceae and Poaceae, regardless of vegetation types, but frequency of occurrence of the two families clearly differed between natives and non-natives and invasive alien species. Ephemeral non-natives and invasive alien species, particularly Asteraceae and Poaceae, seem to have advantageous dispersal strategies or low habitat dependency facilitating their occurrence in curbside cracks, regardless of adjacent land uses and the urban–rural landscape gradient. Expansion of these species may cause a homogenization of regional floras along roads.     

Pelagic primary production during summer along 65 to 72°N off West Greenland

The distribution of phytoplankton biomass and primary production were studied during summer 1993 at 16 stations from 65 to 72°N off West Greenland, ranging more than 900 km. Hydrography, nutrients and chlorophyll a profiles revealed a significant change in structure from south to north. Nitrate was depleted in the euphotic zone at most stations except close to the ice edge (West Ice) or close to outflow from large glaciers. The vertical distribution of phosphate followed that of nitrate, but was never depleted. Despite two stations with relatively high surface concentrations, silica showed the same distribution as the other two nutrients. In the south, chlorophyll a concentration and primary production were lower than north of Disko Bay (69°N), associated with a well-mixed versus a salinity-generated stratification, respectively. In Vaigat, a high-production station was identified, (st. 910, 69°52′69N–51°30′61W) with a chlorophyll a concentration in the euphotic zone of >13 μg l⁻¹ and an area primary production of 3.2 g C m⁻² day⁻¹. This is seldom encountered in arctic waters and was presumably due to nutrient-rich melt-water originating from the Iluliíssat Glacier. The overall primary production for the studied area was 67–3207 mg C m⁻² day⁻¹ (mean ± SD=341± 743 mg C m⁻² day⁻¹), which is within the range of the few results published for West Greenland and eastern Canadian Arctic waters. Accepted: 24 October 1998     

Use of δ13C values to determine vegetation selectivity in East African herbivores

Summary The quantitative plant species composition of the rumen contents of a large number of individuals from eight East African herbivores was determined by direct visual analysis. All plant species were classified as either C₃ or C₄, and an estimated ₁₃C for the rumen sample was calculated. This estimated value was compared to a measured value determined directly from rumen subsample. The two methods of determining quantitative C₃ and C₄ composition differed by less than 1%, and the isotopic analysis has the advantage of being rapid and totally objective.The isotopic analysis allowed us to differentiate between grazers and browsers and to determine the quantitative dependence of each animal on C₃ and C₄ photosynthetic types. Kongoni, wildebeest, cattle, and sheep were nearly pure grazers on the Athi Kapiti Plains; and the Grant's gazelle were predominantly browsers. Thompson's gazelle, goast and impala were intermediate. The species most dependent upon browse showed a marked and rapid shift to grass within a few days following rain. This isotopic method may have general utility in the study of East African ecology.     

Ordination and classification of vegetation along an altitudinal gradient in the Venezuelan páramos

By means of ordination and classification techniques, the relationships between climate, soils, human activities and vegetation along an altitudinal gradient of the Venezuelan páramos are analyzed and interpreted. The altitudinal gradient chosen is characterized by decrease of temperature, precipitation, soil fertility, soil water-holding capacity, and plant cover as altitude increases. The ordination results suggest vegetation changes to be primarily related to environmental changes occurring with altitude, and secondly to disturbances caused mainly by grazing. Some results point toward a disjunction in the vegetational gradient occurring at ca. 3 500 m.a.s.l. and separating low and high páramo. This disjunction might have been caused by the glacial history of the páramos and the occurrence of frequent night-frosts.The soil samples were kindly analyzed by the Laboratorio de Edafologia, Centro Nacional de Investigaciones Agropecuarias. Help in plant identification was generously obtained from the specialists of Instituto Botánico, Instituto Nacional de Parques, Caracas.Nomenclature follows Vareschi (1970).Acknowledgements: This work was supported by the Decanato de Investigaciones, Universidad Simón Bolivar. I wish to thank A. Pacheco for help in the field sampling. Dr O. Arenas help was invaluable in the mathematical treatment of the data. Drs A. Vivas and J. M. B. Smith provided useful criticism to an earlier version of this work.     

Archaeological Soybean (Glycine max) in East Asia: Does Size Matter?

The recently acquired archaeological record for soybean from Japan, China and Korea is shedding light on the context in which this important economic plant became associated with people and was domesticated. This paper examines archaeological (charred) soybean seed size variation to determine what insight can be gained from a comprehensive comparison of 949 specimens from 22 sites. Seed length alone appears to represent seed size change through time, although the length × width × thickness product has the potential to provide better size change resolution. A widespread early association of small seeded soybean is as old as 9000-8600 cal BP in northern China and 7000 cal BP in Japan. Direct AMS radiocarbon dates on charred soybean seeds indicate selection resulted in large seed sizes in Japan by 5000 cal BP (Middle Jomon) and in Korea by 3000 cal BP (Early Mumun). Soybean seeds recovered in China from the Shang through Han periods are similar in length to the large Korean and Japanese specimens, but the overall size of the large Middle and Late Jomon, Early Mumun through Three Kingdom seeds is significantly larger than any of the Chinese specimens. The archaeological record appears to disconfirm the hypothesis of a single domestication of soybean and supports the view informed by recent phyologenetic research that soybean was domesticated in several locations in East Asia.     

Phytoplankton distribution in the upwelling areas of the Moroccan Atlantic coast localized between 32°30'N and 24°N

Marine phytoplankton was studied in January and July 2002 along of four transects: 32°30′N, 29°N, 24°30′N and 24°N. A total of 142 taxa were recorded in this area. The maximal specific richness, both in summer and in winter, was registered around Dakhla (24°N). The global spatiotemporal variability of species richness and specific diversity showed that the most structured and species-rich populations are situated in the coastal areas. The vertical variation of the two parameters showed homogeneity between depth levels. The maximal phytoplanktonic densities are recorded in the southern transects due to the permanent upwelling activity in the southern Atlantic coast. The bathymetric distribution of densities was more heterogeneous during summer, characterized by a high intensity of upwelling. The species Thalassionema nitzschioides, Asterionellopsis glacialis, Melosira, Chaetoceros and Leptocylindrus minimus are indicators of upwelling.     

‘Inordinate Fondness’: A Threat to Beetles in South East Asia?

A recent report on trade in stag beetles and rhinoceros beetles in Japan highlights a number of issues of considerable importance for beetle conservation resulting from such trade over much of south east Asia. The popularity of these beetles has both positive and negative effects, and there is need for more effective control and monitoring of this trade to enhance positive values and reduce likely harm to species and habitats.     

The vegetation history of a coastal stone-age and iron-age settlement at 70°N,Norway

The Holocene vegetation history of the islet of Melkøya at Hammerfest, Norway (70°42N, 23°36E) is documented by several pollen profiles sampled close to excavated stone-age and iron-age settlements. Local paludification began c. 9700 cal B.P. and oligotrophication from c. 7300 cal B.P. onwards. A Betula pubescens—B.nana heath/woodland persisted until c. 8500 cal B.P., when a mixed Betula pubescens—Pinus sylvestris forest developed. Development towards an open heath is recorded from c. 4700 cal B.P. and culminates around 2700 cal B.P. A weak, possibly anthropogenic, impact is recognisable from c. 9200 cal. BP, but a marked local impact by man begins with the climate improvement and local forest development around 8500 cal B.P. The anthropogenic impact on the vegetation was the cutting of local woodland with an increase in grasses and herbs, the latter partly originating from the nitrophilous seashore vegetation. Forest clearance is recognisable at c. 6200 cal B.P., following a short period of re-growth after a burning event. Several anthropogenically related charred layers were formed in the peat before a longer period of abandonment from c. 3100 cal B.P. to c. 2000 cal B.P.     

Ethnic diversity and statistics in East Asia: ‘foreign brides’ surveys in Taiwan and South Korea

East Asian nations have become increasingly diverse in their ethnic composition since the 1990s. A large proportion of recent immigrants consists of women from China, Vietnam, Indonesia, Thailand and the Philippines, who migrated following their marriage to male citizens from South Korea and Taiwan. To study this new group of foreign residents, the governments of both Taiwan and South Korea have conducted national surveys since 2000. This paper conducts a content analysis of the questions of these surveys to elaborate a criticism of the ethnic statistics produced from them. These surveys provide relevant information on this group of new residents, but they also have the potential to reinforce existing negative stereotypes due to prior assumptions that shaped the content of questionnaires. The analysis reveals that the production of statistics on migrants is influenced by three ideologies: assimilation, patriarchy and nationalism.     

Macrofaunal abundance at 79°N off East Greenland: opposing data from epibenthic-sledge and box-corer samples

During the expedition ARK XI-2 with RV Polarstern in September/October 1995, a transect of samples was taken off East Greenland from the shelf down to about 1800 m depth by means of an epibenthic sledge and a giant box corer, in order to obtain information on epibenthic and endobenthic macrofauna. Within the epibenthic sledge catches, the Cumacea were the most numerous taxon with 32,123 (always calculated for 1000 m) specimens, followed by the Isopoda with 26,914 specimens, and Amphipoda with 20,900; Mysidacea and Tanaidacea were less important. Amphipoda were the most numerous taxon on the shelf, while with increasing depth Isopoda and especially Cumacea became increasingly important. Macrofauna analysed from the box-corer samples decreased in abundance with depth. The highest macrofaunal abundance was found on the shelf, with 8128 ind. m⁻² (200 m); below this depth, density decreased from ≈2000 ind. m⁻² (at 800 m) to ≈800 ind. m⁻² (2000 m). Peracarid crustaceans and polychaetes were, next to bivalves, the most frequent. Polychaetes clearly dominated the shelf communities; their relative percentage decreased with increasing water depth while the relative percentage of Peracarida increased simultaneously. Interestingly, the highest number of peracarids in the epibenthic-sledge samples was reported from deep sea, while box-corer samples showed decreasing macrofaunal abundance with depth. The relative percentage of peracarids in the box-corer samples increased with depth, while in absolute numbers, peracarids from these samples were also highest on the shelf at about 200 m depth. Accepted: 14 February 1999     

Cumulative solar irradiance and potential large-scale sea ice algae distribution off East Antarctica (30°E–150°E)

We present a computational model of the large-scale cumulative light exposure of sea ice in the Southern Ocean off East Antarctica (30°E–150°E). The model uses remotely sensed or modelled sea ice concentration, snow depth over sea ice, and solar irradiance data, and tracks sea ice motion over the season of interest in order to calculate the cumulative exposure of the ice field to photosynthetically active radiation (PAR). Light is the limiting factor to sea ice algal growth over winter and early spring, and so the results have implications for the estimation of algal biomass in East Antarctica. The model results indicate that highly light-exposed ice is restricted to within a few degrees of the coast in the eastern part of the study region, but extends much further north in the 30°E–100°E sector. The relative influences of sea ice motion, solar flux, and snow depth variations on interannual variations in model predictions were evaluated. The model estimates of cumulative PAR were found to correlate with satellite estimates of subsequent open-water chlorophyll-a concentration, consistent with the notion that sea ice algae can provide inocula for phytoplankton blooms.     

West–east contrast of phenology and climate in northern Asia revealed using a remotely sensed vegetation index

The phenology of the vegetation covering north Asia (mainly Siberia) and its spatial characterstics were investigated using remotely sensed normalized difference vegetation index (NDVI) data. The analysis used the weekly averaged NDVI over 5 years (1987-1991) using the second-generation weekly global vegetation index dataset (0.144 degrees x 0.144 degrees spatial resolution). In the seasonal NDVI cycle, three phenological events were defined for each pixel: green-up week (NDVI exceeds 0.2), maximum week, and senescence week (NDVI drops below 0.2). Generally there was a west-early/east-late gradient in the three events in north Asia. In the zonal transect between 45 degrees and 50 degrees N, the timing of green-up, maximum, and senescence near 60 degrees E (Kazakh) was about 3.4, 8.7, and 13.4 weeks earlier than near 110 degrees E (Mongolia) respectively. It has been suggested that vegetation near Kazakh only flourishes during a short period when water from snow melt is available from late spring to early summer. In Mongolia, abundant water is available for the vegetation, even in midsummer, because of precipitation. In the 50-60 degrees N zonal transect, the green-up and maximum near 40 degrees E were about 3.8 and 3.9 weeks earlier than near 115 degrees E, respectively. As for the week of senescence, there was no clear west-east trend. This west-to-east phenological gradient was related to the weekly cumulative temperature (over 0 degrees C). Weeks in which the cumalative temperature exceeded 40 degrees C and 140 degrees C had a similar west-east distribution to green-up and maximum NDVI.     

Spatial-temporal variability of ultraplankton vertical distribution in the Antarctic frontal zones within 60–66°E, 43–46°S

The vertical distribution of heterotrophic bacteria and four ultraphytoplanktonic (<10 µm) groups (Prochlorococcus, Synechococcus, pico- and nanoeukaryotes) was investigated by flow cytometry at three process stations located in three different sub-systems belonging to the Antarctic Circumpolar Current frontal zone and to the Southern Indian Ocean (60–66°E, 43–46°S; ANTARES 4 cruise, January-February 1999): the Subtropical Zone (STZ), the Convergence Zone and the Polar Frontal Zone (PFZ). In each sub-system, short-term variability of cell abundance and flow cytometric parameters (right-angle light scatter and chlorophyll autofluorescence) was assessed through a times series of up to 24 h with a 2 h sampling frequency. The ultraphytoplankton vertical distribution exhibited a high spatial variability, with dominance of Prochlorococcus in the STZ (mean: 762.85×10¹⁰ cells m^–2), whereas picoeukaryotes (<3 µm) were dominant in the PFZ (55.46×10¹⁰ cells m^–2), a typically high-nutrient low-chlorophyll zone. Heterotrophic bacteria abundance was maximum (9.84×10¹³ cells m^–2) in the frontal zone, between the Agulhas Front and the Subtropical Front. Nanoeukaryotes showed the largest (up to 80%) variations between two consecutive sampling periods (2 h). Abundance variations could not be assigned to the same water mass during the time series due to the highly variable hydrodynamics of the study area. Trends of short-term abundance variations were opposite between the PFZ (lowest at night) and north of the Subtropical Front (highest at night). The observed spatial and short-term variations illustrate the complexity of the water masses in the Indian sector of the Southern Ocean, and highlight the challenge of extrapolating discrete measurements over space and time for use in evaluating carbon budgets in such dynamic areas.     

Vertical stratification of °13C values in closed natural and plantation forests in the Luquillo mountains,Puerto Rico

Summary The variability of ¹³C values was measured in leaf, stem and root tissues of several tree species growing in closed natural and plantation forests in the Luquillo mountains of Puerto Rico. Results confirm a significant decrease of ¹³C values from the tree canopy to the forest floor. The values measured in understory plants growing in gaps were not significantly different from the average for plants growing under the forest shade. Seedling leaf values tended to be more positive than those of saplings, probably reflecting the contribution of organic matter from the mother tree. Photosynthetic independence on the forest floor results in a reduction in °¹³C value. Stem and root tissue values of seedlings and saplings were less negative than those of the leaves of the same plants. It is suggested that this difference results from the slower change in isotopic composition experienced by the woody tissue, as the seedlings become photosynthetically independent in the forest floor.     

Characteristic and representativeness of the vertical vegetation zonation along the altitudinal gradient in Shennongjia Natural Heritage北大核心CSCD

Aims Mountains contain broad environmental gradients, which are to be an outstanding universal value representing significant on-going ecological and biological processes in the evolution and development of zonal vegetation along the elevation gradients. Exploring the biological and ecological value of the vegetation zonation along the elevation gradients of Chinese mountain natural heritage site is important for biodiversity conservation and management. Methods Based on the community survey data of the six vegetation zonation along the elevational gradients in Shennongjia, the global land use dataset, and the literature data of the communities along the altitudinal gradients of other natural heritage sites and the nominated world natural heritage sites in Oriental Deciduous Forest Biogeographic Province by Udvardy, we explored the outstanding universal value of the zonal vegetation along the altitude gradients by the methods of spatial analysis. Important findings Shennongjia heritage site preserves the intact vegetation zonation of the typical Oriental Deciduous Forest Biogeographical Province in the Classification of the Biogeographical Provinces of the World by Udvardy, including evergreen broad-leaved forests (South Slope of the Heritage Site), evergreen deciduous broad-leaved mixed forests, deciduous broad-leaved forests, coniferous and broad-leaved mixed forests, coniferous forests and subalpine shrub and meadow along the elevation gradients. The altitudinal zonation of vegetation in the Shennongjia heritage site represented a variety of bio-ecological processes, such as the turnover of the dominant trees along the altitudinal gradients, and is an outstanding example of the ongoing ecological processes occurring in the development of intact subtropical mixed broadleaved evergreen and deciduous forest in the Northern Hemisphere. © 2018 Editorial Office of Chinese Journal of Plant Ecology. All Rights Reserved.