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.
Reza Omidipour; Ataollah Ebrahimi; Pejman Tahmasebi; Marzban Faramarzi
Abstract
Vegetation canopy cover (VCC) and Above-Ground Phytomass (AGP) are the most important indicators of rangeland ecosystem’s structure and function, therefore their accurate evaluation and monitoring is vital for ecosystem welfare. Vegetation indices, are essential tools for assessing and monitoring ...
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Vegetation canopy cover (VCC) and Above-Ground Phytomass (AGP) are the most important indicators of rangeland ecosystem’s structure and function, therefore their accurate evaluation and monitoring is vital for ecosystem welfare. Vegetation indices, are essential tools for assessing and monitoring VCC and AGP which have not been addressed under different managerial conditions, so far. In the present study, the effect of long-term grazing and enclosure (26-year) on the relationship between the VCC and AGP with vegetation indices were evaluated in the Sabzkouh protected area of ChaharmahalVaBkhtiari province using Landsat-8 images. VCC and AGP were evaluated in both grazed and enclosed area by 10 plots of 30*30-m in each of which three quadrates of 2×2 square meters were applied (totally 60 quadrates) in the June, 2016. The results indicate significant differences between grazed and enclosed areas in terms of VCC (57% and 46 respectively) and AGP (with 1656 and 1011 kg per hectare, respectively). The soil adjusted vegetation indices show a more significant prediction of VCC in enclosed and grazed areas (TSAVI1=0.828 and PVI3=0.884, respectively). The PVI2 index showed appropriate results for estimating AGP in both enclosed (R2=0.726) and grazed (R2=0.698) areas. The improved performance of these indies is mainly due to the adjustment of soil effects. Our results suggest that grazing caused a significant effect on the relationship between VCC and AGP with vegetation indices due to feasible changes in vegetation structure or composition. Therefore, using different indices is necessary to study and monitor different rangelands under management strategies.
