مجله بوم شناسی کاربردی
پیاپی 15 (بهار 1395)

Measuring the diversity of plant functional types, identifying their characteristics, and their classification will help to identification of woodland germination capacity and implementing appropriate range management programs. The study was designed to measure the species diversity and to identify plant functional types in three adjacent ecological sites in Shimbar or Shirin Bahar region. During winter, spring and summer since 2013 to 2014, the data regarding the percentage of species coverage were taken from 106 plots using stratified random sampling method in the south facing slopes, north facing slopes and the wetland. Species diversity (Alpha diversity) and habitat diversity (Beta diversity) were measured using PAST and SDR softwares. According to the Shannon-Wiener and Simpson indices the greatest species diversity were found in the wetland, south slopes and north slopes respectively. Species richness was higher in northern slope than northern slopes and the lowest in wetland. For classifying and determining response of vegetation to environmental factors and identifying plant functional types, about 66 resistance to disturbance characters were measured and subjected to clustering by Ward method in R software. The annual and perennial species were classified into 21 and trees and shrubs to 8 classes.

Positive and negative (facilitative and competitive) interactions of plants are important issues in autecology and can be evaluated by the spatial pattern analysis in plant ecosystems. This study investigates the intraspecific interactions of Indian rosewood (Dalbergia sissoo Roxb.) trees in Indian rosewood Reserve of Khuzestan province. Three 150 m × 200 m plots were selected and the spatial locations of all Indian rosewoods (239 trees) were specified. Structurally different summary statistics (nearest neighbour distribution function D(r), K2-index K2(r), pair correlation function g(r), and O-ring O(r)) were also implemented to analyze the spatial pattern of the trees. The distribution of Indian rosewood trees significantly followed inhomogeneous Poisson process (α=0.05). The results of D(r) and K2(r) showed that the maximum distance to nearest tree was 12 m and density was decreased to this scale. The results of g(r) and O(r) also revealed the significant aggregation of Indian rosewood trees at scales of 1.5 to 4 m (α=0.05). In general, it was concluded that Indian rosewood trees had positive intraspecific interactions in Indian rosewood Reserve of Khuzestan province and their aggregation showed their facilitative effects on one another.

Detection of effective germination factors on valuable rangeland species is essential in rangelands rehabilitation and restoration projects. This study evaluates the effects of physiological drought stress induced by Poly Ethylene Glycol 6000 (PEG) and alternative temperature on germination percentage and germination speed of Hedysarum criniferum Boiss, a valuable native legume in summer highland pastures of Iran. The experiment was conducted as a completely randomized design using factor analysis, including two factors; two alternative temperature levels (18-20 °C and 24-26 °C day-night) and four drought levels (0, -2, -4, and -6 bar) with three replications. According to the results, different levels of drought stress and alternative temperature had significant effects on germination percentage and germination speed of the species seeds (α=5%). The study showed that increasing temperature and drought levels leads to reducing the germination percentage and germination speed of the species. Higher germination percentage of H. criniferum seeds in different drought levels compared to alternative temperature levels of 24-26 °C indicated that this species is more sensitive to higher temperature than high levels of drought condition. Therefore, it could partly be concluded that the H. criniferum is a relatively drought resistance species.

This study employs the maximum entropy modelling technique to investigate the geographic distribution pattern of wild sheep (Ovis Orientalis) on Tangeh Sayyad Proteced Area. A set of eight environmental predictors is employed together with presence-only records of wild sheep. Two methods has been used to improve the performance of modeling: density-based occurrence thinning and performance-based predictor selection. Using the four different thresholds (Fixed cumulative value 10, 10 Percentile training presence, Minimum training presence, Equal training sensitivity and specificity), potential distribution of species was estimated. Results were evaluated using the threshold-dependent Statistics (Sensivity, Specifity, Kappa, TSS), a binomial test, Wilcoxon signed-rank test, and Area Under Curve (AUC). Relative variable importance was assessed using Maxent’s built-in Jacknife functionality. The results showed that the distributions fitted the provided occurrence data very well (at least AUCs = 0.77 for predictors with randomly selected spots and at most AUC=0.82 for random predictors with random sampling) and threshold-dependent Statistics results showed that prediction success for wild sheep were acceptable. Slope and distance to village were found to be the most important predictors. Generally, results showed that the model performance markedly improved by appropriate predictor selection and occurrence thinning.

In order to investigate the effects of range management plans on species diversity, richness and evenness in Semirum rangelands, 52 sites (28 with treated plan and 24 without treated plan) were selected. The non-parametric indices for species richness (Margalof, Menhinick, Jacknife and counting method) and species diversity (Simpson, Camargo, Smith and Wilson and modified Nee) were compared in two management plans. The mean comparisons were made by independent T Student Test and Mann-Witheny U Test, and correlation was determined between diversity indices and vegetation parameters. Based on the results there was no significant difference between the two management systems regarding environmental features, while the implementation of range management plans caused significant reduction of stocking rate. Among the studied indices, evenness of species in sites without treated plan was significantly more than the sites with treated plan. The correlation matrix showed that there was a significant positive correlation between species richness and vegetation cover, production of perennial plans, and the rangeland condition and trend, while evenness showed significant negative correlation with these indices. Generally, implementation of range management plans has considerable effect on increasing climax species, dominance of Bromus tomentellus and it causes improvement of rangeland condition and reduction of evenness. This behavior could be explained by the balance between species competition and grazing pressure. Further, succession process of the studied communities demonstrates domination of some desirable species, high production and less diversity.

This study evaluates the impacts of clay and gypsum mining on ecosystem structure and function using Landscape Function Analysis (LFA) in Segzi plain, Isfahan. The length and width of patches and inter-patches length were recorded along the 18 established 50-meters transects in mining and reference sites. Eleven soil surface indicators were evaluated using LFA method in these patches and inter-patches spaces. Thirty six soil samples were randomly collected from 0 to 15 and 15 to 30 centimetres of soil surface, and the amount of pH, CaCO3, CaSO4, electrical conductivity, organic matters and the percentage of clay, silt or sand of the samples were measured. According to the results, structural and functional characteristics of the reference sites, including infiltration, stability, and soil nutrient cycling are better than mining sites. In clay mine sites, except indicators of slake test; litter and surface roughness indices were not different statistically (α = 5%). In Gypsum mine sites, all indicators in mining sites were statistically different (α = 5%) from reference sites, but their indicators of cryptogam cover, nature and roughness of the soil surface and deposit material. The extent of degradation in soil and vegetation characteristics of mined sites indicates that there is a strong desertification trend in the study area.

In present study, besides investigating benthic communities and their demographics in Choghakhor wetland, the water quality has been evaluated and classified. Then, 10 stations were selected and sampling of benthos was done every 45 days since April 2010 to March 2011, with 3 replications at each station. Samples were obtained by Ekman grab Sampler (surface 400 cm2). The collected samples were separated and fixed by formalin (4%). The Macroinvertebrates samples were identified and counted in laboratory. Generally 25 families of benthic macroinvertebrates belonging to 5 classes and 12 orders were identified. The results were calculated as community measures, including total richness, Shannon - Wiener diversity index and Hilsenhoff Biological index at family level. The results obtained from temporal and spatial changes of data (Statgeraphics software) and water qualitative classification using Shannon diversity index conformed to biological Hilsenhoff index. And finally, water quality of wetland was assessed to be polluted in average to high level. According to this study findings, it seems that, these indicators could be used as useful tools for evaluating water supplies quality.