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Applied Ecology and Environmental ResearchVol. 11. No. 2. (2013.)

Tartalom

  • Borítóen [33.15 kB - PDF]EPA-02583-00031-0010
  • J. V. Müller :

    Abstract: In semi-arid regions of West Africa, tiger bush vegetation is a striking example of a selforganised, banded vegetation pattern. It consists of regularly arranged woody stripes alternating with areas free of vegetation, whereby the distance between the vegetation stripes increases with decreasing precipitation. In this study, the floristic and structural pattern of tiger bush in Burkina Faso, its current distribution and the relationship between floristic and structural pattern were studied. Five subareas within the study area were chosen for a systematic field survey. Data collection took place along nine continuous belt transects. Occurance of ligneous species was recorded. Diversity indices, the relative frequency and the Importance Values of these species were calculated. For frequent species, quadrate variance and new local variance values (TLQV and NLV) were calculated, and the relationship between habitat factors and the occurrence of dominating woody species was tested. The scales of the underlying pattern varied and re-occurring patch sizes were not detectable. In many areas, tiger bush vegetation had completely disappeared or had been dramatically reduced over the last 50 years probably as a result of increased anthropogenic pressure and grazing. Still existing tiger bush stands are often degraded. 27 ligneous species from 11 plant families were recorded, Pterocarpus lucens, Combretum micranthum, Guiera senegalensis and Boscia senegalensis being most frequent species. Coverage of the woody layer was between 8 and 90%, with mean heights between 5 to 8m and low diversity indices. Soil crusts and the occurrence of woody species were always negatively associated with each other. G. senegalensis showed high coverage in the herb zone where rejuvenation of woody plants occurred. Where present, the ground layer of tiger bush vegetation was highly differentiated. Variance values for P. lucens were always higher than those of C. micranthum and G. senegalensis. With one exception, the size pattern in the different transects was not uniform. The variances of the diversity indices were small. Studying pattern of tiger bush has a potential to monitor further climatic and human impacts in semi-arid ecosystems; this study can be used as baseline documentation for future studies in the same area. Future studies should also look at seedling establishment and biomass distribution and at the plant-to-plant relationship and its role for the pattern organisation.

    Keywords: Sahel, Oudalan, vegetation structure, phytodiversity, quadrate variance analysis

  • B. Klimek :

    Abstract: Root-delivered exudates affect soil microbial communities and may modify effects of environmental factors such as temperature and moisture on soil microbial communities functioning. There were tested the effects of 1-week incubation under different combinations of temperature (5, 15, 30°C) and moisture (15, 50, 100% Water Holding Capacity) on the soil planted with Scots pine (Pinus sylvestris L.) and of unplanted soil. After incubation, microbial activity and metabolic (functional) diversity using Biolog® ECO plates for bacteria and Biolog® SF-N2 plates for fungi were compared. Temperature and moisture affected microbial activity and metabolic diversity of the communities. In suboptimal combinations of temperature and moisture, the cultivable bacteria of planted soil exhibited higher activity and metabolic diversity than those of unplanted soil, and the cultivable fungi of planted soil exhibited higher metabolic diversity than those of unplanted soil.

    Keywords: rhizosphere, Biolog® plates, ECO, SF-N2, metabolic (functional) diversity

  • Abstract: Our study intended to explore the potential distributionshif of Phlebotomusariasi, P. neglectus, P. perfiliewi, P. perniciosus, and P. tobbi, and some other sandfly species: P. papatasi, P. sergenti, and P. similis. We used climate envelope modeling (CEM) method to determine the ecological requirements of the species and to model the potential distribution for three periods (1961-1990, 2011-2040, and 2041- 2070). We found that by the end of the 2060’s the Southern UK, Germany, entire France and also the western part of Poland can be colonized by sandfly species, mostly by P. ariasi and P. pernicosus. P. ariasishowe the greatest potential northward expansion, from 49°N to 59°N. For all of the studied sand fly species the entire Mediterranean Basin, the Balkan Peninsula, the Carpathian Basin, and northern coastline of the Black Sea are potentially suitable. The length of the predicted active period of the vectors will increase with one or two months.

    Keywords: leishmaniasis, climate change, Phlebotomus, potential distribution, climate envelope model

  • S. A. Hashemi ,
    S. A. Mirbagheri ,
    S. A. Sadrnejad :

    Abstract: The increase of phytoplankton and zooplankton in the lakes and reservoirs that supply water to downstream regions is an important environmental issue. In this paper, concentrations of phytoplankton and zooplankton in Chahnimeh reservoir are predicted using an Integrated Seasonal Separate Advection- Diffusion Model (ISSADM). Chahnimeh reservoir is a seminatural deep hole that is stagnant in some part of the reservoir for most of the year. ISSADM is a three-dimensional numerical model based on a finitevolume solution that was developed to predict water quality in lakes and reservoirs affected by seasonal rivers. The model is capable of simulating water-quality parameters, as well as phytoplankton and zooplankton concentrations. To verify the model, field measurements and experiments conducted during a one-year period were compared with model results, demonstrating good agreement. The model is appropriate for predicting phytoplankton and zooplankton concentrations as well as eutrophication processes in similar, seasonal, aquatic environments.

    Keywords: modeling, phytoplankton, zooplankton, reservoir, Chahnimeh

  • B. O. Olugbemi :

    Abstract: Land-use intensification has a direct effect on termite encounters, individuals and species richness in an ecosystem. Species richness decreases with increase in land-use intensity. The functional groups are also affected by the degree of disturbances within the land systems, with a higher percentage of damp-wood termites occurring in the primary forest, while the fungus growers are more predominant in the disturbed environment. However, termite densities are independent of land-use systems. Termite activities and decomposition of tissue paper baits increases with Increase in land-use intensity, and are independent of seasonal changes. Land-use intensification could therefore be an important factor in determining species richness, functional composition and abundance of termites in a disturbed or undisturbed ecosystem.

    Keywords: species richness, land-use systems, termite encounters, party sizes, density

  • G. Rejomon ,
    M. Nair ,
    P. K. Dinesh :
    Biogeochemical significance of eddies of the eastern Arabian Sea237-248en [262.91 kB - PDF]EPA-02583-00031-0070

    Abstract: Within the Arabian Sea, the western part is considered to be highly productive when compared to the northern, central and eastern parts of the basin. Despite the contrasting chlorophyll and primary productivity patterns, sediment trap data show that annual fluxes of organic carbon reach comparable rates in most regions of this highly productive basin. The traditional mechanisms of nutrient supply to the upper ocean waters of the Arabian Sea cannot only account for this. Episodic injections of nutrients associated with cold-core eddies stimulate rapid biological activity and increase biological production in the open ocean waters of the eastern Arabian Sea during the demise of the southwest monsoon. In addition to wind-driven coastal upwelling during the monsoons, annually, an eddy-mediated enhanced biological production, at regional to basin-wide scales is proposed. The enhanced production caused by a high nutrient supply mechanism such as a meso-scale eddy leads directly to organic carbon fluxes to the deep Arabian Sea. The elevated export flux occurred in association with the rapid response of grazers was imported to the deeper layers which leads to a spectacular enhancement of biogenic particle sedimentation.

    Keywords: Arabian Sea, nutrients, eddies, primary productivity, chlorophyll a

  • N. Dyakov ,
    P. Zhelev :

    Abstract: Forty two vegetation samples (0.1 ha nested field plots), taken from lowland riparian forest, located on the right floodplain of Tundzha river (Southeastern Bulgaria), were analyzed. Coarsest picture of vegetation pattern was outlined, using classification and ordination techniques. Detailed analysis of alien and native species distribution was carried out by correlation and regression methods. Described variables were tested for difference with parametric and nonparametric tests. Classification resulted in four plant community types, dominated by different native and exotic trees, shrubs and herbaceous species. Ordination showed that main environmental gradient responsible for the vegetation pattern explanation was habitat moisture. Correlation and regression analyses revealed that most abundant alien and invasive species, such as Acer negundo and Amorpha fruticosa, preferred the most humid part of the moisture gradient, but other alien species had complex response surfaces. Logging is considered as unreliable predictor of alien species distribution at 0.1 ha scale, but as a promoter for xerophylous alien herbs establishment at the 1 m2 scale on the studied territory. Flooding disturbance certainly has played essential role in this context too. Species diversity demonstrated patterns in accordance with Intermediate Disturbance Hypothesis. We recommend using different sampling scales with greater area covered.

    Keywords: riparian forest, environmental gradients, alien species diversity

  • S. K. Chetri ,
    K. K. Singh ,
    A. P. Krishna :

    Abstract: This study has been undertaken to derive resource use impacts on the forest cover vegetation components (species composition, diversity, wood biomass and increment) of Khangchendzonga Biosphere Reserve (KBR). Attempts have been made to seek valuable insight through data analysis along disturbance gradients in different altitudinal zones. Within the KBR landscape, sites corresponding to three levels of disturbances were identified: viz. i) Type III, ii) Type II and iii) Type I based on differing degrees of proximity to habitation. Data analysis revealed disturbance at different levels along all altitudinal gradients to be positively correlated with decrease in values of tree species density, basal area and importance value index (IVI). Generally, number of seedlings and saplings decreased towards proximity of different disturbance levels across all forest sites except in one case. Wood biomass and increment pertinently increased on undisturbed site. It was also observed that diversity is significantly correlated with increase in species richness. Such observations indicate that resource use pressures may lead to substantial impacts on KBR forest cover vegetation. So, in order to curb such future impacts, regular analysis of the ongoing changes and identifying gaps for conservation becomes imperative in this Biosphere Reserve (BR).

    Keywords: protected area, Khangchendzonga Biosphere Reserve, Sikkim Himalaya, forest land cover, diversity, disturbance gradients, altitudinal zones

  • R. M. Navarro-Cerrillo ,
    J. R. Guzmán-Álvarez ,
    I. Clavero-Rumbao ,
    C. Ceaceros :

    Abstract: Changes in forest diversity and the conversion of coniferous plantations into more natural woodlands are of the especial interest in the Mediterranean. The aim of this study was to investigate the changes in land use patterns and vegetation cover from 1956 to 1999 in Pinus halepensis Miller plantations in Montes of Malaga State Park (southern Spain). At a landscape level, a FRAGSTAT analysis was performed using aerial photograph series. At the community level, a total of 47 sample plots were analyzed. Field measurements indicate the presence of a total of 70 species in the different vegetation types sampled. Diversity indices showed a higher species richness for Aleppo pine plantations (H = 1.54 ± 0.2; D = 3.88 ± 0.6), while Holm oak forests (H = 1.37 ± 0.1; D = 3.35 ± 0.6) and agricultural land (H = 1.33 ± 0.01; D = 2.80 ± 0.03) had lower values. FRAGSTATS analyses at landscape and class levels indicated increases in patch richness, number of patches, and percent of landscape mainly for pine plantations, Holm oak forests and shrub. Replacement of agricultural uses by conifer plantations led to a homogenization of landscape structure. This shift has modified the landscape by recovering a natural indigenous tree species, and improving the regeneration of Holm oak species, which are stabilizing and protecting the future establishment of native forests in this area. Our findings suggest that pine plantations could favour woody species diversity by increasing individual abundance and species richness in contrast to the situation in non forested agricultural land.

    Keywords: diversity, fragmentation, landscape metrics, vegetation cover, Mediterranean ecosystem

  • Abstract: Different categories of rhizomes, graded by length and bud number, were studied in small-plot experiments with and without irrigation, and finally the percentage of emerged and growing Miscanthus plants was evaluated. Pre-emergence irrigation under the given weather conditions accelerated shoot emergence and improved the homogeneity and reliability of the process but by June the initially observed salient differences practically disappeared and no statistically significant difference could be identified between plots that had been and those that had not been irrigated. In the case of rhizomes ‘A’ and rhizomes ‘B’ an over 97% and an over 86% crop density was found, respectively. The number of shoots per plant was regularly counted and evaluated during the growing season. Our findings prove that the grading of the rhizomes after their mechanised cutting and lifting, which results in a significant increase in the costs of the production of the propagating material, does not entail a statistically significant advantage in terms of the density of the Miscanthus population, if there is sufficient rainfall during the growing season.

    Keywords: Chinese silver grass, rhizome, biomass, alternative energy