Samaneh Sadat Mahzooni Kachapi; Pejman Tahmasebi; Ataollah Ebrahimi; Mohammad hasan Jouri; Mohsen Faal; Reza Omidipour
Abstract
Ecological processes at different scales led to heterogeneity in the landscape by changing the pattern of the landscape structure. These would result in fragmentation and disintegration of landscape structures and filtering biodiversity characteristics such as species functional diversity. We performed ...
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Ecological processes at different scales led to heterogeneity in the landscape by changing the pattern of the landscape structure. These would result in fragmentation and disintegration of landscape structures and filtering biodiversity characteristics such as species functional diversity. We performed this study to quantify the patches and classes characteristics of the landscape (metrics) and their impact on indicators of species and functional diversity. Sampling was performed in a semi-steppe rangelands of Chaharmahal and Bakhtiari, where the natural structure of the landscape creates various patches such that classified in seven different classes of plant communities. In each class, different patches were randomly selected and within them 5 to 10 macroplots of 30 * 30 m were randomly-systematically established. Afterwards, 3 plots of 2 * 2 m2 installed in macroplots in order to sample canopy cover and number of species. Taxonomic, functional diversity and functional beta diversity indices were measured using "Vegan", "FD" and "betapart" statistical packages in R software, respectively. The landscape metrics were also measured using Fragstats software. Finally, the relationships between diversity indices and landscape metrics were analyzed using linear regression. The results at the patch level showed a significant negative relationship between the shape and functional diversity indices such as leaf nitrogen weight average and leaf specific surface area weight average. The results at the class level indicate the positive effect of the functional evenness index on the edge density metric as well as the functional beta diversity of the patch richness metric.
mahdie mahmoodi; Ataollah Ebrahimi; Mohammad Hasan Jouri; pejman tahmasebi
Abstract
The evaluation of utilization of key species is cornerstone of decision-making in rangeland management. Measuring utilization is essential for regulating grazing intensity, grazing pressure and distribution of animals. utilization of two key grass species of Dactylis glomerata and Bromus tomentosus, ...
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The evaluation of utilization of key species is cornerstone of decision-making in rangeland management. Measuring utilization is essential for regulating grazing intensity, grazing pressure and distribution of animals. utilization of two key grass species of Dactylis glomerata and Bromus tomentosus, as two important rangeland species is determined using height-weight relationship. The research is done in two vegetative periods of prior to flowering and flowering stages in two region of grazing land and exclosure by 32 transects of 100-meter length. To do so, the height of species was measured and cut at 1-cm above soil surface and weighted freshly. The samples are clumped and moved to the laboratory and oven dried at 65°c after separating litter divisions Then, the whole individual plants were weighted and cut in 5-cm intervals and each part was re-weighted and recorded separately for each species. Height-weight relationships were analyzed by different regression models in SPSS v.18 software. Result shows that sigmoid model significantly illustrate the height-weight relationship of both species of Dactylis glomerata and Bromus tomentosus with R2=0.994 and 0.997 at prior to flowering stage in the exclouser respectively. Similarly, sigmoid model also elucidate the height-weight relationship of both species of Dactylis glomerata and Bromus tomentosus with R2=0.975 and 0.998 at the flowering stage in the exclouser, respectively. The sigmoid model also best fitted for depicting height-weight relationship of both species at prior to flowering stage in grazing land for both species with R2=0.996, too.
Mohammad Mahdi Hoseinzadeh; Reza Esmaili; Mohammad Hasan Jouri; Samaneh Pourkalhor
Abstract
Gully erosion is one of the most destructive types of hydraulic erosion and an important process insoil destruction that in some cases creates long, vast, deep canals. Study area was located in thenortheastern Alborz, Mazandaran province and Nowshar County (Firozkola subbasin a portion ofKojur watershed). ...
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Gully erosion is one of the most destructive types of hydraulic erosion and an important process insoil destruction that in some cases creates long, vast, deep canals. Study area was located in thenortheastern Alborz, Mazandaran province and Nowshar County (Firozkola subbasin a portion ofKojur watershed). This paper examines gully morphometery in relation with physical and chemicalcharacteristics of soil. The morphometery of gullies such as width, depth and slope were determinedin field. Physical and chemical properties of soil such as exchange cation (EC), organic andinorganic carbon, soil acidity and soil texture were determined in the laboratory. Data analyses wereperformed by Detrended correspondence analysis (DCA). The DCA analysis indicated that thewidth and slope are correlated with OC and clay negatively but they have positive correlation withpH. Hence, it's expected that following reduction of OC and clay and an increase in PH, gully widthboosts. Besides, if EC increases and CaCO3 decreases, depth and w/d ratio of gully will increase.
