جستجوی مقالات مرتبط با کلیدواژه "آشیان اکولوژیک" در نشریات گروه "محیط زیست"

Predicting the effect of climate change on native ecosystems is one of the longstanding goals of ecologists and is essential for their conservation and management. Species distribution models (SDMs) are the most widely used tools to predict the effects of climate change on the geographical range of plants. In this study, two regression techniques (GLM and MARS) and two machine learning techniques (ANN and RF), along with environmental factors were used to predict the distribution of Onobrychis cornuta L. The species response to future climate (2050-2070) was investigated under optimistic (SSP1-2.6), pessimistic (SSP3-7.0) and very pessimistic (SSP5-8.5) emission scenarios of the IPSL-CM6A-LR climatic model from CMIP6 models. Based on results, the ensemble model and then MARS presented the most accurate prediction. ANN had the lowest prediction accuracy with a significant difference from other models (p<0.05). The sensitivity analysis revealed altitude (24.64%), maximum temperature of the warmest month (20.31%), temperature seasonality (16.57%) and diurnal range of mean temperature (16%) as the most effective variables on the distribution. According to the ensemble model, the suitable habitat occupies about 27% of the area, but its distribution will be decrease under the future climate. The SSP5-8.5 scenario will have the greatest impact on the displacement of the species distribution range. The resulting prediction maps provide valuable information for conservation strategies, including identifying suitable places for its reintroduction and cultivation in the framework of rangeland management plans.

Understanding the ecological niche of the different species is essential in many ecological issues.  Ecological niches of species are one of the important factors in the tree species distribution pattern and for all species, it can be detected by examining distribution of species distribution. Ecological nest models often help to understand more ecosystems. These models are applicable in predicting ecosystem stability and sustainability ratios and ecosystems.

In order to determine the selective pressure of different species, the indicators of the equilibrium level of selected nests, the dominant level of selected nests and the crisis level of selected nests were used and 41.5 hectares of Khirud research and educational forest were fully surveyed (100%). Then, characteristics such as diameter equal to the chest of the trees were measured and using selective nesting indices, the selected pressure and nesting levels of beech, oak, hornbeam and alder species were measured.

The values of the selective pressure were measured for the species on the Fagus orientalis 66.419, Quercus persica 3. 313, Carpinus orientalis 261. 28, Alnus 36. 962 and tilia begonifolia 9. 39 respectively. The final results showed that Carpinus orientalis wasat a Dominates niche level, the Fagus orientalis and Alnus was in the balance niche level and the Quercus persica was in intermediate between balance and critical level and also tilia begonifolia was in the critical niche levels.

The Carpinus species were at the dominant level of selective pressure, the Tilla species were at the equilibrium level and the Quercus species were at the equilibrium level of the crisis nest. The results of this study showed that selective strain quantification is an important factor in determining the current status of endangered species.

Persian Gazelle (Gazella subgutturosa subgutturosa) has been distributed in 14 countries. Among these countries, at least in 12 ones the presence of livestock has been mentioned as a factor of Gazelles habitat destruction. Qaraviz no hunting area in Kermanshah province, with the structure of hill and rising ground, is one of the best Persian Gazelle habitats in the west of Iran. The most important obstacle in this regard is entry of livestock of villagers and nomads into its habitat. The aim of this study is to compare the ecological niche of livestock (sheep and goat) and Persian Gazelle in autumn and winter.
In order to model the Gazelle habitat, the presence of point the species and 12 environmental factors of slope, aspect, altitude, vegetation density index (NDVI), type of vegetation, distance from the river, distance from the road, distance from the areas of human activity, distance from the village, distance from the border stations, distance from the presence of livestock, and distance from spring and trough were used. Moreover, to model the habitat of the livestocks in the region, the presence point of livestock and 9 environmental factors of slope, direction, height, vegetation density index (NDVI), type of vegetation, distance from the river, distance from spring and trough and distance from the presence point of Gazelles were used. Modeling was carried out by ecological niche factor analyzing method performed in Biomapper software.
Findings: Gazelles and livestock in both seasons tended to the low-vegetation density and south direction. Gazelles in both seasons tended to the vegetation types of Poa bulbosa-Annual grass, while the livestock in the region in autumn and winter, tended to the vegetation types of Astragalus spp.-Amygdalus scoparia - Salsola rigida and Poa bulbosa-Annual grass, respectively. Pearson correlation coefficient showed that there is a correlation (P-Value Based on the results, marginality of ecological niche of Gazelles narrows from autumn (1.05) to winter (1.48), whereas the ecological niche of the livestocks widens from autumn (0.927) to winter (0.836). The results show that pressure from the entry of livestock of villagers and nomads has been effective on narrowing the Gazelles’ ecological niche.