bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diamondback moth females oviposit more on plants infested by non‐parasitised than by parasitised conspecifics
Authors: CHOH YASUYUKI , UEFUNE MASAYOSHI , TAKABAYASHI JUNJI 
Published: May 2008

Abstract 1. When offered a choice, female diamondback moths (Plutella xylostella) oviposited more eggs on plants with non‐parasitised conspecific larvae than on plants with parasitised larvae.2. The leaf area consumed by parasitised larvae was significantly lower than that by non‐parasitised larvae. However, this quantitative difference in larval damage did not explain the female’s ability to discriminate between plants with parasitised and non‐parasitised larvae, as females showed an equal oviposition preference for plants infested by higher or lower densities of non‐parasitised larvae.3. Pupal weight and duration of the larval stage of P. xylostella were independent of whether larvae were reared on plants that were previously infested by either non‐parasitised or parasitised larvae.4. The larval parasitoid Cotesia vestalis did not distinguish between plants infested by non‐parasitised larvae and plants infested by larvae that had already been parasitised by conspecific wasps.5. Based on these data, it can be concluded that the moth oviposition preference for plants infested by non‐parasitised conspecifics relative to plants infested by parasitised conspecifics was not explained by plant quality or by the attractiveness of plants towards wasps. It is hypothesised that one of the reasons for this preference is avoidance of plants where a relatively high risk of parasitism is expected due to the emergence of parasitoids from the parasitised host larvae.
Rapid morphological change in stream beetle museum specimens correlates with climate change
Authors: BABIN‐FENSKE JENNIFER , ANAND MADHUR , ALARIE YVES 
Published: May 2008

Abstract 1. Climate change has been occurring at unprecedented rates and its impacts on biological populations is beginning to be well documented in the literature. For many species, however, long‐term records are not available, and trends have not been documented.2. Using museum specimens from southern USA, we show that the stream‐dwelling beetle Gyretes sinuatus has shown an 8% increase in body size and change in body shape (fineness ratio) from 1928 to 1988. Any directional morphological change observed over time could be an indicator of a microevolutionary response.3. During these 60 years, there have also been changes in temperature, precipitation, and location of collection sites. Unlike the global trend, mean annual temperature in the region has decreased, and furthermore, total annual precipitation has increased. By investigating how these various ecological and geographical variables may affect body size and shape, we can examine which pressures may promote larger and/or thinner beetles.4. Results indicate that mean annual temperature was the most predictive variable for the change in size and shape. We suggest there is an adaptive role for temperature on body size and shape of stream dwelling organisms.5. We found that museum specimens can be invaluable resources of information when collection date and location information is available. We promote the use of such specimens for future studies of the morphological response to climate change.
Soil inorganic carbon storage pattern in China
Authors: MI NA , WANG SHAOQIANG , LIU JIYUAN , YU GUIRUI , ZHANG WENJUAN , JOBBÁGY ESTEBAN 
Published: May 2008

AbstractSoils with pedogenic carbonate cover about 30% (3.44 × 106 km2) of China, mainly across its arid and semiarid regions in the Northwest. Based on the second national soil survey (1979–1992), total soil inorganic carbon (SIC) storage in China was estimated to be 53.3±6.3 PgC (1 Pg=1015 g) to the depth investigated to 2 m. Soil inorganic carbon storages were 4.6, 10.6, 11.1, and 20.8 Pg for the depth ranges of 0–0.1, 0.1–0.3, 0.3–0.5, and 0.5–1 m, respectively. Stocks for 0.1, 0.3, 0.5, and 1 m of depth accounted for 8.7%, 28.7%, 49.6%, and 88.9% of total SIC, respectively. In contrast with soil organic carbon (SOC) storage, which is highest under 500–800 mm yr−1 of mean precipitation, SIC storage peaks where mean precipitation is <400 mm yr−1. The amount and vertical distribution of SIC was related to climate and land cover type. Content of SIC in each incremental horizon was positively related with mean annual temperature and negatively related with mean annual precipitation, with the magnitude of SIC content across land cover types showing the following order: desert, grassland >shrubland, cropland >marsh, forest, meadow. Densities of SIC increased generally with depth in all ecosystem types with the exception of deserts and marshes where it peaked in intermediate layers (0.1–0.3 m for first and 0.3–0.5 m for latter). Being an abundant component of soil carbon stocks in China, SIC dynamics and the process involved in its accumulation or loss from soils require a better understanding.
Spatial variability and major controlling factors of CO2 sink strength in Asian terrestrial ecosystems: evidence from eddy covariance data
Authors: KATO TOMOMICHI , TANG YANHONG 
Published: May 2008

AbstractAsian terrestrial ecosystems cover an extensive area characterized by a large variety in climates and ecosystem properties. The observations of ecosystem CO2 flux in this area are increasing both in duration and spatial density, but no synthesis has yet been conducted. We surveyed CO2 flux observation data obtained by eddy covariance methods at 49 sites in terrestrial Asia. The measurements at most sites (44 of 49) began after 2000. The net ecosystem uptake of CO2 (NEE) varied greatly among sites and years and averaged −132.6±73.7, −250.1±206.1, and −180.1±361.7 g C m−2 yr−1, in boreal, temperate, and tropical Asia, respectively, and the coefficient of variation among sites increased from boreal to tropical Asia. The site‐averaged annual NEE was correlated linearly with the mean annual temperature (Tair) and also correlated logarithmically with the precipitation. Multiple regression analysis and stepwise analysis indicated that photosynthetic active radiation (PAR) and Tair were the most significant predictors of the annual NEE. The study results suggest that Asian terrestrial ecosystems are currently significant net CO2 sinks and that the sink strength is largely controlled by temperature, moisture, and light conditions.
Changing land use reduces soil CH4 uptake by altering biomass and activity but not composition of high‐affinity methanotrophs
Authors: MENYAILO OLEG V. , HUNGATE BRUCE A. , ABRAHAM WOLF‐RAINER , CONRAD RALF 
Published: May 2008

AbstractForest ecosystems assimilate more CO2 from the atmosphere and store more carbon in woody biomass than most nonforest ecosystems, indicating strong potential for afforestation to serve as a carbon management tool. However, converting grasslands to forests could affect ecosystem–atmosphere exchanges of other greenhouse gases, such as nitrous oxide and methane (CH4), effects that are rarely considered. Here, we show that afforestation on a well‐aerated grassland in Siberia reduces soil CH4 uptake by a factor of 3 after 35 years of tree growth. The decline in CH4 oxidation was observed both in the field and in laboratory incubation studies under controlled environmental conditions, suggesting that not only physical but also biological factors are responsible for the observed effect. Using incubation experiments with 13CH4 and tracking 13C incorporation into bacterial phospholipid fatty acid (PLFA), we found that, at low CH4 concentrations, most of the 13C was incorporated into only two PLFAs, 18 : 1ω7 and 16 : 0. High CH4 concentration increased total 13C incorporation and the number of PLFA peaks that became labeled, suggesting that the microbial assemblage oxidizing CH4 shifts with ambient CH4 concentration. Forests and grasslands exhibited similar labeling profiles for the high‐affinity methanotrophs, suggesting that largely the same general groups of methanotrophs were active in both ecosystems. Both PLFA concentration and labeling patterns indicate a threefold decline in the biomass of active methanotrophs due to afforestation, but little change in the methanotroph community. Because the grassland consumed CH4 at a rate five times higher than forest soils under laboratory conditions, we concluded that not only biomass but also cell‐specific activity was higher in grassland than in afforested plots. While the decline in biomass of active methanotrophs can be explained by site preparation (plowing), inorganic N (especially NH4+) could be responsible for the change in cell‐specific activity. Overall, the negative effect of afforestation of upland grassland on soil CH4 uptake can be largely explained by the reduction in biomass and to a lesser extent by reduced cell‐specific activity of CH4‐oxidizing bacteria.
Shrub (Prosopis velutina) encroachment in a semidesert grassland: spatial–temporal changes in soil organic carbon and nitrogen pools
Authors: THROOP HEATHER L. , ARCHER STEVEN R. 
Published: May 2008

AbstractRecent trends of increasing woody vegetation in arid and semiarid ecosystems may contribute substantially to the North American C sink. There is considerable uncertainty, however, in the extent to which woody encroachment alters dryland soil organic carbon (SOC) and total nitrogen (TN) pools. To date, studies assessing SOC and TN response to woody plant proliferation have not explicitly assessed the variability caused by shrub age or size and subcanopy spatial gradients. These factors were quantified via spatially intensive soil sampling around Prosopis velutina shrubs in a semidesert grassland, using shrub size as a proxy for age. We found that bulk density increased with distance from the bole (P < 0.005) and decreased with increasing shrub size (P= 0.056), while both SOC and TN increased with shrub size and decreased with distance from the bole (P < 0.001 for both). Significant (and predictable) spatial variation in bulk density suggests that use of generic values would generate unreliable estimates of SOC and TN mass, and subcanopy SOC pools could be overestimated by nearly 30% if intercanopy bulk density values were applied to subcanopy sites. Predictive models based on field‐documented spatial patterns were used to generate integrated estimates of under‐shrub SOC and TN pools, and these were compared with results obtained by typical area‐weighting protocols based on point samples obtained next to the bole or at a specified distance from the bole. Values obtained using traditional area‐weighting approaches generally overestimated SOC pools relative to those obtained using the spatially integrated approach, the discrepancy increasing with increasing shrub size and proximity of the point sample to the bole. These discrepancies were observed at the individual plant scale and for landscapes populated by various shrub size classes. Results suggest that sampling aimed at quantifying shrub encroachment impacts on SOC and TN pools will require area‐weighting algorithms that simultaneously account for shrub size (age) and subcanopy spatial patterns.
Contemporary carbon accumulation in a boreal oligotrophic minerogenic mire – a significant sink after accounting for all C‐fluxes
Authors: NILSSON MATS , SAGERFORS JÖRGEN , BUFFAM ISHI , LAUDON HJALMAR , ERIKSSON TOBIAS , GRELLE ACHIM , KLEMEDTSSON LEIF , WESLIEN PER , LINDROTH ANDERS 
Published: May 2008

AbstractBased on theories of mire development and responses to a changing climate, the current role of mires as a net carbon sink has been questioned. A rigorous evaluation of the current net C‐exchange in mires requires measurements of all relevant fluxes. Estimates of annual total carbon budgets in mires are still very limited. Here, we present a full carbon budget over 2 years for a boreal minerogenic oligotrophic mire in northern Sweden (64°11′N, 19°33′E). Data on the following fluxes were collected: land–atmosphere CO2 exchange (continuous Eddy covariance measurements) and CH4 exchange (static chambers during the snow free period); TOC (total organic carbon) in precipitation; loss of TOC, dissolved inorganic carbon (DIC) and CH4 through stream water runoff (continuous discharge measurements and regular C‐concentration measurements). The mire constituted a net sink of 27±3.4 (±SD) g C m−2 yr−1 during 2004 and 20±3.4 g C m−2 yr−1 during 2005. This could be partitioned into an annual surface–atmosphere CO2 net uptake of 55±1.9 g C m−2 yr−1 during 2004 and 48±1.6 g C m−2 yr−1 during 2005. The annual NEE was further separated into a net uptake season, with an uptake of 92 g C m−2 yr−1 during 2004 and 86 g C m−2 yr−1 during 2005, and a net loss season with a loss of 37 g C m−2 yr−1 during 2004 and 38 g C m−2 yr−1 during 2005. Of the annual net CO2‐C uptake, 37% and 31% was lost through runoff (with runoff TOC>DIC≫CH4) and 16% and 29% through methane emission during 2004 and 2005, respectively. This mire is still a significant C‐sink, with carbon accumulation rates comparable to the long‐term Holocene C‐accumulation, and higher than the C‐accumulation during the late Holocene in the region.
Negative fire feedback in a transitional forest of southeastern Amazonia
Authors: BALCH JENNIFER K. , NEPSTAD DANIEL C. , BRANDO PAULO M. , CURRAN LISA M. , PORTELA OSVALDO , De CARVALHO OSWALDO , LEFEBVRE PAUL 
Published: May 2008

AbstractAnthropogenic understory fires affect large areas of tropical forest, particularly during severe droughts. Yet, the mechanisms that control tropical forests' susceptibility to fire remain ambiguous. We tested the widely accepted hypothesis that Amazon forest fires increase susceptibility to further burning by conducting a 150 ha fire experiment in a closed‐canopy forest near the southeastern Amazon forest–savanna boundary. Forest flammability and its possible determinants were measured in adjacent 50 ha forest plots that were burned annually for 3 consecutive years (B3), once (B1), and not at all (B0). Contrary to expectation, an annual burning regime led to a decline in forest flammability during the third burn. Microclimate conditions were more favorable compared with the first burn (i.e. vapor pressure deficit increased and litter moisture decreased), yet flame heights declined and burned area halved. A slight decline in fine fuels after the second burn appears to have limited fire spread and intensity. Supporting this conclusion, fire spread rates doubled and burned area increased fivefold in B3 subplots that received fine fuel additions. Slow replacement of surface fine fuels in this forest may be explained by (i) low leaf litter production (4.3 Mg ha−1 yr−1), half that of other Amazon forests; and (ii) low fire‐induced tree and liana mortality (5.5±0.5% yr−1, SE, in B3), the lowest measured in closed‐canopy Amazonian forests. In this transitional forest, where severe seasonal drought removed moisture constraints on fire propagation, a lack of fine fuels inhibited the intensity and spread of recurrent fire in a negative feedback. This reduction in flammability, however, may be short‐lived if delayed tree mortality or treefall increases surface fuels in future years. This study highlights that understanding fuel input rate and timing relative to fire frequency is fundamental to predicting transitional forest flammability – which has important implications for carbon emissions and potential replacement by scrub vegetation.
Warming and drought alter C and N concentration, allocation and accumulation in a Mediterranean shrubland
Authors: SARDANS JORDI , PEÑUUELAS JOSEP , ESTIARTE MARC , PRIETO PATRICIA 
Published: May 2008

AbstractWe investigated the effects of warming and drought on C and N concentrations, nitrogen use efficiency (NUE), and C and N accumulation in different ecosystem compartments. We conducted a 6‐year (1999–2005) field experiment to simulate the climate conditions projected by IPCC models for the coming decades in a Mediterranean shrubland. We studied the two dominant species, Globularia alypum and Erica multiflora, and an N‐fixing species, Dorycnium pentaphyllum, also abundant in this shrubland. Warming (1 °C) decreased N leaf concentrations by 25% and increased N stem concentrations by 40% in G. alypum. Although warming changed the available ammonium in soil in some seasons, it did not increase total soil N contents. Drought (19% average reduction in soil moisture) decreased leaf N concentrations in the two dominant shrub species, E. multiflora and G. alypum by 16% and 19%, respectively, and increased stem N concentrations by 56% and 40%, respectively. Neither warming nor drought changed the leaf N concentrations in the N‐fixing species D. pentaphyllum, although warming increased stem N concentration by 9%. In G. alypum, the increase of stem N concentrations contributed to the observed increase of N accumulation in stem biomass in drought treatments with respect to control plots (8 kg N ha−1). Neither warming nor drought changed NUE in the period 1999–2005. Warming increased soil organic C relative to drought. The effects of warming and drought on C and N concentrations, on N accumulation and on leaf/stem N distribution were not the result of dilution or concentration effects produced by changes in biomass accumulation. Other factors such as the changes in soil N availability, photosynthetic capacity, and plant internal C and N remobilization must be involved. These changes which differed depending on the species and the plant tissue show that the climate change projected for the coming decades will have significant effects on the C and N cycle and stoichiometry, with probable implications for ecosystem structure and function, such as changes in plant–herbivore relationships, decomposition rates or community species composition.
The stripe‐backed weasel Mustela strigidorsa: taxonomy, ecology, distribution and status
Authors: ABRAMOV A. V. , DUCKWORTH J. W. , WANG Y. X. , ROBERTON S. I. 
Published: May 2008

ABSTRACT

The stripe‐backed weasel Mustela strigidorsa is one of the rarest and least‐known mustelids in the world. Its phylogenetic relationships with other Mustela species remain controversial, though several unique morphological features distinguish it from congeners.
It probably lives mainly in evergreen forests in hills and mountains, but has also been recorded from plains forest, dense scrub, secondary forest, grassland and farmland. Known sites range in altitude from 90 m to 2500 m. Data are insufficient to distinguish between habitat and altitudes which support populations, and those where only dispersing animals may occur.
It has been confirmed from many localities in north‐east India, north and central Myanmar, south China, north Thailand, north and central Laos, and north and central Vietnam. Given the limited survey effort, the number of recent records shows that the species is not as rare as hitherto believed. Neither specific nor urgent conservation needs are apparent.
Holocene environmental changes and the seal (Phocidae) fauna of the Baltic Sea: coming, going and staying
Authors: SCHMÖLCKE ULRICH 
Published: May 2008

ABSTRACT

The occurrence of different species of seal (Phocidae) during the Holocene in north‐eastern Europe was influenced by a changing geological situation over the last 12 000 years, characterized by alternating freshwater, brackish and marine stages and by spatially and temporally limited opportunities for migration of marine species into the Baltic basin. The patterns of immigration by ringed seal Phoca hispida, harp seal Phoca groenlandica, grey seal Halichoerus grypus and harbour seal Phoca vitulina are reviewed here in order to understand present distributions and population sizes. Furthermore, the future of their populations is analysed.
Phoca hispida immigrated into the Baltic basin during its brackish Yoldia Stage at the Late Glacial/Early Holocene boundary and has persisted in some disjunct populations until now. A second immigration followed at the beginning of the Littorina Transgression – which resulted in the present stage of the Baltic Sea, obviously caused by the strong cooling event that occurred 6200 calibrated 14C years BC. Its present status is not threatened, but global warming will restrict suitable habitat.
Phoca groenlandica had a mid‐Holocene intermezzo in the Baltic Sea. Its later disappearance was probably caused by hunting of subadult animals by humans.
Halichoerus grypus and Phoca vitulina also immigrated at the beginning of the present stage of the Baltic Sea. Whereas H. grypus has been common from this beginning point until modern times, the population of P. vitulina persisted at a low level for millennia. Only since the 18th century has its population increased and spread over the whole Baltic Sea.
A transcription factor regulatory cascade controls secreted aspartic protease expression in Candida albicans
Authors: Dabas Neelam , Morschhäuser Joachim 
Published: May 2008

SummarySecreted aspartic proteases (Saps) contribute to the virulence of Candida albicans, a major fungal pathogen of humans. One function of the Saps, which is specifically mediated by the Sap2p isoenzyme, is the degradation of proteins for use as a nitrogen source. The utilization of alternative nitrogen sources in fungi is controlled by GATA transcription factors and we found that C. albicans mutants lacking the GATA transcription factors Gln3p and Gat1p were unable to grow in a medium containing bovine serum albumin (BSA) as the sole nitrogen source. The growth defect was mainly caused by the inability of gln3Δgat1Δ mutants to express the SAP2 gene, as SAP2 expression from the constitutive ADH1 promoter restored the ability of the mutants to grow on BSA. Expression of STP1, which encodes a transcription factor that is required for SAP2 induction in the presence of proteins, was regulated by Gln3p and Gat1p, and forced expression of STP1 from a tetracycline‐inducible promoter bypassed the requirement of the GATA transcription factors for growth of C. albicans on proteins. SAP2 is repressed when preferred nitrogen sources are available and this nitrogen catabolite repression of SAP2 was correlated with downregulation of STP1 in the presence of high concentrations of ammonium, glutamine or urea. Tetracycline‐induced STP1 expression abolished nitrogen catabolite repression of SAP2, demonstrating that the control of STP1 expression levels by the GATA transcription factors is a key aspect of both positive and negative regulation of SAP2 expression. Therefore, secreted aspartic protease expression, a long‐known virulence attribute of C. albicans, is controlled by a regulatory cascade in which the general regulators Gln3p and Gat1p control the expression of the transcription factor Stp1p, which in turn mediates SAP2 expression.