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Long-Term Nitrogen Addition Leads to Loss of Species Richness Due to Litter Accumulation and Soil Acidification in a Temperate Steppe  [PDF]
Ying Fang, Fen Xun, Wenming Bai, Wenhao Zhang, Linghao Li
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047369
Abstract: Background Although community structure and species richness are known to respond to nitrogen fertilization dramatically, little is known about the mechanisms underlying specific species replacement and richness loss. In an experiment in semiarid temperate steppe of China, manipulative N addition with five treatments was conducted to evaluate the effect of N addition on the community structure and species richness. Methodology/Principal Findings Species richness and biomass of community in each plot were investigated in a randomly selected quadrat. Root element, available and total phosphorus (AP, TP) in rhizospheric soil, and soil moisture, pH, AP, TP and inorganic N in the soil were measured. The relationship between species richness and the measured factors was analyzed using bivariate correlations and stepwise multiple linear regressions. The two dominant species, a shrub Artemisia frigida and a grass Stipa krylovii, responded differently to N addition such that the former was gradually replaced by the latter. S. krylovii and A. frigida had highly-branched fibrous and un-branched tap root systems, respectively. S. krylovii had higher height than A. frigida in both control and N added plots. These differences may contribute to the observed species replacement. In addition, the analysis on root element and AP contents in rhizospheric soil suggests that different calcium acquisition strategies, and phosphorus and sodium responses of the two species may account for the replacement. Species richness was significantly reduced along the five N addition levels. Our results revealed a significant relationship between species richness and soil pH, litter amount, soil moisture, AP concentration and inorganic N concentration. Conclusions/Significance Our results indicate that litter accumulation and soil acidification accounted for 52.3% and 43.3% of the variation in species richness, respectively. These findings would advance our knowledge on the changes in species richness in semiarid temperate steppe of northern China under N deposition scenario.
Biodiversity of Terrestrial Ecosystems in Tropical to Temperate Australia  [PDF]
Raymond L. Specht
International Journal of Ecology , 2012, DOI: 10.1155/2012/359892
Abstract: During the short period of annual foliage growth in evergreen plant communities, aerodynamic fluxes (frictional, thermal, evaporative) in the atmosphere as it flows over and through a plant community determine the Foliage Projective Covers and leaf attributes in overstorey and understorey strata. The number of leaves produced on each vertical foliage shoot depends on available soil water and nutrients during this growth period. The area of all leaves exposed to solar radiation determines net photosynthetic fixation of the plant community throughout the year. In turn, the species richness (number of species per hectare) of both plants and resident vertebrates is determined. The species richness of unicellular algae and small multicellular isopods in permanent freshwater lagoons in Northern Australia may possibly have been increased by radiation released from nearby uranium deposits. Evolution of new angiosperms probably occurred in refugia during periods of extreme drought. When favourable climates were restored, the vegetation expanded to result in high Gamma Biodiversity (number of plant species per region) but with each major plant community having essentially the same species richness (number of plant species per hectare). The probable effects of pollution and Global Warming on biodiversity in Australian ecosystems, that experience seasonal drought, are discussed.
Biodiversity of Terrestrial Ecosystems in Tropical to Temperate Australia  [PDF]
Raymond L. Specht
International Journal of Ecology , 2012, DOI: 10.1155/2012/359892
Abstract: During the short period of annual foliage growth in evergreen plant communities, aerodynamic fluxes (frictional, thermal, evaporative) in the atmosphere as it flows over and through a plant community determine the Foliage Projective Covers and leaf attributes in overstorey and understorey strata. The number of leaves produced on each vertical foliage shoot depends on available soil water and nutrients during this growth period. The area of all leaves exposed to solar radiation determines net photosynthetic fixation of the plant community throughout the year. In turn, the species richness (number of species per hectare) of both plants and resident vertebrates is determined. The species richness of unicellular algae and small multicellular isopods in permanent freshwater lagoons in Northern Australia may possibly have been increased by radiation released from nearby uranium deposits. Evolution of new angiosperms probably occurred in refugia during periods of extreme drought. When favourable climates were restored, the vegetation expanded to result in high Gamma Biodiversity (number of plant species per region) but with each major plant community having essentially the same species richness (number of plant species per hectare). The probable effects of pollution and Global Warming on biodiversity in Australian ecosystems, that experience seasonal drought, are discussed. 1. Introduction During the 1920s to 1940s, scientists in the Botany Department and Waite Agricultural Research Institute of the University of Adelaide (together with scientists of CSIRO Soils Division and the South Australian Museum) studied many aspects of the climate, soils, vegetation, fauna, and Aborigines in South Australia as well as on the rest of the continent of Australia [1]. In 1935, the holistic concept of the “ecosystem” was promoted by Tansley, Professor of Botany of Oxford University [2]. The “ecosystem” concept, relating climate, soils, and vegetation, over time (short- and long-term) was pursued by Crocker of CSIRO Soils Division and the Agronomy Department of the Waite, together with Professor Wood of the Botany Department. During 1947 and 1948 while on sabbatical leave in Cambridge University and the University of California, Berkeley, Crocker developed the concepts of “soil genesis and the pedogenic factors” and their interactions with the dynamics of plant communities—in space and time [3]. The various ecophysiological facets of the ecosystem were to be explored and integrated by one scientist: The holistic study of the dynamic processes that operate throughout the life
Diversity and abundance of photosynthetic sponges in temperate Western Australia
Marie-Louise Lemloh, Jane Fromont, Franz Brümmer, Kayley M Usher
BMC Ecology , 2009, DOI: 10.1186/1472-6785-9-4
Abstract: We sampled sponges on 5 m belt transects to determine the percentage of photosynthetic sponges and identified at least one representative of each group of symbionts using 16S rDNA sequencing together with microscopy techniques. Our results demonstrate that photosynthetic sponges are abundant in temperate WA, with an average of 63% of sponge individuals hosting high levels of photosynthetic symbionts and 11% with low to medium levels. These percentages of photosynthetic sponges are comparable to those found on tropical reefs and may have important implications for ecosystem function on temperate reefs in other areas of the world. A diverse range of symbionts sometimes occurred within a small geographic area, including the three "big" cyanobacterial clades, Oscillatoria spongeliae, "Candidatus Synechococcus spongiarum" and Synechocystis species, and it appears that these clades all occur in a wide range of sponges. Additionally, spongin-permeating red algae occurred in at least 7 sponge species. This study provides the first investigation of the molecular phylogeny of rhodophyte symbionts in sponges.Photosynthetic sponges are abundant and diverse in temperate WA, with comparable percentages of photosynthetic to non-photosynthetic sponges to tropical zones. It appears that there are three common generalist clades of cyanobacterial symbionts of sponges which occur in a wide range of sponges in a wide range of environmental conditions.Sponges (Phylum Porifera) are sessile aquatic metazoans that are found in all aquatic habitats and have important roles in marine ecological processes. Fossil records dating back to the Late Cambrian era 509 million years ago show that sponges have survived largely unchanged in their general structural organization [1]. So far about 7,000 extant species are described [2]. As filter feeders, sponges filter food particles from the water pumped through their body and bacteria are the main component of the sponge diet [3,4].Photosynthetic spong
Taxonomic Richness of Yeasts in Japan within Subtropical and Cool Temperate Areas  [PDF]
Masako Takashima, Takashi Sugita, Bui Hong Van, Megumi Nakamura, Rikiya Endoh, Moriya Ohkuma
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0050784
Abstract: Background An understanding of the role of yeasts in the environment has been uncertain because estimates of population size and diversity have often been based on species identifications that were determined from a limited number of phenotypic characteristics. DNA-based species identification has now become widely used, allowing an accurate assessment of species in different habitats. However, there are still problems in classification because some genera are polyphyletic. Consequently, the identification of yeasts and measurement of their diversity at the genus level remains difficult, as does assignment of genera to higher taxonomic ranks. Methodology/Principal Findings A total of 1021 yeast strains was isolated from soil samples and plant materials collected from Japan’s subtropical Iriomote Island and the cool temperate Rishiri Island. Based on sequence analyses of the D1/D2 domain of the LSU rRNA gene, these 1021 strains were tentatively classified into 183 species, with apparent new species accounting for approximately half of the total species isolated (60 and 46, Iriomote and Rishiri, respectively). The yeast species composition was statistically different between the two sites with only 15 species in common. Rarefaction curves of respective sources/areas gave distinctive patterns when the threshold of sequence identity became broader, indicating that the yeast diversity was distinct at the different taxonomic levels compared. Conclusions/Significance Our isolation study of yeasts in Japan has enabled us to expand the inventory of species diversity because a large number of new species was observed in the sampling areas. Further, we propose use of a particular diversity threshold as an “indicator” to recognize species, genera and higher taxonomic ranks.
Relationship between fragmentation, degradation and native and exotic species richness in an Andean temperate forest of Chile
ROJAS,ISABEL; BECERRA,PABLO; GáLVEZ,NICOLáS; LAKER,JERRY; BONACIC,CRISTIáN; HESTER,ALISON;
Gayana. Botánica , 2011, DOI: 10.4067/S0717-66432011000200006
Abstract: human impact such as forest fragmentation and degradation may have strong effects on native and exotic plant communities. in addition, these human-caused disturbances occur mostly in lowlands producing greater fragmentation and degradation there than in higher elevations. plant invasion should be greater in more fragmented and degraded forests and hence lowlands should be more invaded than higher elevations. in turn, native species richness should be negatively related to fragmentation and degradation and hence greater in higher elevations within a forest type or elevation belt. we assessed these hypotheses in an andean temperate forest of southern chile, araucanía region. we recorded the vascular plant composition in twelve fragments of different size, perimeter/area, elevation level and evidence of human degradation (logging, fire, cattle faeces). based on these variables we performed a fragmentation and a degradation index. pearson correlations were used to analyze the relationship between all these variables. we found that fragmentation and degradation were positively correlated, and each of them decreased with altitude. furthermore, fragmentation and degradation affected native and exotic species richness in different ways. invasion was enhanced by both fragmentation and degradation, and as consequence of the altitudinal patterns of these human-caused disturbances, invasion seems to occur mainly in lowlands. in turn, native species richness decreased with fragmentation, and it was not related to degradation nor altitude.
Annual and Daily Changes of Thunderstorms in Temperate Climate in London, Warsaw and Moscow
Katarzyna Grabowska
Miscellanea Geographica - Regional Studies on Development , 2011, DOI: 10.2478/v10288-012-0007-4
Abstract: The aim of the study is to show and compare variation of the annual and daily course of thunderstorms in selected European cities in 2005-2009. Data on thunderstorms originate from dispatches METAR for three airport stations: London Gatwick, Warsaw Ok cie and Moscow Sheremetyevo. These cities represent the various types of climate: warm temperate marine, transitional and continental. Thunderstorms mostly occurred in Warsaw - 207 (Moscow - 174, London - 71). The maximum of thunderstorms frequency, in the yearly course, in all towns occurred in July (Warsaw - 11,8; Moscow - 13,4; London - 5,0). Thunderstorms predominantly started at 13:30 in London, 17:00 in Warsaw, 18:00 in Moscow (13:30 means period 13:01-13:30, 17:00 means period 16:31-17:00 etc.). Thunderstorms most often ended at 13:30 in London, 17:00 in Warsaw, 20:30 in Moscow. There were dominated, at all stations, brief thunderstorms, which lasted for 30 minutes. The longest thunderstorm remained 9 hours (Warsaw), 5,5 (Moscow), 4,5 (London).
Twenty Years of High-Resolution Sea Surface Temperature Imagery around Australia: Inter-Annual and Annual Variability  [PDF]
Scott D. Foster, David A. Griffin, Piers K. Dunstan
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0100762
Abstract: The physical climate defines a significant portion of the habitats in which biological communities and species reside. It is important to quantify these environmental conditions, and how they have changed, as this will inform future efforts to study many natural systems. In this article, we present the results of a statistical summary of the variability in sea surface temperature (SST) time-series data for the waters surrounding Australia, from 1993 to 2013. We partition variation in the SST series into annual trends, inter-annual trends, and a number of components of random variation. We utilise satellite data and validate the statistical summary from these data to summaries of data from long-term monitoring stations and from the global drifter program. The spatially dense results, available as maps from the Australian Oceanographic Data Network's data portal (http://www.cmar.csiro.au/geonetwork/srv/?en/metadata.show?id=51805), show clear trends that associate with oceanographic features. Noteworthy oceanographic features include: average warming was greatest off southern West Australia and off eastern Tasmania, where the warming was around 0.6°C per decade for a twenty year study period, and insubstantial warming in areas dominated by the East Australian Current, but this area did exhibit high levels of inter-annual variability (long-term trend increases and decreases but does not increase on average). The results of the analyses can be directly incorporated into (biogeographic) models that explain variation in biological data where both biological and environmental data are on a fine scale.
Carbon allocation to biomass production of leaves, fruits and woody organs at seasonal and annual scale in a deciduous- and evergreen temperate forest  [PDF]
M. Campioli,B. Gielen,A. Granier,A. Verstraeten
Biogeosciences Discussions , 2010, DOI: 10.5194/bgd-7-7575-2010
Abstract: Carbon taken up by the forest canopy is allocated to tree organs for biomass production and respiration. Because tree organs have different life span and decomposition rate, the tree C allocation determines the residence time of C in the ecosystem and its C cycling rate. The study of the carbon-use efficiency, or ratio between net primary production (NPP) and gross primary production (GPP), represents a convenient way to analyse the C allocation at the stand level. Previous studies mostly focused on comparison of the annual NPP-GPP ratio among forests of different functional types, biomes and age. In this study, we extend the current knowledge by assessing (i) the annual NPP-GPP ratio and its interannual variability (for five years) for five tree organs (leaves, fruits, branches, stem and coarse roots), and (ii) the seasonal dynamic of NPP-GPP ratio of leaves and stems, for two stands dominated by European beech and Scots pine. The average NPP-GPP ratio for the beech stand (38%) was similar to previous estimates for temperate deciduous forests, whereas the NPP-GPP ratio for the pine stand (17%) is the lowest recorded till now in the literature. The proportion of GPP allocated to leaf NPP was similar for both species, whereas beech allocated a remarkable larger proportion of GPP to wood NPP than pine (29% vs. 6%, respectively). The interannual variability of the NPP-GPP ratio for wood was substantially larger than the interannual variability of the NPP-GPP ratio for leaves, fruits and overall stand and it is likely to be controlled by previous year air temperature (both species), previous year drought intensity (beech) and thinning (pine). Seasonal pattern of NPP-GPP ratio greatly differed between beech and pine, with beech presenting the largest ratio in early season, and pine a more uniform ratio along the season. For beech, NPP-GPP ratio of leaves and stems peaked during the same period in the early season, whereas they peaked in opposite periods of the growing season for pine. Seasonal differences in C allocation are likely due to functional differences between deciduous and evergreen species and temporal variability of the sink strength. The similar GPP and autotrophic respiration between stands and the remarkable larger C allocation to wood at the beech stand indicate that at the beech ecosystem C has a longer residence time than at the pine ecosystem. Further research on belowground production and particularly on fine roots and ectomycorrhizal fungi likely represents the most important step to progress our knowledge on C allocation dynamics.
Factors Affecting Spatial Variation of Annual Apparent Q10 of Soil Respiration in Two Warm Temperate Forests  [PDF]
Junwei Luan, Shirong Liu, Jingxin Wang, Xueling Zhu
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0064167
Abstract: A range of factors has been identified that affect the temperature sensitivity (Q10 values) of the soil-to-atmosphere CO2 flux. However, the factors influencing the spatial distribution of Q10 values within warm temperate forests are poorly understood. In this study, we examined the spatial variation of Q10 values and its controlling factors in both a naturally regenerated oak forest (OF) and a pine plantation (PP). Q10 values were determined based on monthly soil respiration (RS) measurements at 35 subplots for each stand from Oct. 2008 to Oct. 2009. Large spatial variation of Q10 values was found in both OF and PP, with their respective ranges from 1.7 to 5.12 and from 2.3 to 6.21. In PP, fine root biomass (FR) (R = 0.50, P = 0.002), non-capillary porosity (NCP) (R = 0.37, P = 0.03), and the coefficients of variation of soil temperature at 5 cm depth (CV of T5) (R = ?0.43, P = 0.01) well explained the spatial variance of Q10. In OF, carbon pool lability reflected by light fractionation method (LLFOC) well explained the spatial variance of Q10 (R = ?0.35, P = 0.04). Regardless of forest type, LLFOC and FR correlation with the Q10 values were significant and marginally significant, respectively; suggesting a positive relationship between substrate availability and apparent Q10 values. Parameters related to gas diffusion, such as average soil water content (SWC) and NCP, negatively or positively explained the spatial variance of Q10 values. Additionally, we observed significantly higher apparent Q10 values in PP compared to OF, which might be partly attributed to the difference in soil moisture condition and diffusion ability, rather than different substrate availabilities between forests. Our results suggested that both soil chemical and physical characters contributed to the observed large Q10 value variation.
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