Iranian Journal of Forests and Rangelands Protection Research
Year:2017 | Volume:15 | Issue:1 (29) |Papers Count:9

Monitoring of the changes in land uses and forest degradation is an important issue in evaluation and management of the natural resources. In order to investigate the forest cover degradation trends and determination of the main environmental factors on forest degradation in Sirvan county of Ilam province, satellite images for the years 1987 and 2014 of MMS (80 m spatial resolution) and OLI (30 m spatial resolution) were used. To survey the spatial relationship of forest cover reduction with the main environmental factors, regression logistic statistics method was used. The results revealed that about 5910. 15 ha of the forest cover has been reduced Sirvan county during 27 years. In addition, the results of modelling demonstrated that altitude, slope and aspect variables (α ≤ 0. 01) were the most affecting factors on forest degradation in the studied area, respectively. While distance to road and distance to villages had no significant effects (α >0. 01) on forest degradation in this area. Assessment of regression model fitted with ROC (0. 9045) and Pseudo-R2 (0. 3275) indices indicated the ability of the model to describe the changes and to identify the areas prone to change.

Due to the raising concerns about chemical and synthetic pesticides hazards on the environment and the human health, there is a trend to using botanical and natural pesticides increased. To this end, Salvia officinalis L., Lavandula angustifolia Mill and Nepeta pogonsperma Jamzad & Assadi as the potential plants for pest control can be used. The present study was conducted to identify chemical composition, fumigant toxicity and repellence activities of the essential oils from these plants against Sitophilus oryzae L. Dried aerial parts of the plant were subjected to hydro-distillation using a modified Clevenger-type apparatus. The composition of the essential oil was analyzed by gas chromatography and mass spectrophotometry (GC/MS). The experiments were conducted using a complete randomized design with 5 replications at laboratory conditions (28± 1 ˚ C, 70± 5 % R. H. and 12: 12 h dark: light). The major components of S. officinalis, L. angustifolia and N. pogonosperma were Thujone (37. 29%) and 1, 8-cineol (41. 3 and 34. 86%), respectively. All the tested plants showed insecticidal activity against S. oryzae. The LC50 values of essential oils for S. officinalis, N. pogonsperma and L. angustifolia, were estimated 148. 19, 150. 49 and 156. 72 μ l/l air against S. oryzae, respectively. The results showed that the essential oil of N. pogonosperma strongly repelled S. oryzae (86. 5%) compared with the essential oils from S. officinalis and L. angustifolia (67 and 61. 5%, respectively).

Since the global warming and climate changes are the major worldwide driving factors affecting forest fire ignition, investigation of the relationship between climatic variables and fire occurrence is very important. The present study was aimed to investigate the effect of climate factors on fire regime of Neka and Behshahr forests. The records of number and area of fire occurrences in Neka and Behshahr forests during five years (2006-2010) were provided from Mazandaran Natural Resources Administration. In addition, the climatic data (average annual temperature, average annual relative humidity and average annual precipitation) of these counties recorded in five recent years from the nearest meteorological stations was provided from Mazandaran Meteorological Administration. Pearson correlation coefficient was used to get the correlation between climatic data and the number and area of the fires. The results showed that in Behshahr forests there were significant relationship between the number of fires and average annual temperature at 99% confidence level and between the number of fires and average annual precipitation at 95% confidence level. Furthermore, there were significant relationship between the area of fire occurrences in Behshahr forests and average annual temperature and average annual precipitation at 95% confidence level; while the results did not show any significant relationship in Neka forests between the number and area of fires and climatic data. Thus, it seems that the occurred fires in this county have often been due to the human factors.

Efforts to identify and address the factors underlying the lack of participation of ranchers in rehabilitation and restoration of rangelands constitute an essential step towards sustainable development. Many areas of natural resources such as rangelands have been affected by mining operations which has consequently various economics, social, ecological and environmental influences on the local residents. Therefore, the present study aimed to assess the effects of mining projects in this regard in Sanandaj. Analysis of the data was performed through multiple regression (stepwise method) by spss20. The results indicated that the lack of participation among the majority of the ranchers (59. 2 %) was at average and above average. On the other hand, there was a significant positive correlation (p<0. 01) between the indices of economic, social, environmental and ecological impacts resulting from mining activities and the lack of participation. Based on the findings, indicators of economic and ecological consequences in total account for 83% of the variance in lack of participation. Hence, in order to increase participation of the ranchers in rehabilitation and restoration of rangelands in Sanandaj, paying particular attention to the abovementioned factors seems to be essential.

Charcoal disease (Biscogniauxia mediterranea) was reported in Golestan province as one of the major diseases affecting oak decline in 2011. Therefore, this study was aimed to evaluate the influence of tree characteristics, stand and site on the infection risk in oak trees in the Qoroq forest park. In this study, 192 oak trees with the average diameter of 50. 9± 16. 5 cm at breast height were recorded, so that the health status of the trees was evaluated in five semiannual courses from October 2013 to October 2015. Log-rank test and Cox regression analysis were used to estimate the mean survival time of the trees and the affecting factors, respectively. The Log-rank test demonstrated the highest (100. 7 months) and lowest (40. 2 months) mean survival time at the vegetative stage in small pole and mature trees, respectively. Oak trees at a distance of less than 10 and more than 200 meters from the road showed the lowest (51. 7 months) and the highest (109. 6 months) mean survival time, respectively. Nevertheless, according to the Cox regression analysis, among the variables examined only the distance from the road and distribution range had significant effects on the survival rate of oak trees. Estimation of the survival rate and the affecting factors in oak trees could be used in prevention methods to manage and decrease the charcoal disease rate particularly in Qoroq forest park. Using the survival analysis methods in epidemiological studies of the forest tree diseases, the experts will have the better and more accurate understanding on the diseases progress.

In this study, identification of clearwing moths and also effect of some environmental factors on the infestation level of babylon weeping trees to this pest species has been investigated in different landscape regions of Tehran city during 2016-2017. To this end, the landscape areas were divided into two regions based on the altitude: 1) between 1000-1400 meters (south Tehran region) and 2) between 1400-1800 meters (north of Tehran). Five parks were considered in each region. To evaluate effect of grassland type on the infestation, percentage of infestation in each park had been separately recorded for planting trees in meadows and trees on the boulevards. Data analysis was performed as a factorial experiment with a randomized complete blocks design consisting two factors (altitude and grassland type). According to the study, Paranthrene diaphana Torre & Strand (Lep.: Sesiidae) was identified as the dominant species which was not reported from Tehran region so far. The results of the statistical analysis showed that altitude had a significant effect on the pest dispersion so that level of infestation in south of Tehran was about 100 percent and almost two times more than the central and northern Tehran. Also, tree plantation in the meadows significantly reduced the pest infestation, up to 50%.

Nowadays, detection of land cover changes and their effects on natural resources and the environment has been feasible through the technology of remote sensing and GIS. The present study aimed to assess the coverage change in Kiasar area over a period of 46 years (from 1966 to 2012) using remote sensing technology and satellite images. To this end, we prepared the land use maps for the years 1966, 1987 and 2012 using topographic maps, image of TM sensor and image of LISS III sensor, respectively. At first, the required pre-processing workflow comprising geometric and atmospheric corrections, and the creation of spectral and aspect ratio indices was performed on the bands of both sensors. After determination of current land uses in the study area, the training samples were recorded using GPS from each land uses and resolution of training samples was obtained using transformed divergence severability index. Classification was performed using maximum likelihood, parallel piped and minimum distance classifiers. The changes were compared after classification. The analysis revealed that over a period of 46-year the forest areas declined from 98. 16 km2 (53. 12% of land area in 1966) to 18. 39 km2 (9. 95% of land area in 2012). In other words, over this period of time 43. 17% of the forest areas were replaced by uncovered land, agricultural lands, dry farm lands and rangelands. These changed areas increased by 14. 15, 13. 61, 10. 05 and 5. 37%, respectively. In conclusion, RS has a high capability in detection of the land cover changes.

The aim of this study was to investigate the relationships between vegetation changes and climate variables including rainfall and drought using MODIS satellite images during the years 2000-2014 in Chaharmahal and Bakhtiari Province. In order to evaluate the impact of rainfall and drought on vegetation changes in 32 synoptic, climatology and rain gauge stations in and around the province, SPI index was calculated in short time series (3, 6, 9 months) and long time series (12, 24 months). All the time scales were leading to early June in which the maximum growth of vegetation of the province is occurred. To this end, SPI drought maps and NDVI images were prepared at different time scales by kriging method and linear regression analysis was performed to define their relationships. Comparisons of NDVI and SPI over the study period showed that the vulnerability of vegetation to drought mostly depends on the life forms and plant species. In this study, depending on the type of vegetation, different correlation coefficients were observed between vegetation and SPI indices. Among different rangeland and forest vegetation types, higher correlations were found between NDVI and SPI in rangeland vegetation types compared to the forest ones and the highest correlations belonged to the annual grass and annual forb vegetation cover. This confirms the higher impact of reducing rainfall on the decline of rangeland cover compared to the forest vegetation. Overall, the findings of this study indicate that the MODIS NDVI can be used to study SPI in the assessment and monitoring of drought effects on vegetation cover. By studying and recognition of vegetation cover and applying NDVI index to assess changes in vegetation cover, vulnerable types of vegetation to drought could be identified.

Mesquite (Prosopis farcta) is a perennial weed that propagates by seeds and rhizomes. P. farcta became widespread in arid zones of Iran. During 2009-2010, the studies indicated that Stator limbatus feeds on seeds of P. farcta and the larvae can destroy up to 60% of the Mesquite seeds. Biological characteristics of S. limbatus were assessed in various temperatures ranging from 25. 39 ± 0. 5 to 21. 17 ± 0. 55 ° C day: night, RH= 37. 78 ± 1. 38% and LD=11: 13 hours. Some infected fruits were collected from Meibod. Infected seeds were retained in the breeding box until the larva transformed into the adult insects. Incubation period lasted an average of 8. 85 ± 0. 59 days. Eggs were laid individually on fruits. Each female insect laid an average of 47. 57 ± 4. 47 eggs on seeds. The roaches in Yazd climatic conditions had more than three generations in each year and overwintering of the insect is in the form of larvae and pupae inside the seeds and remained fruits on the host plant. The insect pupates and transform into the adult stage in late spring and early summer, coinciding with the start of Kahourak fruiting. After mating, adult females begin hatching on pods. Upon completion of the embryonic period, the larva enters to seed directly from egg shell. Only one larva grows in each seed and after feeding from all the internal parts come out and become white pupates in cocoons. In these conditions, the duration of a complete generation from egg to adult was 39 ± 1. 04 days. The values for larva and pupa periods were 21. 2 ± 0. 7 and 8. 8 ± 0. 38 days, respectively. Mean adult longevity without feeding was 26. 36 ± 2. 06 days and over this period an average value of females lying was 47. 57 ± 4. 47 eggs. Data showed that in average 83. 52± 5. 071% of the eggs were hatched. Therefore, this insect can be a suitable agent for biological control of this weed in Yazd province. In nature the pest larvae are attacked by big black wasps from Braconidae family.