38 research outputs found

    Application of visual surveys to estimate acorn production of Brant`s oak (Quercus brantii Lindl.) in northern Zagros Forests of Iran

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    Acorn production plays a fundamental role in the organization and dynamics of oak forest ecosystems. Regarding acorn importance, visual survey methods have been used to estimate acorn production of oak species throughout the world. In this study, the mast indices of Brant`s oak (Quercus brantii Lindl.) were determined in a section of northern Zagros forests, almost 36 ha area, near Baneh, Kurdistan province. Different types of visual surveys (Whitehead, Christisen-Kearby, Modified Graves and Koenig) were used on 120 trees which were selected using stratified random sampling method. In early September, just prior to acorn fall, each tree was investigated using visual surveys. Furthermore, for each tree, acorn density (acorns number/m2 crown area) was calculated using crown counting to calculate the best regression model in Koenig method. Based on visual estimation indices, fair acorn production of Q. brantii was observed. There was a strong (R2 = 0.73), highly significant (P < 0.001) linear relationship between the Koenig acorn counts (X) and corresponding crown counts. Furthermore, the results of this research confirmed usefulness of the quick visual survey methods to estimate the acorn crop of Q. brantii

    A revision of chestnut-leaved oak (Quercus castaneifolia C. A. Mey.; Fagaceae) in Hyrcanian Forests of Iran

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    Chestnut-leaved oak (Quercus castaneifolia C. A. Mey) is one of the most important native oaks of Iran distributed in the Hyrcanian Forests. The pure and mixed stands of it cover about 6.5% of these forests. The species represents morphological variations which have resulted in the description of several infraspecific taxa by different authors. Eight taxa were recognized as subspecies and varieties of Q. castaneifolia. In this survey, a set of quantitative and qualitative micro-morphological characteristics such as type of trichome, number and length of trichome rays, type of epicuticular waxes, type and shape of stomata, shape and sculptural features of pollen exine were studied using light microscopy and scanning electron microscopy. These characters were analyzed by the discriminant analysis method and combined with the macromorphological characters to designate the variation within the species and to evaluate the existing infraspecific taxa. Based on our results, the studied taxa are defined into four infraspecific taxa as follows: Q. castaneifolia subsp. castaneifolia var. castaneifolia, Q. castaneifolia subsp. castaneifolia var. minuta, Q. castaneifolia subsp. aitchisoniana, Q. castaneifolia subsp. undulate. The studied characteristics showed to be diagnostic for identification of the infraspecific taxa

    MASTREE+ : time-series of plant reproductive effort from six continents

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    Significant gaps remain in understanding the response of plant reproduction to environmental change. This is partly because measuring reproduction in long-lived plants requires direct observation over many years and such datasets have rarely been made publicly available. Here we introduce MASTREE+, a data set that collates reproductive time-series data from across the globe and makes these data freely available to the community. MASTREE+ includes 73,828 georeferenced observations of annual reproduction (e.g. seed and fruit counts) in perennial plant populations worldwide. These observations consist of 5971 population-level time-series from 974 species in 66 countries. The mean and median time-series length is 12.4 and 10 years respectively, and the data set includes 1122 series that extend over at least two decades (≄20 years of observations). For a subset of well-studied species, MASTREE+ includes extensive replication of time-series across geographical and climatic gradients. Here we describe the open-access data set, available as a.csv file, and we introduce an associated web-based app for data exploration. MASTREE+ will provide the basis for improved understanding of the response of long-lived plant reproduction to environmental change. Additionally, MASTREE+ will enable investigation of the ecology and evolution of reproductive strategies in perennial plants, and the role of plant reproduction as a driver of ecosystem dynamics

    MASTREE+: Time-series of plant reproductive effort from six continents.

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    Significant gaps remain in understanding the response of plant reproduction to environmental change. This is partly because measuring reproduction in long-lived plants requires direct observation over many years and such datasets have rarely been made publicly available. Here we introduce MASTREE+, a data set that collates reproductive time-series data from across the globe and makes these data freely available to the community. MASTREE+ includes 73,828 georeferenced observations of annual reproduction (e.g. seed and fruit counts) in perennial plant populations worldwide. These observations consist of 5971 population-level time-series from 974 species in 66 countries. The mean and median time-series length is 12.4 and 10 years respectively, and the data set includes 1122 series that extend over at least two decades (≄20 years of observations). For a subset of well-studied species, MASTREE+ includes extensive replication of time-series across geographical and climatic gradients. Here we describe the open-access data set, available as a.csv file, and we introduce an associated web-based app for data exploration. MASTREE+ will provide the basis for improved understanding of the response of long-lived plant reproduction to environmental change. Additionally, MASTREE+ will enable investigation of the ecology and evolution of reproductive strategies in perennial plants, and the role of plant reproduction as a driver of ecosystem dynamics

    Phenology of native fruit trees in National Botanical Garden of Iran

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    Phenology, as one of the most important subjects of ecology, is the study of periodic plant life cycle events and how these are influenced by variations in climate and ecological conditions. In this research, phonological observations of 5 species (Prunus dulcis, Prunus avium, Prunus armeniaca, Pyrus communis, Prunus domestica) were studied in Iranian orchard of National Botanical Garden of Iran during the years 2004-2008. Ten trees were selected for each species and leaf, flower and fruit phenology were recorded from second decade of February to end decade of November. Occurrence time of phenomena was converted to its interval from first day of the year. Statistical analysis of occurrence time of phenomena showed that there are significant differences between the studied species. Soonest and latest occurrence time of phenomena and their sustainability were observed in P. duclis and P. avium, respectively. Based on study of correlation between climate factors (temperature and precipitation) and occurrence time of phenomena, significant correlations were found in some species

    Pollen morphology of Quercus (subgenus Quercus, section Quercus) in Iran and its systematic implication

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    For the first time, pollen morphology of 9 (4 spp. and 5 subspp.) taxa representing lobed leaved oaks of Iran in the family of Fagaceae has been examined and illustrated using light microscopy and scanning electron microscopy of acetolysed material. Detailed pollen morphological characteristics are given for Quercus section. The pollen grains are single, isopolar, radially symmetrical, tricolpate, tricolporoidate or tricolporate. Pollens were studied to show all possible characteristics like shape, size, apertures, wall thickness, etc., with special reference to the specific features of each pollen type such as structural, sculptural and suprasculptural patterns. There is considerable variation in pollen morphology between taxa so that, three types of pollen shape, five types of structural pattern, two types of sculptural pattern, five types of suprasculptural pattern and three types of perfora distribution are defined. Furthermore, the relationship between pollen morphology and taxonomy is discussed. Overall, pollen characters are shown to be a useful and informative tool for assessing taxonomic position within Quercus section in Iran

    Analyzing the individual and social rights condition of climate refugees from the international environmental law perspective

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    In evaluating international treaties, in particular, the United Nations Framework on Climate Change Convention, this paper shows that necessary preparations have not been made to protect the rights of individuals who are refugees or have been forced to migrate from their homeland. Immigrants are deprived of the most essential human rights, such as language, culture, and having a right to a healthy living environment. The current legal administration has not made the necessary contingencies for responding to the environmental consequences of immigration and is extremely inefficient in expanding this phenomenon. This paper seeks to address the question of to what extent existing forms of legal and operational protection can apply in climate change-related displacement in general and cross-border displacement in particular. In this work some strategies have been proposed for dealing with these existing gaps. It is expected that analyzing these gaps and determining the international community’s duties and commitments (governments and international organizations) can result in efficient management of this crisis and prevent the outbreak of chaos across the globe

    Risk zone mapping of forest fire using GIS and AHP in a part of Paveh forests

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    Forest fires, as an ecological risk, whether with human or natural origin, have profound effects on land cover, land use, production, local economies, global trace gas emissions, and health. Identification of factors affecting the existence of forest fire as well as its zonation in the given watershed is one of the basic tools for forest fire control and fighting actions. The aim of this research is to develop the forest fire risk map based on vegetation, physiographic and climatic factors, human, distance to rivers and roads, in a part of Paveh forests. For this purpose, digitally diffusion forest fires map with field checks using GPS were prepared, initially. Then affecting factors were binary compared using Analytical Hierarchy Process (AHP) method by indicating the weight of each factor as indicator for their effects in occurrence of forest fire. Accordingly, the forest fire zonation risk map was prepared using weighted information layers and weighted coefficient of each factor. Five categories of forest fire risk, including very high to very low, were derived, automatically. The mapping result of the study area was found to be in strong agreement with actual fire-affected sites. The results indicate that the 90% of burned areas are located in high risk class

    An Efficient Finite-Element Approach for the Modeling of Planar Double-D Excitation Coils and Flaws in SQUID NDE Systems

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    Incorporating an efficient approach for the finite-element simulation of eddy current superconductive quantum interface device (SQUID) nondestructive evaluation (NDE) systems, an appropriate finite-element method (FEM) has been presented for simulating and analyzing such systems. We have introduced a new model for the planar double-D coils, which are used as the excitation source in eddy current SQUID NDE systems, and also another model for the description of the flaw effect on the induced current. We have also examined our simulation results with their associated measurements. Our system is based on a high-T-C YBCO gradiometer RF-SQUID sensor with a flux noise level below 100 mu Phi(0)/root Hz at 100 Hz in an unshielded environment while being shielded against external RF electromagnetic interference. The very good agreement between experimental and numerical approaches confirmed our model for the 3-D FEM simulation of the system, which is being done in reasonable time and using reasonable computer resources

    Optimization of NDE Characterization Parameters for a RF-SQUID Based System Using FEM Analysis

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    We have investigated the dependence of the optimal Non Destructive Evaluation (NDE) characterization on different excitation parameters in an eddy current SQUID NDE system for samples with known flaw depths. The considered parameters in our study include the configuration of the excitation-coil and its current frequency. The system is based on a High-T-C YBCO gradiometer RF-SQUID sensor with a flux noise level below 100 mu Phi(0)/root Hz 100 Hz in an unshielded environment, while being shielded against external rf EMI (Electromagnetic Interference). According to experimental results and the associated numerical analysis using Finite element (FEM) simulations, we have derived the optimized parameters for the maximum sensitivity of the system. The optimized parameters are found using a new model for excitation coil and eddy current anomalies caused by the flaws. Very good agreement between experimental and numerical approaches confirmed our model and the resultant implemented optimization method
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