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1

Shrub effects on herbaceous vegetation vary with growth stages and herb relative location

100%
He Y., Liu X., Xie Z.
Polish Journal of Ecology
|
2014
|
tom 62
|
nr 3
In arid and semi-arid ecosystems, shrubs have an important effect on neighboring plants. However, little is known about the interaction of herb growth stages and shrub location on herb performance. We selected Reaumuria soongorica, (Pall.) Maxim a shrub dominant in the semiarid region of northwest China, to determine whether (1) shrubs facilitate or have negative effects on neighbouring herbaceous vegetation, and (2) such effects vary with herb growth stage and with shrub orientation relative to herbs. The presence of herbaceous plant species, plant density, plant height, and percent cover were determined along 2 m long transects spreading in four directions from the base of shrub – east (transect E), west (transect W), south (transect S), and north (transect N); this was repeated for three growth stages (in May, June and July). Results indicated that the effects of R. soongorica on neighboring herbs in different growth stages were similar. Species number of herb-layer plants tended to increase from beneath the canopy to the opening, but plant density, cover and plant height decreased with distance away from shrub base. The presence of R. soongorica had positive effects on density, cover, and plant height, and negative on the number of herbaceous species during the entire growing season. Herbaceous plants growing on transect N under the shrub canopy had significantly higher density and percent cover than those growing in other directions. Biomass of herbs on transect N grown under the shrub canopy was higher than that of herbs on other transects. We concluded that shrub effects on neighbouring herbaceous vegetation were closely related to the shrub orientation relative to the herbs. Therefore, using shrubs as nurse plants for grass-growing must consider the relative placement of shrubs.
2

Key factors in the site selection of Rosa canina (L.) – applying the generalized additive model

100%
Guner S. T., Ozkan K., Comez A.
Polish Journal of Ecology
|
2011
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tom 59
|
nr 3
Determining suitable sites for species is of great importance in the choice of plant species to be used for ecosystem restoration. The number of plant species to be used in restoration of degraded ecosystems is restricted by climate in arid and semi arid regions. Planting with economically important species in addition to ecological aspects is preferred by decision makers in Mediterrenian countries including Turkey. This study was addressed to determine the significant environmental factors influencing the distribution of dog rose hip (Rosa canina) and to obtain its distribution model. The study was carried out in an area of 26,400 km2 in The Inner Anatolia which has semiarid climate. 106 sample plots, 20 x 20 m in size, were selected from different sites with and without Rosa canina in the summer of 2007. Wilcoxon rank-sum statistic for continuous variables and Pearson Chi-square tests for categorical variables were applied. Altitude, slope degree, available water capacity, soil reaction and soil K, Ca, Mg content as well and total calcium carbonate amount as the continuous variables and northwest- northeast group of aspect, metamorphic group of bedrock as the categorical variables were determined as the significant factors influencing the presence of dog rose. Generalized Additive Model (GAM) was performed for modeling the distribution of the species. To obtain the best model, all significant environmental factors were evaluated. The best model result was obtained (training Area Under Curve (AUC) = 0.902 and cross-validation AUC = 0.841) by means of altitude, slope degree, aspect, and bedrock. Interspecific correlation analysis (ICA) was applied to define indicator species accompanying the dog rose. Dog rose distribution was positively correlated with Cistus laurifolius, Pyrus elaeagnifolia, Lonicera caucasica subsp. orientalis, Quercus vulcanica and Amelanchier rotundifolia subsp. Rotundifolia. The results obtained from this study are crucial for estimation of the suitable areas for Dog rose in restoration studies of natural ecosystems in the Mediterranean region, including Anatolia in Turkey.
3
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Sediment yield estimation using a semi-quantitative model and GIS-remote sensing data

100%
Mahmoodabadi M.
International Agrophysics
|
2011
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tom 25
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nr 3
4

Determining the relation between soil properties and spatial variability of Nitraria schoberi Linn. using geostatistical analysis: a case study in Meighan Playa in Iran

100%
Tilaki G. A. D., Kamarei R., Vafakhah M.
Polish Journal of Ecology
|
2013
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tom 61
|
nr 1
This study is an assessment of the relation of the spatial variability of Nitraria schoberi Linn. to the soil properties conducted by using geo-statistical analysis. In an area of 140 ha a regular network from a semi-arid region of Meighan Playa in central Iran was selected. The results showed that statistically most of the variables fit spherical, exponential and Gaussian models. The lowest and the highest coefficients of variation were found with the soil pH (27%) and the density (66%) of Nitraria schoberi, respectively. The semi-variogram analysis showed that the effective range fluctuated from 150 m for silt to 2563.43 m for the acidity of the soil. The electronic conductivity and soil texture showed more spatial dependency than the organic matter.
5

The effect of the halophytic shrub Lycium ruthenicum (Mutt) on selected soil properties of a desert ecosystem in Central Iran

100%
Jalali G. A., Akbarian H., Rhoades C., Yousefzadeh H.
Polish Journal of Ecology
|
2012
|
tom 60
|
nr 4
We compared soil properties beneath naturally-occurring patches of Lycium ruthenicum Murray (fam. Solanaceae) to evaluate the shrub’s potential to improve the fertility of saline soils. Soil pH, total nitrogen and carbon and extractable potassium, magnesium and phosphorus were respectively significantly higher in the A and B horizons of Lycium shrub patches compared to adjacent unvegetated soils. The influence of Lycium on these soil properties increased with shrub density. Total soil N and extractable Mg and K concentrations were 1.8, 2.6- and 6.6-fold higher under dense Lycium shrub patches compared to unvegetated, bare areas and soil pH was 0.5 units higher. In contrast, the presence of shrubs and shrub density had no clear affect on the EC, Na or CEC of the A horizon soils. The shrub effect extended to the gypsum-rich By horizon (20–50 cm depth) and underlying B horizon (30–80 cm depth) for several soil properties. Total soil C and N were 1.8- and 1.6-fold higher beneath dense Lycium patches than bare soil areas. Soil pH remained 0.4 units higher under dense Lycium than bare soil patches. In the B horizon total soil C was twice as high beneath dense Lycium patches compared to the other patch types. Lycium ruthenicum not only tolerates the saline and drought conditions, it also produces sufficient biomass to increase the nutrient and organic matter content of surface mineral soils in this arid ecosystem and may have potential to improve soil conditions, facilitate ecosystem development and slow desertification.
6

Distribution of heavy metals in irrigated vertisol profiles in semiarid region of Turkey

100%
Aydinalp C., Cresser M. S.
Polish Journal of Environmental Studies
|
2009
|
tom 18
|
nr 4
539-545
Vertisols with swell-shrink properties comprise most of the arable land in northwestern Turkey. These soils are important for agricultural activities. Seven sites were selected to represent Vertisols irrigated with polluted water from the Ayvali Canal. The soils occur on flat to gently sloping plains of the region. The soils were formed on marl parent material under thermic temperature and xeric moisture regimes in the western Bursa plain, Turkey. Some agricultural lands in the plain were irrigated with heavily polluted water from the Ayvali Canal. This is a unique surface water source for irrigation in the studied area. The morphology, physico-chemical properties and DTPA-extractable Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn were determined in this research. The heavy metal concentrations were found in high levels in the upper horizon and decreased gradually throughout all the profiles studied. The results showed that accumulation of heavy metals in the upper horizon is due to long periods of irrigation with polluted surface water. Soil characterization was determined to provide useful information to understand the behavior of the heavy metal distribution throughout the soil profiles in the semiarid region with under intensive irrigation with polluted water.
7

Spatial patterns and coexistence of the native forb, Psathyrostachys fragilis (Asteracea) and the native invader, Gundelia tournefortii (Poaceae) in a semi-arid rangeland of Iran

80%
Khojasted F., Chahouki M. A. Z.
Polish Journal of Ecology
|
2013
|
tom 61
|
nr 2
In this study, we investigated the interactions between the dominant native invader, Gundelia tournefortii, and the dominant forage species, Psathyrostachys fragilis in rangelands of Taleghan (Iran). Four transects of 150 meters were considered as sampling unit. Using randomly-systematic method, 15 plots (1 × 1m) were placed along each transect with a distance of 10 m. List of species, the canopy cover and the numbers of plant species were determined in each plot. The spatial association of the two dominant species was assessed by studying association, covariation, and distribution pattern (using the Hopkins’ index) of plants. We found a clumped distribution pattern in both two dominant species. Results of this study revealed a strong competitive interaction between the dominant plant species in studied area with P. fragilis was more frequent and had more canopy cover than the native invader G. tournefortii. So, according to our findings, P. fragilis may present a suitable candidate for artificial re-vegetating and protecting against invaders to restore the biodiversity and ecological health of endangered rangelands.
8

Delayed density-dependent and rainfall effects on reproductive parameters of an irruptive rodent in semiarid Chile

80%
Lima M., Jaksic F. M.
Acta Theriologica
|
1998
|
tom 43
|
nr 3
We examined the influence of density-dependent and density-independent factors on reproductive processes of leaf-eared mouse Phyllotis darwini (Waterhouse, 1837) in a semiarid region of Chile subjected to El Nino-driven precipitation. This species undergoes periodic irruptions apparently triggered by unusually high precipitation. The effects of density and precipitation were analyzed statistically regarding the following reproductive parameters: fraction of reproductive females, reproductive number (juveniles + reproductive females), per capita reproductive rates, and repro­duction index based on long-term data (10 years). The fraction of reproductive females was affected positively by precipitation during the preceding winter and negatively by population density one year before. The reproduction index and the reproductive rate was positively affected by population density the previous year. In addition, the reproductive number was positively correlated with precipitation levels. The P. darwini population studied was affected by delayed density-dependent and density-independent factors in reproductive parameters. We propose that both destabilizing effects on reproductive rates of P. darwini may be major factors underlying the frequent out­breaks of this mouse observed in semiarid regions of Chile.
9

Effects of salt stress on proline content, expression of delta-1-pyrroline-5-carboxylate synthetase, and activities of catalase and ascorbate peroxidase in transgenic tobacco plants

71%
Razavizadeh R., Ehsanpour A.
Biological Letters
|
2009
|
tom 46
|
nr 2
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