Vegetation composition differentiation and species-environment relationships in the northern part of Isfahan Province, Iran

Abstract

A considerable proportion of Iran's territory is covered with arid and semi-arid rangelands and mismanagement and overexploitation of those rangelands have resulted in serious ecological degradation. Thus, the need is pressing to examine the present species composition and the relationships with environmental factors for providing the needed scientific references to species conservation and ecological rehabilitation efforts. The aims of this study were to examine the species composition and to delineate the most important factors influencing the distributions of plant species and groups in the northern rangelands of Isfahan Province (Iran) using two-way indicator species analysis (TWINSPAN), detrended correspondence analysis (DCA), principal component analysis (PCA), and canonical correspondence analysis (CCA). Field investigations were conducted in the growing season of 2014 using stratified random method in 22 homogeneous sampling units. In total, 75 plant species belonging to 52 genera and 19 families were identified. The most important families were Asteraceae and Papilionaceae, the most important genera were Astragalus, Cousinia, and Acanthophyllum, and the most important species were Artemisia aucheri and Artemisia sieberi. Plant species were classified into 10 groups using TWINSPAN. DCA was used to estimate the magnitude of changes in species composition along the first two ordination axes to provide gradient length estimations for PCA and CCA ordinations. The first three PCA axes and the first three CCA axes demonstrated similar cumulative percentage of variance, indicating that the environmental factors (selected by PCA) used in CCA ordination were acceptable for explaining the species composition and the distributions. CCA ordination showed that the first axis was closely related to elevation, slope, surface bare soil cover, surface litter cover, gravel proportion, organic matter, total nitrogen, CaCO 3 content, and grazing intensity and that the second axis was closely related to sand proportion, silt proportion, clay proportion, and saturation percentage. Among these factors, elevation was the most effective factor to separate the plant groups and grazing was the major cause of rangeland degradation.

Floristic and Phytoclimatic Study of a Sacred Grove Vegetation of West Midnapore District, West Bengal, India

“…Same type dominant families of sacred groves in India were observed by Rajendraprasad et al [32]; Jamir et al [33]; Ghildiyal et al [34]; Sen [17] etc. In the global context, such family dominance was shown by Batalha and Martins [35]; Badshah et al [36]; Chigani et al [37] etc.…”

Understory Vegetation Composition and Stand Are Mainly Limited by Soil Moisture in Black Locust Plantations of Loess Plateau

“…The study area is a warm forest steppe where natural forests have been destroyed because of water The fieldwork was conducted from July to August in 2015 and 2016. A total of 33 sites (Figure 1, some large area sites have planted different age's plantations, each stand age plantation has 3 sample) at different stages of development (10,12,13,15,17,18,20,25,30,35,40,45, and 50 years) of R. pseudoacacia artificial forests were randomly selected. Three 20 × 20 m plots were established at each site.…”

“…Hence, the relationship between the availability of light and the composition of species in forests has been elucidated. Soil fertility and geographical factors, however, can also influence species composition [34][35][36]. Species diversity and the development of vertical stratification both increase with the latitudinal thermal gradient [37,38].…”

Identification of the important environmental factors influencing natural vegetation succession following cropland abandonment on the Loess Plateau, China

“…Appropriate multivariate analysis methods, including two-way indicator species analysis (TWINSPAN) (Jafari et al, 2004;Zhang, 2005;Jiao et al, 2007;Jiao et al, 2008;Naqinezhad, Hamzeh'ee & Attar, 2008;Jia et al, 2011;Kargar-Chigani et al, 2017), principal component analysis (PCA) (Naqinezhad, Hamzeh'ee & Attar, 2008;Ruskule, Nikodemus & Kasparinskis, 2016;Kargar-Chigani et al, 2017), detrended correspondence analysis (DCA) (Zhang, 2005;Jiao et al, 2008;Jia et al, 2011;Ruskule, Nikodemus & Kasparinskis, 2016;Kargar-Chigani et al, 2017), canonical correspondence analysis (CCA) (Naqinezhad, Hamzeh'ee & Attar, 2008;Kargar-Chigani et al, 2017) and classification tree model (Jiao et al, 2008;Jia et al, 2011;Wang et al, 2018) can play important roles in identifying the vegetation succession types and their important influencing factors based on quantification of the relationship between the vegetation and environmental factors. On the Loess Plateau of China, several workers investigated the vegetation-environmental relationship by using TWINSPAN, DCA and/or classification tree model (Zhang, 2005;Jiao et al, 2007;Jiao et al, 2008;Jia et al, 2011).…”