جستجوی مقالات مرتبط با کلیدواژه « climate » در نشریات گروه « منابع طبیعی »

Climate changes are an undeniable fact that are expanding at a faster rate in recent years, due to the increase in greenhouse gas production. Climate factors are the most important environmental parameters that directly affect the distribution of different species of nut trees. Climate parameters, especially air temperature, have wide effects on the growth and production of nut trees such as pistachio, particularly in hot and dry regions. The aim of this article was to review pistachio production in line with climate changes. Global warming and climate changes cause an increase in air temperature and thereby a decrease in chilling requirement of the trees during the rest period. On the other hand, the early start of pistachio phonological stages as flowering increases the probability of frost in some areas, which has become one of the most important agricultural problems in recent years. Studying the relationship between pistachio yield and some independent variables during consecutive years indicated that subsequent production, in addition to the previous yield, depends on some temperature-dependent variables, such as the hours of temperature below 7.2 °C and above 18.3 °C during the rest period and the hours of temperature above 26.7 °C at the beginning of growing season. As climate changes cannot be controlled on a wide scale, appropriate management in line with these natural changes, modification of varieties and implementation of suitable physiological programs would be important to reduce annual damage.

Kelussia odoratissima Mozaff. is an endemic and endangered species of Iran. This research was conducted to investigate its distribution, geographical location, edaphic and climatic conditions, vegetation, phenology, and pests and diseases during the years 2016-2020. The results showed that K. odoratissima grows in the central Zagros Mountains at altitudes of 2000 to 3163 meters, with a cold semi-humid climate (minimum temperature of 2.6°C, maximum temperature of 17°C, and average annual precipitation of 1000 mm). The soil of the habitats was silty clay in terms of texture, rich in essential elements, and had a sufficient amount of organic matter. The release of aerial parts of K. odoratissima begins from mid-March to the beginning of April, and its vegetative growth continues until the end of June. The reproductive phase begins in the first half of July, and its flowers are formed from the middle of July until the end of July; then ripening and seed fall occur in the first half of September and the second half of September, respectively. Indiscriminate and incorrect harvesting, pests such as the seed-eating beetle (Anobiidae), a species of moth (Eupithecia sp.), and the larva of the Aethes francillana have put the plant at risk of extinction. Strengthening the role of local communities, continuous exclosure of the habitat, controlling pests and diseases, reintroduction and maintaining germplasm, and collecting populations in future programs can be very important protection strategies to prevent the extinction of this species.

Oak gall wasps among food chains in the Zagros forest ecosystem are highly dependent on these trees. The gall wasps of the Cynipinae subfamily with 1380 species create the most attractive herbaceous plant galls with a very complex structure in the world. In this study, the distribution and diversity of oak gall wasps species, the samplings of oak gall wasps species based on the sexual and asexual generations were carried out in May and October of the year 2019, respectively. The collected gall wasps from Ghasem-rash, Shalmash, and Kani-rash regions were transferred to the laboratory by paper envelopes. 50 galls of each type were collected separately and placed in breeding containers that were closed with a net and could be properly ventilated. Shannon and Simpson diversity and uniformity indices as well as species richness were also calculated. In this study, 22 species of gall wasps, belonging to the genera Andricus, Chilaspis, Cynips, and Neuroterus (5 species of sexual offspring in spring and 17 species of asexual offspring in summer-autumn) were identified. The number of 18, 14, and 15 oak gall wasps species were collected from Ghasem-rash, Shalmash, and Kani-rash, respectively. Neuroterus numismalis was the most abundant in all regions. The highest species richness of the oak gall wasps species was recorded in Ghasem-rash. The calculated indices of species diversity and uniformity were the same in all regions and did not have significant differences.

 The degradation of resources in many parts of the world is a serious threat to humanity due to its growing trend. Desertification, which is one of the manifestations of this degradation, has affected most countries and has been introduced as the third challenge of the 21st century after the two challenges of climate change and freshwater scarcity. Desertification is the degradation of land in arid, semi-arid, and semi-humid areas. This situation is caused by a series of important processes, the most important of which are the two factors of human activity and climate change. Several methods have been developed to determine the process of desertification, one of which is widely used, the Medalus method. Assessing the status of desertification processes (land degradation) in a village, region or country is important because it provides the opportunity to make informed decisions about the financial dimension and the amount of investment needed to control it. Considering the development of the desertification phenomenon in the Sefiddasht-Borujen region and the need to pay attention to the importance of the results of this destructive phenomenon in the future. The purpose of this study is to evaluate desertification using the Madalus model in the Sefiddasht-Borujen watershed with an area of 92565 hectares, located in Chaharmahal and Bakhtiari province.

 Land use changes were investigated and detected using the distance measurement model. For this purpose, the images of 1998, 2009, and 2018 were used. The amount of changes during this period was determined, and the points where the most changes occurred were selected. Then using these points, in the Medalus model, the factors affecting desertification and its current situation were considered. Then, the effective parameters in desertification were studied in these points separately and the Medalus model was implemented in them. According to the Medalus method, effective factors in the desertification of the region were identified and each factor including climate, vegetation, soil, groundwater, and management and policy was considered as a criterion. Then, the characteristics of the mentioned criteria that were effective in the desertification of this region were considered as indicators. After each indicator received weight in relation to its impact on desertification and by evaluating them, their impact of them on the desertification process was determined. Finally, using the indicators of these criteria, the criteria map and finally, the desertification map were obtained from their geometric mean n order to study the climate criteria, three indices of rainfall, direction, and drought index were considered. The study of the climate was evaluated from 3 sample points in the meteorological and water weight stations of the province, which are harvested as points. To evaluate the soil condition, some physical and chemical properties such as soil texture, acidity, electrical conductivity, and the amount of organic matter were selected. To determine the soil properties, the first 170 sampling points were identified in the study area, and from 0 to 20 cm soil level, sampling was performed and transferred to the laboratory.

The results showed a score of climatic criteria calculated at 1.80 was determined in two classes and had the most role in desertification in the region. The score of management and policy, vegetation, and soil criteria respectively were calculated at 1.76, 1.71, and 1.55 and was determined into two classes severe and very severe. Also, water criteria were calculated at 1.33 and were determined in the middle class. Based on the Medalus model, the current desertification score was estimated to be 1.63. According to this map, the desertification situation of the region was divided into two classes, severe and very severe. Finally, it was calculated that 56% of this area is faced with severe and 44% of it very severe desertification. The result showed that the northern part of the study area is highly vulnerable, while the southern part of the region is less vulnerable to desertification. However, this region has high desertification intensity. The foretold sensitivity of this region to the phenomenon of desertification was consistent. In this model, climate, soil, vegetation, groundwater, management, and policy criteria were selected. According to the results, climate, management, policy, vegetation, soil, and groundwater criteria, respectively, had the greatest impact on desertification of this region due to the low precipitation, drought in recent years, illegal excavation of wells, and uncontrolled extractions more than the capacity of groundwater aquifers in Sefiddasht has caused the drying of most wells in this area. Also, the drying of Dehno Wetland is another reason for the intensity of desertification in the study area.

 According to the obtained results, the phenomenon of desertification in this region is accelerating and would cause a destructive consequence. The study area, according to the proposed definition of desertification, has both natural and human desertification conditions. Natural factors such as unfavorable climatic conditions such as lack of rainfall, successive droughts, limited water resources, on the one hand, and destructive human factors such as traditional agricultural system, overgrazing, overexploitation of groundwater, conversion of pastures to land Agriculture, industries, mines and facilities, destruction of vegetation and shrubs, on the other hand, have led to the destruction of pastures and natural resources and accelerated desertification in the region. Evidence shows that in this region water table is lower than in other areas and as a consequence desertification is accelerated. Among the ways to deal with desertification in the region, it is possible to use the pastures and pastures in principle, according to their capacity at the right time, to permanently enclose the region under biological and mechanical desertification activities, proper exploitation of groundwater and prevents land use change.

Since the desertification is increases, providing the appropriate management strategies will decreased the desertification intensity and its expansions. For this, understanding of desertification process as well as its driving forces seems to be necessary to study in a research project. The main purpose of this study is to assess the desertification by using, IMDPA model in three periods those of 2000-2004, 2005-2009, 2010-2014 on Dehloran plain, Ilam province having 543.52 Km2areas. For this purpose, three affective criteria of climate, water and geomorphology-geology have been used for assessment of desertification. Each criterion was also evaluated by using a number of indices. The results of the desertification process in the first period of 2000-2004 showed that the criteria of climate geomorphology and geology and water, respectively, with weighted average 1.38, 1.30 and 1.19 were the most affective criteria in this period. Differently, in the second period of 2005-2009 the criteria of water, climate and geomorphology and geology, respectively, with weighted average 1.80, 1.50 and 1.30, had the most impact on increasing desertification. In the third period of 2010-2014 the criteria of climate geomorphology and geology and water, respectively, with weighted average 1.88, 1.30 and 1.20, were the most effective criteria in the intensity of desertification. Salinity index was recognized as the most affective indices in desertification process in all periods of time. This index hadthe greatest impact in the second period due to the indiscriminate use of farmers from exploitation wells which resulted in both decreasing groundwater levels and increasing salinity index. Overall, in study area the salinity index had an increasing trend which could be because of low rainfall, decreasing groundwater levels, and the special geology conditions.

Asparagus officinalis L. widely distributed in most climates in Iran. The aim of the present study is to use multivariate analysis to understand the relationships between environmental conditions and phytochemical composition of asparagus. For this purpose, plant samples were collected from nine different habitats in Iran, and phytochemical compounds and antioxidant activities were measured. Their relationship with environmental factors was analyzed using canonical correlation and stepwise regression. Based on the results, first to fourth canonical variables were significant according to Wilks' lambda test (P>0.01). The first canonical variable showed an increase in catalase activity in relation to an increase in mean environment temperature. By decreasing the mean, minimum and maximum temperatures in the second canonical variable, total phenol and DPPH increased and flavonoids decreased. According to the results of stepwise regression, EC, relative humidity and altitude justified the highest changes related to the antioxidant parameters. According to the results of both tests, average temperature, relative humidity and total rainfall have the greatest effect on the antioxidant properties of asparagus. In general, in order to maintain the antioxidant properties of asparagus, cultivation in areas with a total annual rainfall of 500 to 900 mm, an average temperature of 11.5 to 17.5°C and an average relative humidity of 50 to 70% is recommended.

Recognition the climatic potential of the regions for planting the horticultural crops is the first step in agricultural planning. In order to achieve this goal, one of the most important tools is to use agro-climatic classification methods. In this research, the Papadakis classification method was used which has a high level of accuracy due to the presence of 440 climatic subgroups and the emphasis on ecological characteristics. Initially, 10 synoptic weather stations were selected with a common statistical period of 23 years (1994-2016) due to the continuity of statistical data. It should be mentioned that each weather station was represented the climate condition of each city and the stations were classified according to the climatic indices of the Papadakis method. The results of the study showed that three stations namely Abadan, Bostan and Mahshahr port had a hot sub-tropical climate which is highly suitable for planting tropical crops. In addition, Aghajari, Ahvaz, Behbahan and Ramhormoz regions, due to the sub-tropical semi-arid Mediterranean climate, and also in Izeh, Safi Abad and Masjed Soleiman regions because of the sub-tropical semi-arid Mediterranean climate, are suitable for planting various types of cold season temperate fruits, citrus and early and late season vegetables.

Desertification is a phenomenon occurred in arid and semi-arid because of climate changes, human effects and leads to decrease of ecosystem productions and its potential. In this research, the sensitivity of the Jaz-Murian watershed to desertification was evaluated using Environmental sensitive area scheme (ESAs) model. For this goal, the work unit map was extracted from Landsat (8 OLI) imagery (2015) by maximum likelihood classification algorithm. In each unit, the indices related to climate, soil, vegetation and land management criteria were weighted on the basis of ESAs methodology and expert advice and combined by calculating geometric mean of indices. The results showed that the ESAs value obtained from 1.46 to 1.72, it means that the study area is classified in the critical class of desertification, so that 3136 km2 and 12299 km2 of the area has been felt in C2 and C3 classes, respectively. Salty clay lands (ESAI=1.83), Playa (ESAI=1.78) and sandy lands (ESAI=1.72) had the most sensitivity to desertification that needs to consider as the priority of the management strategies in order to introduce de-desertification projects. Moreover, the climate and land management criteria were shown the more effects on desertification process and also must be focused by scientists who would like to improve the local methods of desertification monitoring and needs to be considered to introduce management plans.