جستجوی مقالات مرتبط با کلیدواژه « life form » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

Riparian vegetation along the river is one of the most sustainable aboveground covers that is a good source of food for livestock. Considering the degraded riparian areas, studies on soil seed bank is important and, necessary for restoration goals.

The present study was conducted to investigate the soil seed bank in the riparian region of the Gamasiab river in Nahavand city, Hamadan province. First, using Earth Google maps, 5 sampling sites on both sides of the river were identified. Soil sampling was performed to study the seed bank systematically using transects and quadrates. At each site, a transect perpendicular to the river flow was installed along the transect of at least 6 plots of 4 square meters (three on each side of the river) and soil sampling was performed from two depths of 0-5 and 5-10 cm in each quadrat. The seed bank samples were then transferred to the greenhouse for the experiment. Seed bank was examined by germination method. Plants in terms of annual and perennial, herbaceous and woody, life form (cryptophyte, trophyte, camophyte, hemicryptophyte, phanrophyte) and phytochorology of Iran-Turanian (IT), cosmopolitan (COSM), Siberian Europe (Polyregional or more than two vegetative regions (PL) Mediterranean (M), Turanian-Mediterranean Iran (IT, M), Irano-Tourani -Siberian Europe (IT, ES) Irano-Tourani -Siberian-Mediterranean (IT, ES, M) and Irano-Tourani - Europe, Siberia - Sahara (IT, ES, SS) were studied. Then, each of the above cases was analyzed along distance from the center of the river in three intervals (0-10), (10-20) and (20-30) meters from the river using one-way ANOVA analysis.

A total of 84 species including of 20 family and 65 genera, most of which belong to the family Gramineae (29) species and Compositae (18) species, were observed. Annuals, perennials, herbaceous and woody plants occupied 67.91%, 32.08%, 98.68% and 1.31%, respectively at the first soil depth. In the second depth, annuals created 65.42%, perennials 34.57% and in terms of life form, herbaceous were 100%. Also, trophytes with 63.90% and hemi-cryptophytes with 26% had the highest percentage of soil seed bank. In terms of colorology, COSM (35.83%), IT (24.01%) and PL (11.91%) were the highest. Annuals at the upper soil depth (0-5 cm) had the highest value at a distance of 0-10 m from the river and the lowest value at the distance of 10-20 m. In the second depth (5-10 cm), annual and herbaceous plants have the highest value at a distance of 20-30 m from the river and the lowest value at a distance of 0-10 m. In terms of life form, at the first depth, and in the second depth the therophytes had the highest value at a distance of 20-30 m and the lowest value at a distance of 0-10 m.  Regarding the corology of the first and second soil layers, the poly-regional had the highest value at a distance of (0-10) m and the lowest value at a distance of 20-30 m, and then the elements of Irano-tourani at the first depth and second depth had the highest value at a distance of 20 -30 m and the lowest value at the distance of 0-10 m.

Being higher the number of gramineae species increased the soil seed bank density of annuals and, woody plants were observed only at the first depth of the soil seed bank which could be due to the large seeds of the trees that remain at the first depth and can not penetrate to the deeper depths, where it has deteriorated or decayed or eaten by seed-eaters (transient seeds of trees). Therophytes had the highest amount of life form, which can penetrate with more chances due to the production of very large number and small seed size. The high presence of poly-regional elements in the soil seed bank composition can be due to the abundant presence of pioneer plants and the early stages of the succession, which are present in a wide range of plant lands due to low need and extensive ecological range. These species do not indicate a specific affiliation to a particular climate or plant corology. The highest amount of Polyregional elements in the river riparian was due to the high percentage of Cynodon dactylon species. The results indicated that restoration of degraded riparian could rely on soil seed bank. More precisely, recovery of degraded vegetation through soil seed bank of palatable species such as Aloppecurus myosuroides, Trifolium repens and Bothriochloa ischaemum is feasible.

Primary production and the contribution of each of the life forms of rangeland ecosystems are key features. The purpose of this study was to determine the effect of rainfall and temperature changes on the amount of total production and life forms: grasses, forbs and shrubs in Sabalan,s rangelands. For determining of annual primary production (Full bloom stage), different species using one square meter plots by cutting and weighting method in different elevation was harvested in 6 plant types (totally 216 plots). Rainfall classes and temperature parameters were determined using the data of weather stations and derived relevant gradient. Then, climatic parameters for plots was derived by considering the position of sampling plots. Correlation between the life forms and total production with rainfall and temperature parameters were analyzed using multivariate regression method in SPSS16 software. Results show that, climatic parameters with the life forms production of grasses (P<0.01), forbs (P<0.01) and shrubs (P<0.01) have significant relationship, however there was no significant relationship between total production and selected climatic factors. Moreover, results show that the production of grasses are more affected by climatic factors in comparison with the other two life forms and have significant differences in different classes. Additionally, forbs production is more than shrubs affected by the selected climatic factors. The result of study can be used for the calculate primary production in mountain region, supply-demand balance of forage, biomass, health Ecosystem, Ecological balance and carbon sequestration.

The plant communities locating at the margins of the waterways play a vital role in the ecological processes and ecosystem services in the semi-arid mountainous regions. In this study, variations of plant diversity and composition at different distances from the waterway and its slope aspects were investigated. For this purpose, 15 sub-basins with a variety of area and length of waterway, in both northern and southern directions, were selected in the mountainous rangelands of Anbaran Chai. For measurements 20 plots of 1m2 in each sub-basin were established and vegetations were surveyed. Different distances from the waterway (0-25, 25-50 and 50-75 m) were selected for the measurements in the growing season in 2017. By grouping the species into scientific groups and calculating species diversity, statistical comparison of the parameters was performed by one-way ANOVA and t-test. The results showed that the highest diversity happens at the second distance group (25-50 m).This put emphasis on the hypothesis of occurring maximum diversity in the medium environmental disturbance conditions. In this regard, Shannon-Wiener species diversity index values ​​were 1.38, 1.40 and 1.39 for first to third distances, respectively. Northern slopes are more diverse (1.45) than southern slopes (1.30) due to high humidity. The results suggests that if the goal of range management is to prioritize the area on the basis biological practices emphasis should be put on the first and third distances from the waterway.

The purpose of this study was to investigate the composition and biodiversity of herbaceous cover and regeneration in natural forest (dominated by hornbeam-iron tree), plantations (pure and mixed alder and maple) and degraded forest areas (without tree cover) in the Kelarabad of Chalus. A total of 16 large sample plots (20 × 20 m2) to record the vegetative characteristics of the trees and 144 small sample plots (1 × 1 m2) to record the number of regenerated woody species, type and percentage of herbaceous species. The variety of indices were used to compare biodiversity. The highest percentage of herbaceous species belonged to the Brachypodim pinnatum L., while in the degraded area the percentage of Rubus caesius L. was dominant. Among the understory herbaceous plants, hemicryptophytes and cryptophytes were the most abundant biological form. Also, according to the results, the highest percentage of regeneration species was related to the dominant tree species in each forest stands, and among regeneration species, Phanerophytes were the most abundant biological form. Investigation of biodiversity indices in both herbaceous and regeneration layers indicates the negative effects of forest degradation as well as the positive role of natural forest in the study area. As a general conclusion, the present study demonstrates the protective role of temperate broadleaf mixed forest stands for the richness and diversity of herbaceous plant species and the sustainable regeneration and conservation of understory communities.

Fire is one of the most important influencing factors on the structure and composition of plant communities, especially in arid and semiarid rangelands. This study was designed to investigate the role of fire on vegetation dynamics in semi-steppe rangelands of Central Zagros. A stratified random sampling was used to collect the data from six sites with one and five years after the last fire. At each rangeland site, 20 plots with four square area meters, 10 plots in the burned sites and 10 plots in the control sites, were used. The cover percentage of each species was accurately recorded. A one-way analysis of variance and Tukey's test were used to compare each of the variables. The results showed that the fire significantly reduced the vegetation cover and litter, and increased the bare soil surface in the region. The composition of the fire region was close to the control area after a period of five years. The fire caused a decrease in the percentage of shrubs and an increase in the proportion of perennial grasses, annual grasses, and annual forbs in the region. The fire also changed the vegetation composition of rangelands, so that the proportion of hemicryptophytes, therophytes, and geophytes were decreased while chamaephytes increased. Fire also increased the proportion of high and moderate palatable species (class I and II) and reduced the proportion of class III species. Based on the results of this study, it can be concluded that the fire reduces litter and increases the bare soil; consequently, the soil erosion is exacerbated, hence this should be considered in rangeland management. Overall, uncontrolled fires in the semi-arid regions of the country will not lead to the restoration of vegetation cover.

Floristic studies are fundamental for the applied sciences such as rangeland management and conservation. Rangelands of Sadrabad with an area of 40000 hectares is jocated in South West of Yazd province that it remarkable habitat for the floristic studies. In this study the floristic list of the region is presented and their life forms and endangered species are distingushed Plants were sampled following the common method in the regional taxonomic studies and their families, genera, and species were determined using indispensable references. The life form of plant species was determined using Raunkier’s method. The results showed that 235 plant species belonging to 39 families and 169 genera exist in this area. Hemicryptophytes, Therophytes, Chamaephytes, Geophytes and Phanerophytes included 36.45, 25.65, 23.47 , 7.82 and 6.55% of the total species, respectively. Furthermore, the endangered species of the region were identified on the basis of IUCN criteria and Red Data Book of Iran. Accordingly, 43endangered species were identified, of which 34 were in lower risk (LR) class, , 7 species were in vulnerable (VU) class, and 2 were put in data deficient (DD) class.

The purpose of this study was to investigate the relationship between rangeland aboveground production based on total aboveground production and life forms of grasses, forbs, and shrubs with 25-year temperature and precipitation data, the year before sampling, and the year of sampling in Hir and Neur rangelands in Ardabil province. To determine the aboveground production, the amount of production was estimated using the harvesting method in one square meter plots (totally 330 plots) in three elevation classes under the range of 1446-2750 meters. Temperature and precipitation were calculated for each plot. Aboveground production maps were prepared in a GIS environment using extracted regression equations. The results showed that over the years, precipitation decreased and temperature increased, and aboveground production also decreased in relation to those climatic factors. Moreover, there is a significant relationship (P<0.01) between the aboveground production of life forms and total aboveground production with climatic factors, and aboveground production of grasses and total have a direct relationship with precipitation; however the maximum aboveground production of forbs was recorded in the middle ranges and maximum aboveground production of shrubs was recorded in the higher ranges of annual precipitation. Grasses and total aboveground production had an inverse relationship with temperature, and the maximum aboveground production of forbs and shrubs was recorded in the middle and lower ranges of annual temperatures, respectively. According to the accuracy of derived regression equations, the maps prepared by climatic data of 1394 and 1395 were better than 25-year climate data. The results of this study can be used for the supply-demand balance of aboveground production, biomass accounts, and ecosystem carbon balance indicator that is potentially an important tool for sustainable development.

This study was conducted to analysis the changes in plant group species (PGS) in relation to environmental and management factors in mountain rangelands of Baneh-Kurdestan, Iran. For this purpose 4 plant group species: shrub, forb, grass and shrub-forb (3sites for each PGS) were defined in the study area. There were established 30 plots (2m2) in each site via classified random method. Also in the center of plots we had 10 soil profiles into sampling in each site. All of vegetation, soil and topography and management (grazing intensity) factors were measured in the plots (in total, 90 plots and 30 soil samples for each PGS). Principal component analysis (PCA) showed that first and second axes, in total, explain 73% of changes in the traits of plant group species. Two PGS of forb and shrub-forb are directly related to clay, organic matter, nitrogen, soil depth, potassium, silt 1th, and the first depth and electrical conductivity 2th and northern aspect. Grasses affected by silt 2th, pH, CaO 2th, southern aspect and shrubs are related to sand, gravel (surface and below ground), southern aspect and grazing intensity. On the other word, topography, grazing intensity, nitrogen, organic matter and soil physical factors were the most important factors in the separation of plant group species. The plant group species that had different functional groups (Shrub and forb) had more production and coverage.

The purpose of this study was to determine the effects of altitude, slope, aspect and topographic index on life forms and total net primary production (NPP) in mountains meadows in Fandoghlou in Namin county in Ardabil province. NPP in three altitude, slope, topographic index classes and four aspect classes was estimated using one m2 plots (totally 180 plots) by harvesting and weighting method. Correlation between life forms and total NPP with topographic factors were analyzed using stepwise multivariate regression method and using derived regression equations, the maps of NPP were derived. Results show that different topographic factors has significant effects on forbs (p

Rangeland habitats of the Avrin Mountains, Khoy are representing a wide range of mountainous vegetations in terms of climate, soil, topography and plant cover in Western Iran. In this regard, plant species were sampled periodically during the 2013–2014 period, and identified using the existing floral references. Their life-forms were determined based on the Raunkiaer’s classification and rare and endangered species of the area were recognized based on the criteria of Association for Protection of Genetic Resources. Moreover, their geographical distribution was determined on the basis of classification of vegation regions. Floristic study of the collected vegetation resulted in the identification of 287 species belonging to 52 families and 172 genera of vascular plants. The largest plant family is Asteraceae with 46 species and the largest genus is Astragalus of Fabaceae with 19 species. The diagram of plant life formed by the Raunkiaer method showed that the dominant life forms of the area were hemicryptophytes with 47% and geophytes (Cryptophytes) with 18%, whose high percentage demonstrate the cold climate and mountainous region. Cryptophytes(18%), chamaephytes (16%), therophytes (15%) and phanerophytes (4%) have the less degrees of abundance. The geographical distribution of plants showed that 48% of species belong to the Irano–Turanian zone. The distribution of 7% of the flora in the region is multi-regional, 22.5% are Irano-Turanian and Euro-Siberian, 2.5% are Irano-Turanian and Mediterranean, 0.7 % are Euro-Siberian and Mediterranean, 4.5% are Euro-Siberian, and 1.3% are Mediterranean-related. Among the identified species, 2.5% have cosmopolitan distribution and 11% are endemic to Iran. According to the Protection Association of Genetic Resources, 14 species are classified as rare and endangered plant species.

The purpose of this study was to investigate the relationship between rangeland plants production based on total production and life forms of grasses, forbs, and shrubs with topographic factors (altitude, slope, and aspects) in Sabalan rangelands, Ardabil province. To determine the annual total production, the amount of production was estimated using harvesting method in one square meter plots (totally of 216 plots) under the altitude range of 1200 to 2900 meters a.s.l. Using topographic maps, the digital elevation model was derived and classified maps of elevation, slope, and aspect were derived. Then, in each plot, information such as elevation, slope, and aspect was extracted. The correlation between life forms and topographic factors was analyzed using multivariate regression method. The results showed that there was a significant relationship between the production of life forms such as grasses (P0.05). The production of grasses, forbs and total production had direct relationship with slope; however, the production of shrubs decreased with the increase of slope. The production of grasses increased with altitude, and in the east-faced slopes, it was estimated more than the other aspects. The production of forbs decreased with the increase of altitude and was higher in the east aspect in comparison with the other aspects. The production of shrubs and total production in the middle altitude and in north –faced slopes were more than the other classes and aspects according to the suitable ecological condition and low degradation. Although it is obvious that elevation, slope, and aspect can change and affect the production, this effect is unknown, especially in the connection with life forms and the process of change. Overall, it can be concluded that these results could be used in the management of these rangelands, particularly in the improvement and rehabilitation practices.

Effect of different watering durations on soil seed bank diversity and frequency was investigated. The study was conducted in Vaz rangelands of Mazandaran province. Soil samples were collected øin 40 1 m 2 plots from two different depths (0-5 and 5-10 cm) through randomized-systematic method in December 2010. Watering treatments were carried out in equal volume of water in different time interval including: one day, two days, four days and a week. The data were statistically analyzed by the SPSS software program. The differences between the means was compared using Duncan test (P

Identification of rangeland species is an essential step in range management. This study aimed to study the flora, and investigate on the relationships of species distribution with climatic factors in Iranshahr region rangelands. Taxonomic studies were conducted to provide the plant floristic list. Plants life forms were determined using Raunkiaer categories. Twenty seven climate variables were collected from 12 synoptic stations close to the study area. Principal component analysis was used to identify the most effective climatic variables on the plant species distribution. According to the results, 175 plant species from 136 genera and 44 families were identified in the study area. Gramineae, Compositae, Papilionaceae and Chenopodiaceae contained the most plant species in the flora respectively. Results indicated that 25.72% of the plant species were Therophytes, 25.14% Hemicryptophytes, 24.57% Phanerophytes, 20.57% Chamaephytes and 4% Geophytes. According to the chrological analysis, 28.57% of the studied plant species belonged to Sahara-Sindian region, 24% Irano-Turanian /Sahara-Sindian, 20% Irano-Turanian, and 4% cosmopolitan elements. Results showed that the study area is located in Sahara-Sindian region. PCA results also indicated that the average of maximum relative humidity, number of days with thunderstorm, number of days with precipitation and maximum daily precipitation had significant effects on the plant species distribution.

This study aimed to investigate the similarity between above ground vegetation and soil seed bank in order to evaluate the possible potential of seed bank for recovering eroded communities in Vaz watershed located in northern part of Iran. Soil samples were collected from two depths 0-5 and 5-10 cm in 40 plots established along four 100 m transects (two of which parallel to the slope gradient and two of which perpendicular to the slope gradient) in winter of 2010. Above ground vegetation was also studied and recorded in the next growth season, (2011) in each plot. Sorenson index was used to measure the relationship between soil seed bank and above ground vegetation. Paired t-test was applied to compare the similarities of above ground vegetation with upper- layer and deeper-layer soil seed banks. Relative abundance of each plant species in each plot was calculated and the relative abundances were recalculated into life form and life-span for each plot for both seed bank and above ground vegetation. Paired t-test was also used to compare each life form and each life-span between soil seed bank and above ground vegetation. The results showed that the similarity between soil seed bank and above ground vegetation was generally low and the similarity was lower for deeper soil seed bank (27% vs. 10%). Perennials were higher in the above ground vegetation than soil seed bank. Therophytes were higher in soil seed bank while hemicryptophytes were higher in the above ground vegetation. We also concluded that it was impossible to predict soil seed bank using above ground vegetation and vice versa.

Ground cover is a key indicator of rangeland health. Therefore determination of most suitable method of cover measurement in each climatic zone with enough precision and fast is important. To conduct this study four vegetation types (two grass communities and two grass-shrub communities) in Taleghan region were selected. Then in each vegetation type 6 transects were established. Along each transect 10 one meter square plots were located based on random- systematic sampling. Within each plot canopy cover percentage of each species was measured by ocular estimation and photographic methods simultaneously. Also, canopy cover percentage of each species on images was determined using Arc View software at office. Moreover, the spend time for measuring cover percentage using two methods (ocular and photography) was recorded and compared. Then, the percentage of canopy cover by life forms, obtained from ocular and photography methods were compared using SPSS ver.15 software and paired T-test. In general, the results of this study showed that in grass and grass- shrub communities, there were significant differences between canopy cover of grasses measured by two methods. The canopy cover of grasses was measured by photographic method, was more than canopy cover estimated by ocular method. Also differences between means compared with shrubs and forbs were higher. In shrub- grass vegetation type differences between canopy cover percentage of shrubs and forbs obtained from either ocular or photographic methods were not significantly different (P<0.05). The mean of time consumption for field survey at ocular method in order to estimating canopy cover in each plot was more than photography method. As a result we can conclude that photographic method because of less time consumption in ground survey and consequently less ground activities because of using digital images and interpretation by software in office is more applicable.